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Bleeding Clutch Hydraulic System: Method #3-Kempff Method

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Bleeding Clutch Hydraulic System: Method #3-Kempff Method

 
 
Old 04-10-2005, 05:45 AM
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Deb
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Angry Bleeding Clutch Hydraulic System: Method #3-Kempff Method

I was following directions and must have gotten off track
Originally Posted by Wally P
Last resort for bleeding the clutch...

Disconnect the pedal rod.
Remove the boot and snap ring.
Pull the piston out until it is ALMOST out of the bore.
Tilt the piston so that the top edge only of the seal clears the bore and lets the air out.
Reassemble.

I think that Jay Kempf came up with this...
- I removed the two bolts and spacers that hold the piston in place to facilitate bleeding the air out of the piston. Now trying to reassemble I find that the two bolts don't appear to thread back into the piston assembly, are there two nuts that were attached to the bolts and if so where the hell do I access them?

Last edited by bhensarl; 04-30-2005 at 04:46 PM.
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Old 04-10-2005, 09:04 AM
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Default Kempff

I thought that the Kempff method was exclusively for bleeding any air out of the clutch master cylinder whereby the rod from the clutch pedal to the master cylinder is disengaged; the circ clip is removed allowing the piston to be withdrawn into the car interior to let some brake/clutch fluid and hopefully any trapped air to escape. I also removed the two bolts and spacers to facilitate this and now while attempting to reinstall I find that the bolts don't seem to thread back into the "cylinder" so I'm wondering if they were attached to nuts that may have dropped off?? If so where the hell are they and how to retrieve them. My shop manual doesn't have a diagram to show this attachment point.
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Old 04-10-2005, 09:46 AM
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Garth S
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You're well ahead of me, never heard of the name attached to the MC bleeding - looked at PET5, and it shows 2 - M8x40 bolts passing through a plate with 2 spacers between the plate and the MC ( spacers look like 1" tall pieces of pipe). It then appears that the bolts thread into the MC.
Not that PET5 is perfect - there is a gasket shown for the plate and one!? M8 nut. It is not clear where that single nut goes ...
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Old 04-11-2005, 11:46 AM
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SteveG
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Default KFM -- Kempf Fart Method

I recently had cause to bleed the master, but on my '85, no bolts were removed. There is a clip and pin removed to disconnect the rod from clutch pedal. On this rod, peel the boot back and simply remove the rod from the master. Now the hard part as you will be in cramped quarter, probably near upside down. Circlip inside the cylinder of master holds the piston. I prepositioned garbage bag and rag to catch 1/2 oz of fluid that will accompany the psssfffft of air exiting, assuming there is some trapped. Be ready to catch flying circlip and washer behind it holding the piston, as the pressure is pushing the piston out when released. As I remember 1-3 inches is where the piston is tilted slightly to release air. Then the hardest part, re-insert of piston, washer, circlip while upsidedown, as your back cramps; threading clip onto pliers and pushing piston in with deformed clip and downward pressure; this is done with one hand while other is holding piston in, otherwise it will exend allowing fluid to flow. Then rebleed slave. reattach rod to pedal, should give you solid pedal. The "pssssffft" is obvious and VERY satisfying.
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Old 04-11-2005, 03:22 PM
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Deb,

The two bolts you've removed actually fasten the master to the firewall - removing was not necessary. You will more than likely need a helper to reinstall. The bolts pass through the flange, spacers and firewall and thread into the holes on another flange, which is cast onto the master housing. This is a real pain without a helper to hold the assembly.

To make installing the clip a bit easier after bleeding:

-Move master dust boot out of the way, slip circlip and washer over the end of pedal rod.
-while holding the master piston in with thumb, slip pedal rod back into place and attach end to pedal. This will now hold the piston in the housing and give you two free hands to work with.
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Old 04-11-2005, 04:31 PM
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One might think that the piston will just fly out of the housing, but it wont. The piston is spring loaded and once the spring reaches the end of it's travel the piston will stop - no hydraulic pressure is present once you disengage the pedal rod. When I bled my master I was more concerned about loosing the circlip (flying off somewhere once snapped out of its groove), but with the rod slipped in this is not an issue.

One thing to keep in mind is that when the system is bled properly, bleeding the master is almost never necessary. Lack of travel is mainly due to air in the slave. Make sure you follow all of the bleeding steps before resorting to the master.

With pedal rod pre-load removed (ie, loosen lock nut turn rod once ccw)

1. Pressure bleed until no air is observed. Remove pressure bleeder.
2. With slave bleeder open push slave rod all the way until no air is observed. May take a few iterations and be sure to close the bleeder before the rod is allowed to extend so air is not sucked back in. Also reccommend using a piece of tubing submerged in brake fluid while doing this
3. Push slave rod all the way in with bleeder closed. This will force air out of the master. May take a few iterations as well.

When pushing the slave rod in, I use the boxed end of a 8mm combo wrench for leverage. I can usually slip the boxed end over the rod end through the bell inspection hole and use the wrench "neck" as a grip. Slave still needs to be unbolted from bell though.
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