I'll be doing an upgrade on my rear suspension, starting with building a new center section to swap in at the same time as I do the gas tank swap. I've been collecting parts so now it's time to see if those parts will play nice with each other.
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The Jag used a Dana44 variaint for the center section which was called a Salisbury. There are some relatively minor differences but most parts can be swapped. Two sizes of ring bolts were used and two varieties of Timken bearings were used on the pinion, neither of which presents a problem. The Power Lok posi was common and is likely the most robust clutch type unit available and competitively priced. It has to match the selected gear ratio. I have 3.07, 3.31 and a 2.88 gear sets available and have decided on the 3.07 as the best for my car, moving from a 3.54. That's a big jump but I will be reducing the rear tire diameter soon from 26.8" to 24.8".
An argument could be made for either the 3.07 or the 2.88 ratio, the 3.31 clearly being out due to the tire size change. The engine already spins fast enough and the new one will be even better able to pull any of those ratios. The way it stacks up then is that from about 2K rpm at cruising the 3.07 drops engine speed by 125 rpm and the 2.88 by 240 for about 1875 and 1760 respectively with the new tire size. I think the 3.07 is going to be the way to go here. A little slower engine speed but not too much. The tire change alone raises the rpm about 157. So, in effect until I change the rear tires I will be running the rough equivalent of the 2.88 gear set which is what we ended up with in the Roadmaster. The two engines having somewhat similar torque outputs the performance should be similar which is to say, satisfactory, and then somewhat better afterwards, with the potential for better mileage than current as well. Should I decide I like that setup I can then either keep the larger rear tires or swap to the 2.88 gears.
The diff is a NOS Power Lok and IIRC the breakaway on the axle shafts came out at right around 100 ft lbs which is quite acceptable for the MGB. I'll check it again of course, 80-120 being the desired range. The one in my car is at 120 and not having organic friction surfaces that doesn't change much unless abused, and it hasn't.
I will need to find numbers on the housing that I can reference to the ratio range to make sure this housing will work with the 3.08 gears. If not, that's about a $500 purchase but I think it was at least supposed to be the right one.
I will also need a pinion spacer sleeve but the complete unit should have one. New bearings and seals naturally, paying particular attention to the stub shaft seals at the sides. If more heat resistant ones are available they should be installed.
It's possible but not likely that spacer sleeves could be required on the ring gear bolts. Those are needed to use a Salisbury gear set with a Dana diff. To go the other way you would drill out the holes in the ring gear flange to the larger size.
At the same time. to use the Dana pinion in the Salisbury housing requires the correct bearing sets. I don't recall the details exactly but bearings are available to swap both ways, there is a bore size difference and a different bearing angle on one bearing, the other may be interchangeable I think. Not a problem but it requires measurements to get the right ones.
I will need a pinion yoke of the saddle type to match the driveshaft. I upgraded from the flange type to eliminate this potential source of driveshaft ringing. I could use the one on the car of course but that means tearing down the car earlier than I'd like.
It would be a good time to consider ventilated rotors. Those require spacers in the calipers.
I don't know where this 2.88 hogs head came from, clearly an XJ6 but the one from Alex's parts car went into the Roadmaster which had a 3.54 gear set before that. My XJ6 unit came with the 2.88 gears also of course, Dan M donated the one for the RM along with the 3.54 gears, and I bought a take-out center section with a broken cross shaft in the posi. Somewhere in there is the answer. I think that one had the 3.54 gears also, which ended up in my car. Maybe this was the one from Alex's car and I sent mine to the guys to put in the RM. That sort of checks out. Another mystery but better to have too many parts than not enough.
That's about it for now. Lots to do, lots to sort out. Best to get started.
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Jim
I accidentally posted on the Bay Car thread but to catch up, I checked the numbers cast into the Power-Lok case big end (C30755) which identified it as the correct case for gears numerically be below 3.92 so we're good there. It's NOS so the breakaway should be fine. Today has been mostly inspection and parts selection. I'll break out my Jag IRS binder in a minute but so far, I have a ring and pinion with a 43/14 gear count which is 3.07 and the ring uses 3/8" bolts which I also have but the case has the larger holes, probably 7/16" but I haven't measured them yet. I grabbed my bucket of bearings (timken, large) and found some good side bearings and the small pinion bearing (the bore is smaller than what Jag used) but I didn't have anything that matches the large pinion journal and the race. The one on the pinion uses a sharper angle. So far nothing unexpected. I can make or buy sleeves for the bolts and the right bearing should have been in the binder since I've done this before but it has nothing on setting up the gears so I will have to look elsewhere. Probably here:
https://dazecars.com/dazed/JaguarIRS4.html
Which is a good reference. I was active on this site's forum back when I was building the assembly for my car and the MG Roadmaster.
