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R&R of Clutch Master Cyl on Later Model 6er

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ScottAndrews
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R&R of Clutch Master Cyl on Later Model 6er

Postby ScottAndrews » Mon Nov 29, 2004 3:03 am

I finally got around to replacing my clutch master cylinder in my 88 today..Yikes!.. THAT was a PITA!

Took me about 2 hours to R&R the MC, and then another hour, at least, to figure out how to bleed it properly..bleeding with this process is about a 15 minute affair..so read on oh happy 6er fan...

A couple of helpful hints...

DO NOT remove the MC bolts until you have removed the hydraulic line fitting on the end that pokes through the firewall. These bolts are necessary to hold the MC in place while you trun the line fitting nut.

The MC hydraulic fitting nut is really hard to reach, and there is not much room for a wrench, let alone my trusty, but longish, flare nut wrench. Rather than risk rounding the nut , I undid the hard line where it mates to the flex hose to the slave cylinder.
I then snaked an 11 mm BOX wrench onto the line and got it up to the business end of the MC.

This wrench is rather short, and the box can't slip off the fitting, so it was simple matter to then unscrew the line fitting from the MC. At that point removal was a cinch.

The only other hard part was installing the reservoir feed fitting into the top of the MC. I ended up removing the MC again, and snapped in the elbow while I was holding it. It is MUCH easier to attach the elbow to the filler hose than to try to snap the elbow mounted to the hose into the MC. There is just not enough room..that and you are on your back with the pedals in your face...

As for bleeding.. The primary issue I found was that I was pumping air.. I didn't realize that having the car jacked up on the left side tilts the brake fluid reservoir to the right, so the reservoir level is almost even with the filler hose. Once I realized this. I bled according to this process: I removed the slave cylinder. Using an old Holley 2BBL carb spacer, I clamped the output pin of the slave so it was depressed. I did this by I clamping the slave to the carb plate so the pin was poking through one of the carb holes (A 3/4 inch thick block of wood with a large hole would work as well). I then placed a plate of metal over the opposite side of the plate so that it pressed the pin in. I clamped this in place so the pin was depressed and I didn't have to hold it. I then lowered this assembly until the bleed fitting was the lowest point. I attached a hose and fed UP to a jar of fluid that had the other end of the hose submerged under the fluid. The jar needs to be higher than the slave.. I then slowly pumped the pedal by hand and watched all the bubbles come out. I refilled the fluid reservoir several times and ended up wasting about 2/3 of a cup pf ATE Super Blue fluid.. I pumped until I had no more bubbles, and the whole mess was clearly reacting to the pedal. I then closed the bleed fitting, removed the plates and clamps and re-installed the slave. This whole process took an hour, but the actual bleeding only took about 5 minutes..once I worked out the process (and filled the reservoir properly).

The clutch is solid and smooth, and it doesn't stick in the down position now...

So. Let me know if you have any additional questions on this one.

S
---
80 Euro 635 aka Rosanante - Don Quixote's steed...ready to carry me off to dream the impossible dream... La Verdad...the Truth.

Scott Andrews
Petaluma, CA
 

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GRNSHRK
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Brian, this should be posted as a tech article!!!

Postby GRNSHRK » Mon Nov 29, 2004 6:27 pm

This excellent write-up done by Scott should be posted as a tech article for all to benefit from.

In addition, I have personally met Scott recently and can attest to his vast knowledge of our cars, both the E12 and E28 versions. He runs an '80 Euor model while his son is the apparent owner of the '88 :?

Nice job Scott!
:mrgreen:

Cheers, Bobbo
1980 US 633 CSi
Cypress Green/Pearl Beige
2011 F10 528i (the wife's beater)
Image

Those who make no mistakes are probably not doing any work . . .
 

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bcadmin
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Postby bcadmin » Mon Nov 29, 2004 8:20 pm

Scott gets a BigCoupe T-shirt!
 

Sharkie

Postby Sharkie » Thu Feb 26, 2009 4:56 am

Need to replace clutch in my 1988 M6(E24)...looking for any/all tech guides and/or diagrams to provide process and sequence for friend, who knows how to drop trannies and replace clutches on other vehicles.
 

The Sixer Kid

Postby The Sixer Kid » Thu Feb 26, 2009 12:57 pm

Wrong section Pal. Replacing the clutch M/C doesn't have anything to do with replacing the clutch itself, except for the bleeding part of things.
 

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ScottAndrews
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Postby ScottAndrews » Thu Feb 26, 2009 1:55 pm

To replace the clutch you will need to remove the engine or trans. Removing the trans is about 100x easier. it requires some skill to line up the input shaft properly so it all goes together, and the bell housing bolts will require a double ujoint and two long socket extensions...
It's a bitch either way, but nothing that can't be done in a weekend if you have all the parts.

WHile the trans is out I'd replace the seals, especially the selector shaft seal.

S
---

80 Euro 635 aka Rosanante - Don Quixote's steed...ready to carry me off to dream the impossible dream... La Verdad...the Truth.



Scott Andrews

Petaluma, CA
 

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wjtesquire
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Postby wjtesquire » Sun Jun 27, 2010 11:22 am

Scott was dead on when he said this project is a PITA! I also chose to unhook the connection at the slave cylinder flex hose, but instead of snaking the wrench up the line, I pulled the MC through the firewall enough to get to the connection inside the footwell. Hooked up the line and then my 7 year old son pushed the new MC back in the firewall turning it left and right while I got underneath and grabbed at the line. Reattached at the flex hose and went after that feed line elbow. After wasting an hour of trying to "snap" it back into the rubber grommet, I ended up prying the grommet out of the new MC, snapping the elbow in and pushing the grommet back in with a broad tipped screwdriver. I borrowed my neighbor's pressure bleeder to finish up. The online manuals were a great help in showing you how to do this simple project if you have superhuman strength of if your car does not have the pesky steering and brake components installed. Otherwise, get your best cuss words ready.
 


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