4640 clutch

[Anonymous-0]

Have a 4640 quad that grinds significantly going into any gear, it also lurches forward as clutch pedal is released. Clutch has been rebuilt and set with jd tool, had same symptoms with old clutch. Clutch valve has been checked, all springs, and valves check out fine. Any suggestions?

 

[md4020]

Were the flywheel and pressure resurfaced? If either had burnspots or hardspots, or a worn taper to them, it could cause jerking or grabbing problems.

 

[rexhellwig]

There is no friction surface on a 4640 QR flywheel to reface. Burn spots/discoloration will not hurt clutch operation as long as the surface is still smooth and flat.

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tomroy,
The clutch has to be adjusted very carefully with the best inch pound torque wrench you can afford. Let"s say you have done that.

The most likely problem is oil leakage in the clutch piston oil circuit. The clutch valve modulates a pretty small amount of engagement oil. It can't compensate for a leaky piston seal. The most common cause is a very rough piston bore that wears out the seal. The surfaces where the seals runs should be mirror smooth.

You could also have some leakage elsewhere in the clutch housing.

Also, if the clutch hub splines are worn out, the clutch won't work right. How's the pilot bushing?

 

[tim s]

Like Rex stated it "must" be carfully adjusted from the start, with the correct tool spacer shim in place, I use a dial type inch pound wrench, the click type do not work out well,I also back the adjusting levers off and bring them back up a couple of times to make sure they are set evenly, the pilot bearing and input shaft end can also cause a jumpy clutch, it seems like 4630's and 4640's are a bit jumpy any way. Another thing that can cause a jumpy Perma clutch is the operating valve,leakage in this area or a sticky inner piston can make them jumpy. Since you still have the same problem with the new clutch your going to need to look even closer at all of these componants,,some times the smallest little thing can cause a lot of trouble...