I have no problem with reusing good timken bearings and see no need to replace them just for the sake of having new. Used bearings actually are easier to set up as they don't need as much preload.
So I have one parts selection issue to resolve (Bearing 25590 Race 25523) and need to find a pinion spacer, ring bolt sleeves, 3 seals and a couple of large O-rings. Also a pinion yoke, and that seal has to match the yoke.
The spare hogshead is complete so I can go there for spare parts as needed but that won't include seals and I want high temperature seals for the side stubs. I may have to do a little research to see who is doing a lot of Jags these days, maybe west coast. Ken might know. But in the past the daze source was adequate and should still be.
Jim
Been making some headway on the bearings and seals. From all appearances the carrier I'm using is made for the Salisbury housing and gears. It has the 7/16" holes to match the Jag ring gear, the first clue, and it accepts the Jag carrier bearings (25577) so that leaves the R&P which are Dana/Spicer, have the 3/8" bolts and fits the Dana (31594) inner bearing with the 31520 race.
They all use the M88010 outer race but the Dana uses the M88040 bearing where the Jag uses the more common and less expensive M88048. Odd state of affairs there.
The o-rings for the side stubs are common and available contrary to the popular opinion on the Jag sites. Haven't decided on seals yet, but the yoke is available from Summit for about $50 with shipping. Overall pretty economical so far. Much better than springing for a $600 kit from Yukon. A spacer sleeve is not needed.
Jim
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As I muddle my way through this, only going into an axle about every 5-10 years on average, I reach some conclusions that will direct my build.
First the stub axles. If they show no signs of leakage whatsoever and the bearings are smooth, what possible reason would I have to tear them down? That they MIGHT leak? That would still be true if I rebuilt them. Probably best to leave that alone. So I will. O-rings look fine.
The bolt sleeves are better bought than made and DriveTrainSpecialists sells the set for $3.20, a bargain. Let's see if they can supply all my needs. I'm seeing them for as much as $11 and that is each? They don't say, best not assume.
I will buy new carrier bearings and turn these old ones into setup gears by honing the bores. Seems penny wise not to. Same with the pinion bearings.
I believe I am now ready to order parts and will plan to do so tomorrow. The plan is to just call up DTS and see if I can do a one stop shop. They can double check the parts selection. The list:
Timken
25577 x2
25523 x2
31594
31520
M88040
M88010
Dana44 pinion seal
Dana44/1310(?) yoke
IK inserts (bolt sleeves)
Total cost should be under $300 I think. I need to verify the cup diameter on the u-joint, car has to go on the lift so that's this afternoon.
Jim
Got everything on my list except the M88040 bearing from DTS for about $250 + 20 bucks for shipping. Got the bearing from ebay for about $35 delivered. Should all be here within 4 days or less, ready to start assembly right after xmas. Spend some quality time in the parts washer etc for prep, find my yoke holder, hone assembly bearing bores, etc, etc. Good progress. The rest should be pretty straightforward.
Jim
Baking today. Merry Christmas everyone. Pumpkin pie and two batches of chocolate chip cookies, one vanilla TollHouse and one with pumpkin spice and oats. Both good. Should be a fine day tomorrow.
Jim
Been doing quite bit of Christmas cooking, as well.
Tomorrow, it will be my rendition of the World Famous "Evelyn's Brownies". Evelyn is my grandmother that created this special recipe. Have to fold the ingredients just so & bake them just right to recreate the magic. :)
I believe I have all the parts in hand now to begin assembly. Bearings are all Timken brand which I do prefer a bit. I went out today and washed the housing so next is washing the R&P which I didn't do today because my fingers got cold, and then honing the old bearings to use as set up bearings. That's about all I am planning on for tomorrow but it'll be a good start if I get all of it done. Since it's an empty housing I don't have a starting point for pinion depth which means I'll have to pick an arbitrary starting point, set backlash, and then check the contact pattern to see which way the pinion needs to go. That should be pretty straightforward but will tend to increase the number of times it has to be test fitted to get a good pattern.
