The 5-lug MGA post got me to thinking. I've seen at least one guy - Jim Nichols - who has changed his MGB front hubs out for 5-lug versions. 64-66 Mustang hubs I believe. Any one know of any other possible interchanges? Early Pinto or Granada hubs for example. They're plentiful, inexpensive and there are a number of lightweight/performance substitutes available (they're used in several classes of racing). Might be a nice addition to the knowledge base if we can get a list together. And, yes, I'm familiar with the Fast Cars and Classic Conversion offerings. Just interested in something less expensive that might be done with off-the-shelf- components.
Both early Mustang and Camaro/Monte Carlo hubs have been done, with machining required in both cases since the bearing races are set further apart and need to be moved in to fit the MGB spindle. It's a fairly simple operation but does require precision in the set up and machining. However, parts suppliers no longer offer the 2 piece hub and rotor for the Mustang, meaning that a rotor change requires a new machining operation. Brake pads last a very long time however.
The Camaro upgrade has been used for decades on the Arntz-Butler Cobra clone which used the MGB front suspension.
JB
Jim,
Any particular year on the Camaro/Monte hubs? I did a search for the early two-piece Mustang hubs and see that Rock Auto still offers them (or at least their web site claims they're in stock). Wonder if there are any parts suppliers for the Arntz-Butler cars. Not still in manufacture are they? Thanks for the response.
DT
Many years ago Werner Van Clapdurp used 5 lug Porsche 944 vented rotors w/Wilwood calipers & custom brackets.
Late '60, early '70s would work, not sure how long they used the same pattern. Used them with Dodge Dart calipers of the same era, just needed to elongate the bolt holes a bit, and the pads hung over the edge of the rotor a little I think. Splash shields were left off I believe.
It may still be the least expensive option, but a bit heavy.
JB
David, you know Bill Guzman has 5-lug hubs, right? Bill is a member here & you can reach him @ www.classicconversionseng.com
68-72 chevelle rotors and early 70's dodge dart 4 piston calipers are over the counter option.
Outer face of brake rotor requires minor machine surfacing for retaining nut and cotter key to
fit properly on mg spindle. Brand new brake rotor requires approx 1/16" taken off both sides
for the dart 4 piston caliper to fit. Suggest you become good friends with a machinist to use this
route, machine work in Jacksonville, Fl isn't cheap. No dust shield. Forward tang on mg spindle
must be cut off and then rewelded to bolt on the dart caliper. That's the route we took on my
brother's mgb. Heard rumor of toyota pickup truck rotors 78-83 I think it was (chevrolet bolt pattern)
being a slide on fit using stock mg calipers, still researching that one for another car we're building.
Also read somewhere here on this forum that ford ranger 5 lug brake rotors fit, haven't verified that
yet either. Good luck, hope this helps!
Tracy
Toyota truck rotors are Ford pattern.68-72 Chevelle,Monte Carlo and 68-69 Camaro are the same. It would be easier to use a drum brake hub and S-10 4X4 slip on rotor. Then make brackets for the S-10 caliper.Here is a picture of the same years GM drum brake hub with large Corvette rotor.And drum brake hub(taller) compared to disk hub.Last picture early Mustang V8 hub.
Chevydrumhubwith66-80Corvetterotor.jpg
Chevydiscand_drum_hubs.jpg
65-69MustangV8hub.jpg
Jim, good information (again). Could you fill in some detail for me? In the first picture, is the hub on the left the Toyota or the Monte? Rotor on the right in the same picture? I'm a bit confused as there seem to be a number of combinations. Maybe good to do something like: 78-83 Toyota truck hub + etc.
Thanks for your help. Had my sis look up your location in Sequim (benefits of a small town) in the hopes of maybe hooking up with you the next time I'm up that way.
David, Both hubs are 68-72 GM/Chevy. Left is disk brake,right is drum.The one by the rotor is a drum brake hub upside down.The drum hub would move the rotor out away from the tie rods.The rotor is 63-80 12"Corvette slip on. S-10 4X4 also is 10 1/2" vented slip on. I guess you could redrill hubs and rotors to Ford pattern.You might have to find the Chevy hubs in the junkyard also,most disk brake versions new are like the 67-69 Ford all one piece.I think those are what Jim Blackwood used.Toyota hubs won't work,different races/bearings.The Toyota rotors might work with the stock calipers .They are solid behind the hub rotors and would be used with the Ford hubs and Toyota studs. I've found usually it is a good idea to use the studs that go with the rotor.I prefer vented rotors if you are going to all the trouble. It would allow for 5 lug wheels though. I work rotating 12 hour shifts at the paper mill in Port Angeles, Most of my days off too lately. Let me know plenty in advance if you are coming all the way up here.
David, Some excellent pictures of the Chevy/Dodge Dart setup on the Roadmaster thread/page 5, MGB page this site.Note the one piece hub/rotor and close to tie rod end.The 83-92 Ford Ranger hub/rotor I tried looked about the same.B Hive, I think, sells smaller tie rod ends.
Here is a different idea. This guy cut down the GM rotor/hub to 5.73 diameter to use a 4th gen Camaro/Firebird slip on rotor.For the MGB you should bore the inner race hole 3/16" deeper and trim 3/16" off. Also bore to MGB seal size.There is enough material you could drill Ford pattern between the Chevy pattern on hub and rotor.
Chevelledrumbrakehub5.73.jpg
93-97rthgenf.jpg
OK, that is interesting but that last photo looks like a rear suspension. What are we looking at there? Also, what did he do for the caliper?
