Replacement Brake servo

[barryr]

Nothing is ever plug and play these days!

Hi all,

I've received my brand new servo from JRW and I was pleased to find it came with a new one-way valve because on my original servo the blueish coloured original that pushes into a rubber grommet is not a one-way valve but just an empty shell! - I've always suspected this was a problem but never knew for sure.

Anyway, the new one-way valve has a 90 degree elbow on it as do all the others you'll see on ebay etc.

So the question I wanted to ask is if people are getting round this by using the 90 degree one and cutting back the original pipework to adapt it with vacuum hose - or if most simply swap back their old valve?

Can anyone also confirm if my original valve is meant to have internals?

And while we talk one-way valves - is there another one screwed into the inlet manifold at the other end of the servo reservoir?

Gah - I just want something new that bolts on like the old thing did!!!

thanks

Barry

[Phil Nottingham]

A one-way valve incorporated in the manifold on V8s. Its easy to test if not seized up. 3 Litres need one, however.  In line ones are available. There is no point having more than one

[revoxy]

Apr 4, 2019 14:25:43 GMT barryr said:

Nothing is ever plug and play these days!

Hi all,

I've received my brand new servo from JRW and I was pleased to find it came with a new one-way valve because on my original servo the blueish coloured original that pushes into a rubber grommet is not a one-way valve but just an empty shell! - I've always suspected this was a problem but never knew for sure.

Anyway, the new one-way valve has a 90 degree elbow on it as do all the others you'll see on ebay etc.

So the question I wanted to ask is if people are getting round this by using the 90 degree one and cutting back the original pipework to adapt it with vacuum hose - or if most simply swap back their old valve?

Can anyone also confirm if my original valve is meant to have internals?

And while we talk one-way valves - is there another one screwed into the inlet manifold at the other end of the servo reservoir?

Gah - I just want something new that bolts on like the old thing did!!!

thanks

Barry

Hi Barry,

I too received a similar one with the 90 degree valve, so I understand your frustration.

However, I just swapped the valve from the old servo onto the new one and everything works OK.

There is also a one-way valve into the inlet manifold as you suspected but I didn't replace that.

Cheers,

Andrew.

[barryr]

Thanks Andrew

I think that would be my solution too if my original valve wasn't faulty!

There is one straight valve on eBay but 25 quid is too steep for me!

[barryr]

Hi Phil,

The one way valve in the manifold seems fine.

Its the one in the servo end I'm not sure about having never seen one before - on my car this is just a straight through connector.
Looking inside it I believe someone has previously removed the valve bit.

Tonight I'll remove the 90 degree one from the new servo, have a look inside and see if I can mackle the 2 together somehow I think!

Thanks

Barry

[Eric R]

I strongly urge folk to contact www.powertrackbrakes.co.uk/brakes.html As well as being very knowledgeable and helpful, they have all the servo parts.

[barryr]

I bought the special seals for the front calipers from them - yes I may try them next thx!!

***Update - I rang them and asked - they are now unobtainable which is why you are seeing these 90 degree ones fitted to all new servos. So its 2nd hand or adapt!**

I've popped an email to David Green just to try an find an old used one that works. I also looked at the new one to see if I could somehow swap the internals but they look to be heat welded or similar.

[Phil Nottingham]

A straight through connector is all that is needed - if you are missing this then one with a valve will suffice

[barryr]

Sorry Phil,

Just so I understand, are you saying they were just straight through connectors anyway at the servo end - since there is a one way at the manifold?

I ask because even the wsm describes the servo end piece as a one way valve??

Sorry to go on but if they are just straight connectors then I have what I need. Most other cars do have a one way valve stuck in the servo body - I've never seen a car with 2 before but then I've never seen a car with the massive air reservoir the p5 has either!

I've fitted the servo tonight, all piped up in copper and ready to bleed. Only the vacuum to sort after that.

Thx

Barry

[Phil Nottingham]

Yes, they are straight through at the servo on V8s.  Some P4s had the vac tank as which is not needed anyway with a Lockheed servo.  It is this tank with invisible rust pinholes that can cause real problems with brakes and engine performance. 3 Litres do not have the manifold valve so they must have one if a Lockheed servo is fitted (they do not have a vac tank either).  If the one-way valve is faulty the brake pedal will pulse with engine speed or there will be no vac if it sticks.


The WSM should never be treated as 100% gospel as errors were rarely corrected or production mods updated. There are quite a few in there

[revoxy]

Apr 6, 2019 5:43:30 GMT Phil Nottingham said:

.....  It is this tank with invisible rust pinholes that can cause real problems with brakes and engine performance. ......

Is there a test one can do to test if the servo vacuum tank is leaking without taking it off the car?

[Phil Nottingham]

Bypass it and see if it gives more or less pedal assistance than it did with it connected.  Start engine press pedal down and release. Switch off engine and count how many times the pedal can be pressed down before servo assistance disappears (the pedal will be harder and have less travel.)  Repeat with it bypassed (by connecting vac hose direct to manifold)

With vac tank connected you should get 4-5 operations. Without 2-3.

To test servo press and hold down brake pedal and at same time start engine - the pedal must move further down very noticeably

[barryr]

Fantastic thank you!

So all v8 owners can discard the 90 degree one way valve supplied and refit their original straight through connector!
I am stunned nobody has mentioned this before on here.

Many thanks!!

Barry

[Phil Nottingham]

Yes, and I have mentioned before!