On a related note, I just ordered a couple of vented rotors from Speedway. These are 11.75" diameter and .810" thick. The Jag rotors are 11-3/8" diameter but I can easily trim 3/8" off the outside. The thickness is about double what the stock rotors are which means the calipers will require spacers and longer bolts to join the halves plus longer crossover brake lines and the e-brake calipers will need a wider spread on the return springs, all of which has been done before.
My plan is to cut down a couple of spare rotors to make mounting hats out of them and just bolt the new rotors to these fabricated hats, and then hopefully it will all go together the same way. The vented rotors should eliminate any chance of rear brake fade, which I found I *was* able to induce under extreme conditions of testing. There may be some overlap of the pads to the inside of the vented discs, in which case I'll want to trim the pads back to match but that should still leave plenty of pad area. So one step at a time, and soon enough I'll have the new center unit ready to go.
Jim
I finally got everything ready to go except the holder for the pinion yoke which is needed for torquing the pinion. Since that will get done at least 5 times that tool is a big help. I should have one around here somewhere but haven't been able to lay my hands on it yet but it isn't hard to make another one and I have a chunk of channel iron that will work.
So in the first photo below, the parts are laid out and some old bearings have been resized to use as assembly bearings. This is not something you will want to do with a brake hone and electric drill. That hardened bearing steel just cuts too slowly. So instead I resorted to a die grinder and hard stone with the bearing in the lathe. I enlarged the bores of all four bearings until they were a close slip fit plus the OD of the large pinion bearing since the shims go behind that race. The second photo shows the surface finish after grinding. There is a good chance you can buy a set of set-up bearings for the D-44 and perhaps even the ones to fit the Dana pinion to the Jag case. It's more work but less expensive to grind an old set to fit. I had to buy one bearing new for this, the small d-44 to Jag pinion bearing. I think I posted those numbers already, they aren't too hard to get.
The ring gear and the posi mating surfaces have to be absolutely free of any contaminants. Anything that has a chance of preventing an absolutely flat fit between the two must be removed. If not it will affect the gear wear pattern and the life of the gears. It's OK to sand them with emery to do this as the ring gear is hardened and the posi shouldn't take much. If it has any gouges in it a fine file should be used to remove the raised metal around the gouge and bring it flush. I didn't have to do that here but I have seen it.
With everything clean and dry and the threads cleaned with brake cleaner and air, assembly of the ring to the carrier was next. Because the ring uses 3/8" bolts and the carrier has 7/16" holes I bought a set of sleeves, about 3 bucks for the set maybe and used green stud lock, seems like it might be 290. It's similar to the red and has similar properties, but the fluidity may be a little different. Pretty much all Loctite softens at 350 degrees F (a typical baking temperature) and becomes more like a thread lubricant. Torqued the bolts to 60 ft/lbs. There is a range, generally between 50 and 100 but lots of people think that 100 figure is a mistake. I do too. At 50 the bolts should be locked down solid and you shouldn't see much movement at all above that, if any. I do not like snapped off bolts and I think 60 is a good number. Maybe 70 but not in this case.
I've started fitting the pinion to the case and that's an interesting process. First you have to get the right shims to get a proper preload on the bearings and that will take at the bare minimum 2 or 3 test fits even with the best of luck. The pinion yoke is a pretty snug fit on the pinion spline and it isn't going to be easily removed so I think I'll just make up a spacer sleeve to take it's place until final assembly. After preload is giving the right 12 inch lbs or so of rotational resistance I can start matching the gear to the ring and work on the pattern. Each time the pinion has to be moved closer into mesh with the ring, the same size shim that is added under the big bearing race will also have to be added under the pinion bearing so the preload stays the same, and then on final assembly the rotational torque is checked one last time. Hopefully it will then be within range. But before that, the carrier preload and backlash has to be set, again by adding and removing shims on both sides of the carrier of equal thickness after correct bearing preload has been determined, by shifting the ring gear towards the pinion. .008" is a common backlash figure but the pattern is most important. This process is continued until the contact pattern is acceptable and means the pinion could have to come out a dozen times in the process to get it all right. This is why you pay a *reputable* shop to do it for you, and then HOPE that they get it right. (In my experience more get it wrong than right, which justifies going to one of the large houses like Moser.)
