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removing servo... any help??

Posted: Thu Oct 07, 2010 11:04 pm
by nye
i am currently fitting an agu 1.8t lump into my mk2 scirocco and would like to do away with all the servo. linkage setup to fit up some room for intercooler piping etc

i have read that this is possible to do by buying/making a pedal box which sits behind the dash with a brake bias bar and two master cyclinders, one for front, one for back, what im wanting to know is what size cylinders should i be looking to use? also i take it you just t-piece of the cylinder and then run one line to each side, also how do the remote resivours work?? do you also just plumb these in one to each cylinder and have to be located at the highest point of the system? ive not had a chance to have a proper look at the brake system tbh so apoligise if these questions were stupid :oops:

also i have seen on a couple of mk1's that the master cylinder(no servo) can be mounted in the engine bay on the drivers side, from what i have read this is a 17mm master cylinder of the earlier mk1???? is this right, i imagine this setup wont have enough braking force that is ideal for a 1.8t though??

any info on brake setups/pedal boxes etc etc would be extremely appriecated and save me loads of time trawling the net for answers :hehe:

thanks liam

Re: removing servo... any help??

Posted: Fri Oct 08, 2010 7:32 am
by james butler
removing the servo will be like trying to brake the car when the engine is off. (very very difficult) however changing the diameter of the master cylinder will make all the difference and if ur removing the servo then u will need all the help you can get to stop a 1.8t.

Re: removing servo... any help??

Posted: Fri Oct 08, 2010 8:36 am
by Village Idiots
Pedal boxes are available from Car Builder Solutions, Rally Design, Demon Tweeks, etc, etc.
To be able to apply enough pressure without a servo, you need to aim for a pedal with a ratio of close to 7:1 (that is length of pedal from pivot to length to cylinder rod to pivot.
Veloce Publishing do a book 'Suspension and Brakes High Performance Manual'. This explains it all in detail.

Re: removing servo... any help??

Posted: Fri Oct 08, 2010 3:36 pm
by Chaps
Liam,

I looked into this abit ago but it was going to be abit of a pain, here are a few threads off CGTI which you should have a look at and will give you abit of an idea about the work involved.

Shows pedal box and brake line setup http://www.clubgti.com/forum/showthread.php?t=216532
shows pedal box, remote reservoir, setup etc http://www.clubgti.com/forum/showthread.php?p=1442623

you can use a mk1 non servo setup but its not really recommended if your upgrading the engine to a 1.8T, imagining it'd be like trying to brake whilst being towed! not fun.

Its prob going to be £300+ for the setup, but while your doing it, you can also fit a hydraulic clutch pedal so you can use the 02A 5spd or 02J 6spd gearboxes which are alot stronger.

Just depends how much you want to remove the servo.. you should be able to get round it though with abit of clever pipe work.

Re: removing servo... any help??

Posted: Mon Oct 11, 2010 12:31 pm
by marcus
There's an interesting article at http://www.stoptech.com/tech_info/Pedal ... -Guide.pdf.

It's a bit heavy on theory but does give some insight into the issues you'll be confronting eg getting enough braking force without a servo.

Re: removing servo... any help??

Posted: Wed Oct 13, 2010 2:05 pm
by MikeH
In case it's any help, my Porsche 911 with no servo uses a 19mm master cylinder, on some big meaty brakes, over a ton of weight, and 200bhp. Without the extra pedal travel needed to operate the servo, you can afford a bit more travel in the cylinder itself, giving more braking feel, and a bit less heave needed to operate the pedal. Obviously you need to displace enough fluid to move the caliper pistons, so the relationship between master and slave cylinder needs to be right.

I don't see any issue in getting a rocco to stop without a servo. A mate up North has a 0.625 single circuit girling M/C on his track car. This was fine with 256 vauxhall brakes, but is now a bit marginal with 288 VW ones (Mk3 golf).

Re: removing servo... any help??

Posted: Sun Oct 17, 2010 7:18 pm
by nye
well im actually looking to upgrade to only vauxhall brakes anyway and poss rear discs, do you think i would be okay with a single circuit 19mm master cylinder or would you recommend a different master cyclinder for this?