Why Fit Good Quality Race Pedal Box? Does ABS Work With a Bias Race Car Pedal Box - Tech Session

Grant Loc
May 9, 2011

Hello.

This tech session is about why you should use a bias brake pedal box in a race car and can you use the factory fitted ABS system.

A good quality bias pedal box is an absolute must for any serious track day car or race car. Most car brakes systems, even when fitted with ABS, use a vacuum servo to increase the pedal force and help with braking, however in a track or race use this system is often not up to the job and you get an inconsistent brake pedal due to heat build up and general wear and tear. Also on most 'standard' brake system the master cylinder is typically only one unit that splits the braking effort to each brake within only one cylinder, this means that break bias is effectively set and although an inline adjuster valve can be fitted to change the bias. This is not ideal or as ultimately effective as a bias / balance pedal box setup. Most saloon cars now use a dual line brake system so this means just fitting bias lever is not possible.

What is a Bias Pedal Box?

A bias pedal box system firstly removes the vacuum servo that can give the inconsistent brake pedal and the pedal force from brake pedal is connected directly to the brake cylinders. This means there is no longer a reliance on a vacuum from the engine to help with the braking force.

Please be aware you will have different brake pedal feel with the race bias pedal box.

This means the pressure you hit the brake pedal with is exactly the pressure the brakes work with giving you more feel for what the brakes are doing. The other and most important part of the pedal box system in that it uses two brake cylinders as opposed to only one. This means you have one cylinder for the front brakes and one cylinder for the rear brakes, the two cylinders are connected by the adjustable 'bias / balance' bar, giving you control over adjusting the braking efforts between the front and rear brakes helping you to fine tune your brake to suit both your driving style and the weather conditions, typically in the dry you would want the front brakes doing most of the braking and in the wet or damper conditions you would adjust the braking effort more towards the rear.

A 'full' pedal box system will typically replace both the accelerator and clutch pedals/systems.

Will A Bias Pedal Box Work With My Cars ABS system?

In a word with a standard manufacture ABS system NO...... however expensive 'Motorsport' ABS systems are available but these are very rarely used.

The main problem with a using a bias pedal box with a 'standard' manufacture's system is that one of the main reasons for fitting a bias pedal box is to give you more control over your car's front to rear brake balance and a cars ABS system works to prevent your cars wheels locking up under braking...... therefore a 'standard' car's ABS isn't programmed to allow both the adjustment front to rear of the brake balance because as it sense's wheel 'lockup' it would then try moving the brake pressure to the other wheels to prevent the wheel locking and therefore acting against your chosen brake balance.

Choosing the correct bias brake Pedal Box for Your Application.

You need to take into consideration whether your car has a cable or hydraulic clutch system also bare in mind that whilst you are changing the pedal box it may be worth also converting the clutch system to a hydraulic system if it is not already.

Something that is more important in later cars you need to check how your throttle is controlled, a great deal of newer cars use a 'fly by' wire system to control the throttle rather than a mechanical cable.

I hope this has been of interest to you, please have a look at my other articles.

It would be fantastic if you can leave comments about this article, your feed back is very important to us.

Thank you for your time.

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Grant Loc has been involved with Motorsports for over 15 years and the Director of obp Ltd. obp Ltd is a major player in Manufacture and Supply of Quality Race Car Products and provides most of the leading Motorsport distributors all over the World. obp manufacture Race Pedal Boxes, Hyd Handbrakes, Alloy Fuel Swirl Pots, Alloy Fuel Tanks, Alloy Dry Oil Tanks, Alloy Header Tanks, Alloy Oil Catch Tanks, Seat Brackets etc. http://www.obpltd.com