Mysterious Bolt...

[Froglet]

Afternoon all

Just fitted a new silencer box to my JCB 3C MkIII. Went to shift the machine forward and found I had no forward or reverse gears. Check everything in the cab - nothing wrong there. Got underneath the machine and found this lying on the floor... it's 2.25" long by 0.75" diameter (57mm x 18mm). It was sitting directly beneath the gearbox.

Could this be the cause of my lack of gears???

If not, any ideas what I should be checking to solve the problem. I'm supposed to be scraping the surface of the agrden to create a driveway (80m long x 4m wide)....

HELP

[Jeremy Rowland]

Does the gearbox still select the gears or does it feel like the gear lever has suddenly gone very sloppy?
If the gears select okay but there is no drive then its probably the clutch, if not the problem will be with the gear selector linkage, now I am not in anyway familiar with JCB gear linkages, but check that the gear lever itself is connected to the gearbox and follow any other linkages back to the box itself.
If the gear linkage is okay and the clutch is also okay your problem will be the final drive and a broken drive shaft here would be a fair bet.
This is just a general guide for you as I am no expert on JCB.

Jeremy

[martyn williams]

Sounds like a selector fork bolt snapped or fallen out.Last time I had a fault like this it was caused by the high and low gear not in mesh.This was caused by a worn ( high/low) gear stick not throwing the gear far enough to select a range.That would explain no gears.
Worth a look.Any pressure/ resistance on the clutch ?
Martyn

[Froglet]

Does the gearbox still select the gears or does it feel like the gear lever has suddenly gone very sloppy?
If the gears select okay but there is no drive then its probably the clutch, if not the problem will be with the gear selector linkage, now I am not in anyway familiar with JCB gear linkages, but check that the gear lever itself is connected to the gearbox and follow any other linkages back to the box itself.
If the gear linkage is okay and the clutch is also okay your problem will be the final drive and a broken drive shaft here would be a fair bet.
This is just a general guide for you as I am no expert on JCB.

Jeremy

I used to get a 1-second long whirring noise and then a gentle 'clunk' when selecting a gear - that noise is now more like permanent with no 'clunk' so no gear selection. The gear stick still feels as it did before. It's a torque converter drive so no manual clutch, just the Forward/Reverse selector on the dash.

I've just spent 10 mins trying again and had some resistance with the gear selection, mainly in 2nd and 4th (no resistance in 1st or 3rd) - I could feel the vibration of cogs spinning through the gear lever and the machine did move forwards and backwards for a couple of feet. As soon as I put it in neutral and tried again, I got nothing.

Bizarre!!

[Jeremy Rowland]

From what you are telling me I would guess now that its almost certainly a selector fault, again not being familiar with JCB I'm sorry to say I can only offer you a guide in the right direction.
I do not know how easy or difficult it is to access the top of the gearbox but you really need to have a look at the selector linkages as it sounds like thats where the problem lies and if the linkages to the top of the gearbox are okay then the problem lies within.
Being as you have told me that it does drive I now know that its not a torque converter problem or a final drive problem.
Check all of your external linkages to the gearbox first, then take the top off the box and look inside.

Jeremy

[Froglet]

Thanks Jeremy.

Looks like I'm going to have to whip the top of the gearbox off and have a delve inside later in the week.

I'll let you know how I get on.

Thanks again.

Eamonn

[Froglet]

The plot thickens.....

Didn't get round to lifting the lid on the gearbox. I did put 6 litres of gear oil in though and finally got above the MINIMUM marker on the gearbox dipstick

Instead, I've spent a few hours today fitting a new oil filter and a new hydraulic filter.
The hydraulic fluid was in a very poor state when I drained the filter housing - looked more like yellow/brown than clear red. I spent a good deal of time cleaning all the horrible sludge from the housing before installing the new filter and tightening everything up. I also topped up with nearly 50 LITRES of the red stuff.

I started the engine, engaged forward gear and Lo And Behold, the old girl trundled off down the garden . Unfortunately, a couple of minutes later I noticed that the Torque Converter Pressure Gauge was jumping around like a mad thing - anything from 1.5 Bar to 4 Bar (should be 8-8.5 Bar). I parked the machine up with the engine running and checked underneath for any obvious leaks but coan't see ANY leaks - now I'm really confused . The T/C will engage as long as the pressure gauge reads 2.0 Bar or more - anything less than that and the old girl won't budge an inch.

I've checked the T/C dipstick and it's registering nothing - not even a hint of oil. I note from the manual that it needs Mobil Delvac 1310 oil - is there a more readily available alternative to this...

Any suggestions as to what may be causing the lack of pressure

[Jeremy Rowland]

Well firstly let me say that you can get an equivalent oil to the Mobil oil from any decent oil supplier, just give em the Mobil number and they will quote you their alternative.
Now as for your transmission fault the lack of oil in the gearbox may of contributed to part of the problem, you may indeed still have a selector problem?
I cannot tell you about the T/C as I have never taken one apart, the only thing I can tell you is that the T/C is a fluid coupling and as such requires oil to make it drive, sorry but my knowledge runs out at this point.

Jeremy

[Gold Digger]

The plot thickens.....

Didn't get round to lifting the lid on the gearbox. I did put 6 litres of gear oil in though and finally got above the MINIMUM marker on the gearbox dipstick

Instead, I've spent a few hours today fitting a new oil filter and a new hydraulic filter.
The hydraulic fluid was in a very poor state when I drained the filter housing - looked more like yellow/brown than clear red. I spent a good deal of time cleaning all the horrible sludge from the housing before installing the new filter and tightening everything up. I also topped up with nearly 50 LITRES of the red stuff.

I started the engine, engaged forward gear and Lo And Behold, the old girl trundled off down the garden . Unfortunately, a couple of minutes later I noticed that the Torque Converter Pressure Gauge was jumping around like a mad thing - anything from 1.5 Bar to 4 Bar (should be 8-8.5 Bar). I parked the machine up with the engine running and checked underneath for any obvious leaks but coan't see ANY leaks - now I'm really confused . The T/C will engage as long as the pressure gauge reads 2.0 Bar or more - anything less than that and the old girl won't budge an inch.

I've checked the T/C dipstick and it's registering nothing - not even a hint of oil. I note from the manual that it needs Mobil Delvac 1310 oil - is there a more readily available alternative to this...

Any suggestions as to what may be causing the lack of pressure

Bong joor what hapens when you jack up the machine with the wheels off the ground and try and select the gears . .

[Froglet]

Bong joor what hapens when you jack up the machine with the wheels off the ground and try and select the gears . .

I'll try that tomorrow...

Bong swaray