Clutch assistance spring causes bad bite point

I've just brought a genuine parts spring and bushes to help lighten the clutch pedal on my Defender 110 Td5.

Before fitting, the bite point was about half way through the pedals travel. After fitting the spring, the bite point moved to a couple of cm of the bottom of the pedal travel. Reverse gear was only possible when either the engine was off or the transfer box was put into neutral.

No leaks were visible from either the master or slave cylinders and the fluid looks ok, though this wasn't tested.

I don't know how old the clutch is but it doesn't slip or anything.

The spring was removed and the bite point reverted to its original point.

There was no noticeable change in pedal height.

So, is there an adjustment I can make that will move the bite point or do you think bleeding the system will help?

The spring was fitted and removed by a garage with LandRover experience and the the mechanic was left scratching his head.

If there is a post that's already covered this then please do point me in its direction.

My poor knee will thank you for your help

The actual bite point of the clutch is controlled by the clutch unit and plate, as the plate wears the bite point comes higher.
So I recon there could be a geometry problem caused by fitting the spring, check for wear in the pedal pivot point and correct adjustment of master rod.

The spring shouldn’t affect the clutch bite point.
The bite point is altered using a threaded actuating rod on the master cylinder.
I would say there’s something wrong with the actuating rod on the master cylinder, either it’s loose or the mechanism is worn.

Cheers for the suggestions. I'll check the adjustment of the actuating rod on the master cylinder, maybe even replace it.

I still can’t see how the spring could affect it. Even if there was play in the mechanism, the spring can’t make it worse in such a way that the bite point becomes lower.

The only thing l can think, is that it makes the pedal (and actuating rod) sit higher due to the way the assist spring works.

If that means the piston in the master cylinder is able to get too far out, it could possibly affect the operation by allowing fluid to initially bleed back into the reservoir when you start to press the pedal.

That could make for a lower pedal (and bite point) but only until you took off the spring. Did you have a coil spring on the pedal that you took off to fit the assist spring?

See what you mean there Lightning, could be that without the return spring master rod is being stopped from full travel. He needs to come back with more info.

lightning said:

I still can’t see how the spring could affect it. Even if there was play in the mechanism, the spring can’t make it worse in such a way that the bite point becomes lower.

The only thing l can think, is that it makes the pedal (and actuating rod) sit higher due to the way the assist spring works.

If that means the piston in the master cylinder is able to get too far out, it could possibly affect the operation by allowing fluid to initially bleed back into the reservoir when you start to press the pedal.

That could make for a lower pedal (and bite point) but only until you took off the spring. Did you have a coil spring on the pedal that you took off to fit the assist spring?

Click to expand...

Lightning, yes there was a coil spring on the pedal. That was removed when the new spring was fitted.
I've done a fair bit of spannering over the years and I'm left wondering as much as everyone else.
My job keeps me away from home a lot of the time so I'll have a gander when I get back next month. From the comments on here, I'll probably be looking at having the pedal box out, check for wear on the pivot points and just replace the master cylinder while its apart.

Interested in the this. After fitting new clutch, I could only get reverse by doing same as you. Had to take rubber mats out and extend push rod in slave cylinder to make it work. Just waiting for clutch to wear so I can get sound deadening mats back in.

So update on this little issue....

I removed the 17mm adjustment bolt from the back of the clutch box. Jammed the pedal right down and the spring went in easier than I thought possible.

After allowing the pedal to return back to normal I put the adjustment bolt back in and adjusted it so I could slip I finger under the depressed pedal. To start with, this bolt was in almost all the way. After my faffing about, the bolt is in about half way.

The pedal still sits about 160mm of the floor which is a little high but I can live with it as I don't see any way of adjusting it.

End result is a beautifully light pedal and I can select gears without issues.

Happy days

The bolt is not an adjustment bolt it's the pedal stop bolt.
The clutch pedal height given by Land Rover is 140mm. This guide figure ensures that the clutch isn't dragging as yours was when you couldnt select reverse and also ensures that it doesn't slip under load.
I suspect that you'll find that you clutch may well slip on a very steep hill with a height of 160mm.
Adjusting the pedal height is done on the push rod under the cover with 6 screws on top of the clutch pedal box.
It's a simple adjustment and a Google search will turn up a post with a pic from the manual.
clutch slip will cause premature failure of your clutch.
HTH
Mo

Mo Murphy said:

The bolt is not an adjustment bolt it's the pedal stop bolt.
The clutch pedal height given by Land Rover is 140mm. This guide figure ensures that the clutch isn't dragging as yours was when you couldnt select reverse and also ensures that it doesn't slip under load.
I suspect that you'll find that you clutch may well slip on a very steep hill with a height of 160mm.
Adjusting the pedal height is done on the push rod under the cover with 6 screws on top of the clutch pedal box.
It's a simple adjustment and a Google search will turn up a post with a pic from the manual.
clutch slip will cause premature failure of your clutch.
HTH
Mo

Click to expand...

Yeah, I ment to say a stop bolt, my bad for crap explanation. Only found out it was a stop bolt this morning.
I've had a look under the plate with the clutch pedal held down. There is no visible thread left on the master cylinder rod. Should there be?

stoney424 said:

Yeah, I ment to say a stop bolt, my bad for crap explanation. Only found out it was a stop bolt this morning.
I've had a look under the plate with the clutch pedal held down. There is no visible thread left on the master cylinder rod. Should there be?

Click to expand...

There is a specific clearance and adjustment to be set - it’s all detailed in the workshop manual, but sounds to me like your clutch master cylinder is over-adjusted making the bite point to low.

Given a pedal height of 160mm I'd say that's not surprising, slacken off both nuts and set the pedal height to 140mm without the mat on the floor and see how it is.
Mo