remote brake servos

[Sx279]

any body have any experience with them?

currently ive got porsche boxter rear calipers on the front and 325 rear disc set up on the back... oh with bias peda box

but feb time i will be changing to noble m400 calipers on the front with 301mm disc from pug 405hdi

remote servo (front only)

then on the back will be the porsche boxter calipers currently on the front with a 290mm disc from mini cooper s

how can i work out what servo is best for me? currently i am looking at these two.....


http://www.ebay.co.uk/itm/NEW-LOCKHEED- ... 4873e9b869


http://www.ebay.co.uk/itm/NEW-LOCKHEED- ... 4871ee0896


thanks

[Mikey_Boy]

With all those mods, why are you even bothering with a servo??

I'd be doing the sums and having a direct pedal with that lot, especially for track work...

[Sx279]

i dont feel comftable standing on the pedal and feel i could brake abit later with a servo...

what calculation do i need to do to work out a better MS setup then because i could try that first bfour getting a servo

[Mikey_Boy]

Google is your friend - there are lots of articles online...

You will need to know the piston area of your calipers as a starting point and you *may* need to increase your pedal ratio (that is, increase the size do the lever that you are pushing).

Have a mooch - it might save you time and money!

[Sx279]

cheers mate

[Mikey_Boy]

See, the issue with remote servos is that they are just that - remote, and so their response might be compromised due to their location. In reality, even a standard servo could be argued as remote as it's on the other side of the bulkhead on a RHD car and as the connecting bar flexes, that in itself creates issues. Moving it further away is only going to be worse. Best place for a servo is directly on the brake pedal which is why I suggest a direct pedal with no servo.

The maths is fairly complex but stick with it and you should get a good result!

[Sx279]

to be honest i spent 20 mins trying to find how to calculator but found nothing lol

[Motorhole]

If its any use, I have e36 m3 brakes (so single 60mm piston, 315mm disc) up front and 318ti (23mm piston, 260mm disc iirc) rear with a bias box. 6:1 pedal ratio, no servo, 0.625" m/c front, 0.70 m/c rear and its perfectly drivable. Even in town traffic. Doesn't need a great deal of pressure to lock the front wheels, on road tyres. I mean its noticeable over the servo assisted brakes of my daily driver but not at all difficult to drive.

[Mikey_Boy]

Have a look here:

http://www.tceperformanceproducts.com/bias-calculator/

It's not exactly what you need, but it will help you play with the numbers required to get a feel for what's needed for a reasonable pedal effort - their view on 60 pounds pedal force (27.2 kg) is also about right for a track car.

Motorhole is also in a good place with his m/c sizes for the brakes he has so you can use that as a starting point for your set up...

Hope that helps!

[Motorhole]

Have a look here:

http://www.tceperformanceproducts.com/bias-calculator/

It's not exactly what you need, but it will help you play with the numbers required to get a feel for what's needed for a reasonable pedal effort - their view on 60 pounds pedal force (27.2 kg) is also about right for a track car.

Motorhole is also in a good place with his m/c sizes for the brakes he has so you can use that as a starting point for your set up...

Hope that helps!

That web calculator looks kinda similar to the spreadsheet I put together with the help of Geoffbob. The spreadsheet estimated 29.6kg at the brake pedal (with my setup) to execute a 1G deceleration but there are a lot of assumptions involved (coefficients of friction, centre of gravity of my car, weight distribution etc).

In my very unprofessional opinion though, nailing down all these variables to size master cylinders to the nearest mm is really an effort in turd polishing. Cylinders are available off the shelf in certain fixed sizes and there is quite a lot of room when setting up the pedal box for getting the static bias right (i.e. where you want the bias to be before you starting twiddling knobs), provided the master cylinder sizes arn't a million miles off. If you have suitably large piston surface area, a pedal ratio of around 6:1 and sensibly sized masters, you shouldn't need a servo unless you have legs like bambi.

The spreadsheet works by inputting lots of data, then picking a size for the front m/s (because the fronts will be doing most of the braking). It then calculates the size for a rear m/s to match and estimates required force on the pedal. Pick the front m/s size carefully, remembering that a bigger m/s shifts more fluid - so has less pedal travel, but requires more pedal effort.

If it's any use to you, drop me a pm with your email address and I'll fire it your way

[Mikey_Boy]

^^^ And that sums it up very well indeed!!