Clutch pedal goes from normal to hard at operating temp (1 Viewer)

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After installing a new clutch, slave and master recently with an H55 upgrade on a '83 FJ60, have had a problem with the clutch pedal getting hard and notchy as truck warms up. When the truck is started cold, the clutch feels perfect. As truck warms to operating temperature, the clutch will get firmer and like it is grabbing something (like there are notches) as you depress the pedal. Have bled the line several times with same pattern occurring. Can't find any visible oil leaks either side of firewall or where hoses join slave/master and hard line. Fluid level in master reservoir remains unchanged. Does this sound like a slave cylinder or master issue? Guess it is possible either of these new units could have a defective seal?
 

Seth S

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Sounds like it might be a spline issue in your clutch plate where as things get hot there is a clearance issue or alignment issue. Other problems that can cause issues are pilot bearings or something not seated properly....pressure plate not seated all the way on a guide pin etc.
 
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g-man

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you could disconnect the clutch fork from the slave, depress the pedal and see if by process of elimination the problem lies with the hydraulics in the master and slave. If that doesn't narrow it down, attach the fork back to the slave and remove the dust cover from the bottom of the flywheel housing and watch the movement of the clutch fork pivot, throw out bearing and clutch disc looking for whatever may be sticking.
 
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60Works

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Are you certain you positioned the clutch disk with the correct side forward?
 
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Thanks for the suggestions which I will explore. I'm doubtful though there are any issues with the install of the clutch. If this was a clutch plate installation or mechanical issue causing this stiff and notchy feeling pedal as truck gets warmed up, would you not hear evidence of misalignment? There is no contact noise or vibration coming from the clutch area.

One other point I should have mentioned is the clutch worked great following the install. My brother Jim (CenTXFJ60) and I did the install in his San Antonio barn. I drove the truck back to KC with no problems. This clutch issue seemed to manifest several weeks later after install. My gut tells me this is hydraulic related but as I mentioned brand new master and slave with no sign of oil leaking anywhere. If inspection of the mechanical components turn up empty, will switch out the slave then master if necessary to see if I can find the culprit.
 

CenTXFJ60

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Sounds like it might be a spline issue in your clutch plate where as things get hot there is a clearance issue or alignment issue. Other problems that can cause issues are pilot bearings or something not seated properly....pressure plate not seated all the way on a guide pin etc.
Seth, curious as to how any of these type issues would not cause consistent results. As Will mentioned after your post, he drove the truck over a 1000 miles before his symptoms occurred. One thought I had was to replace the slave with the old unit (worked fine until removed) and then the master if necessary. Also a good idea to remove the inspection plate once the trucks warmed up and see if there’s any evidence via the fork and throw out bearing. Appreciate all the feedback as this issue is one I’ve never seen and I’ve done more than my share of trans swaps. Thanks. Jimmy
 

Seth S

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Seth, curious as to how any of these type issues would not cause consistent results. As Will mentioned after your post, he drove the truck over a 1000 miles before his symptoms occurred. One thought I had was to replace the slave with the old unit (worked fine until removed) and then the master if necessary. Also a good idea to remove the inspection plate once the trucks warmed up and see if there’s any evidence via the fork and throw out bearing. Appreciate all the feedback as this issue is one I’ve never seen and I’ve done more than my share of trans swaps. Thanks. Jimmy
I agree but he didn’t mention driving a 1000 miles in the first post. His first post made it sound like he had just done the new components and was having the problem right off.

I have had the springs clutch disc fail before on other cars which caused weird clutch behavior and eventually led to no clutch operation. It certainly sounds heat related so if things are warming up and expanding then That’s why I was thinking clutch Disc splines or a bad pilot bearing. A little wiggle in the pilot bearing can easily cause engagement issues. So either your hydraulics are working fine but when things get warm you are having a Mechanical issue which resists the clutch system or some odd hydraulic issue.

Either way looking forward to hearing what is found.
 

CenTXFJ60

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I agree but he didn’t mention driving a 1000 miles in the first post. His first post made it sound like he had just done the new components and was having the problem right off.

I have had the springs clutch disc fail before on other cars which caused weird clutch behavior and eventually led to no clutch operation. It certainly sounds heat related so if things are warming up and expanding then That’s why I was thinking clutch Disc splines or a bad pilot bearing. A little wiggle in the pilot bearing can easily cause engagement issues. So either your hydraulics are working fine but when things get warm you are having a Mechanical issue which resists the clutch system or some odd hydraulic issue.

Either way looking forward to hearing what is found.
That makes sense with spring failure. I never thought about that as fortunately I’ve not experienced it before. Appreciate your input and please know I recognize you were not privy to the fact Will had driven the new system for a while before the issue started. I’m leaning toward a hydraulic issue somewhere between his master and slave. We replaced both while we were in there with the Aisen brand from Cruiser outfitters. Does it make sense to replace the new slave with the old one and work backwards to the master if needed? Also feel a visual inspection of the throw out bearing engaging once the symptoms start occurring would be worthwhile. Thanks again to everyone that’s provided recommendations. Jimmy
 

Seth S

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I think anything you can try on the outside that might prevent having to pull the transmission off is a good way to start. Maybe inspection cover for a look see first. Also maybe you can measure the travel of the slave cylinder when cold and then do it again when hot to see if you can verify a travel issue.
 
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