Eliminating ABS and installing proportioning valve
 

I want to eliminate my ABS since I dont liek the system and the threads in mine are all messed up. This means I will most likely have to go and fab up some hoses for the engine bay area from the BMC to the valve to the rest of the brake system. I was thinking of using a tilton engineerign valve screw type. But now I am wondering if I will need a Bias adjuster..I'm a little confused. All I want is to be able to control the applied presure between the front and rear wheels? Also I was thinking baout just using braided stainless hose to redo the stuff up in front instead of the usual brake lines...any coments? My original plan was to just get rid of abs and install the line, but I want to be able to control the valve form the cockpit. Myabe keep some of the original line and use stainless to route to the valve in the cockpit?

hello from another wisconsinite:)

i removed my ABS along w the wheel sensors a few years ago. i retained the stock proportioning valve that bolts to the main ABS unit.

i run 18 X 8.5 front and 18 X 10 rear w 245 and 285 rubber.

i run Lockheed AP 4 piston calipers w 13 X1.25 inch front rotors and stock in the rear along w EBC greens on the street.

minimal brake dust on the inside of my rear wheels indicates the rears need to be cranked up a bit.


the $40 splice in to the rear line brake proportioning valves won't work in my situation as i need more rear brakes not less.

when i get the time i am going to switch to a Tilton adj brake bias bar which has been done before and IMO is the only solution. two master cylinders will be needed and sizing will be important both between front and rear but overall as the system will need to be converted from power to manual.

let me know if i can be of further help and you are welcome to stop by.

howard coleman
fredonia wi

ARe you saying I can't control the bias of the rear with a proportioning valve? I thought the whole point was to be able to decrease or increase presure to the rear with one.

I think Howard was too busy telling you what was on his car to answer your question. Lol

You can buy the braided lines from summit racing. You will need the wilwood proportioning valve. You need to remove the stock one. Tee the front lines together run the out of the tee to the bmc then run the second bmc line to the in port of the proportion valve. Run the out line of the valve to the rear brakes. Bledd lines and adjust accordingly.


Have fun:

Thank you very much BOOST. I was actually looking for the lines on summit racing haha.

I wish I could tell you the thread pitch. I don't know what it is off the top of hy head anymore. I was about to swap my homemade hard lines over to some of the braided ones as well so please post if you know the thread pitch. I would appreciate it. Otherwise I'll have to measure it the old fashioned way. :)
Anyway good luck. I'd like to see photos if you end up mounting the proportioning valve in the cabin.

I most definitely will. I think its best to have something like that in the cabin. Or maybe I'll make a little step motor for it and just keep an electronic nob in the car. Though I'm not even sure where to start from if I do that...guess I would have to do some electronics research.

Yea I would think so.
It is kind of a pain to adjust the bias by getting out of the car every 1/8 mile and popping the hood.

the intended point of my post was to present the consideration that perhaps the proportioning need in your car is similar to my car and if that is the case a brake proportioning valve in your rear system will not fix the problem as it can only decrease rear bias. i disclosed my mods so that you'd know i have a number of mods which could be causing my problem, i e larger tires.wheels at the rear and non stock front brakes.



howard coleman

Stock and aftermarket proportioning valves are too completely different animals. Stock proportioning valves are not linear in their reaction. They are tuned to the car and allow the rear brakes to do more work at lower speeds.

http://www.stoptech.com/tech_info/img/figure_c.gif

Using a race type proportioning valve or balance bar gives a truly linear response. However, this response can only be tuned to maximum braking in a straight line. At anything less than maximum braking the rear brakes are being terribly underutilized and therefore the fronts must work harder than they should. Not ideal for street driving.

http://www.stoptech.com/tech_info/img/figure_b.gif

Stoptech has an excellent article here:

http://www.stoptech.com/tech_info/wp...g_valves.shtml

Long story short it's not as simple as most would insist.

I would not use anything but metal brake line under the hood of the car. Don't use flexible braided hose unless you need to. Metal lines give better response.

Ah I read all of the stuff on stoptech before I posted this actually DamonB, and thats why I asked if it would be better to go with metal lines. But isnt it true if I have the dial in the cabin I can simply adjust the proportioning to street use and then tune over to a diffrent setting for track?

No. A stock type proportioning valve and an aftermarket proportioning valve or balance bar are fundamentally different. The stock type valve has a knee in its response where the rate changes and so keeps the rear tires closer to threshold over a greater range of decel rates. Aftermarket valves are linear; notice figures "B" and "C". The aftermarket valve can only be set to work best at a single rate of decel which is fine when racing and at maximum braking all the time. Anytime the aftermarket equipped car is not experiencing the decel the valve or balance bar is optimized for the rear brakes aren't doing much work.

Howard, if you went with the '99 rear brakes, I would think the increased braking power at the rear of the car may help your existing balance. You may be satisfied with the results from just that mod. Just my 2 cents. :)

Does anyone know where to get the for brake line fittings by the way? I'm having a hard time finding them.

Any good auto parts store like NAPA etc should have the fittings and be able to make custom steel lines.

AP Racing has good info like a pressure knee-chart on it's proportioning valves, that I haven't seen for WilWoods, Ford, Summit, Jegs, etc.

http://www.apracing.com/info/index.a...ng+Valves_1240

Lever Type Prop Valves - Single Bore - CP3550-13 / Twin Bore - CP4550-1
Screw Type Prop Valve - CP3550-14

Respective PDFs:
Lever Type Single Bore: http://www.apracing.com/drawings/cp3550-13cd.pdf
Lever Type TwinBore: http://www.apracing.com/drawings/cp4550-1cd.pdf
Screw-Type: http://www.apracing.com/drawings/cp3550-14cd.pdf

:-) neil

BTW: if I'm reading Robinette's site correctly, he placed the proportioning valve on the FRONT brake lines, which per the StopTech article is a no-no (terminal oversteer).

http://robrobinette.com/brake_valve.htm

http://www.stoptech.com/tech_info/wp...g_valves.shtml
excerpt:

We’ll start here with three of the most basic rules regarding proportioning valve installation and selection.

<SNIP>

2. If you have the deeply-rooted need to install your own adjustable proportioning valve, be advised that they should NEVER be installed in-line to the front brakes. The effect would be to make your vehicle rear-biased before you could say “terminal oversteer.” Front brake line pressure should always be left alone – only the rear pressures should be considered for proportioning.