more clutch help please (car in shop ) ....

[gibson36]

okay you guys warned me not to trudge in to my new to me 1982 928 so I took my car to a Porsche repair shop here in Cincinnati to have them replace the clutch master ... they did that and now they can't get it to hold pressure it wants to bleed down .... they have tried bleeding it both ways forward and backwards and now They are thinking about replacing the slave as well ( its not leaking ) but they are out of things to check ..... please let me know what you guys think I should tell them ..... could this be a bad hose or something other than the slave there are no fluid leaks under pressure even when hooked up to machine ? ? ?

Justin

They will be reading this so feel free to ask questions ....

[Opelotus]

I suppose there could be an internal leak in the slave cylinder, or maybe even in the master? Bad/defective seals?

[gibson36]

the part I used was a F. A. G . I was told this was a good brand .... so I don't think it's a bad master

[Opelotus]

I recall that brand being used at the shop I work at, pretty sure they make good stuff. Couldn't hurt to replace the rest of the clutch hydraulics as preventative maintenance too (especially if they are old). What is the condition of the rubber flex line on the driver side of the car? It could be swelling when you press the clutch, therefore not building proper pressure in the slave cylinder.

[Landseer]

I've had them not pump-up.

The way that solve it for me was bleeding it into a towel in the car. It will spurt the fluid, so protect the inside of the car and yourself.

Basically, remove the clutch actuation rod. Remove the retaining clip for the master piston. With one strong finger always on the piston, ease it into the car until it burps air and then fluid, quick push it back into the bore, and replace the clip and rod.

This way always works on mine, same brand, new, as yours.

[Danglerb]

Taking a wild guess this is a Porsche shop, but not very experienced with a 928?

It can be a very expensive path letting a mechanic learn the 928 on your dime.

[Pete R]

clutches are really really hard to bleed. It literally took hours to bleed mine. landseer seemed to have a pretty good idea. The slave is about a 10 min swap and if they are the some age it wouldn't be a bad idea, it's moved as many times as the slave

[Mrmerlin]

also note the new MC may have a longer piston this will reduce the amount of push and then it will result in a dragging clutch,
the thing to do it swap the pistons and put the new seal on the old piston..
OR cut the tip of the new piston off

cut off about 4 to 5 mm of the tip but measure first,

also measure the MC spring make sure its not binding at full push,
I have seen the springs shatter and destroy the MC and slave seals from spring shards,

the solution cut a wind or two off the spring

[Landseer]

^^ I forgot about that issue.

[lizard928s]

Bleed the master from inside the car as previously stated.

[Mrmerlin]

BUT inspect the pistons of the MC parts you have first.

the new piston will be longer than the old original if thats what you have

[gibson36]

Ok I was told I needed a 10" mc and thats what I got .... I sent them the new slave yesterday so maybe that will fix the problem ... also should they need to bleed that from inside even with a pressure bleeder machine ? ?

[Opelotus]

Correct me if I'm wrong, but because of the orientation of the master cylinder, air bubbles tend to get stuck in spots which are hard to bleed out, so a pressure bleeder may not work 100% where bleeding the MC in the car would.

[Landseer]

Originally Posted by gibson36

Ok I was told I needed a 10" mc and thats what I got .... I sent them the new slave yesterday so maybe that will fix the problem ... also should they need to bleed that from inside even with a pressure bleeder machine ? ?

The 10" master may have had a design change to limit travel, that's what others have found. Stan reported that shaving the piston works to remedy.

The MC is installed on an angle. It gets airlocked. There is no way to even angle the car safely to overcome the crazy mount angle.

(If you look at brake calipers, the bleed screws are at the top of the units to aid bleed. Something overlooked in the 928 clutch master design/mount process.)

Pressure bleeder has never worked for me on clutch.
From either above or below.
But the cockpit bleed has.


These cars are so well engineered in general that the design flaws stand out. This is one of them.

Its also interesting to see the little clusters of failure modes develop with age of the cars. Like the insulation in the headlight electrical circuit, where the headlight goes up/down. After 25 years, it breaks.

[stepson]

Originally Posted by Landseer

The 10" master may have had a design change to limit travel, that's what others have found. Stan reported that shaving the piston works to remedy.

The MC is installed on an angle. It gets airlocked. There is no way to even angle the car safely to overcome the crazy mount angle.

(If you look at brake calipers, the bleed screws are at the top of the units to aid bleed. Something overlooked in the 928 clutch master design/mount process.)

Pressure bleeder has never worked for me on clutch.
From either above or below.
But the cockpit bleed has.

+1 I had the same MC problem on my '84 Euro 5 speed. The original replacement MC would not throw the clutch plate far enough to release.(this was prior to the common 928 knowledge of the increased length of the rod)
Pressure bleeder never worked for me either. Inside cabin bleeding was the only thing that completely worked for the air in the system (AFTER BLEEDING FROM THE SLAVE CYLINDER)

[Alizxa]

I have a 2003 Neon R/T 5-speed manual transmission. I believe that I need to rebuild it and would like to buy a kit, but it has proven to be harder that it would seem to find one. Here is the story of the transmission and tell me if you think it needs to be rebuilt or if it is something different.It was slipping out of 5th gear. Over time it became more and more frequent. Eventually it wouldn't hold itself in 5th gear at all. I had to manually hold it in 5th gear. I was going down the highway, and it slipped out of 5th gear. So I tried putting it back, but when i released the clutch pedal nothing happened. It acted as if it were still in neutral. So I put in fourth and thought that i could make the rest of the trip that way and then fix it at my destination. About 5 miles down the road 4th gear went out as well. I parked the car at a shop, and am now seeking a method of solving this problem. Thanks for your help.

[Mrmerlin]

Alizxa I would look at a parts recycler ( junk yard) and buy a used transmission,
no need to try to rebuild a part that can easily be swapped out for a unit in working condition.
By the time you pay for new gears and bearings and labor you will easily have paid for a used transmission.
Put a new clutch in while your in there as well as replace the rear main seal of the engine

[gibson36]

car is off to another shop at this point ... now it won't shift in to gear at all while running in neutral but if you start it in gear you can baby it in to the rest ... ( note that before this whole thing you just needed to pump it up ) the shop it was at said they think it needs a thro out bearing or something but like i said it was fine before they did the mc and slave just had to pump it up ? ? ? i did pass all the info on to the new shop .....as well

[Mrmerlin]

you dont need a throwout bearing unless its making a grinding noise with your foot off the pedal.
As previously posted you have an updated clutch master cylinder and the new piston inside the part is too long have the old MC opened and then swap the pistons and put the seal from the new piston onto the old piston measure the spring so you dont put a longer spring in as it will soon shatter due to being over compressed IE too many spring wiinds

[Landseer]

Any predictions on how this is going to end?