clutch slipping (1 Viewer)

[gash05]

I am finally finishing up with a 5 year frame off on my 72 FJ40. I swapped to a 4 speed (kept 3 speed xfer) from a 77 with a kit from @marksoffroad. My issue now is the clutch slave cylinder is not returning all way back and the clutch is slipping. I have doubled up the spring to the fork an no success. I can fairly easily make it return all the way if I use a long screw driver and pry it back towards the slave cylinder without much effort. I have bled the (new) slave, adjusted the clutch pedal in the cab and a done a lot of head scratching. Any help would be appreciated. See pics showing the cylinder in the position it wants to return to (even with doubled up spring) and the position I can easily pry it back to. One question I have is should I use a slave cylinder from a 77 or a 72?

 

[peesalot]

There is a whole lot more info. , what bell house ?, what clutch ?, what clutch fork ?,
Remember the slave does not control range of travel, Clutch MC does. It seems by your description you have a 3 spd clutch on a 4 spd, something about the hiegth of the pivot and which fork is used is coming to mind but cant remeber the details

 

[charliemeyer007]

There is an adjustment at the clutch pedal and at the rod on the slave. Seems odd that you can pry on the fork and get results. I have a 4 speed I was going to put in my with the 3sp transfer but with a hand built 283. Following to see what parts you used and what you do to fix this issue. Good luck, they people here are very helpful.

 

[gash05]

Pretty sure it is the 4 speed bell house and fork with the old 3 finger 3 speed clutch. Is there an adjustment for the MC?

 

[pb4ugo]

Yes, you have to adjust the pedal height, pedal free play and then the slave rod. Is the slave piston fully retracted in the cylinder? What happens if you open the slaves bleeder? It sounds like your throw out bearing is not fully releasing. I think i remember reading you either need to run all 3 speed clutch parts or all 4 speed parts, less the bellhousing. You can't mix and match. I thought Land Cruiser clutch forks were cast. Your looks like stamped steel.

 

[gash05]

The slave only fully retracts if I pry it back. I have adjusted the pedal height to about 8" and the cap nut on the end of the slave rod is pulled in as far as I could get it. When I open the bleeder with the rod in the not fully retracted position some fluid comes out but the rod does not retract. You are correct on the stamped clutch fork. I believe it came with the 4 speed (it has been in the garage for about 20 years). However, the last tranny that was in was an SM465. It may have come from that and I just dont remeber.

 

[jembourbe]

Your clutch is slipping because there is no play in the slave cylinder rod. In other words, the clutch is being slightly disengaged by the default slave cylinder position.

To fix it, back off the red nut and move the green nut back on the rod (towards the slave cylinder). I'd start by moving it about 3/4" and then work from there.

 

[45Dougal]

If the slave is holding back the (massive) pressure of the clutch spring such that it is disengaged, then a second (weedy) return spring won't change anything.
FWIW mine lost its return spring many years ago and works just fine.
If it was holding back that pressure then you'd expect fluid to gush out of the bleed nipple as soon as you open it as the clutch closes (which isn't the case apparently, so it can't be the master or the pedal adjustment).
If you pry the lever back, are you sure that the clutch is fully engaged?
Sounds to me like there might be more to this than just a hydraulic mismatch - any assembly photos from when the clutch was put together?

 

[pb4ugo]

What's the pedal freeplay? I wonder if the master isn't fully retracted at rest. When you push on the pedal does the slave rod move instantly? That adjustment is made at the rod going from the master to the pedal. Your clutch fork could also be an issue. Is the t/o bearing installed on a hub? Fyi, The attached pic below is from a fsm copyright 1974.

 

[pb4ugo]

Is there any freeplay between the throwout bearing and the pressure plate? Have you looked up thru the bottom of the b/h?

 

[gash05]

Headed back to the house now. Some great insights and questions from all. When I get back will drop front driveline to get to the inspection cover as well as pull slave cylinder to see if I can get any more play from rod nut. Also, will try to get measurement of freeply on clutch pedal. Thanks to all, and please.feel free to keep em coming. My 40 is way smarter than me so I need all the help I can get.

 

[gash05]

So

Headed back to the house now. Some great insights and questions from all. When I get back will drop front driveline to get to the inspection cover as well as pull slave cylinder to see if I can get any more play from rod nut. Also, will try to get measurement of freeply on clutch pedal. Thanks to all, and please.feel free to keep em coming. My 40 is way smarter than me so I need all the help I can get.

