JCB 3C Mk3 Powertrain drive problems

[Valandis91]

Hi all!

First post here and already found heaps of useful information.

I'm on a remote greek island with a JCB 3C Mk3 with a powertrain transmission.

I've come across a problem which i believe is clutch packs but wanted to ask here before I order parts.

The JCB will drive forward fine, although the forward clutches were slipping at times before this happened but now it has no neutral and when engaged in reverse it won't move on the ground and the engine sounds very laboured. Also when I raise the rear wheels in the air the wheels turn very slowly in reverse if throttle is applied at times intermittently. In the neutral postion in the air the wheels go forward.

I have checked and changed all the fluids and they are all fine. I have tried changing high/low ratio and this makes no change.

Also this would happen intermittently before but then if I put it back into forward and then reverse a few times the issue would resolve itself. I then changed the oils and it was working perfectly as this machine had poor maitenance before me. I then left the island for a month and came used it for ten minutes and this happened where its facing against a wall and I am unable to reverse/roll it out.

I guess the only option here is to remove the prop shaft and roll it back?

Any assistance would be greatly appreciated as getting help here is next to none without being ripped off and don't want to order wrong parts as a nightmare to send back...

Thank you in advance!

[Jeremy Rowland]

Hi and welcome somebody on here should be able to point you in the right direction, good luck with it.

Jeremy

[essexpete]

What do you mean by high range? The Power train should have the torque converter, forward reverse shuttle and the 4 speed synchro gearbox. Have you got a big chunky lever or a small lever on the left of the steering column?

[Valandis91]

What do you mean by high range? The Power train should have the torque converter, forward reverse shuttle and the 4 speed synchro gearbox. Have you got a big chunky lever or a small lever on the left of the steering column?

Sorry that's what I meant. I changed the 4 speed gears on the floor.

[essexpete]

Yes that is the proper powertrain with the Borgwarner shuttle. I am no expert and only ever assisted getting the drive train out of the machine and back in. There are some on here that have rebuilt the shuttles. First job ought to be pressure tests but it sounds like you may have had clutch pack overheat and bind up (possibly). The parts are still available and generally the advice is to fit a new transmission pump along with new clutch pack parts and piston seals.
I suppose it would not be a bad idea, when jacked up, to remove prop shaft and just make sure the back wheels can move properly.
When we did ours (I say we, I was helping the proper mechanic), we jacked up on the legs and placed a length of railway sleeper under the cross rail of the back hoe and on to the jack foot. Then let down to take the weight on the timber. Good clearance underneath then. Remove the prop shaft and all ancillary bits and bobs. The engine was supported towards the rear. The guy had a cup for a trolly jack that fitted the small shuttle sump. Take the weight of the transmission on that and then the bell housing bolts and the rear engine/transmission mounts were removed.
The whole transmission was then moved towards the rear of the machine and lowered.
The torque convertor remains on the engine end.
The transmission was separated on the floor between the shuttle and gearbox.
When refitting, the tricky bit was re engaging the shaft into the converter.

[Valandis91]

Thanks for that, more information I know the better.

Wouldn't have any idea best place to look up part numbers as I am finding it difficult to find the correct parts...

Doesn't sound too difficult getting the transmission in and out.
Did you see it by any chance when he opened it up to replace the clutch packs whether it was tricky or not?
My fear is biting off more than I can chew and not being able to put it back together...

It's always easier taking things apart!

[essexpete]

No I did not rebuild the 2 BWs that I have helped to remove (the other was in a Sanderson). I am certain some on here have done the job. The shuttle is known as the T7 soft shuttle, used in many applications, including marine.

[diggerjones]

Isn't there a gauze filter in the sump on the pick up.
Also make sure the lever is actually doing what it should

[Valandis91]

Isn't there a gauze filter in the sump on the pick up.
Also make sure the lever is actually doing what it should

Could you please explain a bit more the first part?

I am back on the island now and I managed to get it out of where it was stuck using the back digger to lift the back wheels and pull me out.

The unusual thing is yes forward works like normal, but I have no neutral but now I am getting intermittently reverse but when I lift my foot of the gas it’s like the brakes are being applied and sounds/feels like there is extra resistance.
Is this still sounding like clutch pack failure or something else? The no neutral is quite frustrating…

Also I used my hand on the lever of the actual box itself underneath and the operation is the same so it’s not the lever in the cab.

Thank you for your help so far and I really hope we can get this going again.

[essexpete]

Can you take the machine of the ground and prop with some heavy timber. Then try shuttling with the lever removed and also make sure the dump spool is returning. Can't emphasise enough about propping securely and keep clear of wheels and prop shaft.
In my limited experience, usually forward fails first and on our machines started with slow engagement of drive followed by slipping. At that point things deteriorate very quickly. I wonder if the forward clutch might have overheated and locked plates together?