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wrs

E36 Clutch Problem

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Recently I replaced my engine and gearbox.

The car is a 92 E36 325i Coupe which had the old engine and Jatco gearbox removed.

It was replaced with a M50B30 + S6S 420G Getrag six speed manual conversion. The kit I purchased included a dual mass flywheel and standard M3 clutch. I decided to by a NZAD BMW E36 M50 M52 S50 Solid flywheel & Clutch kit to get the lighter flywheel and all new parts. The flexi-line to the slave cylinder is braided.

My problem is the clutch doesn't disengage until the clutch pedal is about 10mm from the floor. It also ocassionally doesn'tt disengage fully leading to a bit of a crunch into the next gear. It does help a bit if I quickly tap the gas to rev match. The first 25mm of my pedal travel is very light then it goes stiff for the rest of the travel (pressing by hand you can feel the pedal spring first, then the hydraulic pressure).

Today I decided to try to find out what the problem is.

I've bled the brakes several time, at least twice each time using the pump the pedal - release the bleed valve method, press the rod on the slave cylinder method and the reverse flow method. For the later 2 methods the slave cylinder was removed and held vertical with the bleed valve toward the top or bottom depending on the bleed metohod (top for press the rob method and bottom for reverse flow method).

I got no bubbles and no change in the behaviour of the clutch.

I've checked the pedal pivots and everything is reasonably tight with very little slop.

So, since all the usual issues appear to be covered (have I missed any??) and started doing some measurements.

The slave cylinder rod appears to have approximately 45mm of available travel.

When I put the slave cylinder into the bell housing the rod engages into the release bearing fork with 29mm of the cylinder still sticking out. You then push on the cylinder to push the oil out and get the slave cylinder into position to put on the nuts.

This then means I have a maximum travel on the slave cylinder rod of 29mm of the 45mm possible.

Could this suggest the fork pivot pin is buggered?

Does anyone here know what the correct travel should be on the slave cylinder rod. I would have thought it would be around 35-36mm leaving 9-10mm spare for self adjustment to clutch wear.

If the pivot is ok then what's the solution - extend the rod?

I may have to get a fibre-optic inspection camera to check the fork pivot pin?

Any ideas?

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You may want to also check that the release bearing is seated properly on the fork, it has 2 little tabs that stick out each side of the sleeve that the bearing is attached to, these should be in line with the 2 bumps on the front of the fork. If they are not in the right place the release bearing will not be pushing as far into the pressure plate as it should, and the clutch may not disengage. Good luck :)

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Thanks.

I'm pretty sure it's correctly seated - can just see it using a flashlight and mirror looking through the slave cylinder hole. Is sitting in the notches.

Have been considering using a 325 slave cylinder instead of the M3. The smaller bore-size of the 325 slave means the rod will travel further for the same amount of pedal depression. This won't help if I'm right on the travel limit of the M3 slave already and may lead to the pin blowing out on a 325 slave.

I guess the real question is - is 29mm of engagement of the slave pin the correct amount or should there be more?

If there's supposed to be 35mm + of engagement when fitting the slave cylinder then the likely culprit is the fork pin.

The fork pin looked ok when everything was fitted to the car but the stage II clutch kit may apply more pressure to the pin than the original clutch did and being the original old and possibly brittle pin it may have collapsed. Looks like an inspection camera is required...

The distance from the mounting flange on the bell-housing for the slave cylinder to the dimple in the release bearing fork is 73.5mm. I'm not sure if this distance is correct - there's bugger-all dimensional info available to help diagnose clutch problems on BMW's!!!

Edited by wrs

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There is also 2 different release bearing carriers one is approx 10mm deeper than the other

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Do you mean the metal release arm the release bearing clips onto?

If so, do you know which cars/engines used the different arm?

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Today I purchased a USB camera on a flexi-lead to see if I could get in through the slave cylinder hole to see the realease arm pivot pin.

I got close but just couldn't see it (saw the spring clip a couple of times) and then the camera got stuck!!! Managed to get it out after about a minute of careful wiggling but decided that would do - don't it to get stuck and break off leaving loose bits in the bell housing.

So, I'm still none the wiser.

I want to find out what the problem is withough taking the gearbox out. It could be the pivot pin but I'd rather not take the box out to find it's actually ok.

Here's a picture of the geometry of the clutch - does anyone know if this is correct (or prepared to measure on their car)?

This picture shows the slave cylinder unbolted and sitting at the point where it takes pressure to push the slave rod into the cylinder.

2z4fzbl.jpg

Edited by wrs

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At this stage I think I'll try a 325 slave to get slightly more travel on the pin.

M3 Slave = 22.20mm

325 Slave = 20.64mm

Area diff = 22.20²/20.64² = 1.1569

So there should be about 15.7% more extension on the 325i slave. If it moves about 20mm then that's an additional 3.13mm travel on the pin.

This might be enough...

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Also have the same issue with my 328i touring. Am running a getrag 240 from a 318i with pivot arm, baring and Slave, m3 evo fly and clutch setup, and yea, had to take the clutch stop out so can push it hard to the floor to get it to disengage, but can still feel it's not completely.

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Do you mean the metal release arm the release bearing clips onto?

If so, do you know which cars/engines used the different arm?

This picture shows the different heights of the carriers..... the 2 on the right. You probably need the longer of the two. If you lengthen the pushrod the arm will start touching the pressure plate after a short period of time because the fork angles are wrong. If you push the clutch slave cylinder in and measure the protrusion of the push rod from the mounting face of the cylinder. This distance should be about 4-5mm greater from the mounting face of the bell housing and the ball socket in the clutch fork when the fork is gently pushed against the pressure plate fingers.

post-1129-0-14527500-1447003910.jpg

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On 11/9/2015 at 6:33 AM, *Glenn* said:

This picture shows the different heights of the carriers..... the 2 on the right. You probably need the longer of the two. If you lengthen the pushrod the arm will start touching the pressure plate after a short period of time because the fork angles are wrong. If you push the clutch slave cylinder in and measure the protrusion of the push rod from the mounting face of the cylinder. This distance should be about 4-5mm greater from the mounting face of the bell housing and the ball socket in the clutch fork when the fork is gently pushed against the pressure plate fingers.

post-1129-0-14527500-1447003910.jpg

Best place to get the longer throw out bearings from?

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From memory it was BNT. I think the longer carrier type was listed under E21 6cyl as apposed to the E30/E36 shorter type

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I ended up pulling the D1 clutch kit out and selling it on TM. I kept in contact with the purchaser who fitted it up to a 5-speed box and had no trouble.

I suspect in my case there was an issue with the D1 pressure plate and thrust release distance being incompatible with the 6-speed S6S420G box. I got a standard M3 pressure plate and release bearing through Kayne Barry and it's been magic ever since (still using the standard M3 slave cylinder).

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On a side note, how'd you get your m50b30 together? Did you build it yourself? I'm trying to build one myself but I'm finding m54b30s a tad hard to come by and slightly cost prohibitive. 

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One of the guys at HellBM built it. They'd likely have little issue finding the required parts for their own use.

I purchased as a long block but it had already been running in one of the guys cars.

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I've been running the setup, m52b28 with a 6 speed box and NZAD clutch and flywheel. Didn't install the clutch stop but do feel the engagement point is very low. I feel it has become better and higher since installing it so might install the stop if i can find it. Probably done about 2000km so far

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