Clutch Problems

[killysprint]

My car hasn't been used properly over the last couple of years, last year the clutch was spot on for the first few miles, once the car got warm the clutch pedal almost disappeared and had to be pumped to work. Thought this was either moisture in the fluid, trapped air or the seals gone in either the master, slave or both.

Fast forward to this year -I want to us e the car more, and I haven't got the time to mess around on the car, so its down at the local "classic" specialist. They've replaced the slave and master, as they said they felt they were weeping, bled the system, and they say the problem is still there. they are now pointing the finger at the clutch fork saying there is some movement on this that shouldn't be there.

Is this possible? before the problems last year the clutch was fine, and maybe done 100 miles if that.

The plate and the clutch it self are uprated and less than 500 miles old.

If it is the fork mechanism, rather than just replace with the same again, has anyone any experience of the concentric system that sprintspeed produce??

https://www.sprintspeed.co.uk/pages/pro ... ct-clutch/

If the box is out, might as well fit this and get rid of the problem all together.

Any information and advice would be as ever greatly appreciated.

Thanks
Tim

[soe8m]

First you have to diagnose what is really going on and that's not that difficult. Clutchforks themselves don't fail very often but the bolt/pin holding these on the shaft do break or bend.

Put the car on a ramp or at your classic garage and have it in gear. You can operate the clutch manually by operating the lever with some large pliers. When operating this way you can 'feel' the diafragma spring flipping over and some helper should be able to move the car forwards and backwards. When the car is moveable still in gear it declutches fine and would eliminate the forks, pin shaft etc and it is an hydrolic problem. Is the feel with the pliers vague and you don't clearly feel the diafragma spring and the car isn't moveable in gear while operating the lever then it's a mechanical issue and means gearbox out and see from there.

When pressing the clutch pedal you should have the same movement as you did with the pliers and that you can check visually.

When it's diagnosed as an hydrolic problem it can be a few things starting at the simplest to solve.

- Air in the system because of a wrongly fitted slave. The bleeding screw has to be at the top but many fit it the wrong way as the pipe is in it's way. Having the bleeding screw at the bottom it's better access but won't bleed properly.
- Obstruction of the clutch pedal. Some put some extra sound deadening material or extra overmats in their Dolomite what shortens the pedal stroke. You do need the whole lenght at a Dolomite from start to bulkhead and not some mats inbetween.
- A very old flexi hose. Flexihoses do soften and pressing the clutch pedal makes half of the stroke expanding the rubber hose and the other half of the pedal stroke tries to operate the slave having that stroke to short and not declutching.
- Wrong diameter cylinders. All Girling type cylinders are physically the same but there are a lot of different bores. Non matching bores can have a too short stroke at the gearbox. The master cylinder is not widely available with the correct diameter and the correct threads to fit the reservoir and hose so maybe an alternative is fitted that does fit the hoses but has a smaller internal diameter. At the gearbox it can be a too large diameter as this shape is used in many cars and then also available in many diameters.
- A wrong shape slave cylinder fitted. There are different offset cylinders with the mounting ears differently orientated on the cylinder. These physically do fit but are on the wrong position.

In your statement of needing pumping to work when hot I suspect it's hydrolic and your classic garage didn't solve the issue correctly or did fit the wrong parts. When pumping twice and there is a declutch and the cold/hot issue doesn't point towards a mechanical problem.

Jeroen

[killysprint]

Jeroen - thanks for this, will ask them to check all the points you suggest.

[soe8m]

Just driving home with still a gearbox cover to fit... seeing all clutch movement as live data, another thing to add is checking the lenght of the rod of the master cylinder. Some new master cylinders come with a rod fitted but it doesn't mean that lenght is correct for a Dolomite. You should have the clutch pedal about the same hight as the brake pedal. When the clutch pedal of your car is sitting lower than the brake pedal maybe the rod is too short and making the master cylinder having too less travel.

Jeroen

[new to this]

Check it bleed properly

Dave

[Carledo]

THIS!!!!! ^^^^^^^

Even with the bleed screw in the top position, the slave cylinder sits at such an angle that, with the car on level gound, there is a part of the slave cylinder bore that is ABOVE the bleed screw. Air can get trapped in this space and be the very devil to shift. Worse still if the front of the car is jacked up during bleeding.

So the cure is very simple, jack the REAR of the car up a couple of feet and bleed it like that!

Steve