340 upgrade

[BlownMGB-V8]

Bill J. Thanks, I just about missed your post. Sounds like a very good axle for a S/C setup. There is indeed an aluminum center section available, see earlier post. The price I saw was around nine hundred so a little expensive for 11 to14 lbs. There may be others.

Jim

[BlownMGB-V8]

Believe it or not, I've been looking at a Ford Expedition/Navi 9.75" IRS diff. It seems almost inconceivable that one of those could be small enough to fit the available space, but it may be and they aren't hard to find. It has a side mounting pad for the pinion mount which is reportedly 3-1/2" from the pinion centerline, meaning that a 1/2" offset should be enough to give adequate clearance. The rear mounts are on the cover very much like the Mustang 8.8" unit and the distance from axle centerline to the back of the rear cover is  about 5 to 5-1/2", meaning that it may fit.

Now it's very obvious that this is massive overkill in terms of strength and that probably means extra weight which we don't need. But on the plus side, it is sprung weight, it shifts the weight balance a bit to the rear which isn't a bad thing, and then there's the clutch type posi unit to consider. These units as a rule tend to be less effective than we'd like due to a small clutch area and rapid wear, and are often marginally effective within sometimes as little as 20,000 miles. A bigger unit in a lighter car means it will be under stressed and should work better and last longer, both very good things. In addition, the pinion mount point is very beefy, being designed for a 3 ton vehicle so building a strong enough mounting system should be pretty easy.

My truck should have the same diff, though a solid axle instead of IRS. So in the next few days I hope to have a chance to drive it up on the maintenance pit and take some measurements. Then we'll have a better idea if it's a viable candidate.

Jim

[BlownMGB-V8]

I didn't buy the 9.75" unit. The more I thought about it the more it just seemed too big. The pinion mount surface would have been flush with the battery box unless the diff was offset and then the handbrake would be in the way of the driveshaft and then there is all that weight.

Instead I've been looking at a new approach to the Jag unit. The Dana 44 used in the Jag IRS has an ideal ring size at 8-1/2". It isn't that much bigger (heavier) than the stock MGB unit but it will handle any engine and transmission we could reasonably put in the car. It can be mounted without undue fuss and bother, using a method that will allow pinion angle adjustment, and it comes with inboard brakes. What it does not come with is an upper control arm of any sort and because of this it is much heavier than it might otherwise be. These shortcomings can be remedied.

As I mentioned on the Roadmaster thread, Spicer sells slip yokes which can be used in combination with U-joints, driveshaft flanges and stub shafts to make up short units that can take the place of the Jag half shaft. I will have to do some checking on specific parts but this gets us the push-pull capability that is inherent in CV type half shafts and allows the use of an upper control arm (UCA). Based on past experience with 4 wheel drive and divorced transfer cases I'm confident that the right combination of parts can be found.

Once we're free to use a UCA the logical next step is to triangulate it so that it can transfer thrust loads to the body. By doing this we achieve two very important things in addition to locating the top of the wheel. First we remove the torque loading of the upright which is inherent in the original design. Second we split the thrust load between the lower and upper control arms, allowing the use of lighter, thinner materials. These two changes mean that the combined weight of both CA's is now significantly less than what is needed to prevent deformation of the original LCA. In the process we can eliminate the radius rods used in the original installation as well, with their engineered in binding and slop.

At this point I still plan to use the uprights that I had waterjet cut for the T-bird IRS, which move the outer pivot points outwards to the point that they are actually inside the rim itself, thereby allowing the use of longer control arms for better suspension geometry. By the time it's put together I could decide that a built up unit will work as well or better but since I have these I might as well use them. I will probably stick pretty close to the T-bird arm length and pickup points, and may even use the T-bird bushings for adjustability and because in the lighter car they will be stiffer and therefore more precise. For hubs I haven't decided. I need a compact hub that uses a cartridge bearing and a chevy lug pattern, but there should be several choices for that. A four bolt flange on the stub shaft or a U-joint yoke either one should work.

