Clutch problem: REALLY Need Help!!
 

It's an 88 5 speed gxl. Everything is stock or stock replacement. We had the transmission blow up late 2008 halfway through Kentucky from Minneapolis to Huntsville, Al. We couldn't do anything else but to leave the car and come back the next day with a Uhaul car dolly. With only 4th gear we burned the clutch getting the car up the ramp onto the dolly to get it to Huntsville. The car sat until February this year for us to build money and parts to tackle the repair and parts swap. The tranny was replaced with a used 5-speed pulled off a car from Atlanta Rx7 and had the seals replaced, came with a guarantee. The clutch assembly in the flywheel was replaced with the 3-in-1 kit from Black Dragon Automotive. We also replaced the pilot bearing. We put it all together but the clutch cylinders were not working. We started at first rebuilding both cylinders (found the seal in the master cylinder blown). We put it together and it all was working great. However, we did notice we had to move the actuating rod on the clutch pedal all the way out as far as we could to get enough movement out of the slave cylinder to move the fork back enough to disengage the clutch. It was working this way for a while (few days). Then I drove the car a long distance (about 30 miles) and when I made a turn I shifted into 2nd to make the turn but when I pushed the clutch pedal to shift to 3rd it only disengaged about half way and when I attempted to shift to 4th it did not disengage at all and I was stuck pulling off to the side of the road and calling a tow truck. Got it home and the rebuild kit did not work. The seal failed and fluid back flowed into the reservoir leaving the piston compressed halfway into the cylinder without returning. (the spring might have broken too considering the one from the rebuild kit looked weak). We shrugged it and bought a new master cylinder, installed it, was working, but was loosing pressure as you held it down and you had to pump it to build the pressure back up. We took a look at the slave cylinder and noticed it was seeping fluid past the piston so as you pressed the pedal, it was pushing fluid out, hence the loss of pressure. So..new slave cylinder too. Got it in the car today, bleed the system of what I'm sure to be all the air. At first when you press the clutch pedal it has solid pressure and clutch disengages. However, I am noticing that the piston in the master cylinder is not returning all the way and is sluggish. If you pump the pedal slowly but with little rest it will slowly loose pressure in the system until it does not disengage at all. If you give it a good amount of rest time it returns to normal and has full pressure and disengages the clutch. The clutch system, flywheel, pressure plate, etc all working great and fork always returns forward, in fact you can't even push the fork back by hand with the car on or off. So, if you hold the clutch pedal down is will slowly loose pressure in the system and clutch will reengage on it's own, same thing if you pump the clutch, it looses pressure until it no longer disengages. Now, I am noticing that when the pedal is pressed, the piston in the master cylinder goes in and the slave piston pushes out and presses the fork, disengages the clutch. When you release the pedal the fork comes forward and the slave piston goes back in, however the master piston does not readily come all the way back out. Press it again and it exaggerates and you slowly get less movement from the slave cylinder. If you hold the pedal down, the system looses pressure and you will actually see the fork make it's way forward and compress the slave piston even with the pedal held down. I know you are going to say check for leaks and check the lines. I've done this. The system is solid and not loosing fluid. I do not understand hydraulic clutch systems at all. Please help! I have other problems but can't even begin to work on those until the clutch is 100% and my husband deploys in the last week of May!!! :scratch: :scratch: :(

Reading that wall of text hurts the eyes. Paragraphs.... :)

Anyway, replace the flex line. It may have collapsed internally. Whenever dealing with a failure in the clutch hydraulic system, replace every component. If one part has failed, the rest aren't far behind now that the pressure has been increased by a new component.

Completely understand what you are talking about with other components not far behind. The MC failure was our fault from messing with it while the blown tranny and burned up clutch was still in the car. We kept the motor running while it was down and with depressing the clutch pedal so many times on a non-functioning clutch we may have over extended the piston in the slave cylinder (according to a guy at the autoparts store). We had at one point the pedal would not go down at all, like it was stuck. My husband forced it and it popped loose and from there on out the pedal stayed to the floor. Now it's working apart from keeping pressure and only loosing it as you pump it.

I brought it up to my husband about the possibility of the line being bad and maybe bulging out as pressure builds up and the more it expands, the less pressure we have until it shrinks back down. He said it's not likely what is going on, I figured I'd come here for answers.