JB
Jim, Very observant.That is a rear suspension on a Chevelle. The guy used the same 11.92" rotors and matching calipers from a 4th gen Camaro/Firebird(98-02 LS1) front and rear. That is the only picture he had of the rotor.For the caliper adapter he used a flat plate front and rear. MGB would be different, but I like the idea of cutting the original rotor off and using the slip on rotor.
Here is a pic of the caliper adapter for the Chevelle to F body conversion in above thread.MGB would be similar ,different thickness and bolt spacing. Also a pic of LS1 front rotors and calipers. Jim, the F body brake conversion on front would make a good match to your Jag rear.
100_0830.jpg
032-3.jpg
Not bad. He cut the rotor off the hub? Then machined the back of the hub? Not a whole lot more work to cut a hub from billet I suppose. Something to think about anyway. The rotors look promising. It'd be nice to find an alloy caliper that is a close fit to the MG spindles.
JB
Jim, Those calipers are aluminum. The same as C5 corvette except bolt spacing and fins just on top of caliper.He calls them LS1 calipers but actually all 98-02 Camaro/Firebird even V6 have the same front rotors and calipers. I did a search and found it is a pretty popular swap for early Camaro's and Chevelle's. Some had to grind the fins on top of caliper to clear some 15" wheels. About twice the piston size of previous single piston calipers and much larger pads. Plus rotors are 1 1/4" thick.Also some aftermarket rotors varied, one guy had to go down to 5.6" to slip rotor on.Why would you machine the back side?Oh, yeah. I forgot, the mod for MGB bearing spacing.I have seen 68-72 Chevelle rotor/hubs for as little as $35 on Rockauto.com.Junkyard hub/rotors much less. If I didn't already do the Ford/Toyota setup I would think this would be a better option.
O.K. How about the rear hubs. You could modify replacement Jeep AMC 20 hubs to Chevy or Ford bolt pattern.Same splines as MGB.Trim the diameter down ,copy MGB taper on both sides. Or you could buy flanged one piece axles from Moser(quoted $380 pair last year). You would have to send an axle with hub and bearing for them to copy.I'm still researching my idea of a Dana 30 4X4 type locker conversion and a source for new 3.31 ring and pinion gears. Here are some pics of the Jeep AMC 20 hubs and Jeep one piece axles(much stronger).
amc20rear.jpg
p101056_image_large.jpg
Jim, that sounds like a very good option, and one I may consider over the winter since I need to migrate from my Mustang brakes and bolt pattern. I used stock wire wheel hubs (forged), removed the flanges and pressed on new flanges made from cold rolled steel, welded them in place and then machined them and drilled the new pattern. I could re-drill the hubs for the Chevy pattern easily enough. Then I'd need to work out the backspacing for the caliper mount. Any info on the price of the Chevelle calipers and rotors?
JB
Jim, rockauto.com usually has the best prices. Remember 68-72(put in 70) Chevelle rotor(rotor/hub). Then you need 98-2002(put in 2000) Camaro calipers and rotors. You could get the hub/rotors off a Chevelle in the junkyard,you would cut the rotor off anyway. You might luck out and find an original hub with separate rotor and just turn down to fit the Camaro rotor over it.If you are going to redrill your existing hubs you just need the 98-2002 Camaro rotors and calipers,might have to turn down diameter same as inside rotor for easy slip fit.
I'm seein a lot of "heft" in these photos. Mazda mid 80's+, RX-7 an maybe Miata , nice/strong alum. hub, 5 on 4.5" 1.3/8" inner bear id. Nice alum. 4 pot caliper(same). US. Brake 11" x .810" vented rotor,uses a hat, $40 up. Got more $'s ? Willwood ? Good Luck, roverman.
Art, The GM hubs are probably lighter than stock MGB and use the same bearings. I don't know about the RX7 hubs. I will have to look at them. I do like the calipers; they have been used on 300ZX rotors and are similar to the later 350Z calipers. Will only work with .88 or so thick rotors.The bolt pattern is good but I don't know about bearing spacing or size.You might be able to bore the race holes or use different races for the right bearings. I do know you are partial to aluminum. The Camaro/Firebird/Corvette calipers are aluminum. You wouldn't use the stock iron brackets, slider bolts like aftermarket Metric or S-10 caliper mounts.Plus, the 12", 1.25" thicker rotor would be heavier but less likely to warp.
This thread just keeps getting better. When it comes down to actually putting this stuff together, looks like there will be some choices to make. It's good to have options.
Probably adequate for most sports cars, lighter than RX-7's. Oops, RX-7 is 1.499" and .787" on bearing id's. Like I said STRONG. Alum. bush the hubs down to preferred bearing ? roverman.
"...an maybe Miata"
I believe only the latest generation Miata sports 5 lugs/wheel. The 1989-2005 were 4 X 100.
Story I heard is Miata is SLA. vs. strut ? I don't suspect many of us would convert from short/long a-arms to struts, maybe hard core drag racing. roverman.
Correct, all Miatas are SLA.
A bump for those interested in Chevy bolt pattern Big Brakes.
So is there a car that uses an aluminum hub with a 5 lug 4.750" bolt circle (Chevy and Jaguar) pattern?
JB
Jim B., Yes C5 Corvette, for sure. Don't know about C4 . I've used "larger shoulder" studs, in off-set boring operation, to move the BC. Good Luck, roverman.
Sounds interesting Art, I wonder if they used the same bearings as the rest of the Chevy line. What did they use for brake rotors?
JB
Jim and clan, big gnarly ones, like used on a serious, 3k lb. GT machine. 1.25x 12-13" ? I'm going with Wilwood, 2" dropped , Mustang II, forged spindles,(3x on strength), and bolt-on steering arms,(front/rear steer).Aftermarket crossmember for coil-overs,(QA-1/remote control). Cheers, roverman.
