11 replies to this topic

[sprintmini]

Hi all

Can anyone identify this servo from the picture below?
Im having a problem with the brakes and need to order a servo repair kit but dont know which one to order.
I know its a lockheed but need to know the correct model.
Thanks.

[Guess-Works.com]

it's a Mk2 (type 6) servo ( that's not as in mk2 mini ), first fitted to the MK3 cooper S and 1275GT, it's a remote servo fitted to a single line brake system, so what it's doing connected to a tandam system I don't know as that means the servo is only acting on half the system, which may be the brunt of your problems.

Edited by GuessWorks.co.uk, 09 January 2009 - 09:15 AM.

[WiredbyWilson]

i was thinking of fitting a remote servo, and inserting a T piece - which I think i can see at the back of the servo in the pic??

[Guess-Works.com]

There is no way of fitting a remote servo to a tandem system, because the front/rear ( or even worse diagonal) split is done at the master cylinder.

What seems to have been done there is, both outputs have been joined by the T piece, through the servo, and then split again by a "T", essentially making it a single line system. Bit unorthodox..

IMO, you'd be much better off, removing the servo altogether, they don't increase breaking efficiency, reduce pedal feel and generally get in the way when you want to do anything on the engine.

[Asphalt]

it's a Mk2 (type 6) servo ( that's not as in mk2 mini ), first fitted to the MK3 cooper S and 1275GT, it's a remote servo fitted to a single line brake system, so what it's doing connected to a tandam system I don't know as that means the servo is only acting on half the system, which may be the brunt of your problems.

Works great for me and many others!
Dual circuit master(front/rear split of course!), servo to the front, pressure control valve FAM7821 and 1275GT's rear brake cyls.
Dual circuit & remote servo worked on many cars... One to name is the Innocenti 1300/B39 of which im 100% sure!

The official Rover survey (needed here to convert to S brakes and make them road-legal) says the same.
Dual circuit, R/F split, servo to front circuit, valve FAM7821 or Cooper S (at rear) and smal brake cyls. rear.
(The pressure control valve/'S' reducer is the point here!)

So unless that's done in an other way I don't see anything wrong here

[edit] one thing to add: I'm using a modern GMC227 master cyl.
But to be honest it shouldn't be much of a difference?

Edited by Asphalt, 09 January 2009 - 11:37 AM.

[sprintmini]

There is no way of fitting a remote servo to a tandem system, because the front/rear ( or even worse diagonal) split is done at the master cylinder.

What seems to have been done there is, both outputs have been joined by the T piece, through the servo, and then split again by a "T", essentially making it a single line system. Bit unorthodox..

IMO, you'd be much better off, removing the servo altogether, they don't increase breaking efficiency, reduce pedal feel and generally get in the way when you want to do anything on the engine.

Right Now im lost,I didnt build this car so dont know anything about it.If I simply bypass the servo and leave everything as it is will that work?
I realise it will need the pipes rerouting etc etc but just for testing puposes can I just bypass the servo?

[Asphalt]

Original Innocenti-Setup:


Setup according to legal requirements for German TÜV (ultra-serious MOT):

[sprintmini]

Ok thanks for that, looking at the above pictures I seem to have the second set up fitted to my mini so im assuming it was some sort of standard fitment when the car was originally built.
My problem seems to lie with the pedal going hard when pressed and not much braking occuring,I then pump the pedal once and the brakes work superbly.
Makes me think the servo is at fault.
I can see servo kits for the MKI and MkIII servos but dont seem to be able to locate a MKII servo kit anyone any ideas?

Or should I just remove the servo full stop?

Regards.

Edited by sprintmini, 10 January 2009 - 05:01 PM.

[Ethel]

Both of Asphalt's diagrams look fine to me. If the car has an effective brake limiting device to stop the rear brakes locking up adding any form of servo before it won't make a difference. It is vital to keep both circuits of a tandem system isolated, if you joined the output from a single line servo back in to a line directly from the master cylinder, the servo would actually be pushing against the brake pedal!


Have a look to see where the lines go out of that Tee just under the heater hose.

[sprintmini]

My servo is already fitted thats my engine bay in the first pic.
As mentioned in my last post im having a braking problem which I think is down to the servo so I either get a service kit or remove the servo.
The brakes work fine when pumped but have a solid feel when they are initially pressed hence my problem.

[Ethel]

Well a remote servo would actually make the pedal more solid once it kicks in. You could probably diagnose it by playing with the vacuum hoses. Obviously if it isn't connected to the manifold it shouldn't do anything.

When it is connected, pressing on the pedal starts to move the servo's piston and generates some fluid pressure that lifts the valve in the middle of the white plaggy bit. That allows atmospheric pressure in to replace the manifold vacuum behind the diaphragm in the big can and that pushes on the piston even harder.

So if you remove the hose linking the valve to the can and stick your thumb over the valve's pipe you should feel the vacuum when the engine's idling. Applying the brakes should kick the servo in to action & air should stop being drawn in through the pipe. No air should be drawn in to the can by the connecting pipe other than briefly while the servo applies, if it draws air otherwise the diaphragm is shot.

You can strip down the white air valve, and vacuum can without any spares to inspect it. There are gaskets between the cast iron cylinder and the can and valve base, they're the only bits that won't appreciate being disturbed.

[sprintmini]

Ethel

Thanks for that, I was thinking of disconnecting the vacuum hose to see if the actual servo was working.
I will try that and hopefully that will resolve my problem, if not its back to the drawing board.

Tomorrow will tell.