Sorry for the long post, but I divided it up so hopefully it's not too bad on the eyes.

I have a 93 FD with the following relevant mods:
Tein Flex coilovers
Nylon Suspension bushings
Hawk HPS pads (street, Nick from N-tech is hooking me up w/ a set of track pads)
Slotted/cross drilled rotors (soon to go)
18X9f/18x10r Gram Lights 57Pro +40/+38 respective offsets
BF Goodrich KDW 255/35 & 285/30

So in preparation for a local driver education event, I have been going through my car making sure every thing is in tip-top shape. I went out the other day got up to around 70 on a desolate stretch of road and gave the brakes hell. I could feel it pull to the right. Not violently or anything, but I could feel the car wanting to rotate and one time the front right locked up until the ABS kicked in.

Just out of curiosity sake, I went and grabbed my IR thermometer, got the brakes good and hot, and took some temps. The right side was consistently warmer by 10-20 deg F. For how much it was pulling, I figured the difference would be larger, but anyway. It had been about a year since I bled my brakes so I figured this would take care of the problem.

So this weekend, I completely flushed the system. New fresh fluid all the way around and while I was at it, I made sure all my pistons moved freely, which they did. I used my vacuum pump. Not really my ideal method, but it's a good one person method. So I went out again. SAME thing! Pulls to the right, right brake warmer than the left. The rears were both within a couple degrees and I could feel that the passenger front brake was the problem.

I was pretty well stumped, but thought that maybe I'd try the old fashioned way of bleeding my brakes. I got a friend to come over and help me with that. Everything went well, no air anywhere in the lines. So we took it out for another test drive. 70mph, lay on the brakes, it stopped straight as an arrow. I would have felt comfortable letting go of the wheel from 70 it was so straight. Just for ***** and giggles, I measured temps and they were within +/-5 deg F. So problem fixed right?

Wrong! Today I had to pick a friend up. About a mile from his place, I decided to make sure my brakes were still stopping straight. Don't ask me why, but I was curious. It was PULLING AGAIN! Damn! I was getting frustrated at this point. So I pick him up and I got to thinking that the only time it stopped straight was when I had my other friend riding with me. So I decide to try one last time. TOTALLY STRAIGHT!!

That leads me to the conclusion that I need a 150-200lb ballast sitting in my passenger seat to keep me stopping straight.

But seriously, My alignment feels great, no pulling, no odd tire wear, no nothing (I used to work at an alignment shop so I do have an idea how to read tires.)
That leads me to think that I can "fix" my problem by adjusting my coilovers. Except the way it is pulling doesn't make sense to me. W/o anyone in the right side of the car, it pulls right. I was originally thinking that I would need to raise the preload or raise the ride height (minimally) on the passenger side, but that would make sense if it pulled right when someone was with me, not vice versa.

I was also thinking that the wheels might exaggerate the problem.

Basically, has anyone ever experienced this before? Any ideas how to fix it?

I'm going to go out and play around with it tonight and see what I come up with.

 

Checked all the tire pressures?

Road perfectly smooth?

What kind of alignment you run? If you run much camber or toe out the car will always pull one way or the other if the road isn't smooth as glass.

 

Tire pressure is good.

Alignment specs are factory. I just aligned it to what we had in the computer, of course making sure that it was in the middle of the allowed tolerances. That was probably 5k miles ago.

What gets me is how simply adding some weight to the passenger side makes such a difference. The first friend that went out on the "tests" with me was only 120lbs at the most. Then the next one was somewhere in excess of 200lbs.

 

Play in bushings. It's fun! No, I mean you may have some slop in one or more of your bushings or ball joints. It seems like there is always something worn out on these cars' suspensions. Your Nylon bushings may have developed some play, for instance. I think the stiff bushings make the ball joints wear faster, too (particularly the front uppers).

Or you might try adding some toe-in in the rear. A little rear toe out can make the car wacky, and it is very noticable under braking.

Does it make a difference if you stab the brakes versus a squeeze?

-Max

 

Max, you are getting a little senile in your old age.

Ball joints and tie rods are tight. I suppose that belonged up in my big post somewhere. However, a little slop in my bushings is a real possibility. I try to keep my bushings nice and lubed though!

RE: stab vs squeeze:
It doesn't start wanting to twist until the speeds get lower, or at least I don't notice it until then. I guess you could say it happens under both, just not immediately.

I should probably take it in and have the alignment checked out just for peace of mind.

 

Are your brake ducts still functional and unobstructed?

 

I don't have any brake ducts. For the few sessions I did have at the track, it didn't seem to be an issue. I've got bigger problems now though...I think I have 4 good apex seals between both rotors

 

How old are your calipers?

 

i noticed you have coilovers.

have you had your car corner weighed?

 

I haven't had it corner weighed. I was thinking that might be a contribution to my problem.

My right front caliper is a reman unit about a year old, the left front is factory as far as I know. All the pistons move freely.

 

im inclined to think its a bushing problem also ;__;