Anyone use a Corvette "transaxle" in their Z?

[Jerminator96]

I just picked up a '71 240z for an SBC swap and started thinking that I might try to upgrade that horrible looking rear suspension.

 

So has anyone tried to swap in the suspension and rear mounted trans/differential from the C5 vettes? Looks like a good bit of cutting and welding but this car is all but back-halved already.

 

Any thoughts or ideas on this would be appreciated.

 

Jeremy

[IdfMF]

"....started thinking that I might try to upgrade that horrible looking rear suspension."

 

I haven't swapped a 'Vette rear suspension, but what's so ugly about the 240Z rear suspension?

 

[Jerminator96]

I haven't swapped a 'Vette rear suspension, but what's so ugly about the 240Z rear suspension?

 

Well my car is ugly due to rust and years of dirt and grime, however, I did not mean to imply that there was anything inherently ugly about the suspension. It's "horrible looking" because the design is weak, everything from the rear end onward is just not designed to handle the kind of power I will eventually throw at it.

 

On a side note, that's a really nice looking setup you have there. What does the rest of the car look like?

[naviathan]

I've seen it done before, either on here or on zcar.com, I don't remember which. Search around, I'm sure it'll pop up again.

[primadonna z]

http://www.turbobuicks.com/members/scottiegnz/vette-irs-swap.htm

[rustorbust]

I dont remember his user name but john phillips they guy that had the little z on pinks that hauls ass has a corvette diff in his.

 

James

[Jerminator96]

One thing you guys need to keep in mind is how different the C5 and C6 corvette drivetrain is from the C4 and earlier.

 

Here is a picture of the C5 rear:

 

 

Notice that the transmission is bolted directly to the differential, with the driveshaft/torque tube preceding it.

 

 

It makes for a very well balanced front engined car, but also brings up some difficulties in fabrication.

[tkach]

Not to get too far off track but ,I dont know a huge amount about suspension's but why the leafspring insted of coil springs on the c5/6?

[Jerminator96]

Not to get too far off track but ,I dont know a huge amount about suspension's but why the leafspring insted of coil springs on the c5/6?

 

This can answer your questions:

 

http://en.wikipedia.org/wiki/Corvette_leaf_springs

 

They do make coil-over kits for them.

[Phantom]

It makes for a very well balanced front engined car, but also brings up some difficulties in fabrication.

 

There may be a bit of confusion here. Using the Corvette arrangement to improve your balance is not going to help unless you're looking for something like a Porsche 911. My 280Z with an LS1 and a T56 in the stock position is weight biased to the rear. The car mostly stock was 1400lbs front and rear. When I finished, it was 1400 front and 1430 rear. Addtional modifications took it to 1440 front and 1560 rear. The transmission sits closer to the rear wheels than the front plus the V8 sits further back than the I6 so weight moves to the rear naturally during the conversion.

[Jerminator96]

There may be a bit of confusion here. Using the Corvette arrangement to improve your balance is not going to help unless you're looking for something like a Porsche 911. My 280Z with an LS1 and a T56 in the stock position is weight biased to the rear. The car mostly stock was 1400lbs front and rear. When I finished, it was 1400 front and 1430 rear. Addtional modifications took it to 1440 front and 1560 rear. The transmission sits closer to the rear wheels than the front plus the V8 sits further back than the I6 so weight moves to the rear naturally during the conversion.

 

Huh....well there is something I didn't know about Z cars. That being said, I would imagine with a good bit of horsepower these cars could use some extra weight in the rear. Maybe there is some point to it after all?

 

Either way, I suppose I will have to rethink my idea.

[cygnusx1]

The "ugly" suspension on the rear of an S30 is probably more stout than you think. Plenty of people running high HP through these. Of course it depends on how you plan on using the car.

[Jerminator96]

The "ugly" suspension on the rear of an S30 is probably more stout than you think. Plenty of people running high HP through these. Of course it depends on how you plan on using the car.

 

I'm not really sure where the "ugly" comes from, I never said it.

 

And I'm sure it can handle some power, but it is still a very poor design. So if I have the means to change it, why not right? That's what this hobby is all about.

