JCB 3cx, machine will reverse but not drive forward, is it the clutch?

CMJBUILDER1958 · Post #1 by **CMJBUILDER1958** » Tue Jul 23, 2019 3:15 pm

Hi folks, I have read various threads on this and wonder if it is the forward clutch that has failed?
The machine number is jcb 3cx - 317959/p/s, I think it is 1985, 2 wheel drive fitted with a borge warner shuttle box with manual cable selector.
I have owned her for 10 years doing small jobs on my land, I think I spend more time under it than in it!
Last year I replaced the 2 torque seals as it was loosing a lot of transmission oil.
This year, she will drive backwards, 4 weeks ago it would just move forward up a shallow incline but would not drive into a sand heap.
Parked up, the next time it would not move forward even on the flat, I can still use it by moving her forward with the digger bucket but would like to repair her.
I can move the shuttle box on the box by hand through the full 90 degrees, the oil level is good. With the machine jacked up and engine on tick over, put it into reverse the wheels are strong going backwards, in neutral the wheels are stationary, in forward the wheels are stationary but I can turn the wheels forward ( with force ) by hand but not backwards.
Is this the forward clutch or a shuttle problem?
All advice welcome, CJ.

agrimax · Post #2 by **agrimax** » Tue Jul 23, 2019 3:36 pm

Hi Christopher,it could well be the forward clutch pack is the problem but how are you dipping the torque oil? With the BW torque unit you either dip with the engine running or run for a minute or two and dip immediately after switching off. If you dip cold after the machine has stood for a while,you will get a false reading on the stick as the oil in the cooler runs back into the torque box,with it being mounted at a higher level. Usually if the oil level is low,they will reverse but not drive forward.Problem is if you have continued to try driving it forward for a period,the clutch plates will slip and burn.Here's hoping a top up of oil will get you going again.

CMJBUILDER1958 · Post #3 by **CMJBUILDER1958** » Tue Jul 23, 2019 4:29 pm

Hi, thanks for the quick reply. I dip it running and the oil level is to the top mark. CJ.

agrimax · Post #4 by **agrimax** » Wed Jul 24, 2019 1:09 am

Sounds like you'll have to go into the shuttle box then.........

essexpete · Post #5 by **essexpete** » Wed Jul 24, 2019 8:52 am

We have had both a powertrain and a Sanderson repaired with the Borg Warner trans. A useful tip with the digger was to jack up on the legs and insert a hefty piece of timber between the rear frame and feet.
The prop shaft removed the shuttle and gearbox were removed together. The guy used a trolly jack with a homemade cup that fitted the bottom sump of the shuttle. It seemed to balance quite well at that point.
This particular fitter knew these boxes inside out and carried out the repairs. An alternative could have been an exchange box. Simon Vicary used to carry one on the shelf.
I also seem to recall our shuttles had other components replaced that could fail including a belville washer and the supply pump.

CMJBUILDER1958 · Post #6 by **CMJBUILDER1958** » Wed Jul 24, 2019 1:36 pm

It sounds like the forward clutch pack ? I assume the shims should be ok so need to buy 7 number forward clutch plates ?
Would you replace the 3 number reverse clutch plates as the bulk of the work is getting the shuttle reverser onto the bench.
I have used Vicary for spares as they stock the plates. CJ.

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