Diff seizure ?????
Thread Starter
Burning Brakes
Joined: Dec 2003
Posts: 1,004
Likes: 7
From: Adelaide South Australia
Diff seizure ?????
Had the vette up on a mate's hoist today, to have a quick look before fitting the rebuilt 3.73 diff on Wednesday. I just wanted to spray a bit of penetrene on the bolts, and check on the order of disassembly to replace all the front and rear suspension bushes as well.
As I was rotating the rear wheels, listening / feeling for any bearing noise or excess play, I felt the rear sieze.
with a clunk.
I could spin the wheels forward, but if I rotated the wheels backward, it would sieze up within a half rotation .... wierd.
I drove the car enthusiasticly through the hills a few days ago, and drove it yesterday with no issues... and after just raising the car on the hoist, the diff appeared to be siezing up.
Without the ability to drive the car home now ( I was at a friends workshop) I decided to tear down the rear and start the work a couple days early.
Removed the tailshaft and confirmed issue was with diff, and not gearbox (Phew!)
I then disaasembled the rear suspension and eventually got the diff out.
Curious to know what had happened, I pulled the rear cover off, and could not believe my eyes.
The roll pin was missing from the pinion gear shaft, and the shaft itself had slipped down, fouling on the case as it aligned vertically.
Never seen or heard of that before..... diff ran perfectly up until the moment I had the car on the hoist and was spinning the rear tyres by hand. Everything is in place internally, except the sliding pinion shaft.
If that shaft had slipped out whilst on the mountain roads a few days ago, I figure a nasty incident might have occured.
I bought a lottery ticket this afternoon..... consider myself very lucky.
As I was rotating the rear wheels, listening / feeling for any bearing noise or excess play, I felt the rear sieze.
with a clunk.I could spin the wheels forward, but if I rotated the wheels backward, it would sieze up within a half rotation .... wierd.
I drove the car enthusiasticly through the hills a few days ago, and drove it yesterday with no issues... and after just raising the car on the hoist, the diff appeared to be siezing up.
Without the ability to drive the car home now ( I was at a friends workshop) I decided to tear down the rear and start the work a couple days early.
Removed the tailshaft and confirmed issue was with diff, and not gearbox (Phew!)
I then disaasembled the rear suspension and eventually got the diff out.
Curious to know what had happened, I pulled the rear cover off, and could not believe my eyes.
The roll pin was missing from the pinion gear shaft, and the shaft itself had slipped down, fouling on the case as it aligned vertically.
Never seen or heard of that before..... diff ran perfectly up until the moment I had the car on the hoist and was spinning the rear tyres by hand. Everything is in place internally, except the sliding pinion shaft.
If that shaft had slipped out whilst on the mountain roads a few days ago, I figure a nasty incident might have occured.
I bought a lottery ticket this afternoon..... consider myself very lucky.
Team Owner
Joined: Apr 1999
Posts: 21,953
Likes: 1,443
From: Reno Nevada
2024 C3 of the Year Finalist- Modified
No, it is no problem at all. I had two posi units fail on me. The weight of the car and the engine power. The failed posi case and pin just make bad crunching noises. A smart person would stop, but I just limped on home
The problem with the stock posi unit is the pin is to small and with time and power it elongates to hole through the case and causes stress cracks. The HD aftermarket posi units sell with a bigger diameter cross pin and polished cases to prevent stress cracks.
The problem with the stock posi unit is the pin is to small and with time and power it elongates to hole through the case and causes stress cracks. The HD aftermarket posi units sell with a bigger diameter cross pin and polished cases to prevent stress cracks.
Le Mans Master
Joined: Jan 2000
Posts: 8,918
Likes: 27
From: New Hill NC
Had the vette up on a mate's hoist today, to have a quick look before fitting the rebuilt 3.73 diff on Wednesday. I just wanted to spray a bit of penetrene on the bolts, and check on the order of disassembly to replace all the front and rear suspension bushes as well.
As I was rotating the rear wheels, listening / feeling for any bearing noise or excess play, I felt the rear sieze. with a clunk.
I could spin the wheels forward, but if I rotated the wheels backward, it would sieze up within a half rotation .... wierd.
I drove the car enthusiasticly through the hills a few days ago, and drove it yesterday with no issues... and after just raising the car on the hoist, the diff appeared to be siezing up.
Without the ability to drive the car home now ( I was at a friends workshop) I decided to tear down the rear and start the work a couple days early.
Removed the tailshaft and confirmed issue was with diff, and not gearbox (Phew!)
I then disaasembled the rear suspension and eventually got the diff out.
Curious to know what had happened, I pulled the rear cover off, and could not believe my eyes.
The roll pin was missing from the pinion gear shaft, and the shaft itself had slipped down, fouling on the case as it aligned vertically.
Never seen or heard of that before..... diff ran perfectly up until the moment I had the car on the hoist and was spinning the rear tyres by hand. Everything is in place internally, except the sliding pinion shaft.
If that shaft had slipped out whilst on the mountain roads a few days ago, I figure a nasty incident might have occured.
I bought a lottery ticket this afternoon..... consider myself very lucky.
As I was rotating the rear wheels, listening / feeling for any bearing noise or excess play, I felt the rear sieze.
with a clunk.I could spin the wheels forward, but if I rotated the wheels backward, it would sieze up within a half rotation .... wierd.
I drove the car enthusiasticly through the hills a few days ago, and drove it yesterday with no issues... and after just raising the car on the hoist, the diff appeared to be siezing up.
Without the ability to drive the car home now ( I was at a friends workshop) I decided to tear down the rear and start the work a couple days early.
Removed the tailshaft and confirmed issue was with diff, and not gearbox (Phew!)
I then disaasembled the rear suspension and eventually got the diff out.
Curious to know what had happened, I pulled the rear cover off, and could not believe my eyes.
The roll pin was missing from the pinion gear shaft, and the shaft itself had slipped down, fouling on the case as it aligned vertically.
Never seen or heard of that before..... diff ran perfectly up until the moment I had the car on the hoist and was spinning the rear tyres by hand. Everything is in place internally, except the sliding pinion shaft.
If that shaft had slipped out whilst on the mountain roads a few days ago, I figure a nasty incident might have occured.
I bought a lottery ticket this afternoon..... consider myself very lucky.