Would I take mine to Moser? Yeah, if they were close I would, Or if I hadn't done this a few times before. At least I don't have a deadline.
Now a word on gears. Street gears are harder than race gears and wear longer before making noise. Old timers in the business will tell you that OEM Spicer gears are the hardest and last the longest. They are also the hardest to set up. If wear is not really detectable beyond the contact pattern, a used set of Spicer gears can be expected to last longer and run quieter than a new set of track gears like you might get from Yukon, Richmond and others. As always YMMV, it depends almost entirely on the setup.
More later.
Jim
Good News Everyone!
I think I have the Maserati part number for the vented disc that is a direct fit on the Jag IRS, that number is: 329510200, used on the 1979-1990 Maserati Quattroporte III. Looks like it requires a 1/4" spacer between the caliper halfs that can be locally fabricated and has no fluid passages. Longer bolts will be needed. I'm locating a source. I'm pretty sure the stock bridging brake lines can be tweaked to still work.
This will result in cooler brakes which will in turn put less heat strain on the stub shaft seals resulting in less leakage which in turn will keep the brakes operating more efficiently. The small additional weight will be sprung weight and will not affect ride or handling but may extend service life. The adjuster screw for the e-brake caliper is probably long enough to be used as is, and the forked spring can probably be spread enough to also work.
Below I have some shots, the first of which you might not be able to see but was to show the pinion markings, the most important of which gives a + or - distance from an arbitrary zero reference point used to set up gears at the plant. When you do a fresh tear-down if you record that number it provides a handy starting point for setting pinion depth with the new gear set. Starting with an empty case I lack both that reference and the special gages used to set it and will have to use test fits instead, working from both ends to the middle. This means a full install and pattern check followed by a correction and repeat until the pattern is correct, both pinion depth and backlash affecting the contact pattern. That pattern should be well centered, spread, and may favor the root of the teeth a bit. We aim for perfection here and may even sometimes achieve it. The process is repetitive however.
Next shot is the sort of shim collection you might see after you've done a few. These will suffice for the pinion at both ends but a new carrier shim assortment had to be ordered. Another $30 expense available from most axle suppliers. Following on, a micrometer is the best method to select the right shim combination. Test fitting can get you within about .003" without it, and you might even get the right ones by feel alone but with the mic you know what you are doing. Typical thicknesses start at .003 then .005, .010 and so on so you can see that the 3 and 5 shims are what you have to work with, the rest are just spacers. In my case the original oil slinger and a 5 got me the right preload torque on the bearings but this will increase as the pinion is moved into the ring gear.
Last photo shows the setup spacer and nut. It's important to use a non-locking nut during setup. Back in the early days a buddy and I didn't know that when working on his Jeep and nearly ruined the threads on his pinion. It took a LOT of work with a thread file to clean it up enough to be usable and pretty well wiped out the thread file in the process, then we had real issues getting the replacement nut properly torqued. So don't do that. Use a straight nut then put the metallock nut on as the last step, just after the seal is installed and rotational torque is checked for the last time. This is the step where you install the yoke.
For setup I am using my Milwaukee 3/8" impact driver to torque the pinion nut as this makes that part of the job quick and easy. I can get about 60-70 ft/lbs with that while holding the pinion gear with my left hand and that is enough to fully seat the bearings and shims. Full torque will be over 120 ft/lbs and can be over 225, the specified range is to allow for crush sleeves. No crush sleeve is used here so the preload torque is NOT set by the pinion nut torque but by the spacer shims so it is much the same as you might do with front spindle bearings EXCEPT if you are in the practice of setting your spindle bearings loose as many are you wouldn't want to do that here as it will cause the gears to wear out and won't do anything good for the bearings either. Bearings being bearings, this same method is optimal for spindle bearings as well, but being oversized and grease lubricated the MGB spindle bearings can live with no preload. It's not what the bearing manufacturer would recommend but you can get by with it.
The next step is to set the preload on the carrier and this should be similar to the pinion preload. There are several ways to do this and most commonly a shim method is used whereby you find the zero play position and then add usually about .006 to .010 for preload and this works well. Another method is to put a torque wrench on one of the ring bolts and do a direct measurement. This requires the wrench to be at the correct angle, basically 90 degrees from the line between the bolt and the bearing centerline. Typically as bearings increase in size the preload rotational torque also increases but here that isn't very significant and we can pretty much ignore it.
