Having used this forum many times for help over the years, and having consulted many clutch related posts on here, I have an issue that stumps me. I am totally familiar with bleeding procedure, including the final step of pushing back the pushrod on the slave at the end of things. I have an 86 v6 Isuzu 5 speed Ferrari F40 clone, that goes out once a week for a 50 minute drive. The pattern is always predictable. It runs and shifts normally for about 45 minutes, and at the end, the pedal starts to soften, and gear selection is impossible. Let it sit for 1/2 hour, and things are normal again. A week later, the same thing happens. I have no visible leaks at the master , slave ( a Dickman unit) or anywhere on the line in between. Due to the close proximity of the slave cyl to the exhaust header, I installed a heat shield over the slave several years ago. I am using dot 3 brake fluid, and have purged the system many times. Might I be boiling the clutch fluid during the run? Would going to dot4 fluid help this? My bleeding procedure is by the book, including the final step of pushing in the pushrod to get the last bit of air out of the slave cyl. Any suggestions would be greatly appreciated! Thanks in advance! Steve
At rest, how high does your clutch pedal sit above the brake pedal?
After running a search Here, I see that you've had quite a history of clutch issues. Has your clutch ever worked properly over an extended period of time?
[This message has been edited by Patrick (edited 07-24-2022).]
The symptoms make me suspect a heat issue with fluid boiling. Check the routing of your exhaust and hydraulic lines. Replace the fluid and bleed it- take your time and really bleed it thoroughly to make sure you remove ANY air.
Patrick, thanks for the reply. When I acquired this car years ago, it had sat for several years, so I went through a lot of stuff, and it was a great learning process. My first Fiero. I bought a 2cnd one here several years later, and stripped it completely for parts and the VIN plates needed to make mine legal here in. Mexico ( really LONG story!) After initially experiencing clutch issues, I purchased a Dickman slave cylinder, installed it, and the car performed fine- for the way I use it. It is primarily a toy, not a daily driver. It goes out once a week for an hour or so, and did this well for a couple of years. It has never been driven more than an hour at a time. The Dickman slave seemed to solve the problem; at least for the limited use the car was getting. This replica is low, stiffly sprung, hates speed bumps ( we have lots of them here in Mazatlan) and does not like rough roads ( lots of those here too); The route it gets iits weekly trip is pretty smooth, with some highway driving. I might shift it a couple of hundred times during the drive. This present problem has occurred the last 10 times or so I have driven the car, and always seems to appear at the end of my drive; to the point where I limp it into the driveway sometimes still in 2cnd gear, as it won’t shift into first anymore. I have bled the system twice, as per the suggestions on this forum, and still see no evidence of leaking anywhere. The pedal prior to the problem sits higher than the brake pedal as it is supposed to. Bottom line: everything is perfect until the last 10 minutes of the drive. I,bought some dot 4 brake fluid today, to attempt a fluid change to see if that helps. Has boiling ever been a clutch issue for anyone else? I would assume if I had air in the system somewhere, the problem would be constant, not sporadic as it is now. Steve
Cvxjet, Thankyou for your comments. Unless someone can offer me an alternative, I am going to assume it may be a heat problem. The slave sits an inch away from one of the exhaust pipes. I did make a heat shield years ago because of this. The engine compartment has two cooling fans directed at the motor, which vent the hot air out the louvres in the F40 rear window. There are also scoops on the sides of the car that vent air into the engine compartment as well. Next step might be to wrap the headers? Steve
Unless someone can offer me an alternative, I am going to assume it may be a heat problem.
Heat is no doubt a contributing factor, but it may not be the actual problem.
quote
Originally posted by stevep914:
The pedal prior to the problem sits higher than the brake pedal as it is supposed to.
Steve, that didn't really answer my question. I asked "how high".
The clutch pedal should be sitting a full inch above the brake pedal. If it's less than that, it's possible you've just barely got enough stroke to fully disengage the clutch under optimum conditions. Perhaps after your car is all warmed up and metal components have expanded etc, the stroke of your clutch pedal is now insufficient to disengage the clutch.
