Just had new motor mounts and transmission mounts installed, along with lt headers and exhaust. Now I have a noise in the rear end. The mechanic that installed it said I have a loose rear pinion. Now I am thinking he caused it when he put the mounts in. What do you think? The car is now going to someone I trust to work on the rear end. The car did not have an issue when I took it to the shop. Thanks in advance.

 

The only way that installing motor mounts and a transmission mount (there is only only 1) would damage the rear end pinion would be if the tranny mount was too tall, or the engine was tilted at a different angle, changing the pinion angle. It would take a decent amount of driving for the pinion bearings to wear. I would check to insure the longitudinal axis of the engine/transmission is level, and the pinion angle is within spec.

Not sure what a "loose" pinion even means - worn bearings? What exactly does the noise sound like?

 

Sound like metal on metal,- non-greased bearings. Car seems to drive ok, but the noise is there as soon as you give it gas and continues until you stop.

 

Got the new today, the pinion was shot and that caused some other issues, so I am upgrading the rear from 2.41 (original) to 3.73. Also found out the water pump is leaking and as long as we are in there I will look at replacing the timing chain. Its a 97SS with 110K and I have only had it for two years and 2k miles. Hope this is the last big repair for now.

 

There was never a 4th Gen with a 2.41:1 rear axle ratio. The T56 manual cars were all 3.42:1 from 1994 on up. You will find "GU6" on your service parts tag, confirming this.

Unless you have evidence of significant wear on the timing chain, it should not need to be replaced. Replacing the water pump does not expose the timing chain. To replace it, you will have to remove not only the water pump, but the distributor (Optispark), damper hub and timing cover. To remove the timing cover, you need to drop the oil pan (following factory manual procedure). You will need a new crank seal, Opti seal and water pump seal, timing cover gasket.

 

So is there anyway to check the timing chain without removing everything. If not, I will play it safe and replace it before it breaks. If this is not the original rear end how bad did someone beat up the car. In the past two years I have replaced:
radiator
rotors all around / rotors and calipers in the rear
clutch/flywheel
Headers
3" ss exhaust from Stainless Works
Motor mounts
Transmission mounts

Anyway, thanks for your comments.

 

A broken timing chain is extremely rare.

How did you determine the car has 2.41:1 rear axle? I have never seen that ratio in a 7.6/7.625" 10-bolt. It is used in the 8.5" 10-bolt, but that rear cannot be installed in a 4th Gen. It would seem to be almost impossible to get the car moving from a stop with the T56 and a gear that numerically low.