Brake servo and master cylinder

[Emily]

Re: Brake servo and master cylinder

Sounds like a good idea to solve my problem of a knackered servo as I cant get a replacement. I have been offered a brand new master cylinder as fitted to the Westfield so am thinking of adapting the pedal box to fit this.

[listerjp2]

Re: Brake servo and master cylinder

Hi Angus,

It has Triumph front end and Jaguar IRS rear with inboard discs, not sure what the master cylinder is, will have a look.

Best regards
Tony

Now not wantng to repeat but that sounds really interesting, pictures please, did you have to adapt the suspension width?

Adrian

[Mike]

Re: Brake servo and master cylinder

I suspect the major issue with braking on Roadsters is due to the shortening of the brake pedal, reducing mechanical advantage by a significant margin. The effect of shortening reduces the pedal ratio to less than 3:1...with 5:1 being a more desirable figure. Servo-less the standard setup may be adequate for a light A-series motor but with a B'oat anchor up front I never felt comfortable even with a servo..!

Jez

What servo are you using?

Virtually all the BMW powered Cabrios and Sportster owners were advised to fit the standard 7" Metro servo, as the original 9" Ford/BMW servo would not fit. And like your brakes they were never adequate.
We then found a dual 7" servo which has the same diameter as the Metro, but offers 20% more boost, and has transformed our brakes - disc brakes require more psi than drum brakes. The short Marlin pedal and the Metro servo just do not provide adequate pressure to make them work.

Seeing the Marina servo posted on this thread, it looks like it would be a relatively easy conversion:

The Metro servo on the right has had a non standard input shaft welded on to it (to avoid the awful lash up provided by Marlin) so is normally shorter.
The dual servo on the left locates in the same firewall holes (with 2mm fettled out), and can be easily adapted to fit several different brake master cylinders. The master cylinder of choice for the Cabrio/Sportster guys was a standard Sierra dual circuit 22mm bore unit.

The brakes are quite literally transformed.



This is the kit we made up for the conversion, comprising the dual servo, and adaptor plate to locate the BMC to the servo, and an adjustable clevis for the input shaft to brake pedal.
I ended up importing 50 of these servos in for various Cabrio and Sportster owners, and any one who has fitted it will tell you they make a massive improvement to their cars, and finally give you the confidence to go out and drive your car to the limits of the engine, and not its brakes!



As fitted in my Cabrio



If anyone wants more information, please feel free to respond through the forum, or pm, or Tel : 07968 835101

Mike

[lil_red_roadster]

Re: Brake servo and master cylinder

Now not wantng to repeat but that sounds really interesting, pictures please, did you have to adapt the suspension width?

Adrian

Tony, would that be the ex-Richard Harborne V8 car..?
I still have the old Pitstops containing his build write-up...quite a machine..!
IIRC Adrian (and if it's the same car) he used a '60's S-type rear-end as that had a suitable track (54").

[lil_red_roadster]

Re: Brake servo and master cylinder

Hi Mike

I've got the standard Marina servo, which has a smaller diameter than the Metro. When you publicized the dual-servo originally I did ponder whether it would fit...but my conclusion was probably not. The additional depth would leave me needing to re-route the steering column (again) as it would foul the brake master cylinder. The added diameter would then have fouled the side repeater. There really isn't a lot of room under my Roadster bonnet..!

Having said that the braking now feels pretty good, with bigger calipers & the stock .75 Marina master.