7 replies to this topic

[Zoofy]

Hello,

My mini hasn't moved for a month now after somebody running into it. I am now finally in a financial stage to fix the little bugger. Only to find that when I went to move it into dry cover it wouldn't engage any gears because the clutch isn't working.

Allow me to explain:
There is nothing under the pedal when I press it. Until the last 20mm! If i watch the slave cylinder it doesn't move at all until that last 20mm.... Now if i press the piston back into the slave i can here the fluid moving up the pipe and back into the master cylinder.. (There are no leaks).

A few people have mentioned that it could be the linkage. But I don't know how to get at the linkage and could it be?

Any wisdom is greatly appreciated!

Regards
Zak

[dklawson]

In car hydraulics slave cylinder pistons do not retract as such. (Those of drum brakes will due to external springs... but the cylinders won't by themselves).

With the clutch slave the clutch itself will push the slave piston back most of the way. After the clutch is fully released the external return spring on the throw-out arm moves the slave piston back a bit more until the arm comes to rest on the "stop bolt". You really don't want the piston going back further. If it did, you would require even MORE pedal travel to move the piston forward. (The further the piston retracts, the more it has to travel forward to do its job).

Look under the dash at the top of the clutch pedal where it engages the master cylinder pushrod. Look for wear in the clevis at the top of the pedal. Push and pull on the pedal to see if the pushrod moves with the pedal or if there is play between the two components. If there is play, a new clevis pin MAY help if the hole in the pedal and the holes in the pushrod clevis have not been worn oval. Move next to under the bonnet. The slave itself has nothing you can really check. Therefore, look at the throw-out arm. It will have a clevis pin going through the clutch cover. If that is worn you will loose a lot of pedal travel there. While you are inspecting the throw-out arm clevis pin, inspect the ball on the end of the throw-out arm. It should be round but is likely to have worn a flat spot on the surface that is pointed towards the engine. With the arm "free" insert it in the throw clutch cover without the clevis pin and try to move it "left and right" parallel with the front of the car. If you find the ball can move left and right, chances are the ball and its mating surface are badly worn. Repair is by replacement.

This means you have about three clevis pins to inspect and/or replace (clutch pedal, top of throw-out arm, and bottom of throw-out arm). There is also the condition of the ball on the end of the throw-out arm and the mating hole in the horizontal rod the throw-out arm is inserted into. When all that is added up, the cumulative wear in the parts creates a LOT of play that reduces the effective travel of the clutch pedal.

I'm sure this is more than you wanted. However, check for wear in the system before thinking you have a problem with the clutch slave cylinder. If it is not leaking, it is bound to be fine. Also, don't be tempted to buy an adjustable pushrod for the slave cylinder. The adjustable rods have no purpose on a car with a hydraulic clutch.

[Zoofy]

Well thank you very much for taking the time to type that out. I will inspect it shortly.

Kindest Regards

Zak

[Ethel]

The returning fluid shouldn't really make a sound unless there's air in it. But what you describe does sound like the master cylinder - if you're not losing fluid.

I think they key here is if it was fine before its "holiday", it's not likely to be wear to the metal bits. Rubber seals do get stuck and then damaged when you try and move them. This is typical of the clutch slave, but it would lose fluid; the master main seal can fail with the secondary keeping the fluid in the cylinder.

[bmcecosse]

Almost certainly the lever pivot on the 'wok' has seized up........spray with release oil and work it back and forth.

[Zoofy]

Almost certainly the lever pivot on the 'wok' has seized up........spray with release oil and work it back and forth.

Did just that, I now have a fully working clutch. And bonus I have a brand new slave cylinder for sale. I will put it on the classified ads this week.

Thanks for everyones help. Much appreciated.

Z

[jimnali]

DKLawson - I applaud your systematic approach to solving this problem. Too many forum members jump to suggesting a solution without properly investigation the problem.

All of your suggestions are valid but I suspect the weather in the UK plays a bigger part than it does in USA - corrosion is a common problem with the clutch linkage. Well done but no cigar!

[dklawson]

Thanks ?

Let's wait to hear what Zoofy (the OP) says he found. He said there is no slave cylinder motion that he can observe until the last 20mm of pedal travel. He did not say that the pedal, throw-out arm, or slave were not moving.