350 T/A clutch update

First picture - T/A pressure plate cover tight against friction plate. Second picture - T/A clutch with 1/8" shims.

Back story: Bought a 350 with a bad T/A. Installed an new T/A and clutches. Shift lever jammed in gear and the T/A did not work. Bad words were said.

When the new pressure plate was bolted to the flywheel it was completely compressed, there was no room for it to lift. By taking up all the adjustment on the T/A operating linkage I could get it to lift about 0.002", if I forced it. Installing some 1/8" shims between the pressure plate cover and the flywheel gave room for about 0.06" of lift.

Went out and worked the tractor with a field cultivator. Shift lever was much better, didn't jam, but was not perfect, and the T/A obviously worked. So far, so good. Looking at the T/A clutch afterwards, it would lift about 0.04" with the lever, but the clutch pedal still does not move it at all (<0.0015").

Questions:
1) What is the thickness of a new T/A clutch disk ?
2) What is the minimum clearance between the throwout bearings and the pressure plate fingers ?
3)What are your theories on the source of the problem ?

Thanks

Greg

Good question , i have never run into this where ya had to shim the PPA . As for disc thickness i can not honestly tell ya . As for adjusting the linkage for the clutch due to age and ware other then tryen to get the free travel on the main clutch set as close to spec. as i can i gave up on the book sets a long time ago and go by feel more then anything else . The only thing that may be messed up is that either the PPA is not wright from the get go or the that for some unknowen reason the ears on the T/A flywheel are not correct in hight .

If you remove the external linkag from the lever (on the TA clutch throwout bearing visible in the photos), can you put a wrench on it and move the TA Pressure Plate a usable amount? I assume so because the TA lever works. The clutch pedal should move that lever into release about 1.5 inches after the master (engine) clutch releases. It should begin releasing (contacts the TA clutch fingers at the same point the master clutch is dosengaged. It could be that the TA housing ears (now with shims) was machined by someone to compensate for a thin Disc. Not good, but your shims are in the right direction.

The situation may require additional threading on the clutch linkage to the TA lever. Jim

My reply was ment to be pasted on his comments, We are on the same track. Jim

I didn't know what else to do, so I took a few measurements today. Looking at the results, I am suspicious that the T/A clutch is slipping and getting hot. I didn't measure the temperature, but the T/A pressure plate didn't have as much clearance after using the tractor.

After sitting for a day:
PP lift with T/A lever - 0.065"
PP lift with main clutch pedal - 0.02"
T/A lever moves the top of the T/A throwout bearing crossshaft arm - 7/16"
Clutch pedal moves top of crossshaft arm - 1/4"
T/A Clutch disk thickness - 0.323"
Distance between pressure plate cover and PP friction surface boss - 0.01"
Clutch pedal travel when pressing on throwout bearings 1 1/4" - 4 1/4" (measured at the deck)
Clutch pedal linkage movement - 3/4"

Last night when the tractor had been warmed up:
T/A PP lift with the T/A lever - 0.04"
PP lift with clutch pedal - <0.0015"

Tonight I made a mark on the presure plate and the clutch disk so I can see if they are slipping in direct drive. If they are slipping I think the shims need to be thinner.

If anyone has a 300 or a 350 (I think the SHTAs are the same too...) with a working T/A it would be helpful to know if your measurements are in the same range.

Greg

The clutch link to the TA release lever needs to move the TA pressure plate the same amount, or a little more than the lever. From your description, it is not even close. this is a linkage sdjustment, not a TA clutch adjustment. Jim

It would help if the clutch pedal moved the crossshaft as much as the T/A lever.

The crossshaft arm starts to move as soon as the pedal is moved. The only way I can see to increase the travel would be change the ratio between the linkage pivots on the engine clutch crossshaft or increase the throw of the engine clutch linkage.

Greg

Adding shims will greatly reduce the clamping pressure of the pressure plate assembly. Unless someone resurfaced the flywheel and got the dimensions wrong you should not need any shims.

The raised bosses you mentioned should pass through holes in the pressure plate cover when the levers are moved to release the disk. The levers should be roughly parallel with the friction surface when the levers are released.

Are you sure the bosses on the cast plate are hitting on the cover? If they are the problem is either the holes in the cover are too small or the bosses are too large.

As mentions earlier if the disk is installed backwards the levers will hit on the disk hub resulting in the levers pressing the disk against the flywheel rather than allowing the disk to turn freely.

Clutch disk thickness 0.320
Clutch basket friction surface to pressure plate mounting surface 0.900

Cub149, Thanks for the measurements. I'll check the flywheel depth in the morning.

Jim's comment about the clutch pedal having to move the T/A crossshaft as much as the lever got me thinking and the cartoon light bulb over my head started to glow.

The tractor came with the modified T/A crossshaft shown on the right in the picture above. I replaced it because it looked like a broken part that had been improperly repaired.

Calculating the tangent of the angle that the modified shaft would turn using the motion of the clutch pedal gave the same amount of rotation as using the T/A lever. The shorter arm equals more rotation and more lift at the pressure plate.

I have not reinstalled the modified crossshaft yet because there seems to be an underlying problem that is not found on other 300s, or 350s (or SHTAs) that should be fixed...

To check if the T/A clutch was slipping due to the shimming, I hooked up a field cultivator and ripped up a patch of quackgrass while pulling up hill. The load was enough to stall out the tractor. Rather than use the T/A I pushed in the clutch, let the rpm recover and let the clutch out again. After about half an hour of this the T/A clutch temperature was 86 degrees F.

I think that the T/A clutch clamping pressure is adequate for the amount of power this tractor is making.

So why the short arm ?

Greg

Yes, that short arm looks likes they were trying to compensate for some other issue.

I agree, the bosses should pass through the holes in the pressure plate cover, but if you look closely at the top picture, they are tapered and there is no space between the cover and the boss. Not to mention that the springs in the PP assembly are nearly coil bound.

I set the levers to the spec I was given by the service manager at our local IH dealership. I'll look at them to see that they are nearly level in the morning. That is a good rule of thumb to know.

Greg

I can tell from the top lever in the picture the linkage is out of adjustment.
Would you like for me to send you the adjustment procedure out of my 300 manual? send me an email. [email protected]