Jim, Picture of Camaro LS brakes:
p-assembly.jpg
Those certainly look like they'd work, but after a bit of reading it looks like C4 brakes might be the way to go. About a 7/8" (.81") thick rotor instead of 1-1/4" (lighter) 12" diameter instead of 13" (lighter, and still larger than stock) but it uses a single pot sliding caliper which is OK, but not great. I see the Mazda calipers like a .88" rotor, or .070" thicker. Might be able to mill down the mating face that much, or it might be within the minimum specified rotor thickness.
Or... Speedway has hats for $30 each, steel 2lbs (or Wilwood aluminum for $80) and rotors for $25 ea. That's an 8 lb (same weight as Wilwood) 11.75 x .81" rotor and a 3" offset on the hat. Not too shabby for new parts. Of course the hat is reusable so the extra cost to add lightness may be justified but 100 bucks for 2 to 3 lbs? That's getting pricey. Triple lug pattern which can be handy. For $60/pair the steel hats are an easy purchase and easily upgraded later if desired. So $110 for a medium-lightweight rotor set or $210 for the lightest. Or stock C4 rotors for about $80 which sounds pretty good, and available at parts stores everywhere but undoubtedly heavier, perhaps as much as nearly 16 lbs each like the Intrepid rotors on the other thread. (Are we beginning to see where the 80 lb weight loss of the Fast cars IFS comes from yet?)
The best compromise sounds like the Speedway rotors and hats with the RX7 caliper (about $65 ea reman with pads). for a total cost of around $250 plus mounting brackets. Not too shabby and also lighter than stock I'm pretty sure.
Art, those C5 hubs appear to use cartridge bearings so they won't work with MG spindles at all. Good try though. The Camaro guys are cutting down rotor/hub assemblies to work with the C4 and C5 rotors so there's no help to be found there. Jaguar apparently changed lug bolt circles when they were bought by Ford, creating a quagmire. Do any of the Japanese cars use a 4-3/4" bolt circle?
JB
Jim and clan, I've bushed spindle dia's-larger, and ground spindles smaller,(tool post grinder).I've welded/re-machined, Porsche 911 front hubs, for 4.75 bc.'s,(Vette turbine wheels on 914)." Dorman" makes gaggles of wheel studs, with oversize shoulders,(hint).Good Luck, roverman.
Jim, Just make .035 shims for the RX7 calipers. Or even more to fine tune.My 86-91 ones had shims stock,the slot is 1" wide.They go between the pads and pistons. Use the pads for a pattern,the holes for the slider pins keep them in. You would need 7/8"-15/16" master. Would work good, very light. Did you see the 92-95 ones painted Alfa Romeo on the other thread? Also a pic on the 4 lug thread of the 86-91 Mazda caliper on hat and rotor setup(note spacer to widen it out for 1 1/4" rotor). I just ordered rebuild kit from Mazdatrix for $40 for both calipers(my junkyard jewels). Doesn't include 2 small O rings that seal the halves.Still have to buy Ceramic pads. So your price for reman is a great deal! I'm out $145 and I have to rebuild them($70-calipers,$40-kit,$35-pads)!
Jim, According to Centric specs, C4 12" rotor weighs 14lb.
Chances are good it'd work just fine, the only real concern might be the pad's backing plate slipping into the rotor slot if all the pad was worn off. If you've let it go that long there's no brakes left anyway. The pins wouldn't let them go too far I guess.
On those Mazda calipers, is it possible to pull the pins and slip the pads out the back of the caliper? That is to say, would it be possible to swap the pads without unbolting the caliper from the mount? Some BMW calipers were made that way and it would be a very handy feature to have. Very nice paint work on those "Alfa" calipers btw Jim, those were right sharp.
The $65 calipers were an ebay special, no core required. Painted silver. I might just have to buy a pair of those.
JB
Yes Jim, The Mazda and Toyota have a spring wire to lock the pins in. You can change the pads by pulling the pins. My Mazda calipers had 3 thin shims on each side,looked exactly like pad backing plate but thinner.They can't move because they are pinned through, just like the pads. I'll get a pic of them.You can see in the 4 lug thread picture the pad wear looked pretty even.
Pics of shims, first shim toward piston stainless, angled with arrow(anti-squeal?)other 2 plain rusty steel, all about same thickness. Looks about .030. 3 on each side both calipers. Maybe to adjust to rotor after rotor is turned or these calipers were designed for thicker rotors. The slot is exactly 1" wide where the Toyota is 7/8".
IM001975.JPG
getimage4.jpg
Turns out that wasn't a regular seller on the caliper and he only has the one side so the cost goes up a bit. Maybe I should look a little more closely at the Toyota calipers as they may be a better match on the rotor thickness anyway. I recall you said they are aluminum but a couple pounds heavier?
JB
OK after some review maybe not. Does the Miata use aluminum calipers? Those Lexus calipers were aluminum weren't they? Best not forget the early GM hubs either, two spacings (drum and disc) and fairly light. Not aluminum though, I have sent an inquiry to Bill on his hubs and will report back.
I think the speedway rotors and hats are a good option if the 3" backspacing will work. Soon as the car goes back on the lift I'll look into that. A lightweight (alloy) 4 pot caliper with a 7/8" rotor slot (for .81 rotor) and pinned rectangular pads (removable without unbolting the caliper) would be optimal and we're close with the RX7 caliper. That may be as close as we can get, but maybe not. I think we still have a few options to look into.