My experience with the Isuzu transmission is that it's very particular with the amount of slave movement required. If your slave is not moving the push rod 1-1/8 to 1-1/4 inches, it will not fully disengage the clutch.
[This message has been edited by Patrick (edited 07-25-2022).]
Patrick, I will check the pedal height and get back to you. I went back and revisited all my other posts and replies from 2013, Wow! But seems to be the same issue all around. I know back then, I had pushrod travel within the specified amount. I will try to get my wife to help me check that out again.
I'm surprised it's that high ... but nevertheless, the really important measurement is slave travel.
[EDIT] Is some of that height "slop" in the pedal? In other words, when the pedal is being depressed, how far does it move before it actually starts to push the banjo?
[This message has been edited by Patrick (edited 07-25-2022).]
About 1/2 inch of slop, which still leaves me 1 inch at banjo engagement. Again, please correct me if I am wrong, but the problem is not consistent; clutch even into reverse with no grinding, works properly for about 45 to 50 minutes, and then my pedal softens. And once the car has sat, and presumably cooled off somewhat, the pedal comes back up and I have clutch function again. Cold verses hot. I would love to think there is some “logical” answer here, and I appreciate we are trying to eliminate causes a step at a time. Your expertise and input is extremely appreciated. The first 50 minutes, this car is a blast to drive! The last 10 minutes sucks. I actually take it out and gear the drive anticipating the problem. So far Ihaven’t been stranded anywhere.
When the pedal "softens" (before it "comes back up"), does it actually sit closer to the floor at rest... or does it remain in the same location at rest, but is simply easier to push to the floor?
I would have to think about that one, I believe the pedal is in the same place as normal; just easier to push. I do remember I know immediately when the problem starts; it is not a slow deterioration. Last shift is good, and then the next one doesn’t happen. I just put the car on jackstands to do another bleed tomorrow, using dot 4. Can’t hurt. I will try it again after that to see if and what that pedal does, if the issue still exists. I am not set totally on the fact this is related to heat from the header, but it IS awfully close to the slave. If we can’t figure out anything else, I would consider wrapping the header in that area. Thanks again for trying to find a solution to this! Steve
I had heat soak on the slave fluid line on a couple of cars. My solution after being sure the system was fully bled, was to slip a piece of split wire loom over the fluid line, push it all the way down to the bottom until it stopped, then cut it off just below the metal tubing of the fluid line. Much easier, faster, and cheaper than header wrap.
If the fluid line will easily unscrew from the bottom of the slave, you might rotate it a little (it has a bend that directs it toward the header) then tighten it to give more clearance.
I had heat soak on the slave fluid line on a couple of cars.
Charlie, when you had this issue, did the pedal suddenly go "soft" and then go back to normal again once it cooled down? Did the fluid levels change? I've never had this issue, so it's difficult for me to understand how "boiling" fluid would affect the clutch in this manner.
I'd be more inclined to think that Steve's problem is some sort of valve issue within the master cylinder.
Your problem sounds heat related. Might as well cut thru the chase, do a complete transfusion and remove all doubt. Go with DOT 5.1
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Spoon, I am lucky to find dot 4 in Mexico. No 5 here. I am going to try the dot 4 tomorrow, and see if I can even find header wrap here. I have the line right up to the slave covered in insulation already down to where it curves under the floor. I will let all know, what goes on after I do this. Might take a couple of days. Thanks all. Steve
Charlie, when you had this issue, did the pedal suddenly go "soft" and then go back to normal again once it cooled down? Did the fluid levels change? I've never had this issue, so it's difficult for me to understand how "boiling" fluid would affect the clutch in this manner.
I'd be more inclined to think that Steve's problem is some sort of valve issue within the master cylinder.
