1994 525i Clutch Problems

[Charles]

Hi

Since I have had my 525i E34(2 years) the clutch has always engaged almost at the top of the travel of the pedal. Recently I had the clutch replaced and the engagement point was much lower on the pedal travel but within a week it has crept back up to the top. I have been told that nothing can be done as it is a hydraulic clutch and there are no adjustments.
Is this true? I would definitely like to set the engagement point lower, as it almost feels like the clutch is on the point of slipping.

Cheers
Charles

[dave b]

You could bleed the clutch if you felt like it, but that's what I was told also - that you can't adjust it.

Mine was very high too when I got it replaced.

[Bill R.]

much lower and as the clutch wears over the years that point raises slowly until it right up at the top of travel...If yours moved up that quickly then something is causing abnormal wear....or there's something else causing the problem... bleeding the clutch won't help in this case.

[Bellicose Right Winger]

It's true that the engagement point rises as the clutch disc wears on mechanically (lever or cable) actuated clutches but this doesn't happen on properly working hydraulic clutches. I can only envision two ways the engagement point would rise on a BMW. 1) If the MC return port to reservoir was somehow blocked leaving pressure on the slave cylinder and thereby not allowing the pressure plate to release fully or 2) There is a internal leakage at the MC. This often happens after the car sits outside on a cold night. For the first dozen shifts or so the clutch engages close to the floor. This is because the MC cup seals have become inflexible and/or shrunk from the cold. As a result depressing the clutch pedal only sends a portion of the normal volume to the slave cylinder. The rest leaks past the cup seal and returns to the reservoir. Engagement returns to normal after a few shifts. In Charles case I suspect the clutch wasn't properly bled, and the air gradually worked out of the system. I've got well over 120k miles on each of my clutches, there's been no change in the engagement point and they all engage very close to the top.

Paul Shovestul



much lower and as the clutch wears over the years that point raises slowly until it right up at the top of travel...If yours moved up that quickly then something is causing abnormal wear....or there's something else causing the problem... bleeding the clutch won't help in this case.

[Bill R.]

every hydraulic and lever or cable actuated clutch that I have worked on has followed the same pattern, as the mechanical portion on the clutch wore, the point at which the clutch engaged and disengaged altered, maybe all the hydraulics i have worked on were faulty eh? even the datsun 240z which have an adjusting rod on the hydraulic which must be set to specific clearances as it wears..





It's true that the engagement point rises as the clutch disc wears on mechanically (lever or cable) actuated clutches but this doesn't happen on properly working hydraulic clutches. I can only envision two ways the engagement point would rise on a BMW. 1) If the MC return port to reservoir was somehow blocked leaving pressure on the slave cylinder and thereby not allowing the pressure plate to release fully or 2) There is a internal leakage at the MC. This often happens after the car sits outside on a cold night. For the first dozen shifts or so the clutch engages close to the floor. This is because the MC cup seals have become inflexible and/or shrunk from the cold. As a result depressing the clutch pedal only sends a portion of the normal volume to the slave cylinder. The rest leaks past the cup seal and returns to the reservoir. Engagement returns to normal after a few shifts. In Charles case I suspect the clutch wasn't properly bled, and the air gradually worked out of the system. I've got well over 120k miles on each of my clutches, there's been no change in the engagement point and they all engage very close to the top.

Paul Shovestul

[Bellicose Right Winger]

Well maybe it is a regional thing. Does the Bentley and TIS sold in the SW have a clutch adjustment procedure? Delaware versions don't. If indeed the pedal rises, it seems to me the Black Forrest Elves would have provided a method to compensate. The fact that they don't speaks volumes. Can't comment on 240z's. MGB's don't need adjustment. BMW's have an adjustment too, but it's a pedal height adjustment. Early cars had a threaded rod, later ones have an eccentric...probably to compensate for pedal biushing wear or driver preference.

Paul Shovestul

BTW, Welcome back



every hydraulic and lever or cable actuated clutch that I have worked on has followed the same pattern, as the mechanical portion on the clutch wore, the point at which the clutch engaged and disengaged altered, maybe all the hydraulics i have worked on were faulty eh? even the datsun 240z which have an adjusting rod on the hydraulic which must be set to specific clearances as it wears..

[Bellicose Right Winger]

I hope will help.

As a clutch disk wears and becomes thinner the release fingers on the pressure plate push the release bearing farther toward the transmission. At the transmission end the effect of the new release bearing position is to pushback on the clutch linkage/slave cylinder and pull on the clutch cable.

On linkage actuated clutches, this pushback raises the pedal and raises the engagement point relative to the floor. If the pedal is pushed to it's upper travel stop you can greatly impact the engagement point and may cause the clutch to slip.

On cable actuated clutches, pulling on the clutch cable from the transmission end raises the pedal and raises the engagement point relative to the floor. If the pedal is pulled to it's upper travel stop you can greatly impact the engagement point and may cause the clutch to slip.

On hydraulic clutches the "extra" hydraulic fluid that is displaced from the slave cylinder due to clutch disk wear simply returns to the MC reservoir as soon as the return port is exposed by the MC cup seal. There is no effect on the clutch engagement point or pedal position. This is why BMW's don't need and consequently don't have clutch adjustment. If this "extra" fluid could NOT return to the reservoir, the pedal and engagement point relative to the floor would rise just like the linkage and cable actuated clutches.

Paul Shovestul

[Helm525Im]

May I bring up another issue I've encountered (91 525I m)? It sounds like my hydraulic actuator (do I have one) is sqeaking as I depress the clutch! I hearthis with the car running and door open! Is there a way to service this or will I have to wait for a failure of something?
Any suggestion are much appreciated.
Helm

[Bill R.]

M3's where it was the actual pedal pivot squeaking but if you're hearing yours from underneath the car there are a couple of possibilities, First of there is a ball stud that the throwout bearing arm seats on one end, it has a ball stud and socket on the arm, there's supposed to be grease in this socket to lube the arm as it pivots, if this goes dry after many years it will squeak like metal on metal... There are also pivot points on the clutch pressure plates where the fingers move that can possibly squeak.. Its pretty unlikely though that its the hydraulic slave cylinder squeaking..
I forgot to add that it is possible for the bearing to squeak on some as it slides on the tube housing the input shaft but since the newer ones have a nylon bushing on one surface its not likely that thats what your hearing.





May I bring up another issue I've encountered (91 525I m)? It sounds like my hydraulic actuator (do I have one) is sqeaking as I depress the clutch! I hearthis with the car running and door open! Is there a way to service this or will I have to wait for a failure of something?
Any suggestion are much appreciated.
Helm

[Helm525Im]

Thank you Bill. Once the weather gets better I'll have a look!
Yes you are right about the pedal pivot bushing on the 3 series. The BMW club here in Ottawa had a clinic on it. They bought some aftermarket part from the web.
Regards, alway enjoy your counsel!
Helm