Clutch Trouble

[Faheem]

So after the Bleed I took the car for a drive and all was fine, however at some stages during the drive, I struggled to get it in gear, unless the pedal was right down to the floor. This was intermittent. Being a moron I was not satisfied and decided to replace the slave.

I bought a new slave, connected it to the clutch hose, mounted it up, pumped the clutch a few times, removed it again, opened the bleed nipple and pushed the piston in a few times to remove any air and closed it when the piston went back into position.

I did this a couple of times then mounted the slave back up to the transmission. I then went to press the clutch pedal. When I did the piston shot out into the bell housing....

I managed to retrieve the piston and have removed the new slave but I'd be curious to know why this happened.

Now I'm stuck again trying to Bleed the old one! Absolute nightmare.

I'm beginning to learn something - if it ain't completely broke, don't fix it

 

[t-tony]

@FRANKIE had this issue Faheem, mainly due to the rubber dust cover on the after market cylinder not being rigid enough to support the push rod as you fitted the cylinder. It doesn't locate into the and of the clutch release arm and pushes straight out into the bell housing. Cheap after market parts I'm afraid.

Tony.

 

[colb]

Have a look a this old thread it tells you how to bleed it
https://zroadster.org/threads/clutch-failure-m44.7810/#post-110060

 

[Faheem]

@Brian H hi, from the post you've made in that thread I imagine you mean to clamp the push rod so that it is fully Compressed, then open the Bleed nipple and connect your bleeder onto it, after connecting the bleeder and ensuring the push rod is Compressed, I should pump the clutch pedal a few times until I start feeling resistance?

Then close the Bleed nipple and remove the clamp, fit the slave back onto the bell housing and tighten everything back up?

I want to double check before I attempt this, as bleeding it is a pain in the backside. The first time I bled it, it took me a good couple of hours.

@t-tony the aftermarket was pagid (I always thought they were reputable and made good stuff) I'm really annoyed that it broke that easily, can't even mend it as it has ripped the rubber seals out.

I bled the slave whilst it was out of the bell housing and made sure that I didn't press the clutch pedal, then I put it back, tightened everything pushed the clutch down and *pop*

With my symptoms would you have thought that my slave was faulty? Biting point being quite low and sometimes struggling to get it into gear unless the clutch is pushed right to the floor?

 

[Faheem]

@t-tony I followed this method to bleed it.

View: https://youtu.be/xl5WQCgUjDc


Felt really good at the end and only popped after I'd put everything back together

 

[the Nefyn cat]

Please forgive my butting in, but it may be time to invest in one of these.
http://www.ebay.co.uk/itm/Gunson-Ee...630712?hash=item43c9ee0f38:g:ZlgAAOxyLm9TGaIC
Fit the slave cylinder, making sure the end of the pushrod engages in the release arm, and then bleed it up. It sounds like you've missed the release arm, as soon as you put any pressure on the system the pushrod will just fly out of the end of the cylinder, and that's when the swearing starts. Well, in my experience it does.

 

[Faheem]

@the Nefyn cat thanks! That would make perfect sense. I do have a small bleeder, its definitely not as fancy as that one but it features just a one way valve (so as not to let air back into the system) and a small bottle in which the valve feeds into.

I tried putting the bleeder on the nipple and pumping the clutch, however, the pedal didn't build up sufficient pressure suggesting that there was still air in the system.

Maybe this kit that you've put a link to will Bleed the system properly, however, for occasional use I'd rather not spend that amount if I can at all avoid it.

 

[the Nefyn cat]

That was just the first example I came across, it'll be there for less, I'm sure. And other brands are available. Pressure bleeders will help to overcome the problem of having to force air down-hill, always a tricky thing to do as it just wants to get back up again. If you've any intention of doing any amount of brake and clutch work in the future (and nobody actually wants to, we just have to) some kind of bleeder is a wise investment, if only because you can bleed out a full set of brakes without having to coerce anyone into sitting in the car while you shout DOWN UP DOWN UP for half an hour. Go on, guess how I know this to be true.
A quick edit, you may have seen a thread I started on here a couple of weeks ago about a brake upgrade I fitted https://zroadster.org/threads/325mm-discs-on.17389/ . Bled in seconds, all so easy with the bleeder doing all the work for me. Same when I refurbed the rear brakes, just makes life so much easier.