JB
RX7 calipers are most common, but also 300Z and Mitsubishi 3000(also Dodge Stealth) used aluminum 4 pot calipers. The Lexus one is huge. I think they all use a 30mm thick rotor(1 1/4").They are all rarer to find used and more expensive new. The 300Z used 3.5" mount spacing, Mitsubishi used wide pattern like Mazda. You already know about the aluminum twin piston slider Camaro and Corvette. Newer Mustang also had a similar design. Miata is single piston slider. I think The RX7 is your best bet. The picture on the 4 lug thread shows the earlier one on a rotor/hat setup. The newer one looks a little more modern, but uses the same rebuild kit and pads. The one in the picture is spaced out for a 1.25" rotor. I don't see any problem using shims for .81 rotors.RX7 stock used 22mm(.88)rotor.Maybe they were thinking about going to 24mm and thats why the wider slot. The wider ears on the calipers actually make it easier to make an adapter bracket.Check out rockauto.com for specs on rotors and calipers. I'm not as weight conscience as you. I think the thicker heavier rotors are best for people who use their cars as every day drivers. The Toyota calipers are iron and the larger ones weigh 9-10 lbs but have excellent pads and 4 large pistons for clamping the rotor. They can also use WRX and 300Z performance pads by grinding a tab off. The small Toyota weighs about the same as stock MGB. Lighter is better for racing but I'm more concerned with stopping.
For those obsessed with aluminum,( count me in), said RX 7's have a very nice, forged alum. lca. Mid 80's "Supra" has a beefy, alum., uca. I suspect, both will "fudge" into Mustang II spindle.This makes front/rear steering , manual/power racks-doable. Cheers, roverman.
Art, I have a picture of that setup somewhere! Might be on other computer.Found it! It is a Datsun 510 with Nissan V6. It uses the RX7 upright though.
DSC_4015_small.jpg
Relative piston size is not an intuitive thing and it makes a lot more difference than you'd think whether you have 1, 2, 4 or 6 pistons. You can't just add them up because hydraulics is based on surface area of the piston, so you'll come out with square inches or square centimeters. I'm more familiar with doing these calculations in English so I start by dividing the piston diameter by 25.4 but it's not necessary. The formula is "Pie are square" (cobbler) The stock 54mm pistons then, 54 / 2 = 27 x 27{squaring} x 3.14{pi} = 2289 sq mm X 2 pistons = 4578 sq mm or 45.78 sq cm.
Here's why I like working in inches. 54 / 25.4 = 2.126... / 2 = 1.06... x 1.06 = 1.13...x 3.14 = 3.55... x 2 pistons = 7.1 sq in. You can almost estimate it in your head. To me they are just easier numbers to work with and to visualize. But there is an extra operation.
So the twin piston 54mm caliper has about 46 sq cm of area. Working backwards for a 4 pot caliper we get a 38.18 mm piston, nearly the same size as the RX7 caliper, only .18 mm or about .007" smaller. So the stock master cylinder and rear brakes should work fine with this one. If anything the pedal may be a smidgen firmer though in reality you'll never even feel it.
What about 1 piston calipers? Those used to be sized in inches and it would take a 3" piston to match the stock area or about 76mm. That's fairly big. My Mach 1 Mustang brakes had a 2.38" piston or 28.7 sq cm which explains why the balance bar had to be adjusted almost all the way to the front to get balanced braking. (don't forget when you are converting area the conversion factor has to go through twice)
You can calculate the increase you need in the MC and rear slave sizes too, although converting from drum to disc is not as straightforward because drum brakes are self-actuating among other things. Still, a 10% size increase at one end, coupled with a 10% increase at the other and a 10% increase at the MC will work out just fine. Where you get into trouble is when the percentages quit matching, you go to rear disc, or something along that line.
My next task it to determine the piston size of the Jaguar XJ6 rear brake caliper and the piston size of the XJ6 front brake caliper piston. With those dimensions in hand I can determine the appropriate piston surface area for the 4 pot front calipers, and the balance for that system in an MGB should not be much different than what is used in the stock XJ6. Any error can be easily taken out by the balance bar.
The 1-1/4" thick Speedway rotor is the same price as the .81" version and 8.7 lbs vs 8 lbs so not a real severe weight penalty. With the steel hat that's 10-11 lbs each. This opens a wider range of calipers as usable.
JB
Very scientific , Jim! I based my estimates on master cylinder size on what was used in the stock vehicles.RX7 used 15/16",small Toyota used 7/8" and large Toyota used 1". MGB stock 3/4". The Nissan Z guys like the 15/16" 79-81 ZX master with the small Toyota calipers,probably for a firmer pedal. They also go to 1" master when using the large Toyota calipers because excessive pedal travel. Jim, check out the 90-92 Nissan Z calipers for 1 1/4" rotor or Mitsubishi 3000 GT (Dodge Stealth) or Lexus LS400. Rockauto.com has caliper specs. Not as common but meant for thicker rotor.You can always use a spacer in the more common Mazda RX7 caliper.
Jim, I did some research for you, all these calipers are meant for 30mm thick rotors except the Lexus LS400 which is 32mm. 91-93 Mitsubishi 3000 GT VR4 and Dodge Stealth Turbo have huge 2.25" pistons. The 95-2000 Lexus LS400 has 1.68" pistons, 90-92 Nissan 300ZX Turbo have the smallest pisons at 1.59".
