heavy85 Posted February 13, 2009 Share Posted February 13, 2009 The rear bias valve, if you mean an adjustable prop valve, doesn't change the bias in the same way. It has a knee in its pressure curve, so it is useful to have one so that you can get the max amount of pressure at low speeds and have it taper off at high speeds, this all being in addition to the bias bar. Net result is similar so what's you point? Quote Link to comment Share on other sites More sharing options...
Mayolives Posted February 13, 2009 Share Posted February 13, 2009 As alluded to above, there are combinations of cylinder sizes, stroke, fluid type and, pads that must be accounted for. When doing my basic adjustments, I followed Mr. Coffee's recommendations by setting the propertioning valve in a natural manner and then fine tuning the system with the balance bar. This is what works for me in my 2400 # road race car. Arizona Big Brake Kit on all corners Wilwood pedals, 5/8", 7/8", 1" Wilwood cylinders Wilwood Knob Style Propertioning Valve Wilwood Remote Balance Bar Cable Adjuster Wilwood "H" Poly-Matrix Pads on all corners Motuol 600 fluid Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 13, 2009 Share Posted February 13, 2009 Net result is similar so what's you point? Not similar. As you slow down the rear wheels can handle more braking effort. If you use a balance bar only, then when you're going fast you'll set it so that it is biased correctly, but that will be a lot less braking than the rear tires can handle when you're going slow. By running a prop valve you get a steeper increase in the braking pressure that then tapers off at higher speeds. This in combination with the bias bar, should get you a lot closer than either one alone. The next logical question is "which prop valve gets you the closest?" I don't know the answer to that and I don't have the money/time/patience it would take to get it dialed in absolutely perfectly, but I will run the adjustable prop valve I already have in an attempt to get as close as possible with the least amount of work... More info: http://www.stoptech.com/tech_info/wp_brakebiasandperformance.shtml http://www.stoptech.com/tech_info/wp_proportioning_valves.shtml Quote Link to comment Share on other sites More sharing options...
heavy85 Posted February 13, 2009 Share Posted February 13, 2009 Uh yeah I know how these work I still dont get your point. This is a race car (primarily anyway) so I want to tune the upper range ... which can be accomplished through piston sizes (MC or caliper) and / or bias valve if you are rear biased. Not too concerned at this point with slow performance and I'm not going to run a dual master set-up. I'm trying to develop my set-up based on a real world comparable system with test results and get the basics well balanced. So back to my question to Myron ... do you know if the bias bar is towards the front or rear? In other words without dual masters would I need a rear bias valve to get it nailed? Also,where did you end up with pads? Cameron Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted February 13, 2009 Author Share Posted February 13, 2009 I have a little more bias towards the rear so I don't think a prop valve will help much. I'm still running the same pads(AZC front, Dave calls them "street pads", and porter field R4-S rears) The bias isn't much towards the rear, in fact my balance bar is almost dead center. If your planning to go with smaller calipers up front you might be able to tune the bais with pads. Quote Link to comment Share on other sites More sharing options...
drmiller100 Posted February 13, 2009 Share Posted February 13, 2009 Not similar. As you slow down the rear wheels can handle more braking effort. l Wow. So what is your logic??? The car has different transfer at different speeds??? Quote Link to comment Share on other sites More sharing options...
JMortensen Posted February 13, 2009 Share Posted February 13, 2009 Wow. So what is your logic??? The car has different transfer at different speeds??? I got a little confused there. Higher brake pressures, not higher speeds. I don't hit the brake with the same amount of force in every situation, even on the track. Quote Link to comment Share on other sites More sharing options...
johnc Posted March 5, 2009 Share Posted March 5, 2009 Myron, One thing to check on your balance bar setup... Make sure the clevis' don't bottom against the tube under hard braking. Check it yourself while someone else mashes the brake pedal or put a piece of tape around the edges of the tube and do a track session. Check the tape for marks. A customer had an intermittent front lockup problem last weekend with his home built bias bar setup and that's the problem we found. Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 5, 2009 Author Share Posted March 5, 2009 Thanks for the tip John. I'll be sure to check it out. Just to be clear your talking about the tube that holds the spherical bearing and the clevis's possibly hitting the sides of that tube, right? Quote Link to comment Share on other sites More sharing options...
johnc Posted March 5, 2009 Share Posted March 5, 2009 Yes. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 5, 2009 Share Posted March 5, 2009 Was that an issue where the clevises weren't far enough apart due to someone threading them onto the balance bar wrong, or was it an issue with the tube in the center being the wrong size? I'm having a hard time understanding how that issue came about... Quote Link to comment Share on other sites More sharing options...
johnc Posted March 5, 2009 Share Posted March 5, 2009 Wilwood MCs were mounted too close together so the pushrods, when set in line with the MCs, put the clevis' almost touching the balance bar tube. Balance bar articulation caused front brake MC clevis to bind on the tube and end any further articulation of the balance bar. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted March 5, 2009 Share Posted March 5, 2009 Ah. Tilton has several different widths on the masters. I guess the wider the better. I can't remember which one I bought... http://www.tiltonracing.com/pdfs/28.pdf Quote Link to comment Share on other sites More sharing options...
johnc Posted March 5, 2009 Share Posted March 5, 2009 Tilton has several different widths on the masters. Balance bars. All Tilton master have the same external width (OD). I typically use the -250 balance bar and the Tilton master cylinders need to be spaced 2.5" apart, center-to-center. Funny how the balance bar has the spacing as part of the part number. Quote Link to comment Share on other sites More sharing options...
EMWHYR0HEN Posted March 6, 2009 Author Share Posted March 6, 2009 I took a good look at the system under a good amount of load and everything checks out alright. I remember reading that it's really important to make sure that the clevis to clevis distance is setup properly (in my case it was the Tilton 2.5''). So basically that means your MC center-to- center distance should correspond to your balance bar. I do remember it being a PITA locating the MC position on the pedal assembly. I really helped to have a drill press and a sharp hole saw for the MC holes. Quote Link to comment Share on other sites More sharing options...
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