Clunk when disengaging clutch?

[Omen]

I've had manuals in my last 4 cars but I don't particularly remember a clunk when disengaging or depressing the clutch pedal in 1st and reverse. Is this a normal sound?

 

I only hear it if I'm coasting in 1st through a parking lot and I depress the clutch. It makes a clunk sound which is not as loud if I slowly push the clutch in however the sound is still there. It also does it in reverse. Some times the clunk seem louder when my wheel is turned all the way like going around a corner and depressing the clutch. Any thoughts? Maybe its normal but I sure would like to hear a second opinion. I can be a bit paranoid about this kind of stuff but I don't want to take it to the dealer if I can avoid it.

 

Thanks

Mic

[SBT]

Just curious - have you checked your tire pressures lately? Set them at cold specs and drive around normally for a bit, then try it to see if you still have the clunk.

 

Subaru tech used this technique to isolate noise problems with my drivetrain. Turns out my tire pressures were off f/r, l/r so I had a lot of different turning "circumferences" which was causing undue loading on the center differential.

 

Caveat - this was on a 2nd gen Legacy GT with the same viscous-coupled limited slip center differential setup so it should be relatively the same.

 

Keep us posted on what you find out.

 

SBT

[Omen]

yeah I just checked the tire pressures yesterday and they were low so I added air. The sound is after the air was added as I did not notice before today. But I don't understand how tire pressure has to do with a sound when depressing the clutch pedal? I appreciate your feedback I'm just trying to understand.

 

On another note are any of your cars manual? If so do you have a clunk or any other noise when depressing the clutch during a 1st gear roll? Or is it compltely quet? Thanks again.

[SBT]

Omen,

 

I have a 2nd gen manual and "had" this clunk. It was center differential related and released the "clunk" via the clutch when the clutch was disengaged when rolling along on/off idle in first gear. Much the way you described above.

 

The reason I mentioned the tire pressure is that tire pressure differences cause the tires to be larger or smaller (circumference wise) which causes different rotation speeds backwards from the axles to the differentials and ultimately to the center differential which is the "mother" of the system. I say mother because it's function is to balance the front to rear and rear to front torque loads

 

When you've got one axle spinning at a different speed relative to the other axle, then the center differential "loads" and tries to dispel this load back out to the axles. This is difficult on dry pavement so it chooses the path of least resistance, which happens to be through the transmission and ultimately to the clutch. The clunk is the release of that load.

 

BTW - does your transmission seem hard to shift out of first when you get the clunk? IOW - if you were idling along in 1st gear on dry pavement would the transmission shift really easily on your car? If not, then you are getting torque load from the axles. Try bumping your front and rears up (keeping the 2 psi front/rear bias) in 2 psi increments continuing to monitor the driveline.

 

Would be interested to know what you find out.

 

Sorry for the long post.

 

SBT

[Omen]

Thanks for the clarification on that! I will check that out because right now I have the pressure set equal all the way around. I'll let you know what happens.