 

[gash05]

I had the misses press the clutch and saw almost instant movement if the slave piston. She would press the pedal about a half inch before I saw movement on the rod. I pulled the rod and maybe got another 1/16" movement in before it was bottomed out. The rod to fork has a couple millimeters of freeplay in the fully relatracted position and none in the half cocked position it is getting stuck in.
Top of the clutch pedal to the floor measurement is about 8.25"

I reinstalled the rod and obseved TO bearing with the inspection cover removed. The TO bearing seems to be hanging up and not allowing the rod to fully retract. When I pry against the fork to get the rod to retract I can hear the springs in the pressure plate relaxing, the TO bearing moves slightly and the fork/rod moves back a little less than an inch. I even tried a small contolled couple drops of lubricant behind the TO bearing and working it back and forth. Still no luck getting it to push the bearing back on its own.
At this point I am wondering if pressure plate fingers are too weak to push the bearing back. Fun times. I really am hoping to not drop the tranny.

 

[gash05]

I had the misses press the clutch and saw almost instant movement if the slave piston. She would press the pedal about a half inch before I saw movement on the rod. I pulled the rod and maybe got another 1/16" movement in before it was bottomed out. The rod to fork has a couple millimeters of freeplay in the fully relatracted position and none in the half cocked position it is getting stuck in.
Top of the clutch pedal to the floor measurement is about 8.25"

I reinstalled the rod and obseved TO bearing with the inspection cover removed. The TO bearing seems to be hanging up and not allowing the rod to fully retract. When I pry against the fork to get the rod to retract I can hear the springs in the pressure plate relaxing, the TO bearing moves slightly and the fork/rod moves back a little less than an inch. I even tried a small contolled couple drops of lubricant behind the TO bearing and working it back and forth. Still no luck getting it to push the bearing back on its own.
At this point I am wondering if pressure plate fingers are too weak to push the bearing back. Fun times. I really am hoping to not drop the tranny.

Forgot to add that pedal freeplay is about half inch. TO bearing freeplay when fully retracted is a few mm. No freplay when it hangs up.

 

[gash05]

No assembly photos of clutch but here is tranny and BH before installation.

 

[charliemeyer007]

Try just dumping the clutch (slide your off the pedal) several times with the engine off and see if helps any (percussion therapy).
Yea stuff can break or go bad at any time, maybe the TO bearing or something in the pressure plate.

When you figure it out, please come back and post your solution.

 

[pb4ugo]

The t/o bearing isn't suppose to be riding on the pp when disengaged. The return springs should keep the t/o away from the pp once the clutch is released. Pedal freeplay should be a 1/4 or less according to the fsm. My intial thought is you are using a mix of clutch parts that don't play well together. Maybe you can adjust to make it work. Idk. Like I mentioned b4,
Im pretty sure if you use the 3 speed flywheel, clutch, pp, you need run it's fork, hub, bearing and ball stud. Or use all the 4 speed parts.

 

[V8FJ4078]

Yes, you have to adjust the pedal height, pedal free play and then the slave rod. Is the slave piston fully retracted in the cylinder? What happens if you open the slaves bleeder? It sounds like your throw out bearing is not fully releasing. I think i remember reading you either need to run all 3 speed clutch parts or all 4 speed parts, less the bellhousing. You can't mix and match. I thought Land Cruiser clutch forks were cast. Your looks like stamped steel.

I think if you used the clutch fork from the SM465, it looks like a GM one not Toyota which you release differently on the pivot point.

 

[pb4ugo]

I think if you used the clutch fork from the SM465, it looks like a GM one not Toyota which you release differently on the pivot point.

I also think the gm t/o bearing attaches to the gm fork differently than the toyota parts. The hub and bearing are 1 piece and slides into the fork. GM uses either a tall or short bearing too, depending on the application. I think the op needs to run the proper stk parts.

 

[peesalot]

I dont think you can use the GM fork on the Toyota pivot & which throw out, also you mentioned the throw out not moving on trans bearing retainer, I have seen a rib of grease cause that, get under there with clutch depressed( 2x4 against seat) and clean the snout that throw out rides on or see if you can spot a groove worn into it that has created a shoulder that throw out cant slide past, that could be your problem along with a gm fork & throw out on a toyota trans & bellhouse.