R3VLimited Forums

Go Back   R3VLimited Forums > E30 Technical Forums > Engine & Drivetrain > Transmission & Driveline

Reply
 
Thread Tools
Old 11-30-2016, 08:20 AM   #1
Sh3rpak!ng
E30 Mastermind
 
Join Date: Jan 2014
Location: Los Angeles
Posts: 1,770
bizarre inconsistent clutch pedal pressure

So recently my master cylinder seemed to be going out. I was having inconsistent clutch disengagement and would have to pump it a few times to get good functionality. The slave cylinder is brand new (febi brand iirc) as of a few months ago.

So I installed a new febi master cylinder and now have some very bizarre pedal pressure issues. Not really sure how to describe this. When cycling the pedal with my hand, lifting it up and then pressing down, 4/5 times it feels normal, normal pressure and disengagement effort, but sometimes I get ZERO pressure and the pedal will literally fall to the floor. I mean no pressure whatsoever, it feels like it's just hanging loose as if it's not bolted to the master at all. I lift the pedal, press again and pressure is normal. Sometimes when it "misses" it'll fall straight to the floor, sometimes it catches halfway and feels like normal pressure from there.

This feels very different from, for example, after installing a new slave that needs to be bled and the pedal is soft and travel is longer than normal.

Is the new master cylinder bad?
__________________

'89 325i OBD2 S52 BUILD THREAD
Shadetree30

Sh3rpak!ng is online now   Reply With Quote
Old 12-04-2016, 09:23 AM   #2
TobyB
No R3VLimiter
 
TobyB's Avatar
 
Join Date: Oct 2011
Location: Carnation WA usa
Posts: 3,555
Sure sounds like it- like the seals are occasionally just not sealing.

I haven't had that happen before...

...and yeah, I'd try another master. See if you can get a FAG.
Febi has gone... east... for most of their stuff recently. Sadly.

t
__________________
Quote:
now, sometimes I just mess with people. It's more entertaining that way. george graves
TobyB is offline   Reply With Quote
Old 12-12-2016, 07:11 AM   #3
packratbimmer
Mod Crazy
 
Join Date: Dec 2009
Location: ME
Posts: 703
Is your clutch pedal spring loaded on the back? The pedal will pull toward the floor by the spring action without hydraulic resistance. How did you bleed the system? The system can be tricky to bleed!
packratbimmer is offline   Reply With Quote
Old 12-12-2016, 08:16 AM   #4
Sh3rpak!ng
E30 Mastermind
 
Join Date: Jan 2014
Location: Los Angeles
Posts: 1,770
Thanks guys for the input/suggestions. Turned out it was a DOA febi master. I replaced it with a brand new FTE unit and while it's still been a pita to bleed, it's working.

Some more info for someone who might come across this thread in the future:
I figured out that the weird pedal action only happened when I pressed the pedal gently. If I jabbed it hard, pressure was fine and the clutch operated fine. My thoughts are that hitting the pedal hard ballooned the seals and made it work. Pressing it softly let the seals leak somehow. After I removed the febi master, the fluid that drained out was very dark and contaminated. That MC was only in the car for two weeks and maybe a couple hundred miles and all the fluid was very fresh.

Regarding bleeding technique; initially I just pumped the pedal a bunch of times until I started to feel pressure building. Then I attached the power bleeder, pumped it up and locked the pedal pressed down to the clutch stop holding pressure. Wriggled under the car and cracked the bleeder on the slave and let it bleed until no more bubbles came out. I did this a couple of times, each time the pedal built more pressure higher up in its travel. Right now it's working, but feels a bit inconsistent so I'm thinking it probably needs another round of bleeding both the MC and the slave.

Any further tips for bleeding both MC and slave are much appreciated. I might have a helper on hand this week to pump/press/hold the pedal while I'm under the car instead of using the pedal depressor tool.
__________________

'89 325i OBD2 S52 BUILD THREAD
Shadetree30

Sh3rpak!ng is online now   Reply With Quote
Old 12-12-2016, 08:52 AM   #5
varg
E30 Fanatic
 
varg's Avatar
 
Join Date: May 2014
Location: Palm Beach County, FL
Posts: 1,206
The easiest way to bleed the master on these cars is to reverse bleed. Put brake fluid in a pump-type oil can, run a little hose from the can to the bleeder, open the bleeder, and pump the fluid up to the reservoir. Another way is to run a long hose from a reservoir or funnel to the bleeder, raise the reservoir to windshield level and let it gravity bleed, takes longer but still works.
__________________
@turbovarg
'91 318is, M20B25, T3/T04E 50 trim (14psi), megasquirt, coilovers, Z3 rack, cold AC
[project thread]

raise the lowered
varg is offline   Reply With Quote
Old 12-12-2016, 09:52 AM   #6
Sh3rpak!ng
E30 Mastermind
 
Join Date: Jan 2014
Location: Los Angeles
Posts: 1,770
Quote:
Originally Posted by varg View Post
The easiest way to bleed the master on these cars is to reverse bleed. Put brake fluid in a pump-type oil can, run a little hose from the can to the bleeder, open the bleeder, and pump the fluid up to the reservoir. Another way is to run a long hose from a reservoir or funnel to the bleeder, raise the reservoir to windshield level and let it gravity bleed, takes longer but still works.
Hmmm I'll give this a try. Is it a special sort of pump?
__________________

'89 325i OBD2 S52 BUILD THREAD
Shadetree30

Sh3rpak!ng is online now   Reply With Quote
Old 12-12-2016, 03:52 PM   #7
Northern
R3VLimited
 
Northern's Avatar
 
Join Date: Nov 2010
Location: Halifax, N.S.
Posts: 2,893
I used a 50mL syringe with some clear tubing over the end. Bench bled it beforehand so there really wasn't much air to begin with.
__________________
E30VON_NS 
Quote:
Originally Posted by priapism View Post
My girl don't know shit, but she bakes a mean cupcake.
Quote:
Originally Posted by shameson View Post
Usually it's best not to know how much money you have into your e30
Northern is offline   Reply With Quote
Old 12-12-2016, 07:29 PM   #8
varg
E30 Fanatic
 
varg's Avatar
 
Join Date: May 2014
Location: Palm Beach County, FL
Posts: 1,206
Quote:
Originally Posted by Sh3rpak!ng View Post
Hmmm I'll give this a try. Is it a special sort of pump?
Something like this
https://www.amazon.com/GOLDENROD-707...dp/B00004YK76/
__________________
@turbovarg
'91 318is, M20B25, T3/T04E 50 trim (14psi), megasquirt, coilovers, Z3 rack, cold AC
[project thread]

raise the lowered
varg is offline   Reply With Quote
Reply

Thread Tools

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -7. The time now is 05:00 PM.


Powered by vBulletin® Version 3.8.10
Copyright ©2000 - 2017, vBulletin Solutions, Inc.
Copyright 2004 - 2020 R3VLimited LLC