Jim

[BlownMGB-V8]

Turns out my quest for tires may be marginally easier than I had thought, I'll know more after I do some searching. Could be no better. But I made a mistake. Don't even know how or why but somehow I'd gotten the notion that there was a 1:2 relationship between tread width and tire height. Not so! The BFG 265/50-14 is 10" wide mounted on a 7" rim and tread width is slightly less, say 9-1/2 depending on where in the curve you say the edge is. So while the search is still difficult it may not be impossible. There may be a 15" wheel and tire that will do the trick.

Jim

[BlownMGB-V8]

Big news in the engine department. Mike Tomaszewski of TA Performance has informed me that he is looking into making a set of heads to fit the Rover engine. This came about due to the inquiries of one of our Australian friends, who asked Mike if he could make a product to compete with Wildcat or Wilpower. It turns out of course that TA's existing high performance aluminum head for the Buick V6 is easily converted back into a V8 head by the simple expedient of combining parts of two existing V6 molds, resulting in a Rover head that has every feature of TA's formidable V6 heads. Naturally this head would also fit the 215 provided the valves would clear the bore, but more importantly, it would fit the 300 and the mighty 340! Remember also that the 340 is only a .050" overbore from being a 350, so a lightweight 350 with tremendous performance potential is well within reach. Even more interesting, by the simple expedient of using a 340 cam, intake and exhaust, these heads will bolt right up to the Buick 350 block! (some of the cam bearings will need to be sleeved to fit the block) Buick 350's are both plentiful and cheap, as well as being a bit lighter than either the 300 or 340.

How's that for some news you can use? The release date hasn't been set, in fact Mike is still considering the idea. But once the decision has been made the road to sales should be a short one.

Jim

[BlownMGB-V8]

I will be continuing on with my plan to use the '64 300 heads. Dale has those heads and is working on them now, so probably he will send them along with the engine for the Roadmaster when that comes back next month.

I got the roadster back down on it's wheels today, new brakes and all. It's still too muddy to get it out and see how the suspension is going to act, as it sits the rear is stiff and high. But I expect it to loosen up and settle after it's been driven. Gives it a rather rakish appearance, not that it needed it. Once we get past the tax returns I'm planning on putting down gravel and the mud will no longer interfere with my driving, which would be real nice on days like today.

I've learned a lot about tires lately, and wheels. Exactly what that'll mean on setting up this car is yet to be determined, but one thing I know, I can go a LOT bigger on the rear tires.

Jim

[rficalora]

so did you do an IRS or put it back on the ground using your existing axle?  What tires did you put on it?

[BlownMGB-V8]

I won't get the IRS done until after the one in the Roadmaster, so it's still sitting on the stock axle and the old hard 265/50-14 BFG's. I've got a whole new drivetrain in the works, front to back but it'll take a good bit of time to put it all together and there are still IRS parts to buy and to design. In the meantime I'll have to decide whether to stick with the ford lug pattern or go chevy, look for suitable rear wheels, decide on the rear tire size but I'm thinking that a 315/35-17 would fit just about right. The Sumitomo HTR Z at $99 for an ultra high performance summer radial seems like a good choice, but finding the right wheels won't be easy. Anyway before I go there I still need to find the right differential. I'm not seeing a lot of good choices on ebay right now so that's holding up the project. Did see a sweet Corvette dana 44 3.55 posi aluminum case unit but at 2500 bucks, ouch, not for me. So I'm still looking.

Jim

[BlownMGB-V8]

Not much new to report, but with the weather getting warmer that should change soon. I did however get a couple of rolls of 1/8" stainless tubing ordered. This will be used to plumb the hydraulics for the front tilt assembly. I will attempt to use the existing gas charged cylinders (maybe I should say gas leaked cylinders) and plumb them for the hydraulic lines. The remaining challenges will be the valves and accumulators. This will connect to the tilt/trim pump in the trunk. In this way I hope to finally have the tilt assembly fitting the same way it did before I took it off to paint it. Somehow it has never fit quite as well since and I think it has to do with the force applied by the gas struts.