Usual typical recommendations for bearing preload torque on bearings in this size range are about 6 or 8 inch pounds for used bearings and 10 or 12 for new as the new bearings are expected to wear-in (the rollers and races actually burnish each other) which lessens the preload. Bearing manufacturers do not do this step because microscopic variations still exist in manufacturing and this allows some very slight accommodation. I will follow those recommendations as closely as I can.
Jim
No pictures today (probably) but the shims came in and I've made a little progress. So first you lay out your shims by size, in this case .003, .005, .010, .022 (or so) and .030. That's what I have to work with, the usual. Next the carrier is plopped into the housing with the setup bearings and a screwdriver used to pry it back and forth getting some idea of how much play is in there. In this case it didn't look like a sixteenth so the two .030 shims are out. One 30 and two 22s though, that looked close. At this point slightly loose is best. Now we get the dial indicator which will be needed in any case to check backlash later.
Prying back and forth with the indicator on the back side of the ring gear and trying ever so hard not to move the case around on the welding table, I added first a 5 then a 3 then eventually removed both of those in favor of a 10 and there we are. Just a bit snug to drop in the carrier and races and prying back and forth with the screwdriver shows at most maybe half a thou. Good enough for now, I'll be shifting shims to the other side soon enough. I will be adding 8 to 10 to this stack on final assembly, should be 4 or 5 to each side.
Next step is to find the pinion depth. This pinion is marked with a zero. A good starting point for the shim pack may be .060-.065" so I will try that and see if I can get the backlash close at that depth, then adjust the shim pack to get the backlash. While doing this I think I will remove the shims from the carrier so it can move freely back and forth. Once I'm close on the backlash I'll start adding shins back in to center the carrier on the pinion and hold the backlash to spec. That will likely take a few trys and then I'll move on to the pattern but I'm probably done for today.
Jim
In keeping with my philosophy of trying to do at least one small thing each day, yesterday I fit .060" worth of shims to the large pinion race, which turned out to be a stack of 10's and a couple of 5's, added 60 to the small shim stack and snugged down the pinion before removing the shim pack from the carrier and dropping it back in the case. The pinion bearings are now a bit too tight but that can be dealt with later. Zero backlash was achieved by pushing the carrier to one side, going the other way gave too much backlash so the range has been established.
Next step is to add back in the carrier shims to center the carrier in the correct backlash range and then check the pattern. If I'm extremely lucky it won't be too far off.
Jim
Yesterday I shifted a .010" shim to the gear side of the carrier, reinserted it and found I had 10 or 11 thou of backlash, then with some Prussian Blue dye determined that the contact pattern was too deep. But the blue gives a bad contrast so I looked for something better.
Having trouble finding my thimble of yellow pattern dye from last time, (and it may have been all gone) I came up with an alternative. Some of you may recall Desitin diaper rash ointment. It comes in at least 3 varieties, regular, Maximum Strength, and Maximum Strength Paste. That last one comes in a 2 oz tube for under 7 bucks where the yellow or red dye is about 20 bucks for a quarter ounce or so and I would have to wait for it.
The active ingredient is zinc oxide which apart from being an antibiotic is a bright white finely powdered pigment and a solid lubricant. It makes up 40%. The remaining 60% is petroleum jelly, cod liver oil, lanolin, corn starch, glycerin, beeswax, and 3 minor ingredients. Sorbitan Sesquioleate is added as an emulsifier/surfactant, tetra di butyl hydroxyhydrocinnamate is added as an oil soluble preservative usually less than .5% and the last, fragrance is almost guaranteed to be an essential oil based on the other ingredients. As you can see all are oils or lubricants and compatible additives of one type or another. I think it's safe to say that any of this left on the gears isn't going to do any damage, particularly the zinc which is often used as a lubricant additive to provide a protective film and corrosion resistance.
First shot below is with the Prussian Blue.
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Then the Desitin paste.
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The last two show my progress on the pattern today. I moved the pinion out .005 and shifted the ring towards it .010 and got .007 backlash. It's harder to see the pattern than I would have liked and I think in future I will drive the ring against the pinion instead of the other way around. With .002" added to the space between the pinion bearings the preload there is still too much and it has somewhat stiff resistance to turning. I may measure that next time.