 

[Faheem]

Thanks! Now it is just a case of finding out whether my old slave cylinder is faulty or whether it just needs to be bled.

I also tried to get an old o2 sensor out but can't get enough torque to do it with a breaker bar and a 1/2 inch socket. Tried heating up the exhaust and using wd40 but to no avail! Just started to strip the head so stopped. Don't have a torch so I can't heat the sensor up as much as I'd like to.

 

[colb]

Yes clamp the push rod in then open bleed nipple and press clutch pedal down its a two person job doing it this way so one pumps the pedal and the other opens and closes the bleed nipple. When pedal is fully down it should be held there whilst the person on the bleed nipple closes the nipple. Once closed pedal can come back up and repeat the process til no air bubbles come out at nipple end. Just like bleeding brakes.

 

[colb]

O2 sensor, I used a tight fit ring spanner on mine even though I had a Lambda socket to hand, found the ring spanner got a better grip. Might need a lump hammer to wack the spanner to get it started if it's really tight. Disconnect the wires and thread the spanner onto the sensor, best use the longest ring spanner you have, if you want more leverage find some pipe to slip over the spanner to make it longer.

 

[FRANKIE]

Thanks! Now it is just a case of finding out whether my old slave cylinder is faulty or whether it just needs to be bled.

I also tried to get an old o2 sensor out but can't get enough torque to do it with a breaker bar and a 1/2 inch socket. Tried heating up the exhaust and using wd40 but to no avail! Just started to strip the head so stopped. Don't have a torch so I can't heat the sensor up as much as I'd like to.

This is my fault. I had many film clips that I spliced together on the replacement of the clutch and slave cylinder. The most important part of the film is at the end. Lets go back to your pushrod of your slave cylinder popping out. This was due to the fact that when you replaced your slave cyilinder, the push rod never contacted the throw out bearing arm. As a result, when you pushed against the clutch pedal, the clutch master cylinder pushed the hydraulic fluid into the slave cylinder which pushed against the push rod. Since the push rod was not contacting the arm of the throw out bearing, it had nothing to stop its foward travel and pushed out completely from the slave cylinder. It's like the brake cylinder on a shoe break when the shoes are completely worn or the break shoe comes loose. The break cylinder piston will pop out of the cylinder if the shoe is no longer in place or the shoe is too worn. The problem here is if the slave cylinder can be used anymore as the push rod and seat or grommet can be re-inserted by you as they were probably initially done by a machine. I returned mine, when this first happened to me for a new, and better one. The store gave me credit on the old one (as I bitched about the quality) and only charged me for the cost of a better unit.
If you are putting the unit back in, please see the end of the video I did as it utilized the information of a 30 plus year BMW mechanic and was actually fairly easy. To go over it: Make sure your master brake cylinder relervoir is full You attach the hydraulic line to the slave cylinder which is not yet attached to the bell housing. Open the bleed screw. The fluid will start to DRIP out. When the drip changes to a steady flow, close the bleed screw. With the slave cylinder in your hand. place the push rod against something that won't move such as your transmission. Push the slave cylinder with your hand so that the push rod depresses into the slave cylinder. Do this several times until you begin to feel it getting harder and harder to push. When it gets very hard to push, insert the slave cylinder into its place in the bell housing. If the push rod is contacting the arm of the throw out bearing, you won't be able to fully insert the slave cylinder. This is because the push rod is contacting the arm of the throw out bearing. If the slave cylinder goes all the way in with no trouble and seats conpletely on the two studs that it attaches to, you've missed the throw out bearing arm and you must try again until you can't completely get the slave cylinder fully in without alot of pressure. If you're on the ground looking up at it, it's dirfficult to get enough leverage to pust this into place as the push rod is not going to move any more and you are now trying to move the throw out bearing against the pressure plate. I had to catch one nut on to the end of one stud and then use a screwdriver against the base of the slave cylinder plus another tool as a spacer between the screwdriver shaft and the slave cylinder base to get enough pressure on the slave cylinder base to push it on to the second stud enough to catch the nut on the end threads.
Once you've fully secured and tightened the two nuts, make sure the bleed screw, which should have been closed, is tight enough that it won't leak, Don't over tighten it. Place the rubber cap on it if it came with one. Go into the car and rapidly depress the clutch pedal with your hand about 50 times. Use caution if the car is still up on jack stands, and start the car in neutral and see if you can place the car into gear. Remember not to let out the clutch as you will move the car while it's still up on the stands. If you can't get it into gear at all, repeat the process of bleeding. Don't forget to recheck the fluid lever in your master brake cylinder reservoir and replace the cap. If the slave cylinder was difficult to push against the transmission the first time, you shouldn't have any problem. AT this piont, as I was told by the mechanic and as actually happened to me, I could drive the car but the clutch didn't feel 'perfect' right away. There is still a small amount of air in the system but this soon bleeds itself out after driving a few miles. Mine felt perfect after about five of ten minutes of driving. Let me know how it works out..........................Frankie

