NIACAL4NIA

First problem- The clutch has developed clicking clunking noise in the middle front area when I release the clutch either in neutral or first gear only while engine running, however works normal with no vibration. Clutch was replaced 20k miles ago and I also replaced the clutch release ball cup bushing, master cylinder, slave cylinder, blue hose and clutch high pressure hose.

Second problem- My brakes do not work properly when the clutch is pressed so I'm thinking there is still air in the system. There are 2 methods for bleeding the slave cylinder 1- removing and pushing the slave cylinder rod all the way in. 2- Forcing the air out by pumping clutch fluid into the slave nipple. Do I need to bleed the clutch, brakes or both? Which method is more effective?

1986 Porsche 928 32v 5speed

Mrmerlin

1st issue sounds like the TOB is going bad
2nd issue need more info than brakes dont work properly

Note clutch and brakes both draw from the same reservoir but have different supplies in the tank,
neither will affect the other unless there is a leak and the tank is low or out of fluid

NIACAL4NIA

Thanks but I was told that a bad TOB makes noise upon pressing the clutch not releasing. I don't have problem with pressing , vibration or operation of the clutch just a clunk noise at release in nuetral or first gear. My brakes get harder when the clutch is engaged or feels like the the brake booster cuts off the vacuum but works fine if I don't use the clutch to stop.

NIACAL4NIA

1. Start your car, set the parking break, and put the car in neutral.
2. With your car idling, listen for a growling noise without pushing the clutch in. If you hear something, it's most likely a problem with the transmission. If you don't hear a noise, proceed to step three.
3. With the car still in neutral, begin to push the clutch and listen for noise. If you hear a chirping noise as you press, it's most likely the clutch release, or throw-out bearing. If you don't hear a noise, proceed to step four.
4. Push the clutch all the way to the floor. If you hear a squealing noise, it's probably the pilot bearing or bushing.

If you don't hear any noise during these four steps, then your problem is probably not the clutch. If you hear the noise at idle and it goes away when the clutch is pressed, it may be an issue in the contact point between the fork and pivot ball.


I don't have any of the above problems so could it be a transmission mount or the exhaust hitting some thing down there? The noise happens when the clutch is release and makes a clunking nose like some metal hitting some thing. No noise if I'm driving.

Mrmerlin

check the bracket on the oil pan for the clutch line support

NIACAL4NIA

Did I mess up some thing when I replaced the clutch release ball cup bushing cuz I had to get the pannel near the slave cylinder off in order to replace the bushing?

Mrmerlin

a better question to ask is what was the last thing I fixed

crushingday

I am having the same "clunk" when I begin to let the clutch pedal back up after pushing it to the floor. Did you get this resolved? I would love to know the solution or what needs to be looked at

NIACAL4NIA

I replaced the motor mounts to make the engine more aligned with the transmission and also got rid of the air in the clutch slave cylinder by backward bleeding using a regularly oil can and plastic tube at slave cylinder to force air up to master cylinder. Adjusted the clutch pedal freeplay to 3mm according to manual No longer have brake problem while engaging clutch. The clunk noise has reduced but not completely so I just ignore it and no problem since 2011. My 928 has close to 200k miles and 30 years old so minor noises don't bother me. BTW my timing belt is 13 years old but had less than 30k on it and since I live in southern California in a temperature controleded garage, I don't have the typical timing belt paranoia.

crushingday

Thank you for the update and helpful info.

Livio928

I am having a similar problem. When I depress my clutch I feel a vibration towards the end of the movement of the clutch and hear a rattling somewhat clunking noise. I replaced the whole clutch, TOB and all WYAAITs last fall and have maybe 7k kms on it. It just noticed the vibration Tuesday night after the Sharks in Ontario run. Could it be the TOB again??

NIACAL4NIA

Did you use the Porsche clutch alignment tool to keep the disk balanced? Unbalanced causes vibration.

Livio928

No. This only started vibrating the last couple of days. I would imagine it would have vibrated much earlier if there was an alignment issue.

NIACAL4NIA

[QUOTE=Livio928;13482778]No. This only started vibrating the last couple of days. I would imagine it would have vibrated much earlier if there was an alignment issue.[/QUOTE

If you have the earlier dual clutch, it could be the center pin needing adjustment.

Livio928

I upgraded to the GTS clutch last fall.