Servo

[TVRIK]

I think may have a servo problem but not 100%
Brakes are very week, and on tick over when I press the brake the revs drop almost stalling the car?

Any thoughts chaps?

[Jack Valiant]

Sounds like servo fella but just check the vacuum hose from the servo to the plenum they go hard over time "matron" and fail.

Chris

[TVRIK]

Jack Valiant said:

Sounds like servo fella but just check the vacuum hose from the servo to the plenum they go hard over time "matron" and fail.

Chris

Thanks mate, I replaced the hoses a month or do ago, so that's ok,
I have recently had my back breaks overhauled and they was a bit soft , but stopped ok,so was gonna pop it back to the mechanic, for a bleed, but a week or so ago I just pumped em a few times.
Then suddenly they are like they are now, if I hold the brake on,it constantly hisses, just wondering if there is air in the system, would it have theses symptoms??

[ElvisWedgely]

Here is a quick and easy way to test your servo:-

With the engine off put your foot firmly on the brake pedal and press down fairly hard.

Keeping your foot firmly on the brake pedal and start the engine.

Your foot, on the pedal, should travel down a short way once the engine fires up.

If this doesn't happen, there is a problem with your servo unit.

Tony. TCB.

[TVRIK]

ElvisWedgely said:

Here is a quick and easy way to test your servo:-

With the engine off put your foot firmly on the brake pedal and press down fairly hard.

Keeping your foot firmly on the brake pedal and start the engine.

Your foot, on the pedal, should travel down a short way once the engine fires up.

If this doesn't happen, there is a problem with your servo unit.

Tony. TCB.

Bugger! It doesn't move when I start the engine!
Thanks for this though Tony, at least I'm getting closer to diagnosis,
Can they be repaired ? Also I've seen a few posts on what the servo is off,
If I'm looking at having to replace, do you know the model of capri or fiesta it's off? Or anything else it maybe off?

Rik

[ElvisWedgely]

I am not sure which car the servo is from for a 350i but it's either fiesta, capri, cortina or possibly even rover. You'll have to do some research on this from people who have replaced them previously, as these servos all look similar in shape and size to yours but may have different size internals such as the push rod etc.

Tony. TCB.

[superwedge]

its a capri one,my friend had a capri ,which the wedge has on it, he put one on from a xr4i, which should fit the too ,and gave him better brakes, as the servo is bigger,as more push behind it,

[TVRIK]

ElvisWedgely said:

I am not sure which car the servo is from for a 350i but it's either fiesta, capri, cortina or possibly even rover. You'll have to do some research on this from people who have replaced them previously, as these servos all look similar in shape and size to yours but may have different size internals such as the push rod etc.

Tony. TCB.

Cheers Tony.. Let the "fun" begin!

[TVRIK]

superwedge said:

its a capri one,my friend had a capri ,which the wedge has on it, he put one on from a xr4i, which should fit the too ,and gave him better brakes, as the servo is bigger,as more push behind it,

Thanks for this mate, you wouldn't know what model of capri or xr4i
Would ya, which mark or engine size?
I like the sound of having a bigger one, like the xr4 one!

[mrzigazaga]

Hi Rik..I had the same issue with the 280i..If its hissing constantly then the servo seals have failed..The unit was from a Capri but not the MK3..The actuator/Connector was modified by TVR as originally it would of been too long..If Chris can confirm i think that a later fiesta one fits without shortening the connecting rod?…Cheers…Ziga

[TVRIK]

mrzigazaga said:

Hi Rik..I had the same issue with the 280i..If its hissing constantly then the servo seals have failed..The unit was from a Capri but not the MK3..The actuator/Connector was modified by TVR as originally it would of been too long..If Chris can confirm i think that a later fiesta one fits without shortening the connecting rod?…Cheers…Ziga

Cheers Zig, just to clarify it constantly hisses when pressed, is that the same symptoms as yours?

Rik

[mrzigazaga]

Hi Rik..When we tested mine it was leaking into the footwell and you could hear the air escaping with the engine off while depressing the pedal..If yours is doing it while the engine is running then don't forget that the vacuum from the plenum helps the forces applied from your foot so if it is leaking you will hear a constant hissing noise..Normally in the footwell…If you change the servo makes sure you remove it carefully as it will be held onto the bulkhead with mastic/sealant which will need to be replaced as you do not want water ingress..Ziga

[TVRIK]

Ok mine, isn't making any noise when the engine is off,
Only when the peddle is pressed with the engine on?

Is that not as bad? Sorry if I'm sounding thick! :-/

Rik

[mrzigazaga]

TVRIK said:

Only when the peddle is pressed with the engine on?

Sounds as if the servo seal is knackered..There is a fair amount of vacuum inside a V8 plenum…Im not sure how else you would test it, Certainly NOT by driving it..I guess a replacement needs sourcing..I will try to find out unless anyone else knows for sure?...Once found it should be put on the Wedge parts list…Ziga

[TVRIK]

mrzigazaga said:

Sounds as if the servo seal is knackered..There is a fair amount of vacuum inside a V8 plenum…Im not sure how else you would test it, Certainly NOT by driving it..I guess a replacement needs sourcing..I will try to find out unless anyone else knows for sure?...Once found it should be put on the Wedge parts list…Ziga

Nice one Zig, that would be great! It's I start to think about doing something astheticly pleasing to the beast, something else fails!

[mrzigazaga]

Hi Rik…I have found these…Might be worth calling them first..I think at that price i will grab a spare if they are appropriate…Cheers…Ziga

www.ebay.co.uk/bhp/tvr-brakes

[TVRIK]

mrzigazaga said:

Hi Rik…I have found these…Might be worth calling them first..I think at that price i will grab a spare if they are appropriate…Cheers…Ziga

www.ebay.co.uk/bhp/tvr-brakes

Thanks mate, I've messaged them, it doesn't look like the existing one, but that might not be relevant I guess!
Hope it does fit!

Thanks again pal

Rik

[TVRIK]

Ah shazbat! They have got back to me, saying they only started supplying to TVR in 2001 so it won't fit :-/
Back to the drawing board! Interesting earlier comment about xr4i servo fitting, having said that, guess they are gonna be rare!

Cheers Zig

Rik

[jmorgan]

Somewhere in my memory is a comment that certain hoses are not suitable for vacuum applications. If you replaced the hose recently, was it up to the job? Probably not the issue in your case.

When I had mine changed, the garage had to go to Girling with the part numbers off the casting so they could hunt one out, it was a few years ago and not off the shelf at the factors.

Edit. Doh! That would be the cylinder not the servo that was changed.

Edited by jmorgan on Monday 18th November 09:39

[TVRIK]

superwedge said:

its a capri one,my friend had a capri ,which the wedge has on it, he put one on from a xr4i, which should fit the too ,and gave him better brakes, as the servo is bigger,as more push behind it,

Hi mate, would you mind asking your friend if this is the servo he used (see link)

http://item.mobileweb.ebay.co.uk/viewitem?sbk=1&am...

Cheers

Rik