3rdgenstm

My 89 will pull hard to the left when I brake. It would pull me into the next lane if I didn't turn the wheel, over a 40 ft distance. What can be the problem? This is what I have done and tried.

Installed new pads and rotors.

Replaced the brake hoses from the hard line to the calipers. Both right and left fronts.

Flushed the system with fresh fluid.

Did a 4 wheel bleed, twice. No air in the system.

The only thing I haven't done is replace the master cylinder and the proportioning valve. I don't think the valve will go bad, isn't it more of a distribution manifold?? Could the master be losing vacuum over time and the repeated braking make the brake fail? It doesn't do it until after I am in stop and go traffic for a while. It has 162,500 on it and the master looks to be the OE. The big 3/4" od line is hooked up and pulls vac off the manifold. I don't know what else to do. Please help!!

MrDude_1

if the lines are good

and the calipers are good

and all the air is 100% blead.............



check your alignment..... athough that costs money

3rdgenstm

It only pulls when I brake.

My90Iroc

Look at the slide rails on the calipers. Those are the studs that the pads move to and from the rotor on. On both of my thirdgens I had this problem and it was just a case of one caliper grabbing before the other. Check to see if these studs are dirty and if so clean them up and give them a shot of lube. Hope that helps, good luck finding the problem because I know how much of an annoyance and dangerous that can be.

3rdgenstm

I'll look, thanks!

stuart

i had the same problem, only mine would want to lock up when i braked hard or suddenly hit the brakes........the problem? it was a bad caliper, stupid thing was sticking.

MrDude_1

lol...

i did a normal brake job on my car and it started doing this too..

i had lubed the pins, buyt i left the grime on them..

sure enough, once i pulled the pins out, cleaned them properly, greased, then replaced them, they worked great...


i should have just cleaned them to being with...

3rdgenstm

Are you talking about the allen head screw that holds the caliper to the spindle??? I wonder way that would make a difference. Anyway, when I pulled mine apart, I took the bolts and polished and oiled them before I replaced them.
Thanks for the help.

MrDude_1

think about how its held on..

and imagine this..

the pad on the outside of the car is mounted to the caliper. it doesnt really move in relation to the caliper.
when the piston pushes the inside pad closer to the rotor, the entire caliper must smoothly slide on thoes pins inward so that the inside and outside of the rotor both touch..


now if the slider was dirtier on one side then the other, that side would need more pressure to overcome the gunk keeping it from sliding... and the car wouldnt brake evenly. or it may stick when you let the pedal up, ect..

1gta2c

I had the same problem with my car. The only way to see exactly where the problem was, was to blead the front callipers at the same time

What I mead is put someone in the car and make sure the breaks are blead and get him to push hard on the break pedal and unscrew the bleader.

Do this to the right and left side. The person pushing on the breaks should feel a difference in the restriction of flow either to the right or left side.

Now keep going up the ladder untill you hit the proportioning valve and do the same thing.

This is the easiest way to find out where the restriction on the fluid is, valve or line.

The only thing is, you go through a $hit load on pwr brake fluid in doing this

jamesbob02

Mine was a clogged brake line. It seemed as though there was something wrong with the side it was pulling to, but what was really happening was that the non-pulling side was clogged and not braking at all, so the pulling side was the only one braking. Replaced the line and it went straight ever since

3rdgenstm

OH! Ok, I understand what you are saying MrDude. I will have to look at it and check. So do you think when the caliper heats up, it seems to get worse or do you think it should do it all the time? The car stops great for the first two times I hit them, then it starts pulling. The more I stop, the worse it gets.

I will have to check and let ya'll know. This is driving me nuts!!!

3rdgenstm

Still haven't found the problem. Bolts are clean and lubed. Took them out and just kind of moved stuff around. Still pulling. Anyone think it is a bad valve or master??

1gta2c

Check the flow of the brake fluid too see if thier is any restriction. This will cause it too pull one wat because the same thing happened with my car.

3rdgenstm

I know from when I bled them, there is plenty of flow. I was thinking that maybe the piston freezes in the caliper after it gets hot. The funny thing about this whole thing is it does it after I have used the brakes. It doesn't do it until after I have driven for a while.

3rdgenstm

By process of elimination and advice of ya'll and others, I have narrowed it to the caliper. While I have to change it anyway, is there an upgraded caliper I can put on or is can mine be rebuilt?? Any info would be great!

1gta2c

Ya, you can get a rebuilt calliper and give them yours back in trade. If you want to spend big bucks you can go to the bear up grade, lots of cash.

Abird4u2nv1

iTrader: (-1)

Your prob is the calipers, I would replace both at the same time, or your liable to have one pull harder than the older one. I just did both of mine, and the were 12.99 a piece with a 10 dollar core charge. For 26 bucks, why not replace them both? I did, along with rotors, pads, lines, and wheel bearings, and my brakes work great! Stops great and doesn't pull at all even if you don't hold the wheel.

Jackal8069

ARGH!!!

That really rubs salt in my wound! I replaced my front calipers over memorial day weekend after I started burning brake fluid (this is years after the car pulling to one side during hard braking). Well I went to autozone, who said didn't carry them (after going to the website). And they sent me over to O'Reilly's, the autoparts mafia. They charged me 119 bucks for a set of OE rebuilt calipers, and thats with my core exchanges.

I asked about a cheaper price, but thats 'all they had'. The things you do when you just need to get back on the road.

RJR99SS

you can rebuild them yourself too. The hardest part is finding a quality rebuild kit, auto zone makes the best one in my opinion. Dont even bother with advance auto parts. The napa kit is pretty good.

But the kits will only cost like $3. All thats in there is an o-ring and a dust cover.

To rebuild them you need a air compressor, some sort of sanding equipment, a 3 pronged brake hone, and a c clamp.

You basically take the caliper off, put a piece of wood where the pads should be, put an air gun into the caliper intake and blow. This shoots the piston out. Then you clean the piston up, hone the inside of the bore out.

The hardest part is reinstalling the piston. The way i do it is put the new o-ring in its grove, put the piston back in with a c-clamp. Then i put the new dust cover in the freezer. Then reinstall it back into its groove. The dust covers can be a major pain to get in there, i found the easiest way was to squeeze them in with a oil filter pliers i had.

Then put your wood back in the caliper, shoot the caliper out again so that the dust cover fits over the piston properly and then squeeze the piston back in with the c-clamp.

Then you make sure your slide rails are clean. You usually have to sand them up a little to make sure they're clean of rust and all that. The reinstall, and bleed the brakes.

Might seem complicated, but once you do it a few times it's pretty easy. Personally, i hate buying rebuilt calipers. I've seen many that leaked or pulled from day one. I had one rebuilt caliper that i bought that was pulling, i took it out and disasembled it and it looked like it hadnt been rebuild at all. There was rust down in the bore, the o-ring was all chewed up. Looked like they just sandblasted the outside and sold it as rebuilt. So since then i rebuild all mine personally.

3rdgenstm

I called around around yesterday and got some prices on new and remanufactured calipers and rebuild kits. Remans are 15 bucks each plus cores, new ones were $80 each, and rebuild kits were $6 each. I'll just have to decide.
Thanks for all the help and advice.

88TPI406GTA

Definitely just do the reman calipers...so much easier for an extra $10 per caliper....

And yes...the caliper is the culprit

3rdgenstm

Installed new calipers-- stops straight as an arrow! Now the driver brake is squeaking!! Think I'll bleed it once more.

thanks for the help.