cygnusx1 Posted October 28, 2004 Share Posted October 28, 2004 I am supposed to take my turbo 280Z to a local road course Friday for some driving school and time trials but... ...since I put in the brand new rear shoes and went through the bedding procedures, the rear wheels want to lock up before the front. I will NOT drive on a track like that! I have Powerslot front rotors with the Toyota 4-piston calipers, KVR pads. In the rear I use aluminum stock drums and Nismo green shoes. The rest of the brake system is 280Z stock. The proportioning valve is original. The pedal feel and braking is AWESOME until the point where the rear locks up. I think I may have made the adjuster wheel for the shoes too tight. Is it possible to lose some rear brake bias by backing off on the shoe adjuster? or could I have made an error in the shoe installation? If I dont cure the rear bias quickly, I am SOL for this Friday. Dave Quote Link to comment Share on other sites More sharing options...
jt1 Posted October 28, 2004 Share Posted October 28, 2004 Most likely you can back the adjustment off some and take care of it. If that doesn't do it you need an adjustable proportioning valve, or some harder rear shoes. Too much rear brake is usually makes the car very twitchy under braking. John Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 28, 2004 Share Posted October 28, 2004 Did you use the parking brake to adjust the rears or did you do it manualy? If you used the P brake I would maualy turn a few clicks out and not use th P brake until you figure it out. Atleast you won't miss out on the track time. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted October 28, 2004 Share Posted October 28, 2004 A couple hard laps should take care of those pesky rear brakes... Sorry for the smartass comment. I'm pretty surprised that you have that problem. Makes me think the front pads aren't fully bedded in or are glazed or something. The fronts should be providing a lot more front brake than the stock setup would. This seems to tell me that if you hadn't upgraded the front then you would REALLY have a lot of rear bias. Or it could be that maybe the green stuff shoes start working at a much lower temp than the KVR pads. If that is the case then I wonder how well those shoes will be working when they get really hot... they might just cook right off the car. If it is a bias problem and not a friction material problem then the best quick fix IMO is to get an adjustable prop valve and just mount it under the car where the stock valve goes. It would make installation under a deadline a lot easier. Unless your a really experienced racer you probably don't need to be adjusting during a session or a race. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted October 28, 2004 Author Share Posted October 28, 2004 I dont think that the fronts are glazed because I do get excellent braking..especially after I warm them up with a couple of casual 60 - 10mph stops. It feels like the rear shoes are just grabbier than the fronts. The rears are locking up when I get down to about 30mph under hard braking and the rear end steps out a little just before the stop. I adjusted the rear shoes with a screwdriver through the access hole in the drum to the point where I felt a little drag on the drum while turning by hand. The handbrake also feels tight so I probably have the shoes too tight. I will back the shoes off tonight and see if it helps. Wish me luck. I will be in the STGT class against the likes of the WRX STi. It's too late to do a proportioning valve at this point as I dont have one and I need to drive to the track at 5am tomorrow morning. Quote Link to comment Share on other sites More sharing options...
Clifton Posted October 28, 2004 Share Posted October 28, 2004 I adjusted the rear shoes with a screwdriver through the access hole in the drum to the point where I felt a little drag on the drum while turning by hand. The handbrake also feels tight so I probably have the shoes too tight. I will back the shoes off tonight and see if it helps. I would back it off a little extra and use the P brake lever to adjust with. Quote Link to comment Share on other sites More sharing options...
Drax240z Posted October 28, 2004 Share Posted October 28, 2004 Parking brake adjustments have only ever worked for me when all rear brake components are brand new. In 99% of Z's, you can't adjust the rear brakes very well this way. I have the same issue when my drums are adjusted too tightly, too much rear brake bias. Just loosen them up until you find your sweet spot. Of course, after a few hard stops that sweet spot will change again. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted November 4, 2004 Author Share Posted November 4, 2004 Just a follow up. I did loosen the rear shoe adjuster and it seemed to have cured the rear bias; at least temporarily. So I did take it to the track and the bias was fine. The brake fluid did boil though. http://hybridz.org/nuke/index.php?name=PNphpBB2&file=viewtopic&t=38038 Quote Link to comment Share on other sites More sharing options...
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