I got the piston sizes for the XJ6, 48mm front and 43 for the rear. Front is 4 pot, rear is 2. The area of the front pistons is 11.2 sq in (72.26 sq cm) and the rear is 4.5 sq in (29 sq cm). The area in metric in this case gives a near perfect snapshot of the front/rear proportionality at about 70/30 give or take a point or two. Weight distribution is identical to the MGB. Readily available big piston aftermarket calipers max out at about 1-3/4" or 44.5 mm which would shift the balance towards the rear a bit, 68/32. Use of the RX7 calipers would give 60/40 which I've seen quoted as generically ideal.
So there's the range. Anything between the RX7 caliper and the big piston aftermarket units is going to work, and any of those should be within the range of adjustment and use of my balance bar/dual 3/4" MC setup. (Roughly equivalent to a 1-1/16" single cylinder except in total volume as that is evenly split front to rear.) In all probability the smaller one will have to be balanced towards the front and the larger towards the rear but in either case probably not as drastically as it is now as both those proportions should be within a workable range. My gut tells me to go for the higher distribution to the front. Time to shop for calipers.
JB
picture of caliper spacers:
DSC00206.jpg
I may need those. I bought the Outlaw calipers off ebay with 1-3/4" pistons and set up for a 1" rotor. But 1" rotors are about like finding hen's teeth so I'll either have to use spacers or mill them down for .81" rotors.
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=350435669835&ssPageName=STRK:MEWAX:IT
But the pads might be expensive. Still have to get rotors too.
JB
Jim,You Outlaw you! I think some of those use the same pads as Wilwood. You could copy the pads for stainless shims and use the .81" rotors or make spacers easily for the 1.25". 3" hat would be good for caliper clearance but might make rotor close to tie rod end. There are smaller ones available or Heim joint. Remember to use red Locktite on hat to rotor bolts. Or 88-94 C4 Corvette Heavy Duty 13" rotors are 1.1" thick but have a shallow hat for the 2 piston slider calipers. They are left and right different because of curved vanes. Heavy though(20lbs).Here are specs:
getimageCorvette13.jpg
Yes I think they do use the Wilwood pads from what I've seen. There is a Sportsman class 1" rotor but it is just 10-1/2" diameter and not a bargain item, about $90 each plus the hats. This is why I got the calipers so cheap, $110 shipped for NOS. With good pads a 10-1/2" ventilated rotor is all the MG will ever need, still, if I can find a bargain on the rotors I may still be able to bring it in under $300 total which is in the ballpark of what we are shooting for with this thread and the other two. These calipers weigh around 3-1/2 lbs each plus pads so something in the neighborhood of 4-5 lbs ea.
For anyone using the stock rear brakes the RX7 caliper would be the way to go, or in an aftermarket 4 pot caliper a 1-1/2" piston size, either of which will have the same piston area as stock. For a disc brake rear axle I'd be looking for something with a 48 mm or 1.9" single piston caliper with built in e-brake or maybe a bit larger but not over 2.4" or 60 mm. There should be a stock caliper like that available.
At one time there was a Mitsubishi Eclipse (I think it was the '91 with the base engine) that used a nice rear caliper with an external allen wrench screw head to retract the piston but I only ever saw that caliper on one car. Very nice and super easy pad change. But the piston is too small so you'd need something from a larger car. For a somewhat smaller piston figure the percentage and go that much smaller on the front. The pedal would be firmer but more precise. NASCAR has gone to 1" pistons and high line pressures but go too far and you'll need a smaller master cylinder. The reason for using a single piston slider on the rear is that it allows the incorporation of the e-brake cable. Stay away from the type where you have to spin the piston back into the caliper. On those it's often easier to swap calipers than to screw the piston back in, even if you don't destroy the seals doing it, which is a definite risk. The reason for this is that the internal adjuster has nothing to keep it from spinning backwards so instead of screwing the threads back together everything just spins and even the smallest speck of dirt or rust will frustrate your efforts. I'd recommend a caliper if I could, I know there has to be a good one out there. It is inconceivable that the Mitsubishi design was only used in a limited application on one model, it really was very, very good. A pad change took all of about 5 minutes. Might be worth lunch with a Midas employee.
JB
Anybody ? "Wilwood" likes this process best, but NOT cross drilling ! The RX-7 rear caliper has built-in e-brake. Why not a" line loc", for those without,(including stealth, theft deturrent)? roverman.
Art,
A line lock is not a legal parking brake most places. I always used a block of wood on my Camaro. ;-)
I was at a u pull it yard today and there was an rx7 turbo 2, so i got all the calipers off. What would be the issue of using the caliper withouta spacer for that .07 inch difference with a .81 caliper? Especially if you change it before it wears down to nothing. I know the pads wear down much more than that amount. The RX7 has some really nice calipers, these are very light for their size.
Robbie, Spacers are easy, just copy the pads backplate. Stainless works good. .035 shim each side. You are right, as the pads wear the pistons can bind or pop out. What are you going to use for rear rotors? The RX7 rear rotor is thinner than the front,20mm (.79) instead of 22mm..81 rotor and hat also. I don't think you need a shim there. When you get it all figured out should work excellent. Keep us posted.
Well, This will be a slow process as my car has working brakes. The only reason I got these now is I was there and they were available. I already have rear discs, which are gm but i dont like them, with 1-1/4 rotors. I want to go with 10-3/4 in the front. Will probably keep my rear setup unless i have too large of a proportioning problem. Right now, I have a 3/4 master, so im not sure if that will work or if i will have to go to a 7/8 or 15/16.WIilwood has a .72 hat mounted rotor but is too large, like 11.66 for my 15 inch rims. There are still a lot of things I will have to work out, but im not in a hurry.http://wilwood.com/Rotors/RotorList1.aspx
.035" per side should be in the working range, it all depends on how much gap you have between the caliper and the rotor on each side, and the thickness of the backing plate. Obviously you don't want to wear the pads down to nothing but if you do, you don't want the side of the pad eating into the corner of the caliper, potentially ruining it. I think most backing plates run close to 3/16" thick so if the nominal running clearance isn't too much the extra .035 should be no problem. But the stainless shims make great heat shields (even better if you can get titanium).
