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MG MGB GT V8 Factory Originals Technical - How big's your rear end... (ok, your car's)
|I've been planning to use an 8.8" rear end thinking if the 302/T5/8.8 worked for Ford Engineers, it should be pretty good for me. Plus, they're readily available locally & you can get just about any gear ratio for them... Then I talked with Ted Lathrop at Fast Cars & he strongly recommended the older Ford 8 inch unit. Basic reasoning is it's plenty strong and a good bit lighter than the 8.8 inch. He was saying reducing unsprung positively affects handling... i didn't think to ask him about traction -- unless reducing unsprung weight enables you to add sprung weight, seems like this would also reduce traction??|
Any insight you guys can share on this one?
|I suspect that the rear unsprung weight of an MGB is actually greater than the sprung weight. Thats why they crash about so, part of the 'fun' really. Sixties sports cars, yeah baby yeah.. . |
Go with the new lighter diff' and put the bits of the old one in the boot;)
|I have an 8" Ford with 3.27 Auburn posi in mine. In fact, Ted did the work on this one for me. The diff came out of a 1979 Ford Granada at a local salvage yard and originally had 2.79 gearing.|
I highly recommend D & D's S10 axle. It comes ready to bolt straight in. I chose 3:42 ratio and Eaton posi. Plus a matching driveshaft and my 302 conversion could finally get the power to the road.
D & D's website is www.aluminumv8.com
I believe the weight of this axle is about the same as 8 inch Ford.
69 302 Conversion.
|Take this how you will, but several years ago I put a V8 into my S10, and the 210hp was enough to shatter the gears in the stock differential. Twice. It had the Auburn limited slip carrier. Mind you, it hooked up really well with off road tires and the vehicle was heavier, but a 300hp B may be able to break it as well. I believe the Ford 8" is not only stronger, but easier to rebuild (on a bench) should it break. At least that's my experience.|
|I will say the 8.8 is cheaper because the posi and the rear are everywhere. I put the Ford 8" in my 180 horsepower 3.9 Rover. In the heat of the summer it does better burnouts,in the cooler weather it just hooks up and goes. In the 8" you need axels that are not tappered. When you cut the axles you need at least 4" longer each side to get to smooth part of the axle. Advance Auto and the older type auto stores had everthing I needed to build and all new axle.Use the MG brake tee because it is $12.00 Fords is almost &50.00. Also you can get new axles if you get a short rear out of a Maverick. Denny|
|Unsprung weight is very important in a race car. The 8 inch can be bought brand new from Currie in Ca. That means new husing and third member.|
Do not dismiss the early 7.5 Ford it's also lighter and plenty stgrong for a light car with 350 lb of torque.
If yo can get a 8.8 at a good prize, go for it. Make sure they cut all of the excess metal in the housing which is not needed.
Another rear end that is plenty strong is the 98 and up F Body cars Camaro, Firebird. This units are light and strong and inexpensive they are good for 450+ lb of torque. Good enough for the LS1 and LS2 engines.
If you are serious about racing, then use a 8 inch with thin wall tubing and housing and a alloy third member, rifle axles and alloy calipers.
|I opted for the Ford 8.8"/3.27posi (from a '96 Mustang)in my conversion primarily due to the newer design and the availability of disc brakes. Not sure if the older 8" Fords are readily available with discs. |
D & D's "MGB ready" GM axle does make a lot of sense if one doesn't want to tackle an axle rework.
|I'm in the same boat as far as a rear end search. I have a Ford 327 8.8 posi that I got from a friend for next to nothing, however it's just the differential and ring and pinion, no housing, axles, etc...|
What Ford rear ends have tapered axles, and why are they so undesirable anyway? Do machine shops not typically have the equipment to cut new tapered splines or what??? I can go to the local pull and save and get any rear end out of any car for $15 when they run their sales on them. They have tons of Explorers with 8.8 rear ends. Any reason one of these wouldn't be a good candidate to narrow? What's the big deal with tapered splines?
|I don't think that "tapered splines" is the problem - they are all straight. It's the portion of the axle next to the spline that is necked down on some (Ford 8 and 9 inch axles), so that when the axle is shortened, there is insufficient material to cut new splines.|
Not sure if a c-clip axle can be shortened reliably without using a c-clip eliminator kit - and then I've heard that they are notorious for axle seals leaking. No first hand knowledge, though.
|Yeah, listen to Ted.|
Getting rid of unsprung weight is very good. Unless you are using drag slicks and really hooking up who cares about how strong? I haven't broken the stock rear yet.
Ted is right the 8" is strong enough. The 8.8 is heavy AND just a copy of the 12 bolt Chevy. Lotsa choices out there besides 8.8".
|Carl, the difference is in what use the cars get. There is a huge drag racing following in middle America who get their jollies turning tires into smoke, or watching other people do that. It leaves me scratching my head, but there you are. That sort of use demands heavier rear ends.|
If you don't accelerate off the line like a high school boy with an excess of raging hormones, you are right - you can get away with even a stock diff. It is really the standing starts that are diff killers.
The downside to using a stock rear end is that one day you might give in to some heretofor hidden urge to out-drag that lady in the Maverick pulled up at the stoplight beside you, and will turn your stock diff into scrap with one moment's indulgence....;-)
|I have a Ford/Currie 9 inch 3.00:1 ratio, 31 spline axles with Ford Explorer disk brake setup and emergency drums less than $2,500.00...now available with an aluminum pumpkin if you want.|
|Michael S. Domanowski|
|Ok, I understand the unsprung weight thing now... thanks. Given the dialog above, can anyone provide a comparison of the "popular" rear ends -- sort of like the one Dan Masters did for motors where he compared the various motors & their weights (I think that was Dan, wasn't it)?|
As an example, maybe the weight & relative strenght of (assume posi/locker type for the ones other than the standard MGB)...
Standard MGB rear end
D&D's Chevy S-10
This thread was discussed between 11/12/2005 and 13/12/2005
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