When first starting, the clutch would work normally. After a drive of 10 miles or so, the clutch would begin having disengagement problems. Once after a decent drive, I encountered a traffic light. Had it not been for the empty right turn lane, I would have had to rear-end a car. I got stopped in a mall parking lot and did a gravity bleed and returned home. The operation got better as it cooled, but would sometimes require a bleed. I thought I had a leak that was pulling air, so I replaced the slave with a stock unit. It didn't solve the problem.
I think it was on this forum that I learned of the heat problem and found that my fluid line passed very close to the crossover coolant hose. When I loosened and moved the line away from the coolant hose and sleeved it, the problem was solved.
Don't use auto parts store wire loom. It probably won't hold up to engine bay heat. If you can, get nylon wire loom. It should have a silver or gray stripe running the length. Voice of experience.
Upon inspection, my clutch line is right against the crossover coolant pipe, just below where my clutch line insulation stops. I will address this issue along with everything else. Thanks! Steve
Just to keep all that have helped in the loop: today I think I have eliminated heat as being the source of the problem. All exhaust pipes within proximity of the slave and lines has been wrapped with titanium wrap. Also did the cooling crossover pipe, and the clutch line from the slave down to where it separates from the cooling line under the car. Horrible job, by the way! Hopefully tomorrow I will do a fluid replacement with a bleed, and then see if my efforts, ( and yours) have generated any positive results. It is always good to do projects; while wrapping the exhaust, I found a two inch hole in my one and only muffler. The car has no mufflers other than a single 1 foot long 6 inch wide can shortly after where the exhaust pipes from the headers get together, and two small resonators in the middle rear of the car where they exit. It DOES sound like an exotic. We have no emissions testing here, so anything goes. Steve
Got the system bled, and went out for test drive. $#%* This time it didn’t even make it back to the house. About 40 minutes in, one minute I have full pedal, the next, nothing- pedal dropped to the floor with no gear selection. In traffic, where I had to stop, get out of the car, and push it off the road.I had been testing the pedal after 30 minutes constantly, and it was solid. I let the car sit for 10 minutes. Got it into 2nd, and limped it home. NOT a happy camper! Fed up with it today, but maybe tomorrow I will try to bleed it, and see if any air comes out. While bleeding, I checked pushrod travel , and it is getting full travel about 1 and 1/2 inches or close when the pedal is good. By the way, after bleeding, the “slop in the pedal went away, and it was firm right from its resting position. Steve
By the way, after bleeding, the “slop in the pedal went away, and it was firm right from its resting position.
There needs to be some slop. When the system is fully bled (and supposedly no air in the system), disconnect the clutch pedal and see if it pulls further up. What you're checking for is that the banjo (while connected to the pedal) is not preventing the master cylinder from fully returning to its resting position. If it's not able to fully return, there's a chance that the valves within the master cylinder aren't able to function properly... and maybe this is somehow exacerbated when everything has heated up. (Make sure to reconnect the banjo with the loop located upwards.)
[EDIT] I seem to recall from years past of someone here who had clutch issues created by the clutch safety switch being adjusted incorrectly. This was preventing the clutch pedal (and therefore the master cylinder) from reaching its proper resting position.
[This message has been edited by Patrick (edited 07-27-2022).]
Whose book are you using? Give step by step in detail the procedure you are using. Perhaps something is missing and you're not getting all of the air out. I have a 86 4 speed Muncie. I replaced the front master and rear slave. Parked with nose on a downward angle since air will rise to the highest point at the slave. Removed bleeder from slave and added fluid to the master. Within minutes bubbles began coming out of the slave bleeder. I added more fluid so the master would not pick up more air. Pretty soon the bubbles stopped and I was getting fluid. I let it flow until the fluid became clear. This told me that the old fluid had been evacuated. At that time I depressed the short push rod and closed the bleeder. I then topped off the master and put the cap back on. Pushed the clutch pedal several times. Did a test drive. End of story. I believe the angle I parked the car helped get the air out. No pumping or helper required. Results may vary.
