The Floating Clutch


#1

We just had our master and slave cylinders replaced on our clutch and over about 400 miles, the engagement point (and pedal) moved up and up to the point that the clutch no longer engaged. I was out of town and another mechanic adjusted the pedal (and engagement point?) so that I could return home (about 250 miles) and told me that my clutch was shot based on something the mechanic had done/not done. When I returned to the original mechanic, he could not find anything wrong with the clutch or the cylinders he replaced (he’s done the tests recommended by the manufacturer at their direction). I have been using the car for the last few days and it has been working okay. Until we figure out what happened while I was on the road, we think it’ll happen again. Any ideas??


#2

Is this clutch attached to any particular make, model, year of automobile?


#3

You don’t mention what kind or year of car you have, but there’s always an adjustment to adjust where the range of movement is on the lever that pushes the release bearing as the slave cylinder piston moves through its range. These adjustment systems always need to be secured after they’re made or they’ll work their way out. My guess is that the original mechanic did not secure the adjustment.

This having happened will not cause further damage and once readjusted and secured is as good as new. You’re good to go now. No worries.


#4

It could be as simple as the hydraulic system was not bled of air properly. Could also be a combination of the above post (readjustment issue) with the improper bleeding procedure.


#5

Good question. It’s a 93 Honda Accord.


#6

Ah…useful info. The Accord clutch adjustment is a little fiddly to be honest. You can check that the adjustment is now correct yourself:

With the clutch engaged i.e. without your foot on the clutch pedal, the measurement from the flat floor area below the clutch pedal to the centre of the clutch pedal face should measure 8.27". The pedal stroke measured from the angled floor behind the clutch pedal, fully out to fully in should measure 5.6". Clutch pedal free play should be greater than 0" and shouldn’t exceed .28". Finally the clutch pedal disengagement height (again measured from the angled floor behind the clutch pedal to the pedal center should be at least 3.6" ~ good luck trying to measure that while you have your foot on the clutch!

The clutch adjustment is achieved by adjusting the clutch master cylinder pushrod, this has a locknut that may have not been correctly tightened. However, if that were the case the pedal would have got gradually deeper until you couldn’t engage a gear rather than the clutch not engaging. The same would occur if the clutch hydraulics weren’t bled correctly, you wouldn’t be able to get the car into gear since the clutch wouldn’t disengage.

I can’t think of anything that would cause the adjustment to gradually increase to the point where the clutch was being held out of engagement by the clutch pedal. Are you sure these were the symptoms ?


#7

Thanks for the measurements. We’ll check them out tomorrow. The way I’d describe what happened non-technically was that, when downshifting to boost power, I had to lift my leg up to point that it came around to the left of the steering wheel and the clutch still wasn’t engaging and I was gaining RPMS when I put my foot on the gas (as the second mechanic called it). The second mechanic (on the road) did smell the clutch burning when I arrived. I haven’t smelt it since he adjusted it.


#8

The bleeding procedure that has served me very well on many types of cars is to just open the bleeder on the slave until fluid runs freely. I wonder why the adjustment on the actuating rod was changed? I cant recall this being necessary to complete a master cylinder replacement.Makes me think of a problem with the clutch itself along with the report of clutch burning smell


#9

Gottit…

Most likely the clutch switch wasn’t adjusted correctly or the switch locknut wasn’t tight. This would put all the retension stress on the clutch assist spring which gradually unwound under the load. This probably put the master cylinder pushrod at the wrong angle jamming the piston in the cylinder and preventing the clutch from engaging.

Bottom line: The clutch assembly will have been compromised to some degree by the slippage and the clutch assist spring could also be weakened by the incorrect adjustment. Just drive it until it fails.


#10

This is similar to the clutch problem at http://community.cartalk.com/posts/list/2124007.page