And now clutch problems ???

J

John Buchtenkirch

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Used a Mighty-vac to bleed my brakes on Wednesday, they have a rock solid pedal. Got plates for the coupe on Friday and was getting pretty excited. Installed a freshly rebuilt clutch master today and tried to bleed the clutch without success. Tried a second clutch master and still no success. Jimmy Dee came over & reverse bleed the system, still no working clutch pedal. We pulled the clutch slave and determined that the actuation rod for the clutch is too short.

Tomorrow I’m going to work on lengthening the rod unless I hear a more sensible idea from the group ??? I believe the bell housing is motronic with the 2 sensors. Can’t remember what I ordered the clutch slave for but it’s new & bolts right on. Thank you for any advice, I thought I would be going for a test drive in a day or so but now find my back against the wall once again :(. ~ John Buchtenkirch
 
Did you remove the clutch slave from the bell housing and point the bleed screw up when you bled the system?
 
Don, thank you for taking the time to reply, I know you have quite a bit of experience in these 5 speed conversions.

My concern or worry is that I may have matched up and actually mismatched clutch parts that aren’t compatible. I believe you told me the bell housing with the 2 sensors is a Motronic bell housing but I don’t know what year. I also believe I got a Motronic flywheel from double 02. The clutch, pressure plate, throw-out bearing, clutch fork and clutch slave I ordered were for a 1981- 528I as per Carl Nelson’s instructions. Ideally I know it would have made more sense to get everything out of the same donor car to insure parts compatibility but those older BMWs have already rotted out here in the northeast and gone to the shredder. I tried to piece this together and am now obviously paying for my lack of expertise.
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We didn’t pull the slave cylinder from the bell housing but I’m absolutely certain the bleeder screw was facing upward, the cylinder wasn’t up-side-down. To be honest I was only able to pull the slightest amount of fluid with the Mighty-vac, an unsuccessful bleeding attempt for sure. Jimmy came over and pushed (reverse bleed) 3 ½ syringes full of brake fluid thru till no more air bubbles were coming up in the brake fluid reservoir. We loosened the slave slightly and Jimmy could see the rod move slightly when I stepped on the pedal. He feels like the rod is only pre-tensioned a ¼” or 1/8” when it should be more like 1 ¼” or 1 ½” so there’s more travel to push the throw out bearing. I’m kind of nervous about the clutch fork hitting the back of the pressure plate (if I lengthen the rod) and would like to hear your thoughts on this mess / headache I’ve created.
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Don, believe me I know how hard it is to diagnose problems that aren’t in front of you so whatever information you or anyone else sends my way is very much appreciated. Back in the day I would get people calling me and asking “the alignment shop says my front wheel is back 3/4”, how much to fix it ?”.:confused::confused::confused: what could I say ? ~ John Buchtenkirch
 
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I have never had success with the mighty vac, the bleed screw will leak air at the slightest opening.
 
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The bleed screw must point down with the hose connection pointing up. It is VERY difficult to get all the air out of the clutch hydraulic system. It sounds like you have the right clutch parts, just still have air in the hydraulics.

I nearly always pressure bleed the clutch hydraulics. The Motive pressure bleeder works very well while being relatively inexpensive.

They can be bled manually with two people though.... be ready for lots of hand pedal pumping till there's enough fluid in the system to pump with your foot. Pump the pedal 10 or so times and you may feel a tiny bit of pressure building up, hold the pedal down while person two opens the bleeder screw, then close screw and repeat the pedal pumping.... you will eventually have a properly firm clutch pedal.

You can't harm the clutch hydraulics by pumping the pedal rapidly like you can the brake system....

HTH
 
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bleed screw orientation

I have my bleed screw pointing upwards and the hose down. Other than it being difficult to get to the screw when on top, does it matter which way it mounts?
 
Sven said:
I have my bleed screw pointing upwards and the hose down. Other than it being difficult to get to the screw when on top, does it matter which way it mounts?
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Air is lighter than brake fluid and rises thru it to the top. Any wheel cylinders I’ve ever seen have the bleeders on the top, I’m almost positive that clutch slaves are the same. ~ John Buchtenkirch

P.S. By the way reverse bleeding is also called back bleeding if some people may want to search it.
 
You would not be able to bleed my 5 speed conversion if the bleeder was facing upward. It's passage crosses to the opposite side (ie. Top)
I was able gravity bleed mine. no pumping was needed..... But I used a 2002 MC with it's outlet on the top. So it self bled.......
DaveG
 
John-send me a pm and I will send you my phone #.

Don
 
sfdon said:
Did you remove the clutch slave from the bell housing and point the bleed screw up when you bled the system?
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Hey Don, you know I’m an old body man that has breathed too many fumes & pounded too many fenders so I’m sorry that I’m a little slow on the uptake at times but I finally figured out what you were trying to tell me :idea:. I dropped that slave out of the car tonight and observed that even though the bleeder appears to bleed from the top of the cylinder it actually bleeds from the middle of the bore so unless you tip it like you are suggesting air is trapped in the upper half of the cylinder.
THANKS, I will try your method tomorrow. I will sleep much better tonight. ~ John Buchtenkirch

P.S. I measured in the hole to the clutch fork and it’s 2” and the actuation rod coming out of the slave is 2 ½”, can the clutch be disengaged with only ½” of travel :confused: If so I obviously don’t need to be lengthening any rods.
 
Don't worry about the clutch or the slave rod travel- the travel should be fine.
Let us know how it goes.
You can also bleed the system by hand using a jar with a hose and pumping the slave with your palm. You always need to have the slave out of the bellhousing though.
 
Pedal feels absolutely perfect :-D:-D:-D:-D. With any luck at all I will be going on the first test drive tomorrow. BIG THANKS to Don for getting me pointed in the right direction on this one. Hopefully I will have more good news to report tomorrow after I drop her on the ground. ~ John Buchtenkirch
 
Don't be surprised if you have to pump the clutch 2-3 times after this to bleed the master- masters are self bleeding . Good luck to you.
 
After searching question on the process of bleeding the clutch system. I'm wondering where your pedal operates. After having a blast driving around yesterday my pedal operates at the last couple of inches to the firewall which seems wrong. I have the slave mounted with nipple up on bell housing and used an oil can to push fluid to the reserve. Beside this little issue everything is working great and for the ones running automatics do what ever it takes to go to manual! I only wish I would of done this years ago now because it make these car so MUCH fun to drive.
 
You can adjust where the clutch pedal engages at the pedal.

tmason said:
After searching question on the process of bleeding the clutch system. I'm wondering where your pedal operates. After having a blast driving around yesterday my pedal operates at the last couple of inches to the firewall which seems wrong. I have the slave mounted with nipple up on bell housing and used an oil can to push fluid to the reserve. Beside this little issue everything is working great and for the ones running automatics do what ever it takes to go to manual! I only wish I would of done this years ago now because it make these car so MUCH fun to drive.
Click to expand...
 
Adjust pedal so it is same distance from floor as brake pedal as Scott suggests. If it still disengages an inch or two from floor you still have air in system.
 
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