Let me know if this helped.
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Got the system bled, and went out for test drive. $#%* This time it didn’t even make it back to the house. About 40 minutes in, one minute I have full pedal, the next, nothing- pedal dropped to the floor with no gear selection. In traffic, where I had to stop, get out of the car, and push it off the road.I had been testing the pedal after 30 minutes constantly, and it was solid. I let the car sit for 10 minutes. Got it into 2nd, and limped it home. NOT a happy camper! Fed up with it today, but maybe tomorrow I will try to bleed it, and see if any air comes out. While bleeding, I checked pushrod travel , and it is getting full travel about 1 and 1/2 inches or close when the pedal is good. By the way, after bleeding, the “slop in the pedal went away, and it was firm right from its resting position. Steve
I believed it said somewhere on this forum to elevate the FRONT of the car for gravity bleeding to take place. I had my wife depressing the pedal, while I handled the bleeder valve . No pumping of the pedal- just depress, and bleed, close bleeder valve and release pedal. I purged all the old clutch fluid; replaced with dot 4 and then pushed the pushrod back into the slave. Tomorrow, I will check out Patrick’s suggestion, and follow your procedure with the back of the car elevated-. At this point, I will try all and anything to resolve the issue, Today was NOT fun, and major embarrassing! Steve
I seem to recall from years past of someone here who had clutch issues created by the clutch safety switch being adjusted incorrectly. This was preventing the clutch pedal (and therefore the master cylinder) from reaching its proper resting position.
Found it. It was 12 years ago, so apparently my memory isn't totally shot.
This thread is worthwhile reading for bleeding info, and in there I found reference to This thread that I was mentioning above.
By the way, the majority consensus is to bleed with the nose raised, and the driver's side of the car raised (slave/bleeder screw tilted up). I understand the confusion, some might think that you'd want the rear of the car raised so that the air bubbles could "rise" towards the slave... but with the nose up, the fluid moves fast enough to carry the air bubbles downward... and out the bleeder. With a clear tube attached to the bleeder valve, and the other end inserted into a clear container/bottle, it's easy to see the air bubbles coming out... until they eventually don't. End of bleed!
[This message has been edited by Patrick (edited 07-27-2022).]
I have used the gravity bleed method for a long time. Not having anyone to help, there was no one to depress the pedal. Pumping the pedal can break up the air bubbles, only to come back together later. If the pedal pump method is used, the pedal should only be depressed and held one time for each opening of the bleeder.
If I'm bleeding at home, I jack the left front of the car underneath the front subframe just enough to lift the tire off the ground. If it's underneath the left front control arm, I raise it about 6 inches off the ground. This places the master cylinder higher than the slave cylinder.
I then fill the master cylinder to the top, leaving the cap off the brake fluid and the reservoir for easy refill. Next, I go to the rear and open the bleed valve. As the fluid starts to flow, I use a heavy object and strike the side of the slave repeatedly. This dislodges any air bubbles that may be stuck at the pushrod end and lets them flow upward to the bleeder valve. With the pump method, the bleeder is directly above the fluid inlet and bubbles at the pushrod end will usually stay there.
Keeping watch on the reservoir, I close the bleeder before the reservoir empties, top off the reservoir and repeat. I usually run about 3 reservoirs of fluid through the system, then when the level drops to the FULL mark, I close the bleeder and I have pedal.
When I had the incident I related previously, I ran the left front up onto a curb at the grassy edge of the parking lot. Gravity bled the system and returned the 12 miles home to diagnose the problem. I was lucky that it was an undeveloped outparcel parking lot that wasn't being used. I have bled other person's systems by angling at 45* on their sloped driveway.
The first generation and second generation clutch master cylinders are functionally different.
The 1st generation with the reservoir on the end has a valve in it and the master can be easily bled similar to brake system with the clutch the pedal. The presence of the valve might make this master difficult to bleed by gravity.
