I assume all of the usual suspects are still here and know what’s going from my other thread. Now that the brakes seem to be working correctly, time to address the pulling-to-the-left issue.
When I pulled everything apart most recently to repack bearings and inspect everything I noticed the left (driver side) caliper had a little wonkiness with the piston seal. Maybe the brakes getting so hot (from the power booster push-rod problem, other thread) messed it up.
I can replace it but I’m hoping Nevada will come to the rescue with another brake fix that doesn’t involve disturbing the hydraulics.
I’ve got a couple boxes of new bushings for the stabilizer bar and radius arms. Got them thinking they might have something to do with the wobble/vibration but haven’t put them in yet.
Things got pretty hot in there a number of times. A friend suggested I check for disc warpage too.
But TBH, the pull isn’t such a problem that it requires immediate attention.
For the braking/wobble/vibration I did take it into Les Schwab and had them check for everything they check for there. They gave it a clean bill of health. Useless.
But a good independent shop might be another story.
Do you mean the vehicle tends to move to the left when you apply the brakes? If so, make sure the right side pad and disc are clean. If nothing turns up checking the alignment/suspension parts, anything slippery on those surfaces could cause a pull to the left when braking. You might also try slightly roughening up the surfaces of both the pad and the disc with some 180 grit alum oxide sandpaper. Perhaps the disc surface overheated & glazed from the prior clearance problem. I had a brake-pull symptom on my drum-brake truck one time, caused by a very small amount of brake fluid leaking from the wheel cylinder and getting on front drum & shoe surface, making it slide more than grab, just on one side, so it pulled to the other.
Make sure the boot isn’t interfering with the pad/piston interface of course. The piston surface must meet the rear side of the pad directly, nothing in between. Do you know what’s causing that reverse “D” shaped pattern on the right-most surface of the piston in the bottom photo? Looks sort of suspicious.
I’m a driveway diy’er & I’ve never experienced a brake pull problem on either of my front disc brake sedans, so just offering up some ideas is all.
Good idea as you mentioned above to check for disc warp. Usually however the symptom for that wouldn’t be brake pull so much as noticing a vibration when you apply the brakes.
One thing I would consider is uneven front brake pressure due to a sticking proportioning valve. I ran into such a problem with a 1991 and 1993 Explorers and each had a bad proportioning valve. At the time the dealer only had remanufactured valves, not new ones for some reason.
Ah. Yes. The ABS and hydraulic control unit have been on my radar for a while due to the problems I was having as described in the other thread. All the brake fluid pressure goes through them so I really wanted to know what pressures were coming out the ports leading to the calipers.
But I never did anything with it because:
A) No clue how it worked: ABS control module? ABS pump? Hydraulic control unit? How to troubleshoot? How to fix?
B) Out of stock, expensive, or sketchy used stuff on ebay
C) Did NOT want to mess with all those hydraulic lines!
Sorry, I didn’t call it by it’s proper name. In your Haynes manual it is referred to as a RABS electro-hydraulic valve. The one I replaced was this unit. IF you can find one (big if), it is not difficult to replace if you have any experience opening brake hydraulic lines. Once replaced just bleed the lines like normal.
On non-ABS vehicles (like mine), the proportioning valve controls how much brake force is applied to each of the brake system’s separate hydraulic sections. On both of my vehicles the sections are divided front vs rear, so it controls how much force is applied to the front brakes compared to the rear brakes. I don’t think it is simply a constant ratio front/rear, the ratio depends on how much brake pedal force is being applied. Proportioning valves are not common failure items by reports here. Usually when they fail it seems like the most common symptom is one of the two hydraulic sections doesn’t produce any brake force at all.
No experience with ABS systems. But on many cars it is possible to completely disable the ABS, often just by removing the ABS fuse. So that could provide a clue anyway. I doubt the problem is the ABS system in your case.
The ABS has its own computer which constantly monitors the 4 wheel speed sensors. If one wheel isn’t rotating but the other 3 are, it figures that wheel is locked up and has lost traction. In response it rapidly turns that wheel’s brake on and off. If the wheel speeds are more or less the same, the ABS system doesn’t activate and doesn’t do anything at all. In many vehicles equipped w/ABS, the ABS system never actuates even a single time in the life of the vehicle. A dunsel part.
