Worlds Fastest Comanche Posted July 5, 2010 Share Posted July 5, 2010 We were having a little trouble witht he front end shaking wnen we were coming down from 127mph. We pulled the wheels and found the drivers side rotor had 2 cracks in it and was blue. I ran out to the local Autozone and was amazed that they actually had a couple in stock. Made a couple of runs with the new rotors and they turned blue as well. I did crank in the proportioing valve all the way in, The factory valve under the pickup bed is long gone, i just have a ss brakes unit with a knob for adjustment. The adjustment was set in the middle to start, so turning it all the way in should shift more load to the rear brakes. The front tires are only 22.5" diameter, so at 150mph the front wheels are turning at about 2250 rpm, the reeas have 25.4" tires and would be going about 2000 rpm at the same ground speed. The rear tires are larger and wider, so they can exert more force on the brakes than the front, so i may be better off putting the proporting valve on the front rather thasn the rear. I do have the metric ton option. Lee from Hesco suggested that if we just got rid of the front brakes all the problem will go away. Just use rears. Dragsters don't have front brakes. I think for not i will just pick up some cross drilled and slotted rotors on ebay, and just the chute over 125 Link to comment Share on other sites More sharing options...
Automan2164 Posted July 5, 2010 Share Posted July 5, 2010 Sounds like your cranking out some heat Pete. Is there anyway to introduce some more airflow around the brake area? Maybe a baffle or two to re-direct some air towards the front calipers? A tube from the grill to the brake area? The cross drilled and slotted rotors might help a bit... Any pics? Rob L. Link to comment Share on other sites More sharing options...
jimoshel Posted July 5, 2010 Share Posted July 5, 2010 Brakes interfere with going fast. Leave 'em off. Link to comment Share on other sites More sharing options...
Eagle Posted July 5, 2010 Share Posted July 5, 2010 How hard are you using the brakes to slow down? Blue obviously indicates a LOT of heat. Considering that in my racing days at Lime Rock I was using the brakes quite a bit all the way around the track and I never saw a discolored rotor, I'm inclined to think that you have a dragging brakes problem. Link to comment Share on other sites More sharing options...
kro10000 Posted July 5, 2010 Share Posted July 5, 2010 The cross drilled and slotted rotors might help a bit... I wouldnt recommand them for what you are trying to do, cross drilled rotors really are only to help reduce brake fade after repeated use, which would mainly mean a road race/circle track car. His brakes only need to work once in a long period of time, not many times in a short period of time. Really for this purpose they would present a hazardous situation due to the greater likelihood of them breaking. Slotted would really have no benefit at all, as they are really to help responsiveness. I have had the opportunity to work on a couple track cars, mainly porshes (mostly 944s, and one 911 turbo) I have seen heavily cracked rotors but never any that were blued. I would have to agree with what was said above, you seem to be having a dragging issue. I would also consider cooling ducts as well for the brakes, but I doubt itll solve your issue. I don't know a whole lot about top speed cars, but I'd kinda wonder if having no front brakes would be kind of dangerous. It might be a little squirrly when you brake. Also youve lost your fail safe, cause if those rears go out for any reason, then youd better have enough room to roll to a stop. Of course youve got engine braking as well, so that may be a non-issue. Anyway theres my $.02 Link to comment Share on other sites More sharing options...
500 MJ Posted July 6, 2010 Share Posted July 6, 2010 http://www.frozenrotors.com From their site: "The name says it all: we freeze brake rotors...rock solid. We use a deep-cryogenic process that permanently changes the atomic structure of a rotor at 300 degrees below zero. We’ve got answers to any technical question you might have. But the real truth is our rotors will stop any vehicle cold! In the past six years, we’ve developed an avid following of "Raving Fans" that will tell you (in their own words no less) that their brakes don’t fade, don’t warp and last two to four times longer. And any racer will tell you races are more likely to be won with the brake pedal rather than the accelerator." I have a set of these (Frozen Rotors Slotted model) on the front end of my '90 2wd and I LOVE them... Generic parts house rotors weren't going to cut it for me when I wanted to redo the front brakes last year, I wanted something worth putting on the truck now with the truck's future in mind. This might be something to look into for you too maybe? Link to comment Share on other sites More sharing options...
