JMortensen Posted May 19, 2006 Share Posted May 19, 2006 I don't think most people even know what brake bias is, let alone identify the fact that it is way off. They put huge brakes on the front and they're all proud of how cool it looks in their blingy 18" wheels, but they don't realize that they've actually increased their stopping distances from stock, at least before fade sets in on the stock setup. At least you can pat yourself on the back for realizing what the problem is. Now you just need to figure out how to fix it. Good luck with that. Quote Link to comment Share on other sites More sharing options...
clarkspeed Posted May 20, 2006 Share Posted May 20, 2006 If your bias is way off, you will see noticable difference in wear on the fronts vs. backs. More heat also. Again, you might experiment with pad materials first since that's the easiest. What tire and size are you running? Stopping distance is always limited by the Cof between the tire and the road, not the size of the brakes. The bigger brakes will only allow you to modulate and control heat better. Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted May 20, 2006 Author Share Posted May 20, 2006 clarkspeed & jon, thanks for the continued input. i have noticed greater wear on the fronts. the primary reason that i upgraded the brakes it that i lost mine coming down the front straight at watkins glen [before u ask, i had newly bled system, syn fluid, hi perf front pads, new rear wheel cyl's]-vowing that would never happen again! it was a very interesting experience-hopefully no one on this site will have to go thru. i'm hoping ross will chime in soon and help me out with this delimma. just not safe with the current setup. more info-when i first did this upgrade, i was running dual tilton masters with a balance bar-cable adjusted in cockpit [didn't have enuf rear brakes with that system either, but was better than i have now...]. didn't like the lack of streetability, so i reverted back to the regular old booster & zx master. i have yokohama avs 235.40.17 tires on all 4 corners, custom built compomotive wheels, all tucked under the stock fenders. on pads, i'm not certain what would be the best way to approach this-more bite in the rear or less in the front?? Quote Link to comment Share on other sites More sharing options...
Modern Motorsports Ltd Posted May 20, 2006 Share Posted May 20, 2006 David, sounds like you're closer to getting back to your excellent function you had prior for the last few years before these recent control system changes. For info of others, none of our brake setups are touchy, proper results is quite the opposite experience! The rear is 11-3/8's and well matched with the front, this is long proven with many successfully enjoying this exact brake combo with 7/8's and 15/16's MC's. Others may not be aware, but you've run the combo for ~ 3 yrs now with excellent results - outbraking factory Cobra kit cars as I recall from one of your feedbacks! Your original setup you customized with dual MC's. What I understand you've changed this spring is : went back to the factory '73 brake booster 'upgraded' to the 15/16 master (only an upgrade if you truly prefer that pedal feel, an optional change from the 7/8's factory piece) removed the factory safety valve and prop valve installed new custom front lines to move them away from the headers installed a wilwood prop valve inline for the rears I would look at the integrity of all your changes you noted in above points. Your front and rear brake packages are complete themselves and work excellent as a system with a factory MC as you've changed to. Proven on your car and others in recent years, whether with 7/8's (yes, 7/8's), 15/16's or dual MC's. You've eliminated at least one item with your reaction disk apparently. Are you certain that booster is perfect in all other functions? Any chance any junk got into your brake lines/prop valve during all your line/MC changes? My inclination is you're not getting proper rear pressure so front's are doing excess reaction work and they're getting excess pressure. Could be caused by disfunctioning booster/MC and/or junk in your brake lines/distribution block perhaps including your prop valve? But hard to know for sure. It would surprise me as I know how detailed you are with changes but perhaps some grit got in somewhere or the booster/MC combo itself isn't behaving 100%? Please drop us a direct email to let us know how you make out and we'll see you through to your return performance. Your last email inquiry via our site had an email reply address of , please let us know current email and we'll update our records. Are you going to Texas for the Convention? Lots actively completing their installs right now in preparation for the convention! We've got some products available their from our suspension and billet drivetrain lineup included in their event auction for charity, a few excited about the opportunity! Cheers David and we look forward to hearing back from you, Quote Link to comment Share on other sites More sharing options...
