nskyline34

Still pushing for faster and quicker - I go back down to Mojave in October and want to run 203-205, so gearing/tire setup that allows me to run 205mph @ 7,000 rpm is desired.

So far I'm looking into removing my Z06 rear diff and swapping it with a diff from a normal C5 (non Z06) with 3.15 gears. I'm running 3.42's currently, and with the 3.42's at 7,000 rpm I ran 191-192mph, so I can either go to a 28" tall tire, change gears, or turn the **** outta the LS6...

Mini tubbing the car to clear 28" tires is an option - labor intensive though, the LS6 oiling system cavitates at 7200+ so more rpm is out of the question, and rear gears are the cheapest and easiest option so far I think.

I'm planning to run several 'high speed' races where having grunt outta the hole isnt the best thing, so this is why I'm considering the entire diff swap vs gears only - because I will swap it 3x within the next 9 months anyways. Just easier and takes less care to swap diffs vs carriers to me - neither is hard, but when I'm working on the car and tired/exhausted, I want something that is more idiot proof.

Does anyone know if the standard C5 3.15 Getrag diff can be mated to a Z06 M12 trans, let me know. I mean 100% swap - electrical connectors, bolts, axles and all.

Bill Curlee

YES,,,,,,,,,,, All C5 Getrag differentials will bolt to the transmissions. All the same bolt patterns and shaft lengths.

There is only one electrical connection on all GM C5 differentials (speed sensors)

nskyline34

HELL YES!!!!

I'm guessing the speed sensors are all the same? and plugs are too?

This other 3.15 diff will be used for open road racing - so just high speeds and momentum. I 'launch' the car the same at the track as I do from a stoplight in town with a cop behind me - so its never taking a shock.

Is there anything hp/strength wise I need to worry about with the other standard C5 diff? I dont care if its an open or LSD or locker because its NOT for drag racing or any dig racing for that matter. Just want to make sure I know what I'm getting into. I would get another 3 rib. (current / OE is a 3 rib and is holding up wonderfully).

Car will never make more than about 550-570 on spray (only a 50hp shot for standing mi races - again, baby launch, no spray until 4th and 5th)

Bill Curlee

WELL,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,,, If it were me,,,,,,,,,,, I would FULLY inspect the new (used Diff) before I installed it. There are SEVERAL thing that can be or go wrong especially with your HP range ; even though you state that you are NOT going to abuse or launch it hard.

ALL C5 differentials have a LIMITED SLIP clutch set-up. It is a KNOWN failure item. There is a Beleview Spring that puts the LOAD on the limited slip clutches.

That spring is a high failure rate item and is known to break/crack and cause the clutches to wear out. That HP level, BROTHER, you NEED all the limited slip help you can get. Trust me on that one.

If one wheel breaks loose at WOT (for what ever reason), your going to wind up off road 4X4 ing it or worse.

If the spring breaks, it will fall into the spider gears and destroy them.

So,, If it were me, I would at a MINIMUM pull it apart and install new clutches and springs and also install the higher strength C6 ZO6 output shafts. Also install NEW OUTPUT SHAFT SEALS!!

I have an 02 ZO6 modded to 450 RWHP and this modification holds up extremely well. I do abuse my drive train!!

Check out these post and it will show you how easy it is to incorporate these improvements:

- C5, ragtopws6 , Upgrading your C5 rear with C6 Z06 guts, : http://forums.corvetteforum.com/c5-g...-z06-guts.html
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- C5, Its_Go_Time, Output Shaft Install - Left and Right: http://forums.corvetteforum.com/c5-t...post1573407966

- C5, Its Go TIME, Differential Rebuild post: https://www.corvetteforum.com/forums...1&p=1591127325

- C5 Differential Seal replacement: http://forums.corvetteforum.com/c5-g...on-photos.html
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nskyline34

Awesome input! Thank you! No matter what I get I will go through it and freshen it up. I'm thinking a separate diff would be easier/quicker to swap out 4-5x a year than swapping gears and doing backlash and setup all the time.

Great input on the LSD spring and I will just replace it and try and rebuild the LSD too, couldn't hurt. I found a diff with 41k mi on it for cheap - so I may try and ****** that one

Patches

Realize that, since it's a 3.15 diff, it very likely came from an auto drivetrain so you'll need to remove the seal plate on the tranny side of the diff if it's still on there. If not, you're good to go.

Here's the seal plate I transferred from the 2.73 on my 2002 A4 C5 to the 3.42 diff I transplanted in.



Seal plate in place on the 3.42 diff.

jackthelad

You could also go to the "base" auto trans 2.73 gear ratio, as against the auto only "performance" 3.15 gear. Also less likely to have been beaten on.

I would have thought that a relatively low mileage auto rear end would be very usable "as is" - probably in a lot better shape than your current M6 3.42 ratio rear end, given how much power you have been pushing through it!

p.s. the 3.15 is not the "normal" C5 ratio - all manual C5's have the same 3.42 ratio. The actual gearbox ratios are slightly different though - GM gave the Z06 slightly "wider" ratios in the lower gears to help it in the acceleration stakes. A bit odd really, as normally the performance /track oriented model is the one with the closer ratio gearbox.

nskyline34

Thanks for the posts guys - and good call on the plate that I will have to remove. for the manual trans, is there a plate that still goes there, or do I just remove and toss it?

A 2.73 gear would be worlds too tall - good idea, but I am doing this FOR the 3.15 gears...

Patches

No plate is used for the manual - the 3.42 diff I pictured above came from my 2002 C5 and had no plate when I removed it from the car. I added the plate from the 2.73 diff that I removed from the C5 the 3.42 diff was going in.

Bill Curlee

I think the question that he is asking is, Can the plate form an AUTOMATIC differential be installed on a manual transmission differential with a manual trans.

Bill

Patches

As I mentioned in my first post - that plate needs to come out in order for the diff to be installed on a manual tranny. That plate is A4-only.

Bill Curlee

Thanks for making it ABSOLUTY CLEAR!

Bill

donnie brooks

How do you remove this plate..I have a 3:15 diff and will be removing this plate..I tried pulling it with pliers,but only moves slight.
All help is greatly appreciated.

Bill Curlee

TUG/PULL/TUG........ Its sealed with a BIG O RING and just needs bit of ole fashion GUNDI!

Give her hell!!

BC