The 2nd generation master with the reservoir in the middle has no valves in it. There is a port that is open to the reservoir when the clutch pedal is up. When the pedal is depressed, a lip seal slides past this port so the compressed fluid cannot flow back to the reservoir. My experience with this master is it is difficult to impossible to bleed with the pedal. I have used a Mity-Vac on the slave bleeder to pull fluid through. I've not tried gravity bleeding but I can see how it would work with this master.
The 2nd generation master can be replaced by the first generation master. I just takes a little bending of the tubing. IMHO the 2nd generation was not a reliability improvement, it was just a way to cut cost.
------------------ formerly known as sanderson 1984 Quad 4 1886 SE 2.8L 1988 4.9L Cadillac 1988 3800 Supercharged
Ok, I’ve calmed down a bit since yesterday. Elevated the nose of the car drivers side, and gravity bled- filled 2 feet of clear hose with fluid with no air bubbles evident at all. I then pushed the pushrod back into the slave, and no air bubbles there either. Pumped the clutch pedal about 200 times without the car running, and the pedal stays firm. Pushrod travel is at least 1and 1/4 inches. The 200 times on the pedal would approximate my driving time, where at the end I would lose the pedal. I am assuming the clutch operates whether the engine is running or not. Looking at the pedal and banjo, the pedal seems to come up to the stops with the banjo attached. I did notice some play in the connection where the banjo goes on the pedal. One other thing: I believe my pedal is aluminum, not steel it has an interesting twist in it. Not knowing what anything other than mine looks like, and assuming a bent pedal would provide a consistant problem, I don’t know if this is a contributing factor. Anyone able to post a picture of a normal clutch pedal I could compare mine to? I know many have converted to a steel pedal when the stock one bent. Again, would a bent pedal not offer a consistant problem other than a sporadic one like mine? Next step for me, I guess, would be to run the engine, and do another 200 shifts parked, and see if the problem occurs. So far I have made no real changes, since yesterday’s problem, other than another complete bleed. Steve
It's not the pedal arm that bends, it's the bracket that the banjo attaches to. The bracket should be parallel to the pedal arm when viewed from the side and front.
One other thing: I believe my pedal is aluminum, not steel it has an interesting twist in it. Not knowing what anything other than mine looks like, and assuming a bent pedal would provide a consistant problem, I don’t know if this is a contributing factor. Anyone able to post a picture of a normal clutch pedal I could compare mine to? I know many have converted to a steel pedal when the stock one bent.
Steve, they all have an "interesting twist". That's how they're made. What you're looking for is a bent bracket on the pedal. I first posted this photo of my clutch pedals ages ago.
If your clutch pedal sits 1-1/2" above your brake pedal as you reported, it's probably fine... although I still think that's higher than usual. Is your banjo adjustable?
Ok, Thankyou for the pictures! The pedal is normal, and not bent. Getting a good look at the banjo is a pita, as this car has an F40 interior, including a buttress that rises above the door sills 6 to 8 inches. I have to take the seat and the buttress out for enough room to get my body in there. I remember what a nightmare this was the last time I fixed the banjo! What I can see is the banjo portion is welded onto a cylinder that appears to be threaded? ( can’t get in close enough to confirm this) onto the pushrod for the master cylinder. I assume the banjos are removable from the master pushrod? I measured everything again while in there. Pedal at rest including the slop is 1 and 3/4 inch above the brake pedal. Banjo engagement at 1 and 1/4 inches above the brake pedal. Travel on the slave pushrod is 1 and 1/4 inches minimum when the pedal is depressed. I have not started the car and done the 200 pedal movements with the engine running yet. So far EVERYTHING says I should have good clutch function.
What I can see is the banjo portion is welded onto a cylinder that appears to be threaded? ( can’t get in close enough to confirm this) onto the pushrod for the master cylinder. I measured everything again while in there. Pedal at rest including the slop is 1 and 3/4 inch above the brake pedal. Banjo engagement at 1 and 1/4 inches above the brake pedal.