 

[Faheem]

@FRANKIE cheers, when I bled the new slave for the first time, the push rod got really firm and was difficult to push the rod in by hand.

However, no matter how much I Bleed the old unit, I can't get the rod to the point where it's difficult to push in by hand.

To me, and I'm no mechanical expert so correct me if I'm wrong, but I think that the old slave was easy to put in because the push rod had less resistance. When I went to put the new slave in, because of the pressure and not wanting to force it in, I must have moved it into a position where it missed the arm.

Problem I had was that the push rod of the new slave was flexible to a certain extent meaning that I suspect that when I pushed it in, the rod bent a little, just enough to miss the arm.

 

[the Nefyn cat]

The pushrod won't be flexible, it's just not a firm fit as it has to be able to move through an angle as it pushes the release arm, not much of an angle but it's there all the same. If the piston has come completely out it will go back in, just a bit of a fiddle getting it in as the seal has to be a tight fit, and if you bu55er up the seal you'll have to get another cylinder. Oh for the days when you could get seal kits for anything, grumble grumble.

 

[FRANKIE]

@FRANKIE cheers, when I bled the new slave for the first time, the push rod got really firm and was difficult to push the rod in by hand.

However, no matter how much I Bleed the old unit, I can't get the rod to the point where it's difficult to push in by hand.

To me, and I'm no mechanical expert so correct me if I'm wrong, but I think that the old slave was easy to put in because the push rod had less resistance. When I went to put the new slave in, because of the pressure and not wanting to force it in, I must have moved it into a position where it missed the arm.

Problem I had was that the push rod of the new slave was flexible to a certain extent meaning that I suspect that when I pushed it in, the rod bent a little, just enough to miss the arm.

You are correct in noticing that the pushrod on the old slave has less resistance when pushing it in. I am guessing that the piston behind the pushrod can no longer prevent hydraulic fluid from seeping around its edges along the cylinder wall as it is too worn to keep a perfect seal. When I bought the first replacement slave cylinder, the rubber around the push rod was flimsy and could not keep the pushrod exactly straight as it was inserted into the bell housing. It drooped just a bit making it almost impossible to contact the arm of the throw out bearing. I compared the new slave to the old one. The new one had a flimsy, flexible boot type piece of rubber holding the shaft of the pushrod while the old one had a hard, solid disc of rubber that kept the pushrod perfectly straight and rigid as it came out of the cylinder. The disc didn't allow any movement of the pushrod except in and out. This meant that the pushrod was held in an exact firm position straight out from the slave cylinder no matter what position you held the cylinder. When the slave cylinder is inserted into the bell housing, the push rod has almost no alternative but to contact the arm of the throw out bearing. If your new slave cylinder has a rubber seal that doesn't hold the pushrod firmly, return it to the store and get one that is better made with a solid piece of rubber seal..............Frankie
PS. When you go to put in the new slave cylinder that is fully bled. it will stop from being fully inserted if the pushrod is contacting the throw out bearing arm. It will stop about a half inch or more from being fully inserted. At this point, you might have enough muscle to push it all the way in. I didn't as I was under the car on my back and I'm not as strong as I used to be. If you only have a half inch to go, you're on the right track. Remember that you're pushing the throw out bearing against the pressure plate. If the pressure plate is out of the car on the ground, you would have to stand on the center rings or springs to actuate it:

Your push rod is contacting the end of the clutch release fork which has the throw out bearing at
the edn of it.see it in these pictures:

You can see in these pictures of throw out bearing forks the small area of depression that you must blindly hit with the end of the push rod...............Frankie

 

[Sean d]

well done pal, your mechanical skills are improving no end since you bought your zeds.