I just scored a set of rotors and hats:
http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=140508353345
It'll take a little work to make them fit. But absolutely killer pieces, 13" x 1-1/4" ultra light ceramic coated Red Devil, probably steel alloy. Should come in around half the weight off a comparable rotor, I'll know more when they get here.
I'll have to redrill the hats, redrill my hubs, and either make or buy spacers for the calipers to widen them to the 1-1/4" size. Cost with shipping, about $118, a very good price for these parts. So I'm approaching $250 and with pads will be right close to $300 which is sort of the goal. And if it all works as planned I'll have the lightest and most effective brakes almost anyone could want, at a price almost anyone could afford. It helps that I can do some machine work myself, but hey, this is what we're shooting for here.
I've decided not to chase after aluminum hubs.... though you never know what might show up on ebay. Mine are very strong and well made, only needing re-drilled to go back on the car. So I'll be giving up a pound or two there. My target is a finished unsprung weight about the same as what I had before, and about the same as stock. Once the brakes are fitted and I know exactly what I want it'll be time to get in touch with Greg Smith at Weld and talk options. I may call Centerline too, it's hard for me to believe they don't have some sort of a plan in place to make 17" wheels.
JB
Jim,Super trick rotors for cheap! Looking forward to the "How to do it". I think you won't have a problem with the rears over powering the front. Even with the balance bar setup, if you have excessive pedal travel you may have to upsize your masters.
Robbie, The .79-.81 is so close you could use the hat and rotor on the rear with no problem. For the front use a short hat behind the hub like stock. The only problem is the hats are all 5 lug. You could have a shop tig a ring over it and drill to your hub pattern. You would have to know somebody because if you have welding done on brakes or suspension parts, they either won't because of liability or the cost goes way up. That's why I comb through stock part interchange lists. The 86-88 Toyota Cressida rotor I'm using for the MGB kit is 10 3/4" diameter and 22mm thick vented like the RX7. I think you will find the GM rears way too big. I plan on using 86-87 Acura Legend front sedan rotor,10.4" diameter and 20mm thick vented like the RX7 for the rear kit. Perfect match. You could just drill your hub pattern between the 4 existing holes for the front and drill your wheel pattern between the 4 holes in the rear and slip on. Not knowing the hub diameter or axle diameter of your Alpine, may or may not have to be turned down to fit. You can get fancy slotted and drilled rotors also. On the master if you have excessive pedal travel move up to 7/8", again the same as RX7 Turbo II.
Jim, where do you find stock part interchange lists?
I found a place that sold blank hats about a year ago when I was doing the rears. I can't remember if I saw it online or if I asked Wilwood if they can sell me one before the holes were drilled. I'll try to see if I can dig it up. I don't have power brakes so I'm worried about the pedal stiffness going up to 7/8 or 15/16 and not having a booster.
http://www.summitracing.com/parts/WIL-171-2234/
Summit sells the undrilled wilwood hats, but a year ago I found a different company that made them and ost less.
Rob, not Robbie, Boy this is getting confusing. On Rockauto.com you can click on the blue stock# and it will tell you what years and models parts fit,very handy. Also Centric website for rotor dimensions. Robbie, I had no idea you could buy the blank hats,remember to have the offset so you have a minimum of 1/4" to 3/8"steel to 1/2" for aluminum caliper adapter. The 7/8" master is what the RX7 used. You don't need a booster. If too big you would get a hard pedal. You can try yours and if too much pedal travel go up then.
I'd like to know that other source for hats, I may need a pair. Aluminum?
JB
I don't remember what they were made of but j know they had blanks in all sizes. My computer crashed a few months ago, so looking through all my bookmarks last night, it seems I lost the site. I think I found them by searching for undrilled rotor hats or something along those lines.
Most race suppliers sell undrilled hats in both aluminum and spun steel versions. The big guys like Pit Stop, Pegasus, and HRP World mostly sell Wilwood but look around at some of the more specialized outfits that cater to road racers. That said, the spun steel Wilwood hats come in an endless variety of hole spacings and off sets and at about $40-$45 each are an attractive option to aluminum and almost as light.
David, Your car looks great! Unusual mix of old and new style. I think it would look even better if the rockers flared out to meet the fenders. Or side pipes like a Cobra. You might need wheel spacers to fill the fenders. How are the brakes coming?
Jim,
Thanks for the props on the B. Going with side exhaust similar to LeMans cars so it will exit right in front of the rear wheel. Thought about the rocker flares and still may go that way or may save it for something to do after I'm on the road. I have a set of 1" spacers on hand (from previous project) that I can use if I need to move the front and rear tracks.
On the brake project, I have everything on hand (finally) and a complete write up (less photos) but have been giving my time to the B's bodywork while the weather has been warm (in the 30's for last 2 weekends). Funny how my build seems to revolve around the weather. The brake work is inside stuff (small work are in the basement) so I try and save it for when it's too cold to work in the garage. The new kerosene heater is a welcome addition and has really extended my ability to be in the garage but even it has limitations when the temps drop to zero.
