quote Originally posted by maryjane: Which vehicle is this for jscott?

This is for my Indy...it's been sidelined by so many other issues, I haven't worried too much about the clutch as I can still pump it up enough to drive.

quote Originally posted by jscott1: This is for my Indy...it's been sidelined by so many other issues, I haven't worried too much about the clutch as I can still pump it up enough to drive.

PM sent

I too have been going nuts with air in my system and no visable leaks. Well had ahd t and got new slave even thogh the one in it was not that old or I rebuilt it cant recal which, Anyway, just took the old one off (what PIA as it under my turbo) and it looked nice and dry until i pulled the boot off. Yup just as suggest here, it had break fluid in it! I'm hoping I have it solved now. Just started to rain and didnt get to bleed yet.

i think i found my leak today. there's no actual visible leak, but there's a pool of brake fluid in a depression on the front tranny mount, directly below the pushrod end of the slave cylinder. i think the fluid drips out ever so slowly, pools on the mount. the excess slops off when i'm driving, so i never see a puddle in the driveway.

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'84 2m4 se, a work in progress http://www.mtsu.edu/~mkr2c/fiero.htm
where's osama?

I see this happen all the time with brake systems. A caliper (for instance) can suck in air creating a low and/or spongy pedal. Bleed the system and it will help for a little bit, but no permanent repair. We do a line clamp test to see what part of the system has failed. 100% of the time we can locate it that way. The clutch works the same way. The most common problem is the slave leaking into the bellhousing. I don't remember offhand if the slave goes into the bellhousing on a Fiero or onto an arm, but the masters and slaves can suck air causing you to have to rebleed the clutch frequently. I replace the slave cylinders on my Fieros when I buy the cars. It is on my checklist of new parts whenever I aquire a Fiero.
Just my added $0.03 (I work on German cars....hence the extra penny...lol)
Dave

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1987 GT (my toy-see above), 1987 GT (wife's toy), 1986 SE soon to be VR6, certified master technician/shop owner
www.njautobahn.com

quote Originally posted by bmwguru: The most common problem is the slave leaking into the bellhousing. I don't remember offhand if the slave goes into the bellhousing on a Fiero or onto an arm, but the masters and slaves can suck air causing you to have to rebleed the clutch frequently. I replace the slave cylinders on my Fieros when I buy the cars. It is on my checklist of new parts whenever I aquire a Fiero. Just my added $0.03 (I work on German cars....hence the extra penny...lol) Dave

No-doesn't go into bellhousing. Rod actuates an arm via a push rod.

quote Originally posted by maryjane: No-doesn't go into bellhousing. Rod actuates an arm via a push rod.

I guess it makes it easier to see if it leaks. I'm so used to seeing VW's and BMW's I couldn't remember how the Fiero was set up. Anyway, the principle is the same. It can suck air into the cylinder causing it to need to be bled out.

Put me down for having the same problem- Kept getting air in the lines, but no fluid leakage. I had to bleed every 3 days. My problem was the clutch slave cylinder was worn out.

I've been away from the forum for a good while, but at one time, people were so exsaperated with the hyd clutch setup, a thread developed to try to design the hydraulics out of the picture altogether-- a cable setup etc. Wonder if anyone ever got one to work?

I'll have to find that thread in archives.

[This message has been edited by maryjane (edited 03-08-2008).]

Not a good idea to go with a cable, especailly with where our engines are. Cables have thier short comings too. Even Stainless steel ones can bind and fray. I had a 65 corvair (yeah one of those) with engine out back and that cable system love to fray and snap cables and it was a major PIA to replace. Hydro is the way to go, ust have to get the systme right.

aside from the fiero experience, i'm not that familiar with hydraulic clutches. is this a problem that specifically plagues fieros? is it a design flaw? i don't remember seeing this much trouble with my previous cars. having to rebuild a slave cylinder every year or so is just wrong.

Just be glad it is on the outside. Had one in a Cherokee that was up in the bellhousing.

quote Originally posted by lurker: aside from the fiero experience, i'm not that familiar with hydraulic clutches. is this a problem that specifically plagues fieros? is it a design flaw? i don't remember seeing this much trouble with my previous cars. having to rebuild a slave cylinder every year or so is just wrong.

...hehe...see my post on the first page, for a possible solution(>??< )...

