The problem I have now is the clutch is dragging with the pedal to the floor which makes it hard to shift. I've bled the system three times, tried the drip method of bleeding and it helped some but it still isn't right. I read the tech article about using an adjustable clutch master cylinder push rod. I went to a dealer and he said one from an 86 was adjustable. I tried to take the push rod out from my master and it won't pull out. There's a spring clip in the back of the master that holds a plastic ring in. Does anyone know if the guts of the master are going to come out if I take the spring clip and plastic ring out or does it just hold the pushrod in? My theory about what happened here is this. Since the flywheel was resurfaced twice now the dimension between the face of the flywheel and the throwout bearing face has increased by the amount that was cut off the flywheel. So now the slave cylinder doesn't push the spring in far enough to totally disengage the clutch. One way to fix it would be to install a shim behind the slave that is equal to the amount that was cut off the flywheel but I really don't feel like going thru that again. If I can get an adjustable master cylinder push rod installed then I'll be able to adjust for it at the pedal. I won't be able to reinstall the clutch interlock switch that fits over the clutch pushrod but after looking at the wiring diagram I think I can take care of that with a jumper. Anyone else have a problem like this?

 

Ok ,
Ive read your posts several times trying to come up with a solution . First off , The hydralic line from the the clutch master cyl to the slave valve will disconnect , they come off hard but you just have to pull ...all I have ever used is a screwdriver to push in on the disconnect and pull on the line , it will come off .Are you losing any fluid at the slave valve ? I dont think buying and using the adjustable push rod will work because all that will do is adjust the pedal height ...it has no bearing on how much hydralic pressure is applied to the slave valve ...it either goes in all the way or it doesnt . Did you buy the Slave vavle / Throw Out Bearing combo ? Id suggest having someone push in on the clutch pedal while you visually look to see whats going on . Are all the new parts Ford ? Do you know how much was removed from the flywheel ? Did you get the clutch plate lined up properly with a pilot shaft ? A good machine shop would and should not resurface any part if it takes it below minimum specs . Also too , If the flywheel was below specs , youd have a problem with it slipping . Im betting your problem lies in either in the clutch master cyl or the slave valve . Because the clutch line is plastic and you had trouble with it , Is it possible its damaged in some way ? One other thing ...Are you bleeding the system with the cap off the master cyl ? It will bleed a whole lot better with the cap off .
Paul

 

If the flywheel was cut twice, you will need to install a flywheel shim between the crank & flywheel,or, install a new flywheel. The shim's are available to the aftermarket in the HELP,Motormite,DORMAN,etc. brands of your autoparts store service lines. You will have to remove the trans one more time to install either option.
Phillip

 

Thanks for both responses. All the parts used were Ford and the slave and TO bearing were both replaced. The original hydraulic line definitely wouldn't uncouple due to the corrosion from the salt they use here. After the plastic sleeve gave out I tried screwdrivers, pieces of wire, small drill bits and nothing would release the spring that holds it in. I talked to a Ford service tech and he said a lot of times they have to cut them on the older trucks. When I installed the new one I packed grease around the coupling after it was coupled up to help prevent a reocurrence. Anyway tonight I replaced the plastic bushing on the master cylinder push rod and it made a big difference, the old one had a lot of slop in it so I was losing a little of the pedal throw in the slop instead of it acting on the pushrod. A little slop there costs a lot of travel at the slave. I drove it a couple miles and it seemed a lot better but I'll see what it acts like once it gets really warms up which is when the problem is the worst. If this doesn't work I guess I'll have to install a shim behind either the slave cylinder or flywheel after I mike the flywheel to see how much was cut off and make the shim the same thickness. Shimming the slave should accomplish the same as shimming the flywheel and its easier. It should bring the distance from the flywheel surface to the face of the throw out bearing back to the original dimension and solve the problem. Stopped and looked at an F250 XLT Super Duty SC 4x4 Power Stroke. Nice truck but big price. Think I'll fix this problem, only 135K miles on this one and the payments were done a long time ago.