Worlds Fastest Comanche Posted July 7, 2010 Author Share Posted July 7, 2010 The brakes are not dragging, just way too much energy going into them. I will shift more load to the rear and toy the forzen rotors, we will see what happens. Link to comment Share on other sites More sharing options...
Incommando Posted July 7, 2010 Share Posted July 7, 2010 I know you have probably thought of and eliminated this possibility, but are the spindle bearings up to snuff? I was thinking maybe it could be a combination of issues... Link to comment Share on other sites More sharing options...
Eagle Posted July 7, 2010 Share Posted July 7, 2010 I know you have probably thought of and eliminated this possibility, but are the spindle bearings up to snuff? I was thinking maybe it could be a combination of issues... How fast are you trying to haul it down? The original (1968 - 1970) Javelins and AMXs had small-ish NON-VENTED rotors on the front and drums on the rear. My '68 Javelin was good for a verified 147 MPH and I never had a rotor turn blue. They did have a tendency to warp over time, and when I built another car as a dedicated road race/hillclimber I swapped in the larger, ventilated rotors (and matching calipers) from a '73 AMC Rebel. But I still think you have a functional problem in the front brakes. Link to comment Share on other sites More sharing options...
Comanche County Posted July 7, 2010 Share Posted July 7, 2010 ...when we were coming down from 127mph. Kinda wish I had that problem, max speed my truck has seen is 79 mph coming down a huge mountain in 'Georgia Overdrive'. Link to comment Share on other sites More sharing options...
kastein Posted July 7, 2010 Share Posted July 7, 2010 I've had mine up to 100 a few times, handles great. Never gone much past that though. I'm nowhere near flooring it when I hit 100, and it'd probably help if I closed the windows and removed/opened the tailgate. Link to comment Share on other sites More sharing options...
knever3 Posted July 9, 2010 Share Posted July 9, 2010 http://www.frozenrotors.com I agree. I purchased cryo-stop rotors for my '01 XJ and loved them too. I would recommend HAWK performance pads with the frozen rotors. My friend with a BMW had HAWK HPS pads on his car and from 140mph he said "Want to see how it stopps now?" I was horrified because jamming hard on the brakes at that speed is a good way to get killed. To my suprise the rear end got loose for a split second and then I was faithful in my seat belt from there. With that combination you should be great. Hawk HPS pads are no more expensive than any other nice pads like Bendix or Rayworst's. Link to comment Share on other sites More sharing options...
Pete M Posted July 9, 2010 Share Posted July 9, 2010 I've had mine up to 100 a few times, handles great. Never gone much past that though. I'm nowhere near flooring it when I hit 100, and it'd probably help if I closed the windows and removed/opened the tailgate. Actually, the mythbusters showed that tailgate-up has the least resistance. :D Link to comment Share on other sites More sharing options...
kastein Posted July 9, 2010 Share Posted July 9, 2010 I've had mine up to 100 a few times, handles great. Never gone much past that though. I'm nowhere near flooring it when I hit 100, and it'd probably help if I closed the windows and removed/opened the tailgate. Actually, the mythbusters showed that tailgate-up has the least resistance. :D Interesting. I don't think mythbusters is the most scientific group around (some of their tests are downright stupid and don't prove anything), but I see why it would be that way now that I think about it more. Link to comment Share on other sites More sharing options...
Pete M Posted July 9, 2010 Share Posted July 9, 2010 but how else would I know that in a pinch I can use duct tape to fashion a bridge or a cannon? :yes: They hit the tailgate thing twice. plus, if it were true that dropping a tailgate would improve performance, don't you think the auto manufacturers would do that in a heartbeat? seems a lot cheaper than a hybrid motor. Link to comment Share on other sites More sharing options...
kastein Posted July 9, 2010 Share Posted July 9, 2010 Oh, I'm not debating that it's an awesome show. If I had cable, I'd watch it. I just can't stand some of the shortcuts and leaps of judgement they make while "proving" things :D Link to comment Share on other sites More sharing options...
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