Board logo

Sierra master cylinder without servo?
theduck - 17/10/12 at 07:59 PM

I have a sierra master cylinder with servo at the moment, but the brake pedal is very light with engine running, ok when not. can I simply disconnect the servo and run the existing setup in that way?

[Edited on 17/10/12 by theduck]

phil clegg - 17/10/12 at 08:14 PM

no as you will then be working against the servo,it most 7 style cars do not use a servo at all but it needs to be took out of the system....

britishtrident - 17/10/12 at 08:38 PM

Instant MOT failure you have to completely remove servo.
As after stopping the engine It takes about 5 presses of the pedal to fully exhaust the vacuum in the servo, I would suggest that without a servo you will want a smaller bore master cylinder,

theduck - 17/10/12 at 08:52 PM

Any suggestions as to a suitable and as close to direct replacement as possible items then?

Really starting to dislike the sorting the brakes phase of restoring this car.

EDIT just done a search and realise I have the answer to that question from a previous thread.

[Edited on 17/10/12 by theduck]

robinj66 - 18/10/12 at 09:12 AM

I have a Sierra based S7 with the standard Sierra master cylinder, standard discs on the front and drums on the rear. I removed the servo, made up a new pedal rod and it works fine.

The onlything I can't comment on is how it would work on a track as mine is used on the road atm.

theduck - 18/10/12 at 10:09 AM

Good to hear it works ok on road car. I'm yet to have ever driven the kit so the plan is to get it working, track it, and make changes as required. I think I'll strip the guts out the servo to disable it and go from there. I foubd last nigh that I may have a small leak from where the cylinder attaches to the servo so looks like I need to source another one, third time lucky I hope.

britishtrident - 19/10/12 at 06:02 PM

Fiat 124 (1966 to 1985) is an easy to find and surprisingly cheap cylinder suitable bore size to use without a servo. -- you will find it in the Brakes International online shop at a very good price.

theduck - 19/10/12 at 08:04 PM

Thats only a couple quid more than I paid for a second hand sierra master cylinder


Only thing is, where can I get the reservoir from? I couldnt see it on brakes international, or will my sierra one fit? (Wishful thinking I know)

Also how much work does it take to get it to fit? And are the brake pipe fittings the same?

Depending on the answers to those I'll either get the fiat one or just stop being cheap and buy a new sierra one.

whitestu - 19/10/12 at 08:56 PM

I Fitted the 124 mc so have first hand experience of this.

quote:

Only thing is, where can I get the reservoir from? I couldnt see it on brakes international, or will my sierra one fit? (Wishful thinking I know)


You'll need a remote res. I bought a Saab one that works fine [from Rally Design IIRC]

quote:

Also how much work does it take to get it to fit? And are the brake pipe fittings the same?


No, the brake pipe fittings are different. 1.25mm metric I think. Brakes Int sent me some fittings for free when I rang them to check. Also the mounting holes are in a different position so will need re-drilling.

quote:

Depending on the answers to those I'll either get the fiat one or just stop being cheap and buy a new sierra one.


Don't get a new Sierra servo one as the bore is too big at 22mm. Get the Fiat one [19mm] or for an easier [but more expensive] option get a Fiesta non servo MC which I think will be almost a straight swap, though I haven't done this myself.

Stu