TTop Tony

Ok this is my first manual car so excuse the stupidity. Lately when I've been feathering the clutch to get in my garage or in a parking spot I hear a grinding noise from the drivetrain. Now the clutch is only a year old so at first I thought it was my suspension. But it looks fine so I was wondering if there is any way to test and see if I killed my clutch somehow. This started happening a few months after I put the 3.7 gears in. Would taller gears put more stress on a clutch?

TTop Tony

One more thing it only does it when I've driven the car for awhile. Only when its hot.

68shark

Just wondering....not enough info here...but appreciate it's a frustrating problem and may not be easy to describe. Seeing you noted the problem coincided with the rear end swap, wondering if there is something amiss in the "clutch pack" in your posi unit (I'm assuming a 3.70 posi rear)? For example, do you only notice this when the car is turning, such as turning into or backing out of a parking spot? If not that, then how would you otherwise describe your clutch operation? Smooth or not, abrupt engagement or not, any other sounds/shuddering, anything like that and if so, under what conditions? Was flywheel resurfaced at clutch change, new unit vs rebuilt, stock clutch or high perf. unit? You would know if you killed your clutch. 22 years back a friend bought a '64 coupe. Let me drive it right after he bought it, if you nailed it the clutch basically started to disengage so engine rev's would jump while car slowed. I told him his clutch was dead, he said he didn't have the money right then to fix it. I told him it's real bad and you shouldn't drive it until you fix it. He didn't listen...a week later....clutch packs it in. You can put it in first gear, let the clutch out....and sit there. I thought he got screwed on the car deal. Today, he still owns the '64 (with a good clutch) and it's now worth at least 3X what he paid for it! Sorry for the long story, but hope you can help describe the sound you're hearing to help us help you figure out the problem! :cheers:

PRNDL

I am thinking along the same lines as 68shark. Sounds like differential "chatter" to me. Question is, does it happen when you are turning? You might be able to clear it up simply by adding GM posi additive to your diff.... which raises the question, did you put in the posi additive when you swapped in the new diff? A higher numerical rear end should actually put less pressure on a clutch, but in reality probably makes no difference. MJ

burners

I think I need a little more information. Does the sound go away if you are at a stop? How about at a stop, in neutral, with your foot off the clutch pedal? If you can hear the sound when you start to push the clutch pedal then it's your throw-out bearing.

TTop Tony

At first I thought it was the posi unit too becuase I have a side entry garage I was turning while I heard the grinding. But now I noticed it happens while the car is perfectly straight and seems to be getting worse (of course that could be me). It a centerforce I clutch and I did have the flywheel resurfaced. The clutch is definitley not as smooth as before the gear swap but I thought that might be because of the 3.7 gears. It sure sounds like something is rubbing against the drivetrain. I also noticed that when I put the car in nuetral and let out the clutch theres a slight whirring noise coming from the transmission. This was happening before the gear swap so I don't know if its related. Its hard to describe because like I say this is my first manual tranny car. I'll see if I can get someone in the neighborhood to drive and see what they think. I just thought there might be a way to tell if a clutch is bad.

TTop Tony

It does go away when I stop and doesn't grind when its in gear. It only grinds when I "feather" it into a tight spot like my garage

TTop Tony

MNJack
I did add posi lube. I also took it to an empty parking lot and did donuts and never heard a peep from the rearend. Is there another way to tell if its my rear end as opposed to the clutch?

burners

How much free play do you have in the pedal with your foot off of it? If it's tight, the linkage needs to be adjusted to give you around 1/2" of play before the pedal begins to take more effort to push.

TTop Tony

I'll check the play in the peddle. Would that change over time? Is that something I should check often?
I just got back from a 30 mile ride and for the first 28 miles I had no problems at all. But after that evreytime I get to a traffic light or stop sign and took off from first that grinding noise showed up but always right before first gear would engage. My friend tells me I worry too much so maybe I am blowing this out of proportion. But it sure is a nasty sounding noise.

TTop Tony

Just wanted to thank you guys for all the helpfull suggestions. My clutch was a bit tight but that didn't seem to solve the problem. The manual says to replace the axle oil 500 miles after the rebuild. So I went ahead and did that. I found a small auto store that carried genuine GM axle grease and the posi lube. I just took it for a long trip along with a few donuts in an empty parking lot and the noise has gone away. So now I know what gear chatter sounds like :D
Once again thanks.