83 SC Drive Train Clatter after New CV's Clutch
 

1983 911SC 120,000 miles. Stock. Non-racer. No abuse. Well maintained.

It started with throw-out bearing noise. Tech pulled the engine; replaced clutch, throwout bearing, pressure plate, flywheel... all the "stuff."

Upon completion, noted very slight"clatter" noise on takeoff from stop..... sounded like CV joint clatter (NO grinding) that got louder with engine load, but was independent of engine speed. When backing off acceleration noise softens, but is present in any gear with heavy acceleration.

Clatter worsened with time. Checked CV joints, noted some slop and boots marginal. Changed both axles and CV joints with new parts. No improvement.

Noticed that noise is less prevalent when system is cold. Changed transmission lube to Swepco 201. Slight improvement, but still prevalent.

What did we miss? Any ideas??

Welcome to the Forum SmileWavy
You will find a lot of help here.

First, quit replacing parts and do some diagnosis.

Post all the part numbers for the clutch. Perhaps there is some incompatibility (unlikely). An easy, no-cost exercise.

The tech must have checked for tight engine/transmission mounts and the four fasteners between the engine & transmission. Ask.

How is the clutch adjustment? Are the over-center springs and adjustments correct.

Anything else done / changed?

If no resolution, pull the engine and transmission and look & measure.

Best,
Grady

Thanks Grady
 

Thank you for the input. I'll forward this to my tech friend and see what he thinks. I believe he's checked the mounts, but not sure about the other stuff.

Could it be gear rattle from switching to a spring center clutch disc (from a rubber center one)?

Mine rattles quite noticeably below 2000RPM under power, and a little bit up to 2500 in the higher gears depending on the day. The colder he tranny is, the less it rattles.

I appreciate your thoughts.
 

Talked to my tech and asked about your suggestion of pressure plate change. He's aware of the issue, but says "no." He also says he was VERY careful with measurements and assembly of the new clutch related parts.

We're scratching our heads here in Vermont.

My main concern is that I'm not doing more damage by still running the car to work every day.

Thanks again.

Just for the record, I was not advocating switching back to the rubber centered disc... :)
Another cheap, and probably silly, suggestion would be to pull the plugs and see if one does not look like the others. If there's any chance it could be pinging, also check distributor timing mechanism for free operation.

Could it be an exhaust system rattle? Some baffle in the muffler got dislodged? An exhaust leak someplace not inherently obvious?

In reading posts around the internet there's a lot of talk about the 915 transmissions having a clatter noise anyway. I just never hear it until this latest clutch job. Could it be there's no problem? The noise gets pretty loud..... actually embarassing to hear when driving as it echos in traffic. Gotta get rid of it.