Rear Ix Brakes

[Bmjpv]

rear brakes

I've had the car for about 4 years and did both rear bearing when I got it at 132k, I now have 208k on the car. I installed them with the popular German axle bearing tool that I kept from my shop days. Keep throwing Ideas at me. Thanks, Joe

[u3b3rg33k]

How's the pad wear in the rear? is it even? I recently solved some very uneven front wear by cleaning and lubing up the guide pins and bushings.

[Bmjpv]

rear brakes

Thanks for the thoughts. As I've stated earlier all caliper rebuilt,pins free,and pad wear even. Just thinking, what or how often has the reduction valve on these cars given problems? If it does't work that means too much line pressure/bias to the rear brakes. Now if that's the case than that could be my problem. Anyone/shops have a history of these going bad ? When looking in the bma catalog it's not a special order part . Joe

[flyboyx]

there is actually a bias valve ( i believe it is simply a re-stricter in the line going to the rear wheels) if this is the case, it doesn't make sense that there would be a problem with it. if it were plugged, it would simply not allow the rear brakes to work.

however, by the same token, it is possible that there is some debris in your line going to the front brakes and they are not actuating properly. thus the rears are carrying most if not all the load for the entire car.

my thought is that generally in situations like this the rear calipers are hanging up causing the rotors to heat up during normal driving.

my suggestion: take the car out for a drive where you don't have to use the brakes much if at all. coast to a stop and by using the brakes as little as possible if at all. feel for heat on the rears. if you have a lot of heat, your brakes are dragging and there is your problem.

after that test, take the car for a drive and use the shit out of the brakes. come to a stop and feel the fronts and the rears. if your fronts are pretty cool and the rears are hot, your front lines are plugged with debris.

have you flushed your brake fluid? there is a kit that someone sells with a pump up garden sprayer specifically designed for flushing the brake system. you basically put a quart or so of fluid in the sprayer, hook it to the top of your reservoir, pump it up, crack open your bleed screws and it simply pushes the old fluid out and the new in along with any air bubbles or crap that is presently in the system. just watching the fluid come out the bleeders will tell you a lot about the condition of your system.
this could also perhaps be a problem with the abs pump. something could be screwed up in there too.

i know you have a lot of experience with german cars, but i think this problem might be a lot simpler that you are making it out to be. perhaps there is something minor that you are overlooking.

[Bmjpv]

rear brakes

Read about this from the beginng and that will answer your own thoughts about the brakes. Thanks you for your thoughts, but what you said about brakes and a drive is nuts. But again thanks. Joe

[u3b3rg33k]

flyboyx, a bias valve and a restrictor do not duplicate the same function. a restrictor only restricts flow, not pressure, and with steady state braking, there is no flow, and as such no pressure loss across an orifice. If you want to see if you have a stuck caliper / dragging brakes, pull out an IR temp gun (or put your hand on the wheel). if it's hot after a mile (without much brake use), it's obvious.

Bmjpv, you have mentioned / shown no evidence of true disc warping. I still think you're having hard spot / material buildup problems. Could you post a pic, or some numbers (disc thickness, runout, runout while mounted on vehicle)? without more info, we're all taking stabs in the dark and assuming that you're doing things the way we'd do them, which is in and of itself a flawed process. Time to get your scientific method on.

[flyboyx]

Read about this from the beginng and that will answer your own thoughts about the brakes. Thanks you for your thoughts, but what you said about brakes and a drive is nuts. But again thanks. Joe

actually, it isn't. it is a very simple test that any fucking retard can follow to see if the brakes are dragging or not working. if you want the test to be more scientific? point an infrared digital thermometer at your rotors. i did read this thread though twice before i responded to it. i put a lot of thought and time into what i wrote and i am making a sincere effort to help you out. if you don't want my help, so be it. don't act like i don't know what i am talking about because i probably know more than you do mr mechanic shop. if anything, the description you wrote of your symptoms make you sound like you have no/very little idea what you are talking about.

by the way, i have 4 ix's at this point. 2 88's and 2 91's. i have looked three of the four over thoroughly. two of them, i have almost completely disassembled in the process of parting them out. maybe i am not an expert, but other than nando, i am probably one of the foremost experts for ix's here on this forum and the other one.

flyboyx, a bias valve and a restrictor do not duplicate the same function. a restrictor only restricts flow, not pressure, and with steady state braking, there is no flow, and as such no pressure loss across an orifice. If you want to see if you have a stuck caliper / dragging brakes, pull out an IR temp gun (or put your hand on the wheel). if it's hot after a mile (without much brake use), it's obvious.

Bmjpv, you have mentioned / shown no evidence of true disc warping. I still think you're having hard spot / material buildup problems. Could you post a pic, or some numbers? without more info, we're all taking stabs in the dark and assuming that you're doing things the way we'd do them, which is in and of itself a flawed process. Time to get your scientific method on.

take a look at your system on your car. there is a re-stricter in the system leading to the rear brakes. it is a small fitting on the driver side fender well just in front of the fire wall. it is under the brake booster. i know this because i had a car that the brakes didn't work at all in the rear. i took this fitting out and blew air backwards though it to clean it out. it had a few little pieces of crap in it. the rears worked fine once i put it back together.

it is part #5 in the diagram below. real oem calls this part a pressure regulator. there is nothing there but a little tiny pin hole in that fitting.

none of my cars have part 7 or 8 in that diagram

[u3b3rg33k]

So? it's still not going to limit pressure to the rear under steady braking. Last I checked, bias on an e30 is determined in the master cylinder assembly.

The only thing a restrictor will do is change the rate at which pressure builds - which makes sense. the faster you apply the brakes, the less weight you have on the rear axle, so limiting the rate at which pressure increases can help prevent locking the rear axle. once you stop pushing your foot down further, you've reached a steady state in the system, and thus no pressure drop across the orifice.

Assuming there isn't a blockage that's preventing the rear brakes from releasing, part #5's existence is immaterial to this discussion.

But I suppose we can't assume that, can we?

[flyboyx]

i suppose we cannot. i don't disagree with what you have said above. all i am trying to do is point out the components that are in the system and those that are not. i suppose a "bias valve" would have to come from wilwood. not very likely installed on the car in question.