Ford 6640 SLE Transmission help

   / Ford 6640 SLE Transmission help #1  

grofarms

New member
Joined
Dec 5, 2009
Messages
23
Location
NW NJ
So im looking for some help on a Ford 6640 SLE 16x16 powershift transmission. The background on the tractor is it was one of those auction buys that was too good to pass up and now i know why. It has an Alamo boom mower on it in great shape and i figured it would be very handy to have around the farm. The only catch was it had transmission issues and i figured how hard could it be to fix.

So here is what it was doing. The tractor would barely move in the low gears and not at all in the high gears. The regulated low pressure light would sometimes flicker or barely glow.

I put a pressure gauge on the regulated low pressure and i'm right on spec at 270-280lbs until i put it in gear and let off the clutch. The pressures drop to 170-180psi after a few seconds like there is a huge leak. It did this in all gears.

We split the tractor a rebuilt the c1 and c2 clutch packs thinking we might have an issue in them. We found a broken plate return spring pack and worn friction plates in one pack because of the broken springs. We didn't touch c3 or c4 because you can't take the transmission out with the boom mower frame still on.
Now the tractor is still doing the same thing still. What throws me off is the fact that it's doing it in all gears, not just one.

I have two ideas of what it could be. Either both c3 and c4 are both blown out which is why its losing pressure in every gear. Or an o'ring or seal is blown out in the transmission control valve and when you let off the clutch all your doing is leaking fluid internally where you can't see.
Does anyone have any suggestions?
 

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