[Phantom]

Just for grins measure the center-to-center distance on the wheels on the C-5 transaxle you have and compare it to the same measurement on the Z. Then think about how much you'll have to narrow the 'vette system or widen the Z to accomodate it. That should be entertaining for a while.

[BRAAP]

I personally feel that changing out the rear suspension, (especially ignoring the bigger issue regarding the Z car suspension, which is the front suspension, not the rear), because it is weak and/or can’t handle power, or is a poor performance design for a sports car is an assumed and/or misguided concept that we see come up from time to time. I understand wanting to install a different rear suspension and different differential for the sake of “because we can”, or for “WOW factor” to make our Z a little different from the rest, but I don't understand that swap from a performance stand point regarding drag racing, road racing or performance street use. The OE Z car rear suspension has proven itself in strength and design! From a performance perspective, the front suspension needs the attention WAY before the rear does. The hows, whys, and what fors, have been documented in our "Brakes, Wheels, Suspension and Chassis" section. Peruse through the stickies at the top of that section for some very good in-depth info.

 

Not sure what sort of power you are planning to put to the ground, but below is a picture of one of our members with a Blown, Nitrous dual quad V-8 on drag slicks, (the differential and rear suspension wont see much more brutal, punishing power delivery than that without flipping the car over!) running 9.2 seconds in the ¼ at 153+ MPH! For perspective, that car is going 0-153 MPH in 9.2 seconds, with the stock Datsun Z differential and suspension! This car runs this fast, and every-time that stock Datsun differential and rear suspension is absorbing enough power/torque to "yank" the front wheels off the ground, time and again on the stock parts. I know of at least one other member running 8 seconds at 150+ on the stock Datsun differential and suspension.

Geometry wise, the stock Datsun rear suspension isn’t too bad. It’s not perfect, but not too shabby, especially considering the age of its design. These car with the stock rear suspension design are still successfully campaigning on the race tracks against today’s offerings with much more modern suspension designs.

 

I would agree that there probably is some to be gained handling wise with different suspension, but will take several years in sorting it out, (geometry adjustment, spring rates, balanced to the rest of the chassis, chassis stiffness etc), and only the most discerning road racers among us would be able to notice that difference, and with what is known about how to make the current Z car suspension design truly competitive on the track, would cost far less, time invested in setup and tuning would be shorted by not just months, but years, etc. Again, for the sake of making a Z car different than the rest, wanting to give it WOW factor, or just because we can, I say do it. From a performance standpoint, it will cost more money, require several more years invested in tuning tweaking, before it would be “acceptable” or hopefully, a better performing design than a nicely sorted out OE Z car suspension, and that is only if the person doing the tuning and tweaking is savvy enough regarding chassis design and tuning.

 

That’s my $.02

 

[tube80z]

Not to get too far off track but ,I dont know a huge amount about suspension's but why the leafspring insted of coil springs on the c5/6?

 

I haven't had a chance to look too closely but I can offer some educated guesses. The leaf spring is lighter than steel coils, it may not offer any resistance to roll in how it's mounted (letting the engineers seperate vertical rate from roll rate), and it won't add bending forces to the shocks like a coil over solution. Not sure if any or all of these were criteria.

 

Cary

[tube80z]

One thing you guys need to keep in mind is how different the C5 and C6 corvette drivetrain is from the C4 and earlier.

 

Here is a picture of the C5 rear:

 

 

Notice that the transmission is bolted directly to the differential, with the driveshaft/torque tube preceding it.

 

The large area that sits in front of the tranny is going to be a problem. That looks like it's going to interfere with the seats. There's precious little room in that area of a Z as is. That's the one big item that may nix this mod.

 

Cary

[G.I.jonas]

^ Take that!^

[Phantom]

So Paul - How do you keep from breaking the half-shaft universals? I've twisted two of them now and I'm only running about 390HP - and that's through street tires. Think maybe the wheel hop has something to do with it?

[BRAAP]

... Or you could just buy a C-5 or C-6 and install a Z car steering wheel? And for a little more of that Z car feel, install a set of Z car seats? Chassis is already sorted out, works well on track and street, already has that nifty transaxle, plenty of after-market support... Ah heck, I just talked myself into it...

 

I'm hittin Craigs-list...