Guest Mike Posted January 1, 2007 Share Posted January 1, 2007 WHEELMAN... Thanks for your thoughts. I realize you're trying to remain open-minded. I just don't think it's necessary for us to destroy someone's ego to make a point. That's all I meant to say. Mike,You know sometimes the biggest favor someone can do for us to tell us we're being stupid and to get a clue. Don't be so thin skinned about BJ or any other "older guy" saying something that may sound a little harsh, it might be the thing that gets the guy's attention and makes him realize he's just being dumb. It might even save his life because he stops blaming the equipment for his problem and learns how things work before his lack of experience kills him. Wheelman Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 1, 2007 Share Posted January 1, 2007 WHEELMAN... Thanks for your thoughts. I realize you're trying to remain open-minded. I just don't think it's necessary for us to destroy someone's ego to make a point. That's all I meant to say. Mike, with the number of really bad posts that you've contributed lately (Since November) I'd think you'd lay low and fly under the radar more... But it's apparent to me that you're incapable of being content reading more and posting less... Mikelly Quote Link to comment Share on other sites More sharing options...
datsunlover Posted January 2, 2007 Share Posted January 2, 2007 Ahem..ah, ok.. I think I'll agree that the front lock up is bias induced. It's just being amplified by the heavier forces of the toyota calipers. Its always been there, but you just don't notice it with stock front calipers. I blew the rear main brake line last summer (at the 'T' block above the diff), and in a desperation move to drive the car for another week or so till my truck was ready, I put a pipe plug in the proportining valve at the firewall. IE; I ran with front brakes ONLY. (yes, the stock ones.) To be honest, I couldn't tell much difference. Still took the same "gear down like a madman and mash the brake pedle for dear life" to haul the thing down from any serious speeds.. it was really easy to do a burnout though! heh heh.. I had the exact OPPOSITE problem in my 85 rx7 V8; Chev 10 bolt rear end with all new drums/shoes, and stock mazda front disks. Heavy braking would actually lock the REAR first.. which was a little scarry. Quote Link to comment Share on other sites More sharing options...
mom'sZ Posted January 2, 2007 Share Posted January 2, 2007 OK... I'm just going to throw a couple things out there. Most people report the very common reaction disc issue as being no brakes, no brakes... then they lock up. Could this be the issue? From Gretchen/Jason's description it almost sounds like what he's got. One thing that makes me think it's possible was the master got changed, that's when they get knocked loose. One thing that makes me think that isn't the problem is that he said they switched back to the stock calipers and it went away. Gretchen/Jason: search 'reaction disc' and just read some of those posts and see if it doesn't seem like what you've got, familiarize yourself with that issue. Next time the master is off, take a peek in there and make sure that baby is in place. Next thing is you mentioned not being able to get the rear brakes to bleed up very hard. The stock rear drum brakes are never going to bleed hard until they are properly adjusted. Search for this issue. The stock rear drums must be adjusted out, with a brake spoon, with the drums on, until they drag lightly. By lightly I mean it's hard to turn them with just the drum on, but once the wheel is on, you can turn them by hand. I don't know about the toyota 4x4 set up, but the stock brakes will not bleed hard until the rears are adjusted. Other then that, I think an aftermarket adjustable proportioning valve is in order here. And as BJHines says, with different compounds any set up can be made to work. Oh and what spotfitz says is a good thought as well. I think the z and zx did switch front to rear line location on the master, I remember reading that. check it... good luck! Quote Link to comment Share on other sites More sharing options...
Zmanco Posted January 2, 2007 Share Posted January 2, 2007 I'm a bit late to this thread, but live not far from Jason and have experienced the same thing he has. I think the real issue is the gravel left on the road after the snow melts. Jason, with a stiff suspension and big front calipers, there isn't much you're going to be able to do about it. For me, my Z is a weekend car, but I know yours is a daily driver. I feel for you, but you can't have it both ways. BTW, with all the snow we have had (and still have on the ground) I won't have the Z back out for at least a few weeks. Quite a difference from last winter. I still think you should get a winter beater car/truck. Quote Link to comment Share on other sites More sharing options...
260DET Posted January 2, 2007 Share Posted January 2, 2007 Hmmm.... ............................................................. I have run everything from stock to full race set ups... and the main limitations of the stock set ups are HEAT RELATED... You CAN bias your brakes with good pad material choices... Modern materials have come a LONGGGGGGG WAYYYYY... you can get any friction and heat range you want... ANYTHING... Thats true but its hardly a practical solution to the problem here without suggesting a specific and suitable pad material combination. On the other hand a bias adjuster allows anyone to simply adjust the problem away. Quote Link to comment Share on other sites More sharing options...
Mikelly Posted January 2, 2007 Share Posted January 2, 2007 Couple of other things to check... Did you check the check valve in the line from the intake to the booster? Is it installed properly? The comments about the reaction disc in the booster would be spot on IF the problem existed before the swap. The original poster didn't comment that it did, and that's why I didn't bring it up... Also check the hoses to the booster from the manifold for cracks. As the cars warms up you could be experiencing the hoses opening or "yawning"... Who knows, but I'd check everything else AND install a cheap brake bias adjuster. Mike Quote Link to comment Share on other sites More sharing options...
buZy Posted January 2, 2007 Share Posted January 2, 2007 You need to get rid of the factory bias valve and just use a $50 wilwood unit under the hood where the factory unit is. Adjust as needed. I ran the same brake setup you're using without problems, although I did switch to 280ZX rears with the front Toyota calipers...The bias is the issue. Mike I have kind of similar issues and have been listening. Great info! Bjhines, WAy cool vid! You make it look so fun and easy. Ok my car stock rears with 79-85 toyota fronts. 71 master very new. New booster 71. New check valve. No vac leaks anywhere Ok $50 willwood bias valve. But where is this new bias adjuster located exactly? On the front brake line between master and that big ole brake valve union under the hood? I know nothing about braking dynamics. And Thank you all for your vast experience. I love this place! Quote Link to comment Share on other sites More sharing options...
gretchen/jason Posted January 2, 2007 Author Share Posted January 2, 2007 Sorry i didnt state if the problem existed before hand . But no it didnt stock 280z mastercylinder and toyota calipers didnt give me such a hassel . In fact i didnt care for the way it stoped and wanted some more stoping power . So from another z web site " before i found this one " i asked other members and they said to switch mastercylinders . So that is what i did where as this problem arised . So i put the stock calipers on propblem went away but car stoped like crap . Havent retried stock mastercylinder as i dont have it anymore . I will try a inline adjuster to see what happens as a cheap alternative first , ive adjust the rear brakes at work a few times just to be sure " i work for mitsubishi " so i take advantage of the lifts . But ive always wondered when i bleed the rears i even tried the foot bleed method when i open the bleeder screw and someone pushes down on the pedal the fluid just sorta trickles out . I figured it should come out with more pressure but barley anything comes out . Ive checked for bent lines and found none but who knows could be rust someplace i guess . The people i bought the z from are the kind who " drive it till something breaks " and dont worry untill something does it was in bad shape brake fluid looked like thick mud when i bought the thing . Jason Quote Link to comment Share on other sites More sharing options...
rudypoochris Posted January 6, 2007 Share Posted January 6, 2007 Okay well. I have skimmed the entire thread, and this is what I suggest: Search "Reaction Disk". I am surprised it took so long for anyone to write anything about this. When the reaction disk slips out of place your braking system becomes an on/off switch. If that is indeed what you are experiencing, which I believe it is? Than there will be instructions on how to fix it when you search. Hope that helps. Quote Link to comment Share on other sites More sharing options...
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