Diff upgrade questions
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
Diff upgrade questions
I'm starting to order parts to upgrade my C5, one of the best I've heard of is a rear diff. Currently the car is a low mile A4 with the 2.73. Planning to go to a 3.42.
It sounds like a new diff will bolt in and I just need to swap the adapter plate from my current diff to the new one. But I have some questions. Firstly, are there any seals I'll also need for this, if so does anyone know the part numbers? Secondly, are all diffs from all years compatible? Lastly, can I put a 3 rib in if I don't already have a 3 rib?
Any other experience/thoughts would be appreciated. Thanks!
It sounds like a new diff will bolt in and I just need to swap the adapter plate from my current diff to the new one. But I have some questions. Firstly, are there any seals I'll also need for this, if so does anyone know the part numbers? Secondly, are all diffs from all years compatible? Lastly, can I put a 3 rib in if I don't already have a 3 rib?
Any other experience/thoughts would be appreciated. Thanks!
Last edited by Lord Doomhammer; May 25, 2021 at 08:57 PM.
Melting Slicks
Joined: Dec 2004
Posts: 2,644
Likes: 629
From: Dallas TX
no adapter plate swap. No such thing. Any adapting is done on the trans side at the tail shaft housing.
there is a big o-ring on the diff to trans interface, they are like 10 bucks.
yea 3 rib is fine from a single rib.
there is a big o-ring on the diff to trans interface, they are like 10 bucks.
yea 3 rib is fine from a single rib.
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
Do you know if there is such a thing as a 2 rib? I've seen one or two on ebay, but no documentation about them.
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
.
Joined: Apr 2013
Posts: 5,010
Likes: 1,143
From: Oregon
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
There is a plate that need taken out of you old diff when you swap it out. There is a seal and an O-ring that goes on the seal plate that I would replace
Melting Slicks
Joined: Dec 2004
Posts: 2,644
Likes: 629
From: Dallas TX
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
I think I see what you mean. There is a metal plate that says trans side/diff side (which is only for the A4) and an o-ring that seals around it. Based on older threads it looks like the o-ring part number is 12369456, can anyone confirm?
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Joined: Apr 2013
Posts: 5,010
Likes: 1,143
From: Oregon
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
seal is 24207010 and the O-ring is correct
.
Joined: Apr 2013
Posts: 5,010
Likes: 1,143
From: Oregon
St. Jude Donor '14-'15-'16-'17-'18-'19-'20-'21-'22-'23
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
Here's some more info for you
https://www.corvetteforum.com/forums...ferential.html
https://www.corvetteforum.com/forums...ferential.html
Do you know if I will be able to drive it across town from the shop to a dyno place to get it tuned after the new diff is in it?
Last edited by Lord Doomhammer; May 25, 2021 at 10:48 PM.
Drifting
Joined: Sep 2009
Posts: 1,862
Likes: 594
From: Prescott, Arizona
You will be able to drive it almost anywhere but at full throttle the engine will likely hit rev limit before shifting until you get the PCM reprogrammed for the new rear drive ratio.
I had mine reprogrammed at A&A Corvette in Oxnard CA, 125 miles away.
If you plan to track the car, you may find the following interesting-
https://www.corvetteforum.com/forums...track-car.html
I had mine reprogrammed at A&A Corvette in Oxnard CA, 125 miles away.
If you plan to track the car, you may find the following interesting-
https://www.corvetteforum.com/forums...track-car.html
Thread Starter
Heel & Toe
Joined: Jul 2020
Posts: 16
Likes: 1
As a follow up to my original questions. At what point should I have the new diff rebuilt if it was not already refurbished by the seller? Should it always be rebuilt or only if it has worn clutches?
For reference, the new diff has about 60k miles, my car has about 40k, and neither were track cars.
For reference, the new diff has about 60k miles, my car has about 40k, and neither were track cars.
Drifting
Joined: Sep 2009
Posts: 1,862
Likes: 594
From: Prescott, Arizona
Following are guidelines I would use to initiate a rebuild:
- Obvious metal particles in drained gear lube
- Worn clutches and or broken Bellville washers
There may be some debate on whether to rebuild because of broken Bellville washers. A racing friend raced his '66 Corvette without the coil springs providing pressure to the clutches in the differential, similar to more recent C5 Bellville washers(springs). His theory was that the differential gears inherently provided thrust to compress the clutches under acceleration far in excess of that provided by the springs. With no springs, the differential acted like an open differential for non spirited driving.
If you rebuild, consider a geared differential. WaveTrac or similar. No clutches or springs to wear out or break.
To test the condition of at least the Bellville washers, raise the rear and check to see if you can easily turn one rear wheel in gear (Manual) or park (Auto).
- Obvious metal particles in drained gear lube
- Worn clutches and or broken Bellville washers
There may be some debate on whether to rebuild because of broken Bellville washers. A racing friend raced his '66 Corvette without the coil springs providing pressure to the clutches in the differential, similar to more recent C5 Bellville washers(springs). His theory was that the differential gears inherently provided thrust to compress the clutches under acceleration far in excess of that provided by the springs. With no springs, the differential acted like an open differential for non spirited driving.
If you rebuild, consider a geared differential. WaveTrac or similar. No clutches or springs to wear out or break.
To test the condition of at least the Bellville washers, raise the rear and check to see if you can easily turn one rear wheel in gear (Manual) or park (Auto).