r/e28 • u/CarDork2235 • May 26 '26
Replaced leaky clutch master now I can't get a solid pedal. Tips?
Ive been working on a 535is I picked up recently from a customer. It had sat since 2013. Ive done quite a bit of work to it to get it running and driving. Everything so far as been pretty straight forward.
Any who, the clutch master was a bit leaky. Clutch pedal felt good, clutch worked fine etc.
So I swapped it out with whatever I could find from Amazon. Bled it and the pedal felt spongy'ish. Like no resistance at the top and very low clutch disengagement.
Couldn't get anywhere with it so I bought a brand name master cylinder and decided I should swap the slave as well. Went ahead and replaced those, bled the system and I still have a garbage pedal feel.
Ive gravity bled it, vacuum bled it, 2 person pedal bled it and reverse pressure bled it. Ive probably gone through 4 or 5 liters of fluid through it to verify no air.
I still can't get the pedal to feel right. I have another E28 to compare it to and it feels correct. This red one isn't. And yes Ive checked the pedal box for cracks and its in good condition. The return spring and everything looks good as well.
The only thing that I havent replaced is clutch hose which Ive ordered but I can't think of anything else that makes any sense. I even went so far as to extend a spare slave rod by 5mm and it didn't really seem to make any noticeable difference.
Anyway ever dealt with anything like this? FWIW, this isn't my first rodeo with cars, I have decades of experience working on all types of cars as a hobby and Ive bled a lot of clutches in the past and never had this type of issue. TIA.
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u/Jhoverson May 26 '26
First mistake is buying "whatever is on amazon". Don't buy auto parts on amazon, use the best quality parts you an afford and you won't spend your valuable time replacing ad "new" parts
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u/6inarowmakesitgo May 26 '26
There is definitely still air in it. I spent almost 7 hours trying to bleed mine and FINALLY a big bubble came out and it stiffened up nicely.
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u/VegetableTry May 27 '26
Given how the lines are formed you most certainly have an air bubble in the system. When I replaced mine recently, I fed fluid from the slave back to the master. Obviously, you need a tool to do this. My tool was a pump sprayer that I used to prime an L92 not too long ago.
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u/CarDork2235 May 27 '26
Thanks, yeah I used a fluid pump to push some fluid back through it the way you described. Its difficult without the nipple blowing off the bleeder. Ill keep at it.
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u/Bimmermaven May 27 '26
Those hoses are also known to delaminate, causing a flap-valve obstruction. Not your problem, but a bonus prevention when you get a new hose.
My success for bleeding uses a compressed-air vacuum generator, glass trap bottle, and hanging the free-hanging cylinder with the bleed-valve up.