Clutch hydraulics problem?

[Barkychoc]

Dave M has kindly lent me his wedge for Chatsworth - but I have a concern with the clutch hydraulics (I will still be coming in it Dave!)

Driving along with the clutch at the top of its travel - if you rest your foot on it lightly it will suddenly unexpectedly plummet either almost to the floor or part way. Pressing it right down to the floor doesn't necessarily disengage the clutch enough to engage gears - you have to bring it up and press it down again (so pumping up the hydraulics).
Taking your foot off completely so the pedal returns to the top if its travel returns the clutch feel to normal - until it drops again.

I'm assuming a set of seals are giving way - but which end?

I haven't had chance to look under the bonnet to check the fluid level or to look to see if there are any telltale leaks visible.

Edited by Barkychoc on Thursday 22 April 21:37

[Number 7]

I think the only way is to look at the level and colour of the fluid. If it's dark / low, a bleed through may help. If it's the master cylinder, you would normally see fluid running down the pushrod and onto the pedal box. IME just changing seals is a short-term fix. Part of the problem with the Wedges is the pushrod can be wound out quite a long way on the adjuster, which means that the force is not being directed straight into the bore - it's at a slight angle, and over time the bore wears. Best to keep the rod as short as possible.

7.

[leorest]

Simple things first.

Check the fluid level, then bleed the system.

[C O Jones]

This sounds like it's the Clutch Master Cylinder valve that is failing.

On the clutch M/C pishrod there is a piston with a seal but at the end of the piston there is a little thingy that cuts off the reservoir from the circuit to prevent the fluid from going back into the reservoir rather than down to the slave.

This shows itself up if you lightly press the pedal (less pressure than the normal clutch takes) and the pedal goes to the floor - but if you press the pedal quickly the clutch will operate.

The cure is to renew the seals and rubber in the Clutch M/C (or replace the whole thing).

Russ

[Wedg1e]

C O Jones said:

This sounds like it's the Clutch Master Cylinder valve that is failing.

On the clutch M/C pishrod there is a piston with a seal but at the end of the piston there is a little thingy that cuts off the reservoir from the circuit to prevent the fluid from going back into the reservoir rather than down to the slave.

This shows itself up if you lightly press the pedal (less pressure than the normal clutch takes) and the pedal goes to the floor - but if you press the pedal quickly the clutch will operate.

The cure is to renew the seals and rubber in the Clutch M/C (or replace the whole thing).

Russ

Seconded. The other issue with the m/cyl on the wedge is that due to the angle the pushrod makes with the piston, it tends to force the piston to one side and the bore wears oval... so even a new set of seals won't fix it (or not for long).

[Barkychoc]

Thanks Guys, this sounds like exactly the symptom, and if thats the case I reckon I should be OK going to Chatsworth, as its not actually leaking is it? Just pushing the fluid back into the reservoir.

I'll have a proper check tomorrow.

Chris

[DeadSpider]

Old thread I know was driving Dave M's Wedge around Bruntingthorpe yesterday (cracking day) and noticed fluid dripping onto my left foot upon further investigation looks like the master cylinder has let go. Fluid is a dirty black colour what was left of it.

Can anyone tell me what the 350i master cylinder replacement part is off.

cheers
DS

[simonwedge]

An old thread said it was a Lucas Girling Q0012, not sure what it's off but I expect someone will be along shortly...

[Wedg1e]

DeadSpider said:

Old thread I know was driving Dave M's Wedge around Bruntingthorpe yesterday (cracking day) and noticed fluid dripping onto my left foot upon further investigation looks like the master cylinder has let go. Fluid is a dirty black colour what was left of it.

Can anyone tell me what the 350i master cylinder replacement part is off.

cheers
DS

Yep, Lotus Cortina

Girling seal kit SP2102 if I recall correctly, but that won't necessarily fix it as, due to the angle that the clutch pushrod attacks the m/cyl piston, the bore wears oval. I'd strip it first, measure (or just eye-up, if it's really bad) the bore and take it from there. On the other hand the seal kit is about a fiver and takes 20 minutes to swap, so it's up to you.

[350zwelgje]

Several master clutch cylinders out there for the wedges, mine is rover sd1 (seems to be an exception!). Knew this due to having an sd1 in the garage and they are the same... Overhauled mine with a kit, as it was not oval and carefully reinstalled it to have the pushrod as centered as possible. It is still ok after a couple of years and many miles of use. Now the clutch started slipping, so another job to be planned to complete the clutch operating picture.....

Rob

[Dave_M]

Thank you guys

We had a great day out yesterday, 16 TVRs in the photo shoot and a fantastic variaety of models too.

The photographer liked the wedge as a platform to shoot from... until I accelerated a bit quick - oops!

Can't wait to see the results. Then we met Combine on the way home too

[ROOODBOY]

My clutch hydraulics were doing very similar things to this a few weeks ago on my 1989 350I.

I replaced the master and slave for brand new ones (tvrcarparts.com) and all is good.

You may find that replacing either one cylinder will be followed by the failure of the other cylinder soon after.