Guest DISCUS Posted May 20, 2006 Share Posted May 20, 2006 I am not a brake expert but I have the same set-up installed with the factory 240z mc. I did install the wilwood proportioning valve to the rear brake lines. It took a bit of tuning but achieved great results! All my lines are stock with stainless braided at the wheels! 13 on the front and 11- 3/8 on the back! The car is LT1 with 375 hp at the rear wheels. Initial settings gave me a lot of rear wheel lock-up and I had to keep tuning to get the proper balance! Did not change the pads provide or alter any other parts of the set-up! Good luck with the fine tuning! Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted May 26, 2006 Author Share Posted May 26, 2006 when u state 'same setup', can i assume that you've also removed both of the factory safety valve [driv fender] and prop valves [firewall]? I am not a brake expert but I have the same set-up installed with the factory 240z mc. I did install the wilwood pro-portioning valve to the rear brake lines.It took a bit of fiddling but achieved great results! All my lines are stock with stainless braided at the wheels! 13 1/2 on the front and 11 on the back! The car is LT1 with 375 hp at the rear wheels. Initial settings gave me a lot of rear wheel lock-up and I had to keep fiddling to get the proper balance! Did not change the pads provide or alter any other parts of the set-up! Good luck with the fine tuning! Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted May 26, 2006 Author Share Posted May 26, 2006 completed changing the master cyl last evening, bench bled it first, bled the brakes-actually took less time that i anticipated. clean fluid, nice firm pedal, took it out for test drive...front brakes still locking. can't get rears to lock. i've [if you've seen earlier posts] removed the wilwood prop valve as well so my system is now is as simple as possible. stock 73 vac booster, zx 15/16" master [with the front & rear lines connected correctly], no factory safety valve or prop valve. any thoughts if i were to swap the lines to the master, ie-connect the front to the rear and rear to front? HELP!! Quote Link to comment Share on other sites More sharing options...
JMortensen Posted May 26, 2006 Share Posted May 26, 2006 All swapping the lines would do is give you a smaller reservoir on the front brakes. You want the large reservoir to go to the fronts, because they'll displace more fluid as the pads wear down. I think you need to go back to your dual masters. You could play with compounds but if it's a street car you don't want some weird mix of pads where the rears are super aggressive but need to heat up to work, because that would probably actually be worse than what you've got now. Quote Link to comment Share on other sites More sharing options...
Guest DISCUS Posted May 26, 2006 Share Posted May 26, 2006 Yes, ! Tuff Z, I removed the factory proportioning valve on my 73 240z, installed the front 13 Xtreme setup along with the wilwood proportioning valve inline with my rear brakes. All items supplied by Modern Motorsports ltd. I adjusted my setup at a loacl autocross event where my initial problem was too much rear lockup in the stop box. Adjusted during the days runs achieved the bias to where I was very satisfied. The install was in the summer of 2002 and the balance has stayed excellent since for several autocross events. Last summer, 2005, my wife and I avoided a certain t-bone style collision when a truck came across the highway unexpectedly in front of us. The extreme braking caused a lot of neck discomfort for my wife and I but saved an accident. We were travelling approx 85 mph when I came to a panic stop! Brakes worked perfect, no collision and my confidence in the setup is complete! Sorry if my initial comments were incomplete or not as detailed as you wished! I believe i did not specify the sizes correctly but have edited my initial post to reflect the appropriate dimensions front and rear! With respect to the factory valve on the driver fender I believe it is still intact! If you wish I can double check on that! Hope this additional information helps. Quote Link to comment Share on other sites More sharing options...
Guest DISCUS Posted May 26, 2006 Share Posted May 26, 2006 Hi TuffZ, I have received your request for further confirmation of exactly how mine are hooked up, so i think the best way to deal with this is as follows. When I get off work tonight approx 10 pm MST I will take pictures of the exact pieces left connected and post those tomorrow when I return to work. I only have the internet hookup on my office laptop with high speed or I would relay the stuff tonight! hope this helps! Quote Link to comment Share on other sites More sharing options...
Guest DISCUS Posted May 27, 2006 Share Posted May 27, 2006 Hi David, quick summary, I have a group of pictures showing my setup but am having difficulty attaching them to a HybridZ reply due to file size! Perhaps also my computer skills are lacking to make the adjustments. Please send me a private message with a regular email address and I will send out the pictures. They will show changes made to prevent heat problems from my headers and the valves used in proper positioning! The firewall valve has been removed and replaced by the Wilwood, the factory driver fender valve is in use but shielded and on the frame rail! Farside front line is lengthened and repositioned away from headers on that side as well. I have also modified my front air dam to provide cooling air to the front brakes under heavy use. i can also send you a picture of that if you wish. Frank Hope this will help you. Quote Link to comment Share on other sites More sharing options...
1 tuff z Posted August 9, 2006 Author Share Posted August 9, 2006 spent much time on the phone with several brake company engineers [they continued to refer me to another one] and i began at classic tube then baer brakes then kvr and finally hawk. my last move prior to any mechanical changes was to install the new kvr pads on all 4 corners [got them from ross], properly bed them in and still had too much front brake. so, what i wound up doing was to change rear pads from the kvr's to a higher coefficient of friction pad-the hawk hp+, bedded them in and went for a test drive. initial drive went well, bias appeared to be acceptable and all felt 'good'. the real test-track days at watkins glen. well, if you're a regular here you already know that the 2 day event at wgi went very well for me. brakes worked great, no fading or pulling, good modulation and minimal wearl. overall i'm extremely happy. i discovered that none of the components were 'bad' and i now suspect the bias problem is solved through some fine tuning via brake pads. i can supply the hawk pad numbers for anyone interested as well as their race pads. glad that problem is solved! now on to tackle my q45 diff install...this winter Quote Link to comment Share on other sites More sharing options...
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