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The pattern is hard to read as you can see. I'm hoping more pressure will thin it out for the next time. Also it might be that the Desitin Max creme is a better choice than the paste as it would be thinner. but it looks to me like the pinion needs to be backed out a little more.
Jim
Latest patterns, completely consistent with the pinion sitting too deep:
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Today is a day off, I'll get back on it tomorrow. Going out of town to get new hearing aids.
I had run the pinion in another 10, maybe another 20 will do it provided I don't run out of shims on the carrier. We will see. Pinion preload is now at 7 inch ounces, a smidge on the light side. That will change.
Jim
OK I lied. Not doing anything on it today. It's in the 20's and I had a derm appointment and I ain't going out any more until tomorrow when it's supposed to hit 40. Yesterday was cold too. But, I have been really enjoying the heat in the MGB. Between yesterday and today I logged maybe close to 500 miles and have been toasty warm the whole time. In the rain yesterday, and a bit of blowing snow flakes today. Didn't have to swipe at the windshield with the towel one single time and most of the time all the windows were clear. No water got in either and I think that's a first. In my experience that's pretty uncommon in an MG.
Jim
Yesterday I ordered an inch/ounce torque wrench. Those aren't that easy to find, but they do come up used on ebay. I found one with a missing screw for $19 shipping paid, has a 3/8" drive, goes to 100 and is a beam type so that should work fine. Pinion torque with new bearings should be 20-40 in/oz, half that with used bearings.
I decided to go to the direct reading method and avoid the calculations, simple though they are. The more I can reduce the error vectors the better. None of my clicker types go low enough and using my spring scale and 1/4" drive 6" long breaker means the reading has to be divided (multiplied, see what I mean?) by 6 which, yeah that's simple but why even deal with the math at all when for less than 20 bucks I don't have to?
Anyway, moved the pinion forward another 10 and saw that I had just 20 left at the carrier. So I shifted that shim to the other side, assembled and found it bound up. Fair enough, I think I may just take out another 10 on the pinion and just see where I am. If that doesn't move the pattern across to the other side it means I'll have to pop the carrier in the lathe and skim a little off the shoulder. That I can do easily enough.
Jim
"I ordered an inch/ounce torque wrench. Those aren't that easy to find"
Real easy to find at Harbor Freight. Not so easy to trust the calibration.
Inch pounds, yes. Inch ounces? I don't think so.
Jim
Oops. My brain misread that one. Can't say I ever had a need for one of those.
Yeah that's a real lightweight. But with a 100 in/oz range (0-6.25 in/lbs.) it's perfect for setting up pinion preload, or for that matter, spindle bearings. Typically you want full contact with very light pressure so that all the rollers spin instead of skipping but not any more than is needed for that as it will generate heat and also be less efficient. for bearing preload if you are thinking in terms of in/lbs they are probably going to be a bit more snug than is necessary. Happily they can tolerate a fairly wide range relatively speaking but it's way too easy to overdo it. If thinking in terms of in/oz OTOH roller pressure will be minimal with plenty of overhead, but at some risk of roller skip.
Sometime when you have a new set of Timkens in your hands you should clean them with solvent, let them dry fully, and then assemble the bearing to the race in your hands, place it between your palms and turn it while applying different amounts of pressure. With no or very light pressure you can actually feel the rollers skip and this is what you want to avoid as it causes point contact wear of some amount on a microscopic scale any time it happens, and if it happens once it will tend to happen again in the same place, increasing the rate of wear. Timkens can tolerate a good bit of this and still have a decent service life which is why we use them but optimized is best. Now visualize what happens when you apply a side load like you do with a wheel bearing and it's not too hard to see that the top rollers are more prone to skip. Which means that you need a bit more static preload to prevent that. So where the pinion preload might be from say 20 to 40 in/oz on the top end the wheel bearings might indeed be happier up in the in/lb range, 10 in/lb being equal to 160 in/oz. As we know, the pinion is only under heavy load under heavy throttle/engine braking whereas the wheel bearings are always under a side load and even more so when cornering or braking.
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Here's the latest. Poor lighting but on the drive side the pattern is towards the inside of the ring gear while the coast side looks good. Both are about right top to bottom. This is with zero backlash.