Dale Spooner is working on the 300 heads and they will be coming back with the 455 engine for the Roadmaster project in about a month and a half. At that point I will tear down the reman shortblock and reassemble using ARP rod bolts and making whatever other changes seem appropriate, and then install heads, valve covers, pan and front cover. Focus will then shift to the blower intake and the transmission.

In the meantime all I need to be able to drive the car is fresh gravel on the driveway to the lab and that's just waiting on the weather.

Jim

[Citron]

Jim,
So I guess I willbe picking up, from Dale, the 455 block, crank, heads, pistons, rods and 2 340 heads?
Just trying to decide what trailer to drag along.  I would prefer the luggage trailer.  Think all that will fit?
Also, do you need another engine stand?  I could bring it along also.  If so it will probably be the open trialer.
I think I will be picking it up on April 24 if Dale has it all ready.

Steve

[BlownMGB-V8]

Another stand would be handy, especially if we decide to do any work on the 430 BBB. The load should be identical otherwise to the one we delivered to him. You might get all that stuff in your white trailer, but I could see a possibility of some of it ending up in the trunk.

Jim

[Citron]

Jim,
What trunk.  My BGT has no trunk.  I think it will all fit in the white trailer and that would mean protection from the weather.
I'll disassemble on of my engine stands and see if it will fit in the back of the GT.

Steve

[BlownMGB-V8]

I just won an auction for a set of Corvette rear wheels (plus one front which I won't use). They are 17 x 10" and the price was right. They should work just fine for the rear. This pretty well means I've decided to go to the GM bolt pattern, and Jag or Corvette parts may be used in doing it. What I'll do is, buy or make a set of billet spacers/adapters of the correct thickness to let me use these wheels with the stock axle (they have a lot of backspacing) and then make the IRS the correct width to fit them.

For the time being though I will lend these wheels to the Roadmaster project and use them to set up the Jag IRS on that car. Once that is done I will then use them for my roadster.

Jim

[rficalora]

Hey Jim, I saw this in the current issue of KitCar... thought it might give some ideas... rear cover for a Dana 44 diff...  shown here on the company's aluminum dana 44 housing...

[74ls1tr6]

Jim, I thought you might get a kick and others out of this youtube vid.... I know it's not british but using an R200 diff in this supercharged ls1( correction LT1) 240z...kind of shows that an R200 can handle the power.

http://www.youtube.com/watch?v=FIL6C25Vfrc

[mgb260]

Jim, Here is a 9 sec. 454 supercharged Z running a R200 diff.

[BlownMGB-V8]

Thanks guys, that's good info. I did a little research on the r200 diff and it's true that some of them are holding up to very high power levels. What I was seeing at that time was their use in a awd configuration and with some incidence of axle breakage and differential concerns. These problems were being addressed with high strength alloy aftermarket parts iirc, which is something I'd rather avoid if I can, but it's still a good idea to follow what's being done there. That last photo is pretty impressive. The alloy D44 housing and hanger are sweet. I'll try to do a little research on that, it'd be nice to know how dearly they like that one. Probably out of my budget, but you never know.

Jim

[rficalora]

Don't know what your budget is Jim, but I'd say they like it pretty dearly... http://www.newmancarcreations.com/differentials.html  I was thinking it might spur some ideas more than a purchase order

[BlownMGB-V8]

I saw Larry Shimp's post on the Jag IRS thread and fired off an email to the recommended parts supplier. I'm considering going that route. Also I just ordered rear tires to fit the Corvette rear rims. Some will no doubt think them a bit excessive but I couldn't resist. Sumitomo HTR-Z's for $99 each in 315/35-17. It'll be a tight fit but I think I can make them work.

Jim

[MGBV8]

"Sumitomo HTR-Z's for $99 each in 315/35-17"

That's amazing!

