Thank you I will keep that in mind.
I also have a parts manual and shop manual for this
machine.

dk

Congradulations! Nice to see that you were able to isolate & repair the issue.

As far the the ATF fluid- I do know that Ford type F is more sticky than Dexron- in my younger days when I played with cars- whenever you put a shift kit in a GM model- the instructions always said to replace the Dextron with Type F for improved shift performance.

Also- I have a parts book for your truck so if you ever need part numbers feel free to contact me

Problem FIXED

Well, 10 hours yesterday (Saturday) and I am HAPPY to write the EPILOG to this dilemma.

I measured the travel of the throw out bearing, and took off the trans cover, and made a wood block spacer equal to the travel when the clutch pedal is depressed. I was able to now inspect the clearance between the disc and the pressure plate.
There was none.....
The "warp" in the disc was causing the drag. I had to use channel lock pliers to turn the input shaft with the clutch in the 'release' position. It did not turn really hard, but there was noticeable effort required to turn it. Certainly enough drag to prevent getting it in gear...

Took it all back apart, and put the disc on the input shaft between to shaft collars to capture it on the shaft.
I managed to straighten the disc. Actually, I got it very straight
and running true. I did not think I would be able to get it back that straight, but it worked out really pretty good. There were a couple spots that were 'kinked' but I put it back in the truck with the pressure plate, and the wood spacer to check again.

Those 2 spots did drag......BUT now I could turn the input shaft by hand with just some slight drag! I could also feel the 'stickiness' or 'grip' of the fluid when I was turning the input shaft. I marked those spots on the disc and took it back apart again.....for a second go-round.
Got those spots bent back as well, now the disc is really looking straight! Back together again, and very little drag with the ability to wiggle the disc between the PP and flywheel.

I also put the pressure plate in the hydraulic press on a flat plate, and checked the travel and the flatness of the plates adjustment. It was flat within about 5 thousandths all around, which is not surprising considering the PP looks 'like new'.

Well, I re-assembled it all again, and started it up....WAY way better! I am able to shift from neutral to any gear with just a bit of gear 'grind'....not any big deal, and from one gear to another it is silent. I think the slight bit of grind is typical of these transmissions, and it's just a gentle pull on the shifter and it 'bumps' into gear.
WOW......finally!

Apparently, the bit of 'warp' that -was- in this disc was causing the problem from the start, and the 'extra' warp I put in, made it worse.
The disc was not sticking to the flywheel and this was not a case of oil 'suction'. It was the drag from the 'warp'.

I don't know if I will change the oil from Dexron II to type F or not. Maybe down the road a bit....
I'd like to learn more about the difference between Dexron and Type F.

THANKS for all the reply's, ideas, and suggestions on this problem!

dan k

sounds like you 2 got this under control

good luck

Yes, basically that is it......no set screw tho......there are 3/8" thru bolts that go thru the shafts and the fork casting.

Your idea is excellent, and I will do this!
Then I can know the actual gap dimension.

thanks
dk

The fork for the throw out bearing is in the top cover, pivots on 2 half shafts, one of which is hooked thru linkage to the clutch pedal- is this correct? If so,is the fork positioned correctly? There should be a set screw that's screwed into the fork that indexes the fork to the shaft, does this sound correct & is it indexed correctly?

If these check out ok, I'd measure how far the fork moves forward when hooked to the clutch pedal, then make up a test rig & move the throw out bearing the same distance with the top half of the cover removed & check the clearances that way

I appreciate your friends years of knowledge and his comments....

It is for sure a dilemma....the disc fits nicely on the input shaft.
I can move the shaft back and forth in the splines and in the trans input bearing seat (half the bore is in the trans and half the bore is in the top cover). The shaft slides freely back and forth.....I can't imagine it is binding on anything.

The pressure plate is an unknown.

The clutch fork and release arm are located in the top trans cover.
With the cover on, I think it is not possible to reach up far enough to the clutch to insert a feeler gauge in the gap.
(But I will TRY!)

I know I can't see up there for a visual inspection. And with the cover off....well.... no way to operate the pressure plate....

I spoke with a friend of mine today who has 50+ years in the equipment repair business (not confined to just forklifts). He has seen wet clutches on all types of equipment with flat & wavy clutch discs. He's also had multiple oils used in these applications.

His 2 cents is that he has never personally seen an oil misapplication cause a sticking issue- it's always been a slippage issue. He has found that a wrong application of oil will cause a clutch to slip- not stick. Also- some discs are wavy, some are flat & he agrees that the wave is there to help with separation (I stand corrected).

His suggestion was to disassemble the clutch assy, make sure that the disc isn't binding on the input shaft & to make sure that the pressure plate was working correctly & not binding.

If the clutch assy passes these 2 tests, then assemble the clutch back together & measure the clearance of the disc to the pressure plate & flywheel while the clutch pedal is depressed.

I know you said that you can't see inside the bellhousing when the unit is completely assembled, you may have to take these measurements while it is partially disassembled.

Hope this helps

Some of your points may be valid......
The machine was doing this when I got it.

However I have written the possible reasons (as explained to me) as to why the disc is 'warped'.
It was explained to me why it is warped on purpose not because of some fault in use.

I put in Dextron II when I changed it because there is no such thing as type F anymore I don't believe?
What are the differences between Type F and Dex II ??

I do plan on checking the PP setup....
I am not sure new parts are the answer, and I am on a limited budget as well.

I appreciate all comments and input!
I don't know the answers to the problem, that is why I am asking for information from you professionals on this forum.

it has ATF in it for a reason, like bbforks said, it is thinner than normal hydraulic oil and it has gripping qualities. Now before you go throwing in just any ATF it might help to find out the recommended type of ATF it has. Reason i say this is because alot of those older lifts used mercon fluid which is a ford type F fluid i believe, and it is non-synthetic also. You dont want any kind of synthetic based fluid because it will indeed make it slip then. The same thing applies to regular hydraulic oil like AW32 etc, i wouldnt change the type of oil at all if i were you. If you do it will cause bad slipping and then once that gets in the disc its done... you will wind up replacing it.

As for straightening the existing clutch disc? i suppose you can try that but ask yourself why it was warped in the first place? those fingers on the pressure plate should all be even. If any of those fingers are uneven then you have a spring pressure problem and it is probably applying uneven pressure on the disc. This could be why the disc is warped?

with all the time your spending dissassembling and reassembling this you could just try and get a new clutch and pressure plate and rule out those possibilities all-together?

just a couple more things to ponder while scratching your head ;o)

It shouldn't slip with hyd oil, the pressure plate should be calibrated for the oil. If it does slip, get the disc resurfaced for a dry application & remove the oil if possible.

Maybe it will slip too much with Hyd oil??
I may have to add some ATF!

Standard hydraulic oil should work if that's the problem (wrong oil). The challenge is not the viscosity ( ATF is much thinner than any HYD or engine oil you're going to find), but what the oil is designed to do. ATF is designed to clean, remove heat/moisture & grip ( Dextron,vs Ford, etc), whereas hyd & engine oil are designed to not only remove heat & such, but lubricate as well- there are no additives to promote engagement of any kind.

My plan is to

1. Take it back apart, put the disc on the input shaft in a lathe and bend it back as straight and flat as possible.

2. Check the setup of the pressure plate, make sure the fingers are adjusted equally, etc.

3. If it still drags upon re-assembly, I will take out the ATF and put in the thinnest Hyd. oil I can find.

I'm thinking that since you were originally going to redo the disc anyway, I'd try draining the system of ATF & install hyd oil & check operation then. The type of oil depends on the friction material of the disc & since we don't know that, trial & error will have to guide us.