 

I did some deep thinking about the adjustable pushrod myself because I will have a simular problem when I re-do my clutch next time. Ok,if you first bleed the system with the pushrod relaxed,the slave/t-o bearing will be at it's further most relaxed position as well, away from the pressure plate, right ? Then if you expand the pushrod,causing the master to send additional fluid into the slave, you can control the distance between the t-o bearing and the pressure plate while the system is just resting. So, you can get the t-o bearing a lot closer to the pressure plate before you even press on the clutch pedal ! Now of course you wouldn't adjust the pushrod until it drove the t-o bearing into the pressure plate at all times,but,you can judge your pedal freeplay(not height) by allowing an inch or so of pedal engagement before feeling the pressure plate load up.Keep in mind that hydraulic principals apply here...you cannot compress liquid,so,you have to move it...&....the slave will only rest where the master dictates it rests.
Phillip

 

Yep , Phillip has a point there . Something that occured to me about shimming the flywheel ... what about the flywheel bolt length ? Also , if the flywheel is shimmed this will also mean the starter will have to be as well . I know it will be more expense , but I think Id opt for a new flywheel . I was just comparing the time all the other modifications will take vs the cost of the new flywheel . The trans / transfer case is going to have to come off regardless . When It comes to jobs like this , Id just as soon spend the time and money wisely rather than fiddling with all the other stuff .
Paul

 

Don't know this particular Ford part because my 81 F-100 doesn't have a hydraulic t/o bearing ... but... my son and I recently replaced the hydraulic t/o bearing on his Wrangler because it had been pushed out beyond its limit - like hyperextending. Don't know if this could happen here; if you start the bearing partly out from it's base, then add a full clutch stroke, may be too far? Just a thought. If you shimmed the base, with no extension (or relaxed as a previous writer put it) I think it would make more sense.
Raul

 

I'm going to a junkyard tomorrow to see if I can find an adjustable push rod and install it in my master cylinder. I've got about 1/2" free play in the pedal if I can eliminate some of that it should fix the problem.

 

Well I finally fixed the problem. I found an 87 F150 at the junkyard with an adjustable push rod and bought the whole master cylinder with the push rod for $25. I figured I'd just bolt the master into my truck but it didn't quite work out that way. Turns out the 87 has a different bolt pattern than the 90 and on top of that the 87 hose has a slightly different nose piece where it slides into the master and is secured with a roll pin so my hose wouldn't go into the 87 master. So then I detached the adjustable push rod from the 87 master by unscrewing the end of the push rod and sliding a piece of 3/8 copper tube over the rod and down into the socket in the back of the piston that the push rod seats into. The rod is held in by a spring clip with three fingers that have to be pushed back before the rod will pull out. You have to hold the rod and push the copper tube in to push back the fingers and then the rod will pull out. But to use this method on my push rod I had to cut the copper lengthwise and open it up enough to slip over the rod and then pinch it back together. But for whatever reason I couldn't get the fingers to release the pushrod. I got tired of screwing around with it so I took the retaining clip off the back of the 87 master and pulled out the piston and spring. I did the same to the 90 master and then cleaned everything up and put the 87 piston and spring into the 90 master and then snapped the adjustable rod into the back of the 87 piston that was now in my 90 housing. I reattached my hose to the master, coupled it to the slave and went thru the bleeding operation. I adjusted the push rod so there's just a slight amount of freeplay at the pedal and the thing shifts just great even when it gets hot which is when the problem occurred before. I've had enough clutch work for a while. If anyone does a clutch job on one of these with the internal slave and without an adjustable master pushrod and you have the flywheel resurfaced I highly recommend you mike the wheel before its cut so you can determine how much was cut off and then shim out the slave from the base by the same amount so you don't get into this problem. Shimming the slave would be easy. Determine how much you need and by combining various thicknesses of gasket material you should be able to get close to what you need.

 

I will be replacing the M50D in my '91 probably next fall with an NP435/NP205 using an '85-level bellhousing with an external clutch slave cylinder.

I assumed I could reuse the existing '91 clutch master cylinder, but after having read through all this, I think I'd be wise to replace the master with an adjustable unit.

Did anybody find out if Ford makes a bolt-in adjustable for the '91-model year?
Eddie