Under braking the car is pulling to the left. There's also a significantly larger amount of brakedust on the driver-side front wheel compared to the passenger side. Also seems to lock up sooner on the driver side. The pads a oem pads with plenty material left. The rotors a stock, and quite old...

Tire pressure is equal left/right with a 30/28 split front to rear. Car tracks straight during accelleration, steady speed, and off throttle.

I had the wheels of and checked the brakes, but didn't notice anything unusual.
I tried to see if they apply uneven force by applying the brake to the point where i could barely move the wheel with all my strength. Both side seem to be equal, did full rotations. (I know this isn't exactly a very scientific test )
Letting off the brakes both wheels rotate freely. Well, sorta they still seem to rub slightly against the pads, but that's normal, right? I can spin the wheels and they keep going...

I'm going to get an alignment done just in case, and because it's time anyhow. After that I guess I would need to check if any of the pistons are starting to seize up.

Could the rotor be slightly warped, or have some uneven thickness be causing this?
Any further ideas on what to look for, or test?


Thanks guys.

 

could be the hose. crak the bleeder and see if you get any fluid to come out on it's own, pull the caliper check the pad thickness from inboard to outboard. see if the slides are clean. the wheel does spin freely right? check the tie rods for end to end slack as that can cause a pull. tire wear look even? rotor warp will show up as a pulsation under braking

 

if it was just pulling to one side, id say lower arm bushes - but since there is more brake dust on one side, i dont know.

how long since you have bled the system? Give it a full brake fluid change and bleed and then see what happens.

 

Already did a complete flush, replaced whatever was in there with ATE Super Blue.

 

Ok, got an alignment done. Same problem, pulls to left under braking. Actually, maybe I need to specify that it only seems to happen under hard braking. Though that could also just be that it's nearly imperceptable under light braking and slower speeds...

 

You may have a seezed piston(s) on your right front side..

 

Things to consider:

Is this occurring prior to ABS activation? If so, you can rule out that system.

Tire wear even? Switch sides and see if anything changes.

Left front shock bad? That corner could be diving.

Have you checked the rear brakes? Right rear could be bad

Check the integrity of all suspension components, especially sway bar mounts.

If all else checks out, flush the brake system thoroughly and rebuild the calipers if that doesn't help. See an earlier thread where I posted pics of the rebuild process. Solved all my brake problems.

 

I would guess that the caliper on the opposite side (passenger side in your case) is sticking. That's usually the most common thing with any car, not just the RX-7. So the driver's side caliper is doing all the work, thus the excessive brake dust and the ABS kicking in.

 

Checked the pistons on the passenger side, no problems I can see. The all move when stepping on the brake.
I did however notice that the outside pad only seems to make contact with the outer half of the rotor. This is also confirmed by the way the pads look.

I think my rotors might need to be machined/replaced.
I need to get a micrometer and check the thickness in different spots on the rotor to see if there's anything going on there.

 

BINGO! This is the thing you should check. And I wouldn't be surprised if your brake fluid hasn't been changed in quite some time.

When I look in FD engine bays I always check out the brake fluid reserviour. It's amazing how many I see in which the fluid is totally brown. People who change their oil every 1,500 miles will let years and years go by without a brake fluid flush and refill.

Brake fluid loves to absorb moisture. This creates corrosion in the caliper bores and the pitting causes the caliper to stick. That's how you wind up with problems like the one described at the beginning fo this thread. I think the brake system of the FD has remarkably few problems, but you've got to change the brake fluid every two years.

 

Ok, it's not the pistons, I checked them already they all move freely. Fluid was flushed a couple weeks ago.

Anyhow, on a hunch I decided to swap the pads from the driver side to the passenger side and vice-versa. And now the car is pulling the other way, to the right. Is it possible the pads have a slight curve to them, that prevents them from making full contact with the rotors?
What are some other causes I should look into?
The pads are somewhat newish < 1000 miles.

Thanks for the help.

 

If these are new OEM brake pads, did you bed them in properly? It sounds like the pads that aren't working too well (now on the driver's side) may not be bedded in, somehow got glazed over, or got some substance on them that is affecting their performance.

 

I thought I bedded them in properly. Did a number of pretty hard decellerations without full stop at the end.

I noticed that one of the pads looked very smooth, whereas all otheres seemed to have some kind of "scoring".

How would I identify a glazed pad? And what should I try to do to get them sorted out? Try another bedding?

Thanks again.