[mgb260]

Here is a Australian idea for a Jag lower control arm, I would use a brace on both sides. I like the single shock mount also.You would have to use a stiffer coil over spring ,say 350 lb instead of 200.

[mgb260]

Jim I almost  forgot, I remember your thread on brakes for your roadster. You can get brake drum hubs from early Mustang,Fairlane,Cougar  and remove drums and have a nice 5 lug hub, You need a swedge cutter. Then find a slip on rotor.Also you can buy 265-50-15 tires at Summit (Cooper Cobra Gt).The link Larry mentioned  on the Jag rear on part 3 tells how to go to Ford pattern.

[BlownMGB-V8]

What I thought was amazing was that they called to make sure those were the tires I wanted to order for an MGB. So I sent them a hyperlink.

Jim, that looks like a pretty good idea. Better than gussets since the coil-over is supported in double shear.  I still think something along the line of a radius rod is a good idea though, at least for acceleration. The more I think about the rear strut that Arthur suggested the more I like it, and if the LCA has enough torque resistance to resist twist from axle torque then there's no reason why a 5/16" cable wouldn't be stout enough to handle the tension load on that link. Not saying that would be the best solution, just an indication of the minimum requirement.  Thanks for the tip about the tires, only thing is that I was looking for 14 inch. It'd still be good if I could find them.

Converting to the Chevy bolt pattern is going to be a little complicated but not too bad I guess. If I use jag parts on the rear that part will be taken care of and I should be able to use Camaro rotors on the front similar to the Arntz/Butler Cobra. But then I'll also have to find a GM space saver spare and I hate to give up my powder coated aluminum spoked Lincoln one. It's a sweet piece. But, maybe I'll get lucky and run across something suitable.

Jim

[BlownMGB-V8]

Got the roadster out for a drive today and definitely enjoyed the weather and the somewhat softer suspension. I'm not sure the rear leafs have loosened up yet though as the car sits a bit high in the rear but that's better than sitting low. I took a page from Bill G's book and added two half-leafs to the front of each spring pack to control the wrap-up, but I also banded the pack tightly in the front and I believe that's causing it to ride high and stiffer than it would otherwise do. I'll give it a week or two and then consider removing the front clamp. There is no hint of wheel hop, though I did lose some of the even traction I had before and the right wheel is now laying about 3 times the rubber that the left one does. This may also be from the clamps, I really have no way to tell except to remove them and try it again.

Since I won't even be able to start on the IRS for a couple months and my new rear tires are on loan to the Roadmaster project until after the summer meet, I plan to use some of that time to either buy or make (most likely) a set of adapter/spacers to center them in the wheelwells and convert from the ford to chevy lug pattern. That way I can run them on the stock axle while I'm developing the bolt-in IRS package. The extra 2" of fresh rubber may shorten the life of the axle but it's a chance I'll take, there's still one more spare axle in the shed.

Talked to Dale a few days ago and he's going to try to send my 300 heads back with Steve when he picks up the 455 for the Roadmaster. That should get me going on the 340 build, which I can do while waiting on the Jag IRS. Considering the push to get the Roadmaster ready for the meet I may not get much done anyway. But the two cars should end up with very similar rear suspensions.

It doesn't look like I'll be able to bring my roadster to the meet this summer, not unless I can convince Edith to drive the truck and pull a trailer with the Roadmaster on it with me in a different car. That's going to be a real tall order. She doesn't mind driving the truck at all, but towing a trailer by herself isn't something she's going to take to very well. So I'm having just a little trouble resigning myself to not having my car there. At least I'll have the Roadmaster there, but of course it will not be driveable. That was one of the choices I didn't recognize I'd have to make when we started that project. I don't mind doing what has to be done, and it will be a good chance to ride in some fine cars so it's still a good thing, just don't expect to see a certain winged beast.

Jim

[rficalora]

Jim, how about a trailer that'd hold both the roadmaster & your car?  That way you get the best of both worlds.