Wow, it's almost scary how well the dimensions worked out. I still need to make spacers for the calipers and drill bolt circles but the caliper mounts are going to be dead simple it looks like. The hats that came with the rotors are 3.4" from the flange to the backside According to my calculations the new calipers will need to mount 3/8" (.363") inboard of the spindle mounting lugs. Couldn't get any simpler than that. I'll have to double check again of course but it looks right. They will also have to mount 1" outboard to accommodate the larger diameter. There is 2-3/8" on the front side so plenty of clearance there.
These rotors are a floating design mounted with about a dozen beefy fasteners. There is a floating block anchored by each SHCS that fits into a rotor slot. Weight is about 10 lbs with the hat. I dunno, NASCAR or something I guess. Extreme overkill for sure. Bill, over on MGE is going to have a cow when I tell him.
JB
Oh. Except for the tie rod ends. Knew it was too easy, the rotor is sitting 1/2" farther inboard this way. So a shallower hat, and close clearance on the wheels, or bend the steering arms inward. Hmmm.... decisions, decisions. Maybe a little of both and 1" thick aluminum mount adapters. After I remove the dust shields maybe I can get by with a 3" hat.
Those darn tie rod ends. I ran into that several times trying stock part alternatives. I also thought , boy this is easy! That's what makes this fun, the challenge! I have a healthy respect for the factory engineers and still I have problems.
Heim ends instead of tie rod ends.
Nah, that doesn't help any.
JB
FWIW, I just completed aluminum, sleeve/spacer/adapter, to fit series II RX 7 hub on to Mustang II spindle. Using Ford outer bearing in Mazda outer cup. Welded beads on inner RX 7 cup, to drive it out,(no punch-out ports). Adapter holds the inner ford cup and moves it .700" away from outer bearing. Adapter also holds Mustang II inner seal.Yes, I could have bought a Wilwood brake conversion kit, for a lot more $'s, for less braking. What's the fun in that ? Dem's da brakes, roverman.
Art, That's cool! Are you going to use the RX7 calipers with a hat and 11 3/4" .81"rotor set up? You need about 2 1/2" from face of rotor to face of hub that wheel bolts on. Plus 2 .035 stainless shims. See pictures on 4 lug Cressida rotor thread on MGB page.
Jim N. and clan, I got convinced .81" rotors would warp, on front. I went 1.25"thick x 11.75", bout a lb. more, $31 ea. and Wilwood 4 pots @ $126 ea. .81" x 11.75 with RX 7 pots, should work fine on rear.Car weight approx 2,800. Approx 500-600 hp. will NEED enough whoa. Price for "cryo" is $35./ea.. I'm thinkin, "radial" holes in the hats for additional cooling ? Wouldn't ceramic or pyrolitic graphite,( 200/1 thermal flow ratio), work better for shims, less thermal transfer ? Cheers, roverman.
"I don't see any problem using shims for .81 rotors.RX7 stock used 22mm(.88)rotor.Maybe they were thinking about going to 24mm and thats why the wider slot. "
Sorry to dig up this old thread, but Jim, you were right about the 24mm sizing.
http://www.racingbrake.com/RX7_FRONT_93_95_p/2099-381.htm
And from this site:
The rotor thickness has been increased to 24mm from OE 22mm for increased thermal capacity. Read more here.
1.Some brake pad manufacturers have increased their pad thickness (ie. EBC) therefore our rotor will not fit. Please verify your pad thickness is below 16mm.
2.Remove any factory brake shims from the pads before installation so that the rotor will fit in the caliper.
Robbie, Thanks for verifying that. I thought it was strange that Toyota used a 22 mm thick rotor and Mazda RX7 slot was so much wider and pads always come with shims. My junkyard calipers had 3 shims on each side. One stainless(anti-squeal) and two plain steel about .030. I saw your thread on the Sunbeam Alpine board on your 4 link. Are you doing the RX7 brakes also? This thread was about to be resurrected anyway as David Townsend has done a comprehensive article on the Mustang hub/Intrepid rotor set up.
This weekend I just got started on my 4 link. I got the tires, brakes, gas tank, leaf springs and perch mounts removed. The rest of my
Parts should be in this week so I can start going in the back together direction with it. While I have my car up I was looking at what it would take to swap the rears for now since I have them off already. I think I could reuse my brackets that the gm calipers are on and just cut them a little shorter and drill 2 new holes in them. If everything else goes smoothly with the suspension I'll probably do that while it's apart. If it drags on I'll just put it back together as is and do it this winter.
Looks like either 22 or 24 mm rotors would work just fine with my Outlaw calipers. I was leaning towards Speedway's scalloped .81" two piece rotors as they are very light but now I wonder if someone might not be making those in a 22 or 24 mm thickness. It'd be worth paying a bit more for them if so as long as it isn't an extravagant amount. Still have some front end work to finalize before I'll know for sure what offset I want for the hats but I suppose in a worst case scenario I could turn and mill a set myself if I had to.
JB
Jim B., Check out these hats on Ebay: http://cgi.ebay.com/ebaymotors/New-Performance-Stamped-Steel-Racing-Brake-Rotor-Hat-/190499478152?pt=Race_Car_Parts&hash=item2c5aa75a88
I talked to a guy at coleman today, and their aluminum hats are around 70ish, and a custom made rotor for their hats are about 80ish.
"I plan on using 86-87 Acura Legend front sedan rotor,10.4" diameter and 20mm thick vented like the RX7 for the rear kit. Perfect match. You could just drill your hub pattern between the 4 existing holes for the front and drill your wheel pattern between the 4 holes in the rear and slip on. Not knowing the hub diameter or axle diameter of your Alpine, may or may not have to be turned down to fit. You can get fancy slotted and drilled rotors also."
