Brake servo repair

[ATE399J]

Firstly, is there a way of checking whether the brake servo is working correctly (apart form disconnecting it and going for a drive)? And, secondly, is home repair an option? I've heard that these things are almost impossible to get apart and once you have there appear to be about 9385349 difference variants only distinguishable by the pitch of the knurling of the sprocket push-rod lever pin (or something).

Forgot to say, it's the TR6 unit.

Edited by ATE399J on Wednesday 13th June 14:17

[GAjon]

Simple check.

With the engine stopped.
In neutral, hand brake on.
Depress the brake pedal a few times to exhaust any vacuum in the system.
Depress the pedal and start the engine.
If the servo is working youu should feel the pedal fall away slightly from under your foot, and less pressure is required to hold the pedal in position.

John

P.S. Check hoses and connections for leaks or blockages before forking out for a new servo.

[ATE399J]

Car failed MoT on braking efficiency. Servo was U/S. When I replaced it it made little/no difference.

Stripping the master cylinder down I discovered that the piston was sticking half way up the cylinder and not returning fully "out". I was a little surprised since I had only replaced all the seals about a year ago and can only assume that the one on the main piston ass'y had swollen. Has anyone else had this problem? Are there fluid / seal incompatabilities that I am unaware of?

I replaced then all again and it seems to have solved the problem but will I be doing the same thing again next year? I presume that one seals kit is the same as another - or am I being naive?

Answers on a postcard to.......

[Adrian@]

Phil, It is some 10 years since I last relied on the OE master cylinder with the assoc. 5 way valve, but here goes. The piston and bore wear oval, you replaced the seals and they are at opposite wear points and you get accelerated wear, and they jam.
Adrian

[ATE399J]

Adrian,

OK, I see what you mean. However, the piston did move freely without the seal seemingly in any orientation although I understand that's not neccessarily a sign that all is well. Is there a straight swap with a modern unit (having JUST bought a new servo!)?

Phil.

[Adrian@]

As such, 2 new pipes to the front brake flexi's and a joiner to the rear system and then add the later M series master cylinder (Ford) with a Saab 99 cap (rewire the short out on the 5 way valve to earth out via the cap) for level indication .........then you have front/rear (disc or drums) failsafe as opposed to opposing corners (1 disc and 1 drum), all within the master cylinder.
The master cylinders connections become metric, (the 2 at the front are the front and 1 at the rear, the rea), set the nose bolt on the servo using blutack as a guide.
Adrian@

A note to whom it may...IF you need EVEN think about how this goes together then you need to ask a person who can fit it, to do it for you. Please.

[ATE399J]

Adrian,

I dispensed with the PDWA some time ago as I couldn't get a replacement seals kit. I have both front from one master cyl outlet and both rear from the other (can't remember which way round off the top of my head). So I guess I've already done most of what you suggest. My question still is does the Ford master cylinder fit straight on to the Triumph servo?

Phil.

[Adrian@]

Yes, set the adjuster using a piece of bluetack to gauge about 1/16 inch gap, having replaced the imperial fittings with metric.
Adrian@

[pumpkin]

What year, or chassis number did the brake master cylinder change from Triumph to Ford?
I just bought a new Triumph unit for fitting to my 1978 M (4272FM) at the weekend having assumed that it was Triumph.
I have the car with me but not the part so what is the easiest way to check or am I OK with Triumph for a 1978 M?

[Adrian@]

John, They changed mid 77........the early master has a 3 inch cap NO wires and the late has small 17/8 inch cap and 2 wires (fluid low)
Adrian@
The inner wing gets a indent mid 75 IF you convert an earlier car then you need to either mod the inner wing OR buy another with an indent....I can sell people those.

Edited by Adrian@ on Wednesday 8th August 22:00

[Daftlad]

Adrian@ said:

John, They changed mid 77........the early master has a 3 inch cap NO wires and the late has small 17/8 inch cap and 2 wires (fluid low)
Adrian@
The inner wing gets a indent mid 75 IF you convert an earlier car then you need to either mod the inner wing OR buy another with an indent....I can sell people those.

Edited by Adrian@ on Wednesday 8th August 22:00

How much is an indent these days Adrian

[Adrian@]

Daftlad said:

Adrian@ said:

John, They changed mid 77........the early master has a 3 inch cap NO wires and the late has small 17/8 inch cap and 2 wires (fluid low)
Adrian@
The inner wing gets a indent mid 75 IF you convert an earlier car then you need to either mod the inner wing OR buy another with an indent....I can sell people those.

Edited by Adrian@ on Wednesday 8th August 22:00

How much is an indent these days Adrian

With or without an inner wing sir?
Saw the the video ....looked good, was that Linda driving?
Adrian@

[Daftlad]

Adrian@ said:

Daftlad said:

Adrian@ said:

John, They changed mid 77........the early master has a 3 inch cap NO wires and the late has small 17/8 inch cap and 2 wires (fluid low)
Adrian@
The inner wing gets a indent mid 75 IF you convert an earlier car then you need to either mod the inner wing OR buy another with an indent....I can sell people those.

Edited by Adrian@ on Wednesday 8th August 22:00

How much is an indent these days Adrian

With or without an inner wing sir?
Saw the the video ....looked good, was that Linda driving?
Adrian@

Cheeky sod - that me was me giving it my all.

Quite impressed with the old bus actually. Turbo recently refurbed and it came on boost very well (a little delay, but as soon as it did, the tyres lit up)