I got a 86 f-150 4x4 with a 300 inline 6 and a 4 speed that I need to do a clutch job on when I start it up in gear it wants to go forward with the clutch fully pressed and i can't change gears while its running. How hard of a job is it going to be or is there an adjustment I can do or is it to far gone

 

Sine it is a hydraulic actuation system with an external slave cylinder, I have a hunch it's more likely a failure of your master>slave function. This is good news cuz it's more easily fixable if so. Have someone push the clutch in while you watch the slave cylinder move the clutch fork. You can do this from uneath the hood or the rig itself. If ur not gettin much movement your slave or master is suspect.

You need to get up to speed wiht how your clutch works, and since ur here asking about build your confidence to address the issues. It may just have leaked down the fluid in the master or or the slave mey be suspect itself...either way service is most likely in order.

It is A remote possibility that your shift "fork" is bent/or broken ( it happened to me in a 77' van)...it is fixable even so w/o removal of the trans assembly. In the 90's Ford trannies had to come out to replace the slave assembly. You're blessed owning an "86" in this case.

When your clutch "fails" generally it does so by "slipping" because of excessively hard use causing the engine ot over-rev under load.

A hydraulic failure is much easier to fix on your rig IMHO..

Another note..I drive an "83" version this "bullnose" Ford so as to be able to adjust my clutch via a 9/16" end wrench. ("83" was the last year for this type of mechanical clutch actuation...My particular preference..)

 

You could have problems with your clutch, but you could also have issues with your firewall cracks and flexing so that your clutch doesn't disengage completely. I found cracks behind the seam sealer on the reinforcement plate, but I discovered it went much farther than that. Pictures are posted in the thread https://www.ford-trucks.com/forums/1...-cylinder.html. Having someone pressing the clutch while you watch the firewall around the clutch master cylinder will allow you to see if there is ANY movement which would predispose it to cracking. If there are no cracks and no flexing, then a worn clutch is likely. Replacement is pretty straightforward. Just follow the steps in the Haynes manual. Good luck.

 

I agree with john smith. Sounds hydraulic.

 

Well, I'm not disagreeing with anybody, but firewall flexing and cracks can result in the clutch not pushing in on the clutch master cylinder (as the master cylinder moves forward under pressure) resulting in less clutch travel and symptoms similar to a failure in the clutch hydraulics. Just something else he should check in diagnosing the problems.

I went through the same process when I had similar symptoms. Checked the clutch MC and slave, both seemed okay. Replaced the clutch which helped a lot for about six months, then the problem returned. Decided to rebuild the truck and discovered firewall cracks that allowed firewall flexing so the MC moved away when i pressed the clutch precluding complete disengagement.

Easy enough to check, and these old trucks with hydraulic clutches are notorious for this problem. Hopefully, it is the clutch or hydraulics. The firewall is a pain to repair.

 

Very good points..perhaps "firewall flexing" should be at the top of the list for MASTER CYLINDER failure...easily detected while watching as the clutch is depressed.

 

If it does come down to having to replace the clutch assembly, you might want to look into upgrading to a 11" clutch. The original one is 10". The 11" units were used in the larger trucks which were equipped with the 4.9L engine. The flywheel is already drilled for mounting the larger assembly, but you will have to replace the flywheel bolts as they are a different size. The cost differential is only about $25-35 for the larger clutch assembly.

 

Hey thanks for the info I got someone to push the clutch in as I watched the firewall and it is cracked which kinda sucks

 

I was afraid that might be the problem. Terrapin Manufacturing is the only place I know of who makes the reinforcing plate and they are currently down for a move. Hopefully they will be back open soon.

There is a sticky at https://www.ford-trucks.com/forums/1...tallation.html that provides detail on the installation of the reinforcement place. Best of luck to you on getting if fixed quickly and easily.

 

I was agreeing with the hydraulic instead of worn clutch. Not crack. If the clutch was worn it should be slipping. Less friction. Well worn disc anyway.

No offense.

 

No offense taken.
Every case is different, and for these trucks, there are 3 primary failure points. In my situation, it was the clutch pedal not able to push into the master cylinder completely because of the firewall flex. It didn't allow the clutch to fully disengage, resulting in slipping, etc, which simulated (and caused) excessive clutch wear. Hoping to get back to work repairing El Guapo's firewall this weekend.