Clutch Grabbing and Bucking in Reverse

[goldencub]

It's a '47 Cub, and grabs and bucks as I let out the pedal to engage the clutch. Only happens when backing up an incline with a load (trailer). On level ground it's OK. All three forward gears are smooth as silk on all types of terrain. What do I start looking for?? Thanks, Al D

[Nelson 634]

Based on your description, I would start by looking at the reverse gear in the transmission. Pull the plate below the shifter and look at the reverse gear. Remove the plate gingerly so as to save the gasket and not have to replace it this time. Reverse gear I think is on the right and to the rear of the transmission box. I sure others will be on here soon and have more or better ideas as well as correct any miss statements I have made. Look that all the gear teeth look the same. Look for broken parts. Good luck. Stay safe. Walter

[Slim140]

One of our 140's was doing this. I never did find the exact cause of it but replacing the clutch, pressure plate, and throw out bearing cured it. If I had to guess I'd say your pressure plate is weak in places or just grabbing.

[Don McCombs]

How much weight is on the trailer when you are trying to back it up an incline, in reverse?

[goldencub]

I don't know the weight, Don, but it had a pretty heavy load of firewood. The trailer bed is 4x6, with 2' sides, and was filled full of carefully stacked split maple firewood. Al D

[Matt Kirsch]

It could very well be your technique for bracing yourself while letting out the clutch. What happens is, the tractor starts moving backward, your inertia causes you to move forward in relation to the tractor, causing your foot to push the clutch in slightly. The clutch releases, the tractor stops, and you move backward with relation to the tractor, lifting your foot back off the clutch pedal slightly. This causes the clutch to engage, sending the tractor backwards, and you forward in relation to the tractor again. This cycle repeats and often increases in intensity until you finally shove the clutch to stop it.

I've experienced it many times with many tractors myself. The solution is to reset and try again. Nothing at all wrong with the clutch or the tractor.

[Don McCombs]

I don't know the weight, Don, but it had a pretty heavy load of firewood. The trailer bed is 4x6, with 2' sides, and was filled full of carefully stacked split maple firewood. Al D

Given the lack of issues in other gears and modes, this may be the root of your problem. I know that trying to back a trailer that is probably heavier than the tractor, up a hill from a standing start, would give me a little pucker factor that could cause me to pop the clutch too quickly. Try backing the tractor on the same incline without the trailer and see what happens.

[lowgearfarm]

My guess is that the clutch chattering is caused by an unhealthy contact between the clutch disk and the pressure plate or between the disk and the flywheel. Perhaps there is unequal pressure on the PP fingers, oil on the disk, or a disk worn out down to rivets. You might be able to see the issue through the inspection hole, but aside from adjusting the PP fingers, you'd probably have to split the cub to fix the problem. You might also consider just living with the chatter - it's not right, but it probably only hurts the clutch.

[goldencub]

Don - I'll give that a try in a day or two - right now it's raining hard and the wind is gusting to 55 knots (or mph or something) WIth this wind, I"ll probably have some more wood to haul in! Al D