91 carerra 2 low speed tranny noise (not normal) any ideas?

[MatthewBrum]

I have a 1991 C2 that has 46K on the clock with a new clutch. When the engine is lugged say from 1500-2400 RPM there is a noise that sounds like a bearing noise coming from the rear of the car. I have done some testing as follows.

1) The noise only occurs under high load low RPM

2) I have driven these cars before and it is MUCH louder than normal

3) Owner had complete clutch job previously done and problem is still there

4) Every mount and heat shield is good underneath.

5) Putting pressure on the clutch pedal had no change in noise (not t/o bearing)

Could this be detonation as the car also has a slight idle problem (surging)?

I also suspect possible change slapping but the miles are low

I also would suspect bearing in trans but miles are low ans is unlikely

Any ideas? (I did a search but found a lot of people that seem to have a similar problem but on older cars with higher miles)


thanks-Matt

[DRACO A5OG]

Do you know if PO replaced the mounts to a harder compound or OEM?

[MatthewBrum]

stock mounts, I just realized I may have posted this in wrong forum, will re-post in right forum

[ddubois]

Did the clutch mechanic inspect the DMF per TSB 9203?
Provide an email address and I can send you the TSB, unless someone knows how to attach a pdf.

[KTL]

My '87 G50 does this, as do a number of others i've driven. Over time it appears the main bearings in the transmission can wear, causing this condition. Solution is to replace the main bearings (bearings alone are big $, aside from the labor costs) or just live with it. It's not terminal and these cars don't like to be lugged at low rpms with heavy throttle input.

[MatthewBrum]

put the car on the lift and found the source. It is internal to the trans about six inches behind the shifter u-joint. I have rear that intermediate bearing may have something to do with it? or another bearing in there