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Backlash is currently way too tight so the pattern should change a bit. My current understanding of it is that adding some backlash should move the drive side towards the center of the tooth, however the pinion may still be a bit too deep so the first thing could be to back the pinion out a bit more to get the backlash into range and see what that does. However, this pattern is consistent with at least one guide referring to setting up used gears and is also referred to in instructions for setting up gears for competition. Due to the applied torque I suppose.
https://www.mopar1.us/backlash.html
Fortunately there is a little consistency between online instructions if you dig deep and wide. I've gathered that most likely I need to move the ring gear away from the pinion, which would give me the backlash that I need. But it will probably also move the coast side away from it's nicely centered position as well. That being the less critical of the two I may have to accept that but I can also try moving the pinion forward a bit more so I'd estimate I'm within a half dozen attempts or so of getting a pattern that's within acceptable standards, I just need to decide what I move next. Actually that's not even a decision since I can't move the ring gear away without trimming the shoulder on the carrier. I'll take another 5 out of the pinion shim pack and see how that looks.
Jim
Been staying inside and avoiding the cold, doing other stuff. Yesterday I put a new back on my phone and plugged in the face camera that I'd missed last time. Today I'm going for the treated deck boards I'll be using under the basement floor that I'm repairing so I'll have something to work on this weekend when the storm hits again. If I'm real lucky we won't get snow. Might get a little done on the diff but it really depends on how fast my fingers start hurting. I have to make room in the shop for the MG so I can put lumber and the chop saw in the garage. Sure would be nice if I could head southward next winter. These are the days when I don't get much done that isn't inside work, but it's wonderful for the HoneyDoo projects.
Even on these cold days I'd still prefer to drive the MG, the heater is now just that good. But it won't haul a big stack of 1 x 10 x 10's. Not with the top up anyway and no matter how good the heater is it's too cold to drive it with the top down except in an emergency.
Jim
Brought home a bunch of treated deck boards and that part's all set to go. Went out and did a little more work on the diff.
The inch/ounce torque wrench is a big help. I had to tweak it a little to read zero but I got it properly centered and was able to get a good read at 20 for my last install. My backlash and pattern looks like crap but I'm one step closer. I'm going back out in a few minutes to have another look at it.
I keep getting a little crossed up on the shims. There's no reason for it and it's straighforward enough but still somehow I end up having to readjust the shim stack to get the pinion preload right and If I'm doing that there it's being compounded by the big pinion bearing shim stack and by the carrier shims as well. For whatever reason I had the carrier shifted in the wrong direction all the way. Well it didn't take much today to get 10 thou backlash but then the contact pattern is at the tops of the teeth so it's time to start working back the other way. The nice thing though is that I can now get an accurate number on the bearing preload and it's easy to measure. Just put the socket from the 3/8" impact driver on the little torque wrench and turn it. I'll be able to measure the carrier bearings the same way using the ring bolts so that's another plus.
I also figured out that if I turn the case on it's side I can plug in one of the stub shafts and then use a long combination wrench on the studs to spin the ring gear against the pinion to get a clear contact pattern. That's taken a significant bit of the effort out of the job.
It's also easier to load the carrier with it on it's side.
Jim
Still no pictures but I'll post something soon. I'm sneaking up on it. The contact pattern looks exceptionally good on the coast side but on the drive side it's still too far towards the inside of the ring gear. I've been reducing the backlash but my last check showed I still have .007" so I'm going to shoot for about half that and see what I get. That'd be a little tight but I don't expect to stay there. Apparently tightening it up is moving the pattern the right way but maybe not enough. I'll check it again and re-assess. Probably post a couple shots then.
I've been trying to find the optimal way to position the housing for each operation. I've got the lower pivot brackets bolted on and they help give a stable position whether on the bottom or the side. Definitely better on the bottom for turning the stub shaft to generate the pattern, I just hang the flange out over the edge of the table. That's working pretty good for popping the diff out too but on the side is best for reading the pattern and a little easier for putting the diff back in. May/may not do any more today.
I sent Moser an email asking what they would charge me to set up the pattern, asking for photos and the backlash spec. We'll see what they say, if nothing else it'd be good to know what they think the job is worth, and there'd be some reassurance in having it set up by someone who has seen it all.
