C1 Differential Problem--Need Experts
Thread Starter
Le Mans Master
Joined: Sep 2008
Posts: 5,662
Likes: 2,344
From: Lake Minnetonka, Mn
2018 C1 of Year Finalist
C1 Differential Problem--Need Experts
The following message is from a good friend of mine who races a vintage Chevrolet Echidna, a sister car to one that I formally owned. Any suggestions would be appreciated.
Here is his question:
My 1958 Echidna, a Chevy based- Devin bodied road race car has suffered two differential failures. The car uses a late fifties P case with a stock period Corvette posi. Both were caused when one of the differential carrier caps split in its top radius through the bolt hole which secures the carrier adjustment clip. As the carrier cap fails, the ring gear ***** to the side quickly resulting in catastrophic failure.
These caps are cast iron and could be modified with a steel girdle of some sort or perhaps be machined of 4130 chrome moly or equivalent. But rather than reinvent the wheel, is there anyone out there I can learn from who has experience modifying these caps or better yet, currently supplies differential carrier caps in stronger form?
The car is 2,200 lbs wet, 482 HP, runs treaded tires with approx. 6” contact
All ideas and leads appreciated. Thank you.
Here is his question:
My 1958 Echidna, a Chevy based- Devin bodied road race car has suffered two differential failures. The car uses a late fifties P case with a stock period Corvette posi. Both were caused when one of the differential carrier caps split in its top radius through the bolt hole which secures the carrier adjustment clip. As the carrier cap fails, the ring gear ***** to the side quickly resulting in catastrophic failure.
These caps are cast iron and could be modified with a steel girdle of some sort or perhaps be machined of 4130 chrome moly or equivalent. But rather than reinvent the wheel, is there anyone out there I can learn from who has experience modifying these caps or better yet, currently supplies differential carrier caps in stronger form?
The car is 2,200 lbs wet, 482 HP, runs treaded tires with approx. 6” contact
All ideas and leads appreciated. Thank you.
Race Director
Joined: Nov 2000
Posts: 10,340
Likes: 664
From: Beverly Hills (Pine Ridge) Florida
Had a 57 Chevy bracket (drag) racer that had the same type failure. Previous to that we were twisting axle shafts. Finally gave up after the catastrophic cap failure and bought an altered roadster........
I know not any help, but those rears are weak, and best advise is to put in something stronger (F*rd 9" or a least a 12 bolt Chevy).
Plasticman
I know not any help, but those rears are weak, and best advise is to put in something stronger (F*rd 9" or a least a 12 bolt Chevy).
Plasticman
Race Director
Joined: Mar 2001
Posts: 14,619
Likes: 4,671
From: Mustang OK
2026 Corvette of the Year Finalist - Modified
2025 c1 of the Year - Modified Winner
2024 C1 of the Year Finalist - Modified
2023 C1 of the Year Finalist - Modified
2015 C1 of the Year Finalist
Yep, I buy them from Aubrey Bruneau in Canada (they may be available from other sources, but I don't know of any). http://www.bruneauperformance.ca/intro.html
I don't do many of these because very few people want to spend a lot of money on these early rears. They prefer to put their money in a later style rear.
These cap saddles are moderately easy to do at home on the workbench. ANYBODY that does the majority of their own mechanical work can do this. It's not hard, but it's time consuming because the stock cap has to be VERY carefully trimmed to fit the under contour of the saddle and a .010 gap must be made at each end of the saddle.
The rear in the pictures below was a NON-posi case that I built up from scratch for a customer and converted to a posi with the Eaton unit.
Tom Parsons
I don't do many of these because very few people want to spend a lot of money on these early rears. They prefer to put their money in a later style rear.
These cap saddles are moderately easy to do at home on the workbench. ANYBODY that does the majority of their own mechanical work can do this. It's not hard, but it's time consuming because the stock cap has to be VERY carefully trimmed to fit the under contour of the saddle and a .010 gap must be made at each end of the saddle.
The rear in the pictures below was a NON-posi case that I built up from scratch for a customer and converted to a posi with the Eaton unit.
Tom Parsons
Last edited by DZAUTO; Jul 18, 2011 at 11:21 PM.