I just rebuilt my clutch hyd. system, I made a few changes from what I think others have done, or at least have read about here on Pennocks, I have an 88 coupe. I used a clutch slave cylinder piston from a 1986 Toyota mr2, it has TWO umbrella seals and is 13/16 or .8125 in diameter, the piston is almost identical in every dimension to the 88 coupes stock clutch slave cyl. piston ( I did NOT use the mr2 spring, I used the fiero spring ) the rebuild kit is only around $9.00 anywhere, the rebuild kit is the only part I bought from autozone, but it is on www.partsamerica.com they have a pic if You want to see one, btw, that is where I bought all of the other parts I used, the new clutch master, and new slave cylinder, I also bought a 7x1.0 mm threaded speed bleeder at partsamerica pn 12708 and machined the clutch slave cyl. bleed screw for the speed bleeder to fit, ( removed material top and bottom, drilled and tapped for the 7x1.0 thread, I looked everywhere for a speed bleeder with the 12x1.0mm thread, which I think is what is on the slave and could not find one anwhere ) but what really amazed me was that I could just push the slave cyl. piston in with the rod, the way Archie recommends, and the slave piston actually sucked the fluid all the way from the master when I let go of the clutch push rod, honest to goodness 1 man clutch bleeding, it works fantastic, because with the speed bleeder I can use both hands to push the clutch slave piston in and not worry about air being sucked back into the slave when I let go of the rod. The piston should work with any slave cyl. that has a 13/16 bore, I do not know if all fiero slaves have a 13/16 bore, but like I said I have a 88 coupe. Has anyone else tried this, the mr2 clutch slave piston or the speedbleeder on the clutch slave? Thanks

quote Originally posted by Mickey_Moose: ...hehe...see my post on the first page, for a possible solution(>??< )...

yes, the o-ring solution. which leads to...

quote Originally posted by gtu300r: it has TWO umbrella seals

today i priced slave cylinder rebuild kits. $23 at the zone, $9.99 at advance. so i bought 2, thinking maybe i can put 2 umbrella seals on the piston back to back. maybe, maybe not, we'll see. they arrive tomorrow morning, so i'll let you know how it works out.

quote Originally posted by Fierobsessed: Im going to have to agree 100% with Maryjane. Infact, I have seen it happen countless times. It's just the nature of the umbrella seal. It can seal against incredibaly high pressures in one direction. But, if there is ANY pressure on the wrong side, or even the slightest vaccum on the pressure side, I can guarentee that air will enter the slave. Heres where I tell you exaclty what I do with slaves that do this: First I have to say that I have only seen a couple of slaves that needed to be replaced. Most just need a rebuild. When I rebuild a slave, I take the assembly apart. I remove the umbrella seal, you have to be careful when doing this. One tear and it's over. I thoroughly clean the seal with WD40 and a rag, inspecting it in the process. I also clean the piston with a solvent and a wire brush. Then I put the seal back on the piston. The slave bore is where the problems occurr. Brake fluid is hydroscopic, It absorbs water which pools up in the slave and causes rust spots in the bore. To clean this up, I take a "brake hone" with my drill and plenty of WD40 and have at it for a while. This is where the problems are really taken care of, the instant that the enitre bore is clean and fresh is where I stop with the hone. I use a solvemt and some rags to clean out the residue. Then, I always make sure I apply a really light fresh skin coat of grease into the bore. You don't want much in there, as the more you put in there, the more it can contaminate your fluid. I put the spring onto the piston and insert the piston into the bore and put the snap ring in. I push the piston in all the way and add a touch more grease to the inside of the bore. I found that the light coating of grease is pretty important, it not only allows the installation and free movment of the piston, it acts as an air seal, and keeps air from penetrating past the piston to the umbrella seal where It can begin to give you trouble. I always install the bleeder with a little bit of grease on the threads, this way air doesn't leak past the threads when you are bleeding the slave. This is a necessity if you are using a mityvac to bleed the system. I put the pushrod and the boot on the slave. I wrap my slaves in heat reflective fiberglass tape. This protects and prolongs the life of the slave for years to come. My biggest concern with the slaves has always been heat. My 88 didn't have the magic heat shielding on the "Y" pipe, and never came with the little heat shield that the 85-87's did. The heat killed the slave every 6 months, each time the problem was the same. I would start to lose the disengagment of the clutch, I would constantly have to let the air out of the slave to keep me going till I could rebuild the slave, yet I wasn't losing fluid. And every time, I would rebuild the slave and be good for another 6 months. Fixing the heat issue, and limiting the amount of grease I used in the rebuild has solved the problem. I never replaced the slave to this day.

Nice write up, but I did have one concern. You’re putting grease in your brake system, most grease is petroleum based and that will attack your seals in your hydraulic system. Brake systems can not take any petroleum products it will make all the seals swell and distort.. Just my 2 cents.. Vince

I'm gonna bump this, I want more information. I'm going to replace my master cylinder, and pull the slave, it already has the mr2 piston, i'll do the non-petrol grease, and see how that works out for me.