[klavith]

Hey guys & girls, I just picked up my 71 GT and i'm currently planning out ideas on how to modernize it a bit. I have heard on a few sites that the rear axle isn't that strong. I'm planning on doing an engine swap and hopefully getting the thing up to 300 HP. Will the factory axle handle that kind of power?? What i would really like to know is if there is a setup i can get off a different car that has rear independant suspension and disk brakes. Anyone got any ideas on what car would be good to try this from or if it's even worth trying? Any help with this would be great!

Thanks
Brandon

 

[ConreroGT]

The short answer is no. It probably won't hold up to 300hp for an extended period of time.

Do a search on the site. This topic has been discussed quite a bit.

~kyle

 

[GT-Freak]

Q: Will the factory axle handle that kind of power??
A: No.

Q: ...is if there is a setup i can get off a different car that has rear independant suspension and disk brakes.
A: Yes. 260Z-280Z-280ZX-300ZX is one, actually 2 differential types. See www.hybridz.com for details. They use a mustache bar (difficult to work around) but are the correct width, can be LSD and have rear disks. These can handle 300 hp/torque. There are others, but I'm not the guy to ask on those. Vette rearends are typically too wide to be narrowed this much (bad 1/2 shaft angles). I have an unused 280ZX in my garage.

Note: Torque is the big killer on axles. And it's the biggest problem for finding a narrow rearend, as most narrow rearends are meant for 4 bangers.

For live axles, many people use late model GM's (S-10) and Ford 8.8 (Mustang). I found the right width Dana 44 off a 1970's postal truck. Dana 44 come from some Jeeps (like Grand Cherokee which also has disks), IH Scouts and many trucks (full size domestics). Narrowing any rearend is expensive (by my standards). Plus, you'll need to remount all the correct hardware. Disk brakes/kits are available for all these.

 

[RallyBob]

I'm planning on doing an engine swap and hopefully getting the thing up to 300 HP. Will the factory axle handle that kind of power??

I've exploded MANY rear Opel axles with under 150 hp. With 300 hp, and more importantly, higher levels of torque, you will likely destroy the rear axle on the first day you get your transplant rolling.

Going by the vehicle width, I've always thought a Miata rear suspension would work well on an Opel, but with 300 hp, you'd have to swap in the RX-7 differential. This was done a lot with Ford 302 transplants in Miatas a few years ago.

Bob

 

[Nathan Acree]

Bob,

Do you have any ideas on how to fit the Miata rear suspension? I have done some looking into the idea, but it seems like it would be necessary to either narrow the Miata setup by 3" per side, or use the stock width and go with large fender flares. I am not sure I like either idea but I have a line on a Miata setup that I can acquire fairly cheaply.


Nathan Acree
Albuqueruqe New Mexico

 

[72opelguy]

or you could use a fwd offset rim to fit in the fender right
i was thinkign my elf about a bwm rearend they can handle plenty or power and they use cv axles rather than driveshafs youd just have to find a junk yard with them
they kindof have to swigarms with hubs and a chucnkin the center not best thing but its a strong irs

 

[speedracer]

You will need to use a FWD wheel. The Miata wheels are FWD even though the car is RWD.

 

[Old Hippie]

I'm gonna ask a question on this thread, since it's on rear axles: The guy gave me the drive shaft back from the PO he bought it from for my 69. Problem: it is a sq. bolt on (with carrier), no tourqe tube. Is it a late model GT? a Manta? I can steal the one off my 71, since it's gonna get a V6/T5 combo and axle change, but I'd rather find out what I got.

 

[Mike Preble]

Am I to understand that the Isuzu pickup truck rear axle will fit and came with disk brake setup? Isn't it only a few inches wider and with fwd wheels should tuck up inside stock wheel wells? I thought someone had done this swap but had narrowed the axles. I am curious to know what span of years I should be looking for in the recycle yard. Or do I just need to go out and start measuring?
Thanks. Mike