Jim
I pretty much ran out of luck and patience on trying to find the Quattroporte inboard vented rear brake rotors and what I did eventually find was extremely expensive, like around $350 each IIRC, clearly unsupportable for an MGB unless you just happen to have some money to throw at it, which I don't feel like I do in this case. Still an option, but not one I feel like taking. Nor is the $1200 conversion package even though it includes everything needed. Just too rich for me.
So I ordered the Wilwood rotors from Speedway and downloaded and printed off the latest version of the drawing for the adapter disc (brake rotor hat although in this case it is flat.)
Wilwood 160-3450 Ultralite 30 Vane Vented Iron Rotor, 10.50 x .750 In.
Part #: 8351603450
Qty: 2 @ $ 110.20 each
Link for the hub drawing:
https://www.jag-lovers.org/xj-s/book/Hub%20for%20Vented%20Brake%20Rotor.pdf
Unfortunately it's been too long since I worked with pdf files so I wasn't able to paste the image into this post. What it shows are several improvements as I understand it. The hub works with the Wilwood rotor above. It enlarges and rotates the big holes 90 degrees from the stock rotors and spins the rotor pattern to match so that all the bolts can be reached with the greatest ease past the universal joint. This incorporates all of the evolutionary improvements to the design without adding any complexity. The part can be made using a lathe, a mill and a rotary table, or possibly an indexing head. It also should be possible to use the old rotor and the new rotor as patterns to mark the hole patterns but doesn't allow for using the old rotors as raw material as I had intended, due to the changes in the hole positions as either the new big holes or the old ones would intersect two of the new rotor mounting holes I think. I will check that and see if there is a workaround. Maybe rotating the new rotor pattern 45 degrees or something similar will work. Maybe 30 degrees, it's not at all critical as long as holes don't want to occupy the same space.
Anyway, the raw material required is 3/8" thick by 6" diameter. This can be purchased as slices of round stock and faced to 3/8", the feasibility of this approach determined mostly by the cutoff fee. Or it can be bandsaw cut from 3/8" plate. As I probably have some of that in aluminum I may do that. Someone suggested the aluminum would conduct heat inward faster but with the vented rotors I suspect it might not be an issue. Also 4 more large holes could be drilled for better cooling and less heat conduction. I like that thought well enough that if the old rotors can't be used I may use that approach.
As to the small parts, I have a set of rotor bolts from Speedway so that shouldn't be an issue. It's important that the bolt shank bridge the parting line. The pins get made from 4" bolts, possibly stainless such as the following:
https://www.mcmaster.com/92186A558/
The spacers get made from any handy 1/4" plate, the crossover lines get spread a bit and work as is, longer cross bolts are needed which can be hardware store grade 8 2-1/2" long, McM has these:
https://www.mcmaster.com/products/screws/hex-head-screws-1~/threading~partially-threaded/material~stainless-steel-2/material~steel-1/high-strength-grade-8-steel-hex-head-screws/
Or these for the extra strength stainless but expensive version:
https://www.mcmaster.com/93810A460/
The brass forks can be split and a retention plate with a lip bolted on top. I have some stainless square tube that those can be cut from. The lip replaces the section cut to spread the fork legs 1/4" and allows the spring action. That leaves the adjuster screw which may be OK. The simple fix here is to use the adjuster screws as is and accept minimal thread engagement. Perfectly valid. Or the screws can be replaced, SCCS were recommended, I would suggest flat stainless countersunk capscrews but that doesn't leave provision for the cotter.
McMaster-Carr has some options. I think these are standard 1/4 x 20 thread so something like this might work. Sorry, I don't have the exact length needed handy at the moment.
https://www.mcmaster.com/91802A552/
Here is the reference:
https://www.jag-lovers.org/xj-s/book/InboardBrakeUpgradeSmallParts.html
Jim
Here's the image, Jim.
That's it. Thanks John. I'll get the length for the adjuster screws, just maybe not before it gets a bit warmer. And go a few more rounds with the pattern.
The MG is in the shop until the snow goes away but not on the lift, and I'm not ready to tear it down until after I've replaced the rear airbags in my truck. That will take me up to my date for gall bladder surgery and then we're getting perilously close to spring. Which means I'm in danger of falling behind. But I'm holding to the sequence. I want to test the new gears and fuel pump before switching engines.
Jim
Jim