Yes, sounds like the banjo has indeed been made adjustable, which is not a bad thing... but the clutch pedal sitting 1-3/4" above the brake pedal does seem excessive to me. I imagine then that your clutch pedal does not hit the floor when fully depressed?
quote
Originally posted by stevep914:
I assume the banjos are removable from the master pushrod?
There is no "master pushrod". The banjo is connected to the master cylinder at one end, and to the pedal at the other end. The clutch master cylinder needs to be removed from the car to detach the banjo from it.
Even if you can't get your body up close to the banjo, can you perhaps hold your phone (or an actual camera) down there and get a shot of it. Make sure to add a light source. It would be interesting to see what's been installed.
[This message has been edited by Patrick (edited 07-28-2022).]
The mechanics of the brake pedal and pushrod should not make the disengagement problem come and go with heat cycling, the distance you drive, or the number of times you use the pedal.
As for bleeding the Generation 1 and Generation 2 systems, I've had success with my 85's, my 86, 87, and an 88, so both systems were gravity bled. I've replaced my 86 and 87 with a Rodney Dickman master and slave and this is where many claim to need the adjustable banjo rod. I haven't experienced the need and am using the stock pushrod on both.
[This message has been edited by fierofool (edited 07-28-2022).]
I will attempt that tomorrow. I did not get my head in close enough to confirm there are threads. The banjo portion is welded to what appears to be a brass cylinder that is connected to the rod portion that goes through a grommet at the firewall.
Fierofool, I would agree. My problem is confusing because it works normally for awhile, and then it doesn’t the failure always seems to be at the same point in the driving cycle. And the route I drive is the same each time out. So what happens at the 40 minute point in the drive to cause failure? Most of the things Patrick is walking me through should cause a constant problem, to my understanding. The only thing constant about this issue, is that it WILL happen.I really appreciate all the assistance and suggestions! Steve
There's obviously something not right with his car. Yes, I think we're all in agreement that heat appears to be a contributing factor... but none of us are experts in how heat may affect every clutch component and how well (or not) they work together. I'm just trying to find out from Steve what isn't "normal" about areas of his clutch system. The fact that he has an Isuzu 5-spd bolted to his 2.8 indicates to me that this Fiero kit car has had modifications from the factory setup. I'm trying to find if there might be at least one that's contributing to this long-standing issue.
[This message has been edited by Patrick (edited 07-28-2022).]
Not luck yet? Plan (B).. Do your bleeding procedure until you have a firm pedal. Wedge a piece of 2-by-4 lumber against the pedal and the seat frame or something solid. Let sit overnight. Check results in the morning for a firm pedal. This will remove the heat factor as the cause. A weak pedal means you have a leak internal or external. Master & slave new or rebuilt?
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
Spoon, I'm surprised none of us have brought that up. The most difficult leak to find is at the pushrod of the master cylinder. Add to it the difficulty steve914 indicates with getting underneath the dash just makes it more difficult to find.
The carpet and matting would need to be pulled back from around the boot area on the back of the master cylinder to find a fluid leak. That could be where air might be entering the system and would certainly occur only with the operation of the clutch pedal. Of course, the slave cylinder boot could be easily popped off to find fluid at that end if there were a leak.
Patrick, I wasn't dissing your information. It was just for Steve's knowledge in case he decided to replace the pedal. But it never hurts to explore all areas.
Did Plan B last night and blocked the pedal fully depressed ( and yes, it does go all the way to the floor) . Left it all night like that. This morning, removed the piece of wood, and the pedal snapped right back firm. So , if I interpret this correctly, I have no internal or external leaks. I will try to get a picture of the banjo sometime today; One step at a time! Unfortunately our main AC unit for the house got surged by a lightning strike last night, and a new unit is the project of priority right now. We have over 90 degree heat here every day now. I will get back at this once I have THAT issue sorted out. Steve
I asked "how high". 
... but nevertheless, the really important measurement is slave travel.
