Jerky throttle

[Tyre Tread]

The throttle pedal on my car has become jerky.

If I remove all 3 springs it will move smoothly but even one spring makes it jerky.

I am assuming there's a bush in the throttle body which may be worn such that when a tension is put on it, it sticks?

Any advice appreciated

[steviegtr]

I would in the 1st instance try getting some lube in the cable or change it. Mine is a bit like that. Not had a look yet.
|Steve.

[Tyre Tread]

Thatnks Stevie but it's definitely not the cable as it's new, has been covered (internally) in graphite and the pedal moves smoothly without the springs in place.

[Belle427]

There were 2 springs as normal on most mechanisms, people used to remove 1 to lighten the throttle feel.
There are some spindle bushes in there that do wear but it be looking at the closed stop first to see if its not been messed with allowing the throttle blade to close too much and bind.
Make sure its all nice and clean too.

[BritishTvr450]

Belle427 said:

There were 2 springs as normal on most mechanisms, people used to remove 1 to lighten the throttle feel.
There are some spindle bushes in there that do wear but it be looking at the closed stop first to see if its not been messed with allowing the throttle blade to close too much and bind.
Make sure its all nice and clean too.

Sounds like the area to be looking at.

I remember that trend of removing one spring which I thought might be a bit risky if the only remaining one snapped so simply put a less springy spring in place of one of them so retaining two springs for safety but having a softer pedal.

Maybe also look at the pedal pivot point which might be binding slightly when more tension is placed on it.

[Loubaruch]

Removing one spring definitely risky, some may remember Colin Blower in his Tuscan racer hurtling into the Armco when his throttle jammed on, fortunately Colin escaped serious injury.

[Tyre Tread]

As standard there are actually 3 springs. A rotary one and 2 linear springs.
If I remove the 2 linear springs it's still jerky and not just off the throttle stop but all the way through it's travel.
If I remove all 3 springs it's really light but smooth action which would suggest to me that the issue lies in the bushes that the throttle spindle runs in.

The car in in the body shop for some paint repair this week but I hope to get it back next weekend so I can continue my investigation.

[Belle427]

The rotary one is oem but im not sure about the other 2, they are return springs to safeguard the throttle jamming open as suggested but i dont know if the original Range Rover had them.

[Tyre Tread]

After doing some more investigation this afternoon I've notices that the new throttle cabel fitted 2 years or so ago has stretched quite a bit, but that isn't the cause.

Can someone please put up a picture of their throttle spring return with particular attention to where it is hooked at both ends. I have a feeling mine is fitted wrong way round

TIA

[Loubaruch]

This may help. It is correct. Taken from under the plenum. Yours looks the same.



.

Edited by Loubaruch on Sunday 6th October 16:50

[Belle427]

The spring looks a bit odd being to one side but its in the right place.

[PabloGee]

I had that thought too, until I looked at mine...
Here are some indirect photos of mine (taken for different reasons).
I believe one of the two long springs has been removed - though if this is the case it was done before I bought the car.

[Tyre Tread]

Thanks all.

I have spent most of today removing the steering wheel and seat for access to the footwell (I'm getting old, stiff and fat) and removed the throttle pedal.

The pedal did have some stiffness on the spindle so I cleaned and lubricated the shaft and put it back together.

Still had the jerkiness.

The only think left was the cable so I rigged a nipple onto the end of the old cable that I'd held onto and part fitted that so I could hold the engine end in my hand while the pedal end was connected and guess what - No jerkiness.

The old cable was 60K miles and 21 years old when changed. The new one is 3 years and 6K miles old!!!

I'm reluctant to order another new cable at £60 to £70 if it's only going to last a few thousand miles.

New parts really are not good

I may see if I can get a new collar and nipple on the original cable.

[Tyre Tread]

Oh and apologies to StevieTVR

[steviegtr]

Just glad you got to the bottom of the problem.
Steve.

[Belle427]

I would guess you could get the cable made for a lot cheaper than £60, im not sure of any places that do it though but there are some that make them for classics etc.

[BritishTvr450]

Tyre Tread said:

Thanks all.

I have spent most of today removing the steering wheel and seat for access to the footwell (I'm getting old, stiff and fat) and removed the throttle pedal.

The pedal did have some stiffness on the spindle so I cleaned and lubricated the shaft and put it back together.

Still had the jerkiness.

The only think left was the cable so I rigged a nipple onto the end of the old cable that I'd held onto and part fitted that so I could hold the engine end in my hand while the pedal end was connected and guess what - No jerkiness.

The old cable was 60K miles and 21 years old when changed. The new one is 3 years and 6K miles old!!!

I'm reluctant to order another new cable at £60 to £70 if it's only going to last a few thousand miles.

New parts really are not good

I may see if I can get a new collar and nipple on the original cable.

I had a new cable fitted many moons ago and within a couple of years it became jerky so had to have it replaced for another new one which has been fine for gosh at least a decade so a bit odd but true!
I thought all along it must be the cable.
I replaced one of the springs for a less tensioned one rather than run it with just one spring for two reasons
Firstly because only one spring worries me if it was to snap and secondly because I wanted a more even pressure being applied to the mechanism thinking it might wear unevenly.
A simple mod that cost a few pence but does give me a lighter and smoother pedal feel.

[Sardonicus]

You actually have 3 return springs stock TVR/LR so even if you remove one you still have 2 fitted the one in the shots above on the spindle itself is the give away