Brake system????

rallye bob · Post by **rallye bob** » Tue Oct 23, 2007 7:27 am

Who can help me design the hydraulics part, of a disc drum 3500 lb. drag car, that runs in the mid. 10's @ around 120-130 mph? I am looking for advice on M/C bore size, (i am going to use a Strange Eng. M/C) residual valves, prop valves, do I use the stock combo. valve? I am using the Aerospace ac-205 front disc kit, and the stock drums on the rear. Any help in this area would be greatly appreciated, as the braking as I have it set up now is atrocious.

MileHighMan · Post by **MileHighMan** » Wed Oct 24, 2007 9:02 pm

rallye. I also go mid 10s @ 129mph. I have the stock front disc brakes, and a touch larger chrysler rear drum on the rear. Here in Albuquerque, we have a decent in length , but a little lumpy shut down area. Anyway, It seems your car has the ability to accelerate faster [and most do] than stop. That too, is dangerous. Good Luck. Dan.

af2 · Post by **af2** » Wed Oct 24, 2007 9:14 pm

The smaller the M/C bore the more pressure. I run a 1" bore with 4 wheel 4 piston disks. Works good.

rallye bob · Post by **rallye bob** » Thu Oct 25, 2007 5:25 am

af2 wrote:The smaller the M/C bore the more pressure. I run a 1" bore with 4 wheel 4 piston disks. Works good.

Just to clarify, this is for a drag race only system/car...
What are the other components to your brake system?
Is your m/c higher than your calipers (mine is)?

af2 · Post by **af2** » Thu Oct 25, 2007 3:00 pm

rallye bob wrote:
af2 wrote:The smaller the M/C bore the more pressure. I run a 1" bore with 4 wheel 4 piston disks. Works good.
Just to clarify, this is for a drag race only system/car...
What are the other components to your brake system?
Is your m/c higher than your calipers (mine is)?

Mine is drag race only also. (Notice Avatar) 33 Willys Coupe.
I use a Wilwood 1" master that is higher than the calipers.
I am using 4 piston Outlaw calipers front and 4 piston Wilwood superlites rear. There is a line lock also that I don't use. Other than that it is very simple and straight forward.

af2 · Post by **af2** » Thu Oct 25, 2007 6:04 pm

rallye bob wrote:Who can help me design the hydraulics part, of a disc drum 3500 lb. drag car, that runs in the mid. 10's @ around 120-130 mph? I am looking for advice on M/C bore size, (i am going to use a Strange Eng. M/C) residual valves, prop valves, do I use the stock combo. valve? I am using the Aerospace ac-205 front disc kit, and the stock drums on the rear. Any help in this area would be greatly appreciated, as the braking as I have it set up now is atrocious.

I hit quote this time!

Make sure the rear output doesn't have residual 2lb valve installed before you add them!!!!
I would NOT use the factory combo valve! Orifices in the original slow the pressure to the calipers. Just make sure the drums get 2lbs residual and you will be fine.

David Redszus · Post by **David Redszus** » Tue Nov 27, 2007 4:54 pm

The braking performance of any vehicle depends on the ability of the tires to transmit braking forces to the ground.

The force transmission of the tires is depenpent on vertical loading at each tire, tire to ground slippage and friction coefficient of tire and ground.
The vertical tire loading is modified (rear to front) as a function of longitudinal weight transfer. The amount of weight transfer results from the vehicle total weight, center of gravity height, G force and wheelbase.

If a substantial amount of weight is transferred to the front, the rear tires cannot contribute to stopping the vehicle and only the front tire must do the entire job. Pretty tough on front brakes and front tires.

A proper brake design will provide braking forces to each wheel in proportion to the load capacity of each tire.

rallye bob · Post by **rallye bob** » Wed Nov 28, 2007 7:16 am

David Redszus wrote:A proper brake design will provide braking forces to each wheel in proportion to the load capacity of each tire.

................and that is what I would like to accomplish.

David Redszus · Post by **David Redszus** » Wed Nov 28, 2007 9:19 am

The easiest way to test a brake system is to try to lock up all four wheels simutaneously. If the distance between the front skid mark and the rear skid mark is equal to the length of the wheelbase, the brakes are working properly.

Engineers will use a wheel speed sensor at each wheel and measure wheel slippage to the ground.

Designing a proper brake system on paper before buying any parts is the smart path. But it does take a great deal of vehicle information such as: vehicle weight, wheelbase, center of gravity height, brake/drum diameter, tire diameter, tire coefficients, master cylinder size, caliper and wheel cylinder size, friction material coefficients, brake bias, etc.

And then there is the task of trying to keep the tires on the ground.

Don Terrill’s Speed-Talk

Brake system????

Brake system????

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