One question: How would the line collapse internally? Is it a multilayer line of some sort? I thought it was braided...anyway, I appreciate the help, I will need more soon!!

The line is braided with multiple layers of metal and rubber, but they certainly can collapse at times.

Another more sinister issue is that perhaps the clutch fork popped off of the ball in the bellhousing. Though that would not result in intermittent operation.

Yeah, the problem is definitely not beyond the fork. Thanks. I'll get a line on order today even though my husband says he wants to try a different bleed method first. I'm trying to save time :P

Do you know anywhere better than black dragon to order one from? My local auto part stores who are faster to get parts can't order one for this car. Black dragon wants $27 for the line which isn't too bad but I have to pay for shipping. Already spent $60 and $43 on the MC and SC not including the rebuild kits I tried.

I'm surprised the local auto parts store can't get it. There is always the dealer, but if you don't want to go there, last time I needed one I ordered a stainless version from Mazdatrix. I don't recall but I think it was around $30. If you are autox'ing then it's a worthwhile upgrade anyway.

Thank you. I have the steel line on order. I definitely feel more comfortable with something like that versus OEM. Just much stronger, less flex, more consistent pressure in my opinion. :lol:

Anyway, I also got the extensive wiring diagram book. My husband has been saying that we need one to battle that 3800 hesitation ghost. Ever since we got it back on the road it's been haunting us. Just hits a wall at 3800. We noticed before the car went down that it was cutting back for a second then kicking in and going for more but we contributed it to our exhaust leak behind the manifold.

Now that we have a new cat no longer causing blockage, a new pipe, new gasket, our exhaust leak is not there (for the time being at least). Since the car has sat, it's worse. We are looking at electrical. We bought the car after it had some work done to it. Systems replaced, new engine, etc. The guy didn't do the greatest job with the wiring and we have found two opens two small systems already (ie: the wipers and one dash speaker). So we expect more. I recently had to redo a splice he had done to the O2 sensor wire coming from the engine because there was exposed wire that was corroding.

I have read all over the forums and learned a lot so far. We are going to look at grounds first, clean them up and see what happens. Then my husband wants those diagrams so he can take a multimeter to the system before we replace ANY parts because we have determined all possible parts to be expensive and not worth throwing at the car for our budget.

Thanks for the help!!

Amanda

The 3800 RPM hesitation is generally due to a grounding problem: http://www.aaroncake.net/rx-7/grounding.htm

Wanted to update this thread since it was never finished. Clutch problem was fixed a while back.

Causes: The majority of the problems were caused by not using the right fluid...biggest newbe mistake ever!

Make sure it's DOT brake fluid!

Replaced both cylinders and cleaned out the system thuroughly with iso. alcohol, filled with proper fluid. Also using the steel line from mazda trix...love it!

Got the bleeding process down to an art. Best way to do it!

Get a larger syringe and a tube for the end of it that fits over the bleed valve in the master cylinder.

With the entire clutch system out of the car (both cylinders and the entire line):

position the system so the bleeder valves are the highest points to minimize creating air pockets.

fill the syringe with the brake fluid and attach it to the master bleed valve, pour a small amount of fluid into the reservoir.

Open the bleed valve in the slave cylinder to allow air to escape and fluid to begin to fill the cylinder and come through the valve. capture the fluid in a jar or bowl.

continue this process until you see no more air come out of the bleed valve. you may need to adjust the cylinder position to persuade air towards the bleed valve. You also may need to syphon fluid from the resorvoir to keep it from over filling.

Also, position the piston in the slave cylinder slightly further out from where it needs to be to have strong pressure on the shift fork on the transmission. This way, when you install the system into the car you can push the piston in (takes a bit of force). I found if you do this at a slight angle just so you can get one of the bolts in but not tight, then drive the other side pushing the piston inward until you can get the second bolt in is the best way to install. This way when the system is in place, the piston is at the proper position to the fork.

Make sure all parts are secured and you should be good to go!

I hope I typed this out correctly since it was about 6-7 months ago since I had to work on my clutch system.

What is the best fluid to use?? I heard dot brake fluid is like same stuff.. I'm not sure tho..

The manual calls for DOT 3 brake fluid but I think they have combined it all into one so it says DOT 3 and 4? It was combined when I bought it. Get COT 3 if you can or the combination is fine. Mine is running great with it.

COT? or DOT3??

Typo, sorry....stick with the DOT :lol: