Gearbox issue

[Josh]

Hello,

I have had my discovery 300tdi for a while now and have never had any problems with the manual gearbox, nor did the previous owner.

However, last weekend after going on a bit of a run out, and getting stuck in slow moving traffic for an hour, the gearbox started to act up.

The gears dont seem to be where they used to be (if that makes sense ) 1st and 2nd are hard to engage and crunch, 2nd up to 3rd can jam sometimes and 3rd seems to engage further to the right than before, 4th is fine, 5th doesnt seem to enage all the way propeerly and grinds as does reverse.

Changing down gears is also interesting as they stick and wont disengage easily. 1st and reverse are the worst for disengaging.

So far i have checked the master cylinder and slave cylinder. There are no leaks and the fluid level is fine

I changed the gearbox oil to see if that made any difference and it hasn't.

Is this a clutch problem or is it the gearbox itself?any ideas would be great.

Thanks

Josh

[jerboa]

Unless there is something wrong with the selector mechanism I reckon its most likely a clutch issue - its probably not disengaging the driveline properly - resulting in difficulty disengaging/engaging gears. Gearbox failures tend to be gradual, rather then sudden. Might be a bent or fractured clutch release arm, which will result in the slave cylinder not being able to totally operate the action of the clutch.

Alternatively, there's a little plastic clip somewhere in the selector system, might have snapped, though that usually results in lack of the 3/4th gear bias.

Most likley clutch/clutch release system..

Maybe new clutch then, and while you're at it, rear crank oil seal. I made mistake of not doing that.

[drkwack]

Hi, not sure if this helps, but on top of the box just under all the sound deadening there is a small plate with a section bent at 90 degrees,this plate is where the gear lever enters the box,occasionally the plate breaks posssibly this is obstrucitng things, also easier to get to and check before stripping to do the clutch.

[Josh]

Thanks for the reply guys,

I agree that it is most likley a clutch related problem and not the gearbox. I have had a look through some info on the internet and it seems that problems enaging and disengaing gears can be down to either the slave or the clutch fork, like you said jerboa.

I have had a look at the slave an there is no fluid dripping out of it and it looks in reasonable nick. Is there any other way of checking it?could the clutch damper be responsible?

Thanks

Josh

[cipx2]

To me it sounds like a selector issue. Try with engine off, clutch engaged/disengaged and see how does the gearbox feel and were the gears are compared to where they used to be.

If you suspect clutch dragging, no matter the cause, lift the right front wheel, handbrake on, start the engine, clutch pedal depressed, 1st gear and watch for the lifted wheel when engaging/disengaging the clutch. If the wheel doesn't turn with the pedal depressed and firmly stops before you reach the end of the pedal travel then the clutch is ok.

Try see what happens when you engage different gears with the clutch pedal depressed. If you fell the gears grinding but no wheel movement, the chances are the selector tries to engage 2 gears at the same time.

[Josh]

Ok,

Today i removed the centre consol and accessed the top of the gearbox. The vertical part on the bias plate had snapped off and was rolling around in the top of the box (as drwak ^^^ pointed out). It looked pretty hammered, like at some point it had been jammed in somewhere. I sourced a replacement and fit it with no problems.

This seems to have solved the probem of getting into 3rd,4th and 5th. However, 1st, 2nd and reverse are still a real bugger to engage and disengage.

Cipx2 (and anyone else out there), if this is a selector problem, how do i go about fixing it?

Thanks

Josh

[cipx2]

I was referring to the selector as to the whole mechanism used to shift the gears, starting from the gear lever knob down to the insides of the box.

It seems you found the problem. The only thing is that the bias plate needs to be adjusted. Try bolting it in different positions.

The important issue in your current condition is the fact that 1st and 2nd don't disengage properly. I don't think this has something to do with the bias plate setting, it could be a clutch thing after all.

[Josh]

Thanks cipx2,

Didnt know that you could adjust the bias plate, but now you mention it i do remember the holes being elongated. I will try and adjust it tomorrow and see if things are any better.

Thanks for your help.

Josh

[paintman]

Have a look at this part of ashcrofts FAQ. http://www.ashcroft-transmissions.co.uk/faq.html#a7 'I've just fitted a rebuilt gearbox to my Discovery...' etc

[Josh]

I finally got around to taking the top off the gearbox and had a peer inside.

The first thing that struck me was that the gear lever yoke was not secured in it usual place and was sat on the gate plate below. There were no signs of the circlip or any other bits that should secure it in place.

I removed the gear lever very carfully and it came with no resistance, so i dont think it ripped it out.

Any ideas what has happened here?

Thanks Josh

[cipx2]

Not 100% sure I understood which yoke was loose, but here I go ...

This is a (blurry) picture of the yoke in place (although part of the case and some bits are missing).

It should have a grub screw that keeps it in place on the shaft (almost removed in the pic).

Here's another picture where you can see the screw is missing and also its threaded hole.

Check if the screw is still there and that its pointed end (towards the shaft) isn't shattered. The screw is loctited in place (use heat if it doesn't come off, use loctite when you put it back). Replace it with a new one as the book says- specially if something wrong with it.