 

[Faheem]

Hi @FRANKIE that was an interesting read, thanks.

The replacement I purchased yesterday I managed to get replaced, no quibbles as I was a "loyal" customer (something breaks in the zed every week, basically!) However, it is unfortunately the same part.

I've yet to compare it against the original as the original is still in the car. However, here is a video of it and some pictures.

Is this what you meant about the rubber being flimsy?

View: https://youtu.be/an9dfzvZzbQ



@Sean d that suggests that my zeds have too many issues spend more time fixing them than driving them.

 

[oldcarman]

Don't Dispair @ Faheem. You are getting a crash course in fixing the z3 which will serve you well later in life like when you turn 22!!! lol. JIM

 

[FRANKIE]

Hi @FRANKIE that was an interesting read, thanks.

The replacement I purchased yesterday I managed to get replaced, no quibbles as I was a "loyal" customer (something breaks in the zed every week, basically!) However, it is unfortunately the same part.

I've yet to compare it against the original as the original is still in the car. However, here is a video of it and some pictures.
View attachment 55195
Is this what you meant about the rubber being flimsy?

View: https://youtu.be/an9dfzvZzbQ



@Sean d that suggests that my zeds have too many issues spend more time fixing them than driving them.

That looks more than sturdy enough to maintain a straight line while inserting it into the bell housing. If I were to do it again, I would have the new slave cylinder close at hand with me under the car, unbolt the old one, remove the hydraulic line from the old cylinder and quickly attach it to the new one screwing it all the way in. Refill the master brake reservoir and then go back under the car and loosen the hyd. hose so it starts to drip and tighten it when the drip turns to a steady flow. The BMW mechanic gave this as the only bleeding proceedure up to this point. After this is done, pump the push rod against the body of the transmission until it is hard. From the time that you begin to unbolt the old slave cylinder to the time you have the new one pumped up against the transmission might take you only 15 minutes. When you insert the new one into the bell housing and make contact with the fork of the throw out bearing arm by noticing that you still have about one half inch or a little more to go is the time where you might have the most trouble. The difficulty lies in how much power you have to push it in the rest of the way and the time it takes you to get both nuts on so that you can then easily start to tighten the nuts. The amount of time this takes is limited to your strength or the degree of cleverness you have in the use of your tools to acquire the needed leverage to use against the base of the cylinder so that the studs extend far enough through the base to get a nut started. The first nut you might get started by just your hands, the second one---you'll have to think about that. Again, I used a long screwdriver against the trans body with the head of a vice grip as a spacer. Just take time to think about it first as 3 minutes of thinking might save you an hour of struggle.............Frankie

 

[FRANKIE]

Hi @FRANKIE that was an interesting read, thanks.

The replacement I purchased yesterday I managed to get replaced, no quibbles as I was a "loyal" customer (something breaks in the zed every week, basically!) However, it is unfortunately the same part.

I've yet to compare it against the original as the original is still in the car. However, here is a video of it and some pictures.
View attachment 55195
Is this what you meant about the rubber being flimsy?

View: https://youtu.be/an9dfzvZzbQ



@Sean d that suggests that my zeds have too many issues spend more time fixing them than driving them.

In watching your video again, it occured to me to caution you about when you have the hydraulic line attached and you go to push the push rod against the transmission while holding the body of the slave cylinder. Make sure that when you position the end of the push rod against the transmission and you begin to push the slave cylinder that's in your hand against the transmission pushing the push rod into the cylinder that you don't allow the force you use to go in any direction but straight in as if you move slightly to the side, you might cause the push rod out of position to the side. I hope you get what I'm saying here. You wouldn't want the push rod to move in any direction but straight in and out.................Frankie