Clutch Problem

[monkey636]

Been having issues with my clutch, happened at the Ring and at Spa, basically clutch pedal went to the floor withour engaging, had to scoop it up with my toe and wait then it started working again.

It seems it cooked for a bit then recovered. I had a look at the repair manuals, it appears that the slave hydralic circuit is self contained within the clutch itself and is a gearbox out job? I think i've basically boiled the fluid in it a few times!! Anyone experienced something similar?

The primary hydralic circuit is via the master cylinder, but since the brakes didn't fail i'm ruling that out. The fact it recovered leads me to believe that the slave cylinder isn't up to the job.

 

[k1ano]

i had a clutch issue where the clutch would not engage and the pedal went to the floor ... On inspection of the system and under the bonnet i realised the level in the shared fluid reservoir had dropped below that of the clutch outlet and let air in. The clutch outlet is higher than the brake one so as the pads wear the level seemed to drop below the clutch outlet. I just topped it up, pumped the pedal a few times and it ias been fine since may be worth a check ? Martin

 

[Ginagarus]

Though the reservoir is shared you should have a seperate master cylinder for the clutch completely independant of the brakes and potentially the seals can fail in these, on other cars I have worked on in the past (saabs mainly) we found that if you lost the pedal but stamping on it or using it sharply could bring it back then it was often the master but it could be either end, I wouldn't discount it and as you say its the easiest to access so check it first would be my advise. :s

 

[monkey636]

The repair diagrams simply show a pipe connecting from the reservoir going to the gearbox where is must connect to the slave cylinder? Just perculiar that it happens when it's really hot and been used in a 'competitive' situation!

 

[clarkiev6]

the slave is part of the clutch release bearing and can't be changed without removing the gearbox.

 

[monkey636]

I would be interested to know if a variant of the trophy clutch (with the right splines) would be heavy duty and cope with this problem? I doubt I can simply replace the fluid in the slave unit as it looks like a complete part?

 

[k1ano]

Levels and fluid loss is easy to diagnose so you should be able to include or exclude that ... As the pedal is depressed the level increases and decreases slightly so can draw in air if the level is low - as I described in my case.

The fluid is hydroscopic so absorbs air and so when it gets hot it releases the air and the pedal can become spongy - this is what happens with brakes (which can sometimes appear or be associated with brake fade) ... Symptoms could be the same with clutch I would suggest manifesting in poor engagement when the fluid is hot ? With the slave cylinder in the bell-housing I would think localised fluid temperature would get hot enough for the fluid to release it's air.

Have you replaced clutch and brake fluid at all ? Or to the manufacturers recommendations - think it is every 2 years normally. Most people don't bother with many cars.

Martin

 

[monkey636]

Never replaced the fluid, for the record didn't have any problem with the brakes but I will replace the fluid just in case (it'll give me an excuse to fit my goodridge brake hoses!). As for the clutch slave circuit, as it is enclosed the only way I can replace that is gearbox out, I would like to know though whether that is a completely self contained unit ie. can you or can't you replace the fluid within it?

 

[ed_harland]

Yes you can bleed the clutch circuit as you would the brakes

 

[monkey636]

Like this?

LINK

I'm assuming that the brakes and the clutch share the same fluid then? as they use the same reservoir? - would this mean that aggressive braking could contribute towards clutch problems and vice versa?

 

[monkey636]

For the record, it doesn't really confirm my thoughts that the fluid within the slave circuit is sealed and can only be changed by replacing the slave/clutch release bearing unit? My belief is that it is not possible to bleed the fluid in the slave part of the circuit, once the fluid is in there it is "trapped".

 

[Anonymous]

Levels and fluid loss is easy to diagnose so you should be able to include or exclude that ... As the pedal is depressed the level increases and decreases slightly so can draw in air if the level is low - as I described in my case.

The fluid is hydroscopic so absorbs air and so when it gets hot it releases the air and the pedal can become spongy - this is what happens with brakes (which can sometimes appear or be associated with brake fade) ... Symptoms could be the same with clutch I would suggest manifesting in poor engagement when the fluid is hot ? With the slave cylinder in the bell-housing I would think localised fluid temperature would get hot enough for the fluid to release it's air.

Have you replaced clutch and brake fluid at all ? Or to the manufacturers recommendations - think it is every 2 years normally. Most people don't bother with many cars.

Martin

Ehhhmm Martin little correction here, Hydroscopic means it absorbs the moisture which is in the air. Due to rising temperatures the water vaporates and creates damp bells, hence the spongy brakes, or clutch.
That is also the reason you should change the brakefluid once every second year, specially in the brittish climate.

If you push the car really hard for a while, I managed to do a 15 minutes flat out run on an empty germann autobahn, the whole gearbox got locked into sixth gear. Had to cool it down for about 10 minutes before I could engage the gears again.

 

[Anonymous]

For the record, it doesn't really confirm my thoughts that the fluid within the slave circuit is sealed and can only be changed by replacing the slave/clutch release bearing unit? My belief is that it is not possible to bleed the fluid in the slave part of the circuit, once the fluid is in there it is "trapped".

Normally in those constructions the bleedvalve comes from the cylinder, so it is a bleedline inside the feedline. elsewise you could also be left with airtraps in the cylinder. Don't know how it is with the Vee though. Can have a look, got the gearbox dismanteled anyway.