Clutch Questions

When I started rebuilding my Ford 640 I wanted to replace the clutch, pressure plate, pilot & throw out bearings. The reason was the clutch would jerk when it was feathered or slipped like doing precise work that require a gentle touch (pulling another stuck tractor out, dirt scoop or precise work). What caused this? The clutch plate or the pressure plate becoming warped due to heat?


Question 2:
After getting far enough along to install the new clutch and components and bolt the tractor back together I can only get 1& 1/2 inch of clutch pedal and a lot of free play. The new clutch kit came from YT and does not have the adjustable fingers or counter weights like the one I took out . Did the different style pressure plate cause this? Anything else I need to look for?

more then likely the friction material on the disc was gone leaving metal on metal , rivets digging into the pressure plate and flywheel

"more then likely the friction material on the disc was gone leaving metal on metal , rivets digging into the pressure plate and flywheel"

WOW! Lots of things can go wrong with a clutch, but I have a hard time believing that "more then likely the friction material on the disc was gone leaving metal on metal"!

This is a 28 HP tractor, seems like it would be tough to tear up the clutch that bad, but then again, there are guys that could ruin an anvil with a rubber mallet!

any clutch plate that has oil on it will be jerky.

why do you find it hard to believe bob I worked in a clutch and brake machine shop I have seen lots of damaged discs, plates and flywheels caused by the nut behind the wheel not smart enough to lift his foot off the pedal WOW

On question 2: You're saying the pedal goes all the way down to the last 1 1/2" before the release bearing contacts the pressure plate release fingers?

And you have used all the adjustment?

If so, something is wrong.

Typically, if the disc has an offset, the thicker spring side of the hub goes away from the flywheel.

Otherwise could be the wrong release bearing or pressure plate.

maybe give us some info on that used disc you took out. picture is worth more than presuming.

The clutch plate looks good. Almost as much material as the new one. It is actually hard to tell the difference in material thickness by eye. The pressure plate looks good also. It has no blue or burnt spots. The fingers do show some wear but nothing bad. The throw out bearing shows some wear where the fingers make contact with it but nothing out of the normal on either. By wear I mean shiny spots on these items. Not gouges or deep marks.


I was thinking maybe oil getting on the clutch, but it and the pressure plate were dry. I was thinking if it was oil it would do it on start up after oil had time to leak after sitting overnight, but that was not the case.

I was thinking the pressure plate was warping due to letting the clutch be feathered some. I don’t know if that is a thing or not but it seems like the logical explanation.


As far as the adjustment of the new clutch and pressure plate goes I ran out of adjustment and only got the 1 &1/2 inch pedal. I will have to split the tractor again and inspect. Everything looked like the original except for the pressure plate fingers. I did not measure them against the old pressure plate (should have) but I would have not known if it would work or not till I installed it.

Now as my old daddy would have said “I am hard on stuff” compared to an old timer putting around. When I use it, I use it. I do try to keep equipment well maintained and I don’t run it into the ground as I know it cost more to fix it then.

"there are guys that could ruin an anvil with a rubber mallet! "

Well you might be right Bob but it's none of your business how MY son use's MY tools.

Back in high school, I rebuilt the engine
in my Grandpa's Jubilee Ford, very
similar to your 640. The clutch wasn't
that old, so I didn't do anything to it.
After bolting it back together, the
clutch acted like you describe. I could
force it into gear, but then it would
move, even with the clutch pedal mashed
to the floorboard. Split it again, and
found that what I thought were washers,
and had put under the bolt heads holding
the pressure plate to the flywheel were
actually spacers, meant to go between the
pressure plate and flywheel.

My Case oil clutches do not jerk.

Once you get it apart, before taking the pp bolts out, get a measurement on the height of the release fingers. You can stick a screwdriver down through the pilot bearing, mark where the release fingers are.

Then remove the new clutch, put the old disc and pp back in, take the measurement again. Since you said the new disc was near the same thickness as the old, the measurement should be real close to the same, within 1/8" just as a guess.

Also compare the length of the release bearings, be sure the release fork is engaging the bearing as it should be.

Again, look at the disc, be sure the springs are oriented away from the flywheel.

Found the problem:

1. New pressure plate fingers are not as high as the old one, making the adjustment way off. Will have to return to YT.

2. Jerking by old pressure plate was caused by the adjustable fingers not being adjusted equally. One of the fingers was adjusted to be a lot higher than the others.

Got the new pressure plate with the adjustable fingers. It was exactly what the tractor needed. I have plenty of pedal now with some extra adjustment in the linkage. A millimeter here and there make a great dig difference.

Thanks for the help.