I was looking on rockauto and it loks like the Acura rotors are 21mm, while the RX7 rear rotors are 20mm. The mid 90s Miata front rotors are 20mm 4 lugs. My local auto parts store had neither in stock so I couldnt put a tape measure on them to see if it would clear my axle flange. If I remember correctly, my axle flange is somewhere in the neighborhood of 6-6.25 inches. Is there any resource that shows the measurement of how large rotors are where they slide over the axle flange?
Robbie, Check the Rockauto site again under Centric. It should show the dimensions. Brembo might also. Or junkyard shopping. A 1/2 mm on each side shouldn't matter. Those 8" Ford hubs might have to be turned down.
Rockauto doesn't show those dimensions. I guess I'll have to go jy shopping soon.
Robbie, Rockauto has hub diameters on some vehicles. Looks like 5-5.5 inches most common. Wilwood lists 2 hats in Sunbeam bolt pattern(same as 79-83 Mustang 4"X4.25"), Check this link out. http://www.revolutionbrake.com/wilwood_rotor_mounting_hat.html
I should have. Went with 16" wheels instead of 15. That's what's causing the problem for me. The hat for the rotor the thickness I need and will fit over my axle flange only has rotors that are too big to fit inside 15" wheels.
Jim N, RX7 upright ? (McPhearson strut). I need a light, strong spindle, for SLA. and tall enough to have low roll center migration, with bolt on steering arms. Jensen Healey seems too weak,(11/16" and 1and1/16") dia's. Suggestions ? Thanks, roverman.
Art, Newer Mustang and Camaro are Mcpherson strut. I thought you were going double A Arm. Some Locost builders cut the strut down and weld a 3/4" bolt on top and use a Heim for upper ball joint. That is probably what the 510 with RX7 lower A arm and Supra upper A Arm did.
Jim, In the picture your showing "a" Supra lca.,"b"RX7 uca and "c" ? kind of spindle ? Thanks, roverman.
Art, It is on a Datsun 510. I thought the article said it was RX7. Maybe It is Z or 510(also strut), If you do a search on Strut conversions to Upper and Lower A Arm on Locosts you might find some pics on the Heim. Or you could use a upper ball joint like this newer Mustang. They cut down the strut and use it as a spindle..
t_sla_griggs.jpg
If I thought I could "trust" the JH spindle @ 1.5 g in 2,400# car, but if not enough, could get messy !" Wilwood, Mustang II, I feel is too heavy, but I want bolt on steering arms. update, considering "like" Mustang II, but has centerbolt at top,for wheel cylinder? Identicle ball joint sizes top/bottom(5/8") large end of tapers. N.O.S., think I can make work. What's that air bag # that works on MGB's ? Thanks, roverman.
I thought I'd revive this thread as it has so much info on brake calipers and I need to do an upgrade.
As last reported, I have XJ6 rear brakes (1-5/8 dual pot fixed calipers), Outlaw front calipers (1-3/4" dual pot fixed), dual master/balance bar with 3/4" rear and 5/8" front. The brakes are ineffective due to high pedal pressure, traced to the dual pot front calipers. I must have simply overlooked that somehow.
Earlier in this thread (page 3) we have the XJ6 front caliper piston size as 1-7/8" 4 pot. I suspect that is the size I should be looking for which is a little over twice the piston area of the outlaw calipers.
The question is, what is my best option? I would prefer a light weight caliper, cannot really justify ones that are tremendously expensive, and as for the mounting, I can make adapters. I have 15" wheels. A direct mount caliper would be nice but it may require me to buy different rotor hats. I'm running .81" rotors but can get thicker ones from Speedway if I need to. Any suggestions?
I'm looking at the RX7 calipers, what years used the aluminum 4 pot calipers and what size were the pistons?
Also will look at the Willwood Dynalite but Max says they have caliper flex.
Jim
A quick look on RockAuto indicates that RX7 last year was 1995. Front calipers were aluminum with two 1.0" dia pistons.
RX8 came on board in 2004 with cast iron caliper with single 2.13" dia steel piston..
Edit: For the record, my front brakes are Wilwood Dynalites with dual 1.75" pistons. (Pads are Wilwood BP-40)
Wiloodfront1.jpg
Since I've been prompted for an update, first to point out some errors.
My front Outlaw calipers are 4 pot 44mm, rears are 2 pot 43mm, and I had a bad master cylinder on the front. Since then:
Using an online brake calculator from this page:
https://www.tceperformanceproducts.com/dual-bias-calc/
We were able to determine that suitable MCs would be 3/4" front and 5/8" rear and that 350lbs of line pressure at the front would be sufficient to develop .7g of braking force, with only a couple turns off center on the balance bar. I ordered Tilton cylinders in those sizes in the 75 series, which has a shorter stroke but leave much more room for line connections. I used custom made reservoirs that retain the tops of the old ones and attach with a small setscrew.
Measuring front line pressure after the install I was able to develop upwards of 400 psi at the front. Balance bar motion looked appropriate. I will not be able to road test it until I do some more tuning work on the engine but all indications are good.
Max pointed out that the 0.41 coefficient of friction on the Porterfield pads is rather low, so this gives me a path to lower pedal pressures should I feel the need. As he was talking CFs in the .75 range it appears I should be able to cut pedal pressure to about half what it is now with careful pad selection. But there is no free ride of course. Testing will determine what is needed.
Jim
Reservoirs
IMG_0006.JPG
Tilton 75 series
IMG_0008.JPG
Balance bar
IMG_0010.JPG
Ok, once again, series II Mazda RX-7 non- turbo and turbo. 5 0n 4.5" . Inner bearing is BIG !. better than too small. Std. rotors are vented and decent in size.
Dems da brakes, Art.