JCB 408 fwd/rev

[Old Spot]

Hi all, my 408 fwd rev has decided to stop working.
the switch is good wires appear fine, it’s “stuck” in forward.
i understand most JCB ( of a certain age) are similar. It has a 4 speed gear box.
is there a solenoid somewhere?

 

[ACEngineering]

Hi all, my 408 fwd rev has decided to stop working.
the switch is good wires appear fine, it’s “stuck” in forward.
i understand most JCB ( of a certain age) are similar. It has a 4 speed gear box.
is there a solenoid somewhere?

it its not the switch or the relay stuck then that is going to be a clutch pack issue, probably got them rubbish plastic pistons in it that like to stick or its had or got water in the transmission oil from failed oil cooler.

Pulling the wires off the forward and reverse solenoids will tell you if its a wiring issue or the clutch pack itself.

 

[Old Spot]

it its not the switch or the relay stuck then that is going to be a clutch pack issue, probably got them rubbish plastic pistons in it that like to stick or its had or got water in the transmission oil from failed oil cooler.

Pulling the wires off the forward and reverse solenoids will tell you if its a wiring issue or the clutch pack itself.

Great thanks, idiot question, where are the solenoids? Are they under the cab?

 

[ACEngineering]

Great thanks, idiot question, where are the solenoids? Are they under the cab?

Top top of gearbox

 

[Old Spot]

Ok thanks, so as it would only go forward I needed to get the bucket off.
the hydraulics then wouldn’t work, I bled it by the pump (oil a bit low so topped it up).
then bugger me it goes fwd/rev as it should, fed the cattle shuttling around no problem.
i don’t understand!
She’s done 10k plus hrs so I might treat her to a new pump.
should low oil pressure affect the shuttle.

 

[ACEngineering]

Ok thanks, so as it would only go forward I needed to get the bucket off.
the hydraulics then wouldn’t work, I bled it by the pump (oil a bit low so topped it up).
then bugger me it goes fwd/rev as it should, fed the cattle shuttling around no problem.
i don’t understand!
She’s done 10k plus hrs so I might treat her to a new pump.
should low oil pressure affect the shuttle.

Hyd pump and its oil level has no effect on the transmission, transmission is a seperate oil level and pump.

 

[Old Spot]

That’s what I understood, been fencing all afternoon, no problem.
i agree with you, so I am sure the shuttle problem will come back, probably at the most inappropriate time!

 

[Jontym]

I would check the relays, there will be 2 of them under the righthand side panel below the steering wheel, if the same as the 406. If and when it does it again just swap the relays over and see if it goes in reverse and not forwards, the relays are generic 4 or 5 pin, can’t remember, but only cost a few quid if you want to rule that side of it out.

 

[Old Spot]

Yes, I’m about to check them.
I swapped the relays around when I was trying to get it going.
i am sure that what magically made it start working!
fed bulls in the dark last night no lights, I will find the duff relay.