The never-ending brake, rotors and track pads thread

[Mike Mount]

Hey all, I noticed some of you (from Jon Caldito's Road Atlanta post) started discussing one of our favorite threads. Brakes and track pads!
Okay, I've noticed that even using my BavAuto pressure bleeder that my pedal doesn't seem as firm as it used to be. Braking still seems fine though. Odd?
Lately, I pressure bleed as usual, then do the old "have a friend pump the pedal thing." Doing it that way, I get some of the tiny bubbles that seem to hang around.
I've even forced a whole quart of ATE super blue and had a less than rock solid pedal.
FWIW, I pressurize to 14.5 psi. The paperwork with the bleeder said to go 2x that, but I found in the manual a warning to not exceed 14.5 psi (page 340-3)
Using ~ 14.5 psi, it seems as if there isn't enough volume going through the lines to clean out air bubbles. But, I don't want to risk rupturing the reservoir. (Talk about ruining a track weekend! yikes!)
Any comments?
Oh yeah, I'm trying PF90 pads with Brembo rotors. So far, so good. Very dusty though.
Mike

[Ryan H]

Its possible that there is air in the ABS reservoir. To fully get all the air out of the system, it is best to flush or bleed, then go activate the ABS and get the new fluid into the ABS reservoir and the old fluid out from the ABS reservoir, and then flush again or rebleed. Its a pain, but I've heard thats the only way to get all the air out.

Ryan H

[BMWguy206]

I really don't have a good explaination of whats been going on with your brake pedal feel. However, I do not recommend the 2-man method because its not a procedure recommended by BMW on their vehicles plus it doesn't give a really good brake pedal feel. I pressure bled my own M3 last week and I had some bubbles coming out but this is due to air getting caught right at the bleeder screw and drain tube.

I also noticed that if I let my brake fluid catcher on the ground, bubbles start flowing through the tube. If its hanging, no bubbles flowing.

If could be that the rubber brake lines have been a aged or a bit worn out causing extra flex in the lines. Maybe stainless steel brake lines would give you a better feel.

Have a fun time at the track!

[Scott Yu]

....while we're on the subject of brake bleeding, has anyone tried out those little solo-bleed spring-loaded bleeder screws? Seems like a good idea, I'd love to know how it holds up in execution. Are they designed to be used specifically with pressure bleeders?

scott yu

Originally posted by Jon Caldito
I really don't have a good explaination of whats been going on with your brake pedal feel. However, I do not recommend the 2-man method because its not a procedure recommended by BMW on their vehicles plus it doesn't give a really good brake pedal feel. I pressure bled my own M3 last week and I had some bubbles coming out but this is due to air getting caught right at the bleeder screw and drain tube.

I also noticed that if I let my brake fluid catcher on the ground, bubbles start flowing through the tube. If its hanging, no bubbles flowing.

If could be that the rubber brake lines have been a aged or a bit worn out causing extra flex in the lines. Maybe stainless steel brake lines would give you a better feel.

Have a fun time at the track!

[Mike Mount]

Hey Jon, do you know what pressure the BMW pressure bleeder puts out? Also, there's some good points made by Ryan re- the ABS maybe having some air bubbles. I remember Sean Hester (from Suzy Kraft's list) said he would bleed, then drive around and activate the ABS, then re-bleed. (now that is a PITA)
Also, as Jon suggested, since my M3 has 73k miles and a fair number of track events, maybe the brake lines are flexing. Idunno, maybe I'm just gettting used to some really awesome brakes? I had no problems at Laguna Seca in November, other than having to bleed them on Sunday morning.
Ciao,
Mike
'95 M3
da kar is yellow

[derek]

Purchased a set of solo bleeder screws from BMP since I do a lot of brake work at home and the fluid gets flushed at least once a year. I must say they do the job of not letting air back into the system.

I had a similar problem this year with the brake pedal not engaging the brakes soon enough. Basically, the brake pedal had to be depressed almost an inch before I felt the brakes engage. Repeated bleedings and fluid flushes (using the not recommended 2-man method) did not resolve the problem. Brakes finally went back to the proper feel after I took it to a local shop and had them use their pressure bleeder.

Interesting that no air bubbles were detected during the bleeding process and I was unable to detect the change until I took it for a test drive.

Current setup is with the factory calipers, KVR slotted rotors, Hawk HP Plus pads, ATE Super Blue and steel-braided teflon lines. Very dusty and noisy, but they work great for track schools. I would not recommend the pads for street use.