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Well, After my clutch pedal stopped coming up, I fretted about it maybe being the slave cylinder, and decided to change the master first. That fixed it! Thank heavens.
A few tips that might help others:
1. Read the directions real carefully about the bicycle tube bleeding pressure technique. It works, but here are two things I forgot to do that caused me some grief:
A. The directions say you need to keep the resevoir filled to about an inch from the top. I omitted this and had just air blowing through the system until I re-read the directions.
B. The directions say you also need to pump the clutch pedal about 20 times before it works. I omitted this and couldn't figure out why the clutch was not coming up even though the bleeding seemed to be successful. I re-read the directions, pumped the clutch 2o times and it works.
I can't remember who posted these great directions (Was it Bill Davis?) but I am repeating them here. They work great.
I've tried Yaofeng's inner-tube technique and it works very well. Go to your local Harley-Davidson shop and ask them if they would give (or sell cheap) a used 21" inner tube. They should have some lying around waiting to be trashed. This size fits the reservoir, and although a tad large will seal well when clamped. Someone mentioned once that a trail-bike tube, I think, fit the reservoir perfectly. Don't quote me on that, though.
Anyway, cut the inner tube 18" or so being sure to include the fitting in the section cut, of course. I then used some hot glue on the other end to seal it, then folded it over several times and finally clamped it with one or two clothes pins. Be careful filling with air as you don't want to blow the tube or something else. It might be prudent to set the pressure regulator on your compressor to 30 or 40 psi, though I don't recall how I set mine.
I like this technique over the fitting-in-the-reservoir-cap idea because the inner tube is forgiving and absorbs excess pressure, though I have not tried the other technique. The idea is to blow it up a bit like a balloon (don't overdo it!) and let the pressure subside thereby pushing the fluid out through the slave cylinder on top the transaxle. You'll have to close the fitting on the slave before the pressure subsides each time, refill the tube with air, top off the reservoir with fluid, and repeat. You'll have to remove the tube each cycle to replenish the fluid and you'll probably have to perform the cycle a dozen times or more to 1. insure all the fluid has been purged. Have a tube attached to the end of the slave fitting to catch the old fluid in a container, watching for newer, clearer fluid to show.
I use a crude home made kit. You need,
1) a 14" bicycle inner tube,
2) a 1 1/2" hose clamp, 3) a 1" binder clip,
4) a 1/4" ID clear plastic tube about 2' long, and
5) a bicycle pump.
Cut the bicycle tube with a pair of cissors. Fold it several fold from one end and clamp it with the binder clip. Slip the other open end onto the reservoir cap. Tighten it with the hose clamp around the neck of the reservoir. The clear plastic tube is for the slave nipple to check bubbles and 1. brake fluid as they come out of the slave cylinder.
Some time ago I promised to take in everything I've read here, experiment, and report back on an ideal method for purging the clutch fluid. At that time I ran into some trouble, for one thing a bent and clogged slave-cylinder nipple, and I wasn't sure how to approach a fix. I found that the nipple was available separate from the slave cylinder and was a matter of just screwing the old one out and the new one in. I tied a string to each in case the nipple fell into the case, as access isn't ideal and I didn't feel like engaging in a fishing expedition.
There was some talk about using a hiking water bottle lid with a 1. tire valve attached, but I decided against that method for two reasons: (1) The setup doesn't allow for air pressure build-up and (2) finding a top with the correct size and threads was problematic. Reason #1 was suggested by a seasoned crane mechanic I've known for about 30 years, and his suggestion made sense.
I ended up using the tried and true inner-tube trick, using a 21" tube (diameter = 2") acquired from my friendly neighborhood Harley-Davidson dealer. Many dealerships replace the inner tubes as a matter of procedure whenever a new tire is fitted, so they usually have several lying around that will eventually get discarded. I got mine free, cutting it about two feet long with the valve in the middle, sealing one end with hot glue, folding it over, and clamping it with a small photographic clamp I had in the studio. The other end was inserted over the brake reservoir filler opening and secured with a 2" clamp. Tighten firmly around the reservoir, but be careful, as you don't want to crack the plastic reservoir!
But first, fill the reservoir to the brim with DOT4 fluid! For some reason, as Quasi warned me about before the fact, if the level gets below about 1" from the top, air will be forced through. Since it isn't even near the "min" marker, I can't imagine how air is getting in, but it does.
I set my air compressor regulator to 20# to avoid over-inflating, and let the inner tube blow up moderately, but I didn't go as far as the full 20# from the compressor. Setting the regulator lower, maybe at 10#, would be even better--but I didn't experiment further with that. When pressure was applied, I loosened the slave-cylinder nipple with a clear hose attached to it, the other end dangling toward the garage floor atop some newspapers and a recepticle for the discarded fluid. The fluid will come out slowly but surely after loosing the nipple about 1/4 turn, but loosening too much will cause fluid to leak from around the threads. I bled about 8 oz. out, which was just a guess but the fluid being ejected looked clean, so I felt that enough had been purged.
I think this is a good, safe, fairly simple method of purging the fluid. Checking my work revealed that the clutch pedal fell limply to the floor, but after pumping about 20 times it regained its proper firmness. I'm not sure why the pedal collapsed, but it may have been when the air was allowed in when I let the reservoir level fall below that magic 1" level.
Thanks to Quasi and others for their help with formulating this procedure. It isn't far different from some other reports I've seen here, but I thought repeating the good ideas and adding some other details would be helpful to y'all. One assumption is that the reservoir filler is 1¾" in diameter, as it is on my '95 Aero, so check your diameter before trying to locate the inner tube!
posted by 69.254.67...
, Sat, 12 May 2007 20:04:35
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