Transmission noise

[ZR-1]

Hello, I am getting quite the noise from my transmission. It is a rattley/knock kind of sound. It only occurs while driving. The sound does not go away while in neutral or clutch disengaged/engaged while driving. I can make the noise quieter if on the throttle in gear but if I let out or "engine brake" in gear its very loud. What could this be?

[KILLSHOTS]

I see you're new to the site. How much do you know about the car? Sounds like your OEM dual mass flywheel may have been replaced with a lighter aluminum unit, which is great for performance but generally not so great for tranny noise. Just a guess.

[ZR-1]

I don't know much on the history of upgrades, however, the noise has not been there for about 2000 miles that I have owned it. It always had the growl in first gear which I assumed was normal for a 90. The car does seem to shift fine. However, this is definitely the noise of something failing. It sounds like engine knock at anywhere above 40 and letting out of the gas while in gear.

[A26B]

Difficult to say, but there are a couple of things you can do to look for more clues.

1. Have you noticed any change in oil pressure, before & after the knock?

2. Can you feel the knock in the shifter?

3. Change oil, send sample for analysis.

4. If nothing abnormal in 1~3 above, consider removing the transmission & inspecting entire clutch/flywheel assembly, loose bolts, cracked/broken/worn parts.

[Dynomite]

Originally Posted by ZR-1

the noise has not been there for about 2000 miles that I have owned it. It always had the growl in first gear which I assumed was normal for a 90. The car does seem to shift fine. However, this is definitely the noise of something failing. It sounds like engine knock at anywhere above 40 and letting out of the gas while in gear.

Originally Posted by ZR-1

I am getting quite the noise from my transmission. It is a rattley/knock kind of sound. It only occurs while driving. The sound does not go away while in neutral or clutch disengaged/engaged while driving. I can make the noise quieter if on the throttle in gear but if I let out or "engine brake" in gear its very loud. What could this be?

So......this is very confusing. You have a Noise under the car or under the hood while driving only (even if coasting in neutral). No noise when car is not moving in neutral? No noise when car is not moving in neutral if you rev the engine?

This could be driveshaft U joints for all we know.....if only while driving even if the Transmission is in Neutral. And noise depends on torque applied.

More self diagnosis of exactly where the noise is located would help for sure.

Jerry is going on the basis that your engine is in serious degradation from something letting loose (could be the case from your description)....in which case....do not run the engine until you are sure a Rod does not let loose entirely. That is why Jerry is asking about Oil Pressure

To check your U Joints just go under the Z and with rear wheels off ground and trans in neutral, rotate drive shaft by hand back and forth and look for movement/play in the U joints on both ends of drive shaft and when we are at it....U joints on each side of differential.

Use Jack Stands

Just in case of the Out side chance (from your somewhat deceptive description) your noise is related to U Joints
See U-Joints

This is where Bill's ZF Doc Drive Shaft Safety Loop may be of interest.

[ZR-1]

Oil pressure is good. Nice and high. Definitely not the engine. I can rev with no change in sound. I can only hope it's a u joint but it doesn't sound like one. I'll do the check tomorrow. Already arranging to sell things including an arm and a leg for the trans repair.

To clarify. It only makes noise while driving. It is definitely coming from the trans area. Heavy Deceleration in gear makes it louder. More speed makes the noise more rapid. As far as feeling it in the shifter I can't remember. If it was the flywheel or clutch then engine rpm would be a factor rather than car speed correct?

[BigJohn]

probably has the wrong trany oil.

[A26B]

Originally Posted by ZR-1

Oil pressure is good. Nice and high. Definitely not the engine. I can rev with no change in sound. I can only hope it's a u joint but it doesn't sound like one. I'll do the check tomorrow. Already arranging to sell things including an arm and a leg for the trans repair.

To clarify. It only makes noise while driving. It is definitely coming from the trans area. Heavy Deceleration in gear makes it louder. More speed makes the noise more rapid. As far as feeling it in the shifter I can't remember. If it was the flywheel or clutch then engine rpm would be a factor rather than car speed correct?

U-joints are the likely problem. Be sure to check the half-shaft joints too.

Do this before removing the transmission. Hold off on selling body parts.

[ZR-1]

The half shafts did not seem to move at all. The drive shaft seemed fairly solid nothing noticeable if im not being VERY picky.

[gbrtng]

Your profile says you do not have a ZR-1 - please describe your vehicle.