'91 Celica Passenger Brake Locking Up

[toplessFC3Sman]

This is on a '91 Celica GT, 5SFE engine, with front disks and rear drums, and no ABS.

Whenever braking, the front passenger wheel seems to be doing much more of the braking work. In the wet, its very easy to lock up the front pass wheel under pretty mild braking. In the dry the same wheel is always the first to lock up, considerably before the drivers front, and much before they should, based on the deceleration.

I recently had to replace all the brake hoses, and a long run of hard brake line from the engine compartment back to the gas tank. I've bled the system multiple times and doublechecked all the connections, and cannot find any leaks. With no brakes applied, all wheels spin freely.

It seems like the braking circuit for the driver front wheel is not working as well as it should be. Is the passenger rear brake on the same circuit as the driver front? This seems like air still in the lines somewhere.

Could the master cylinder be causing distribution problems between the two circuits?

Thank you!

[PEN]

I dont think this is the exact problem but on my car my brake shoe bolt came out and the brake would lock on and of and sometime be normal. Either way this is very dangerous because that side that locks will cause you car you yank into the other lane or curb if it locks up.

[Bitter]

Honestly with a car of that age I would just get two semi loaded calipers to install and be done with it. It could be seized slides, sticking piston, pads caught in the clips, who knows. Hell it could be that the one side that is working is doing ALL the work for both sides which is why only one side is locking, catch my drift? does the other side even do any braking?

[RobMilkshakes]

I agree with Bitter, I would suspect seized caliper slides or piston sticking.

Loaded calipers can oddly be much more expensive, depending on source, though than semi loaded calipers (w/ bracket and hardware, just without the pads) and a set of high quality pads.

[toplessFC3Sman]

Hmm, I didn't think about the caliper sticking; it had been working fine before changing the lines, and it wasn't difficult to push the piston back in when replacing the brake pads. I know both wheels spin freely when the brakes arent applied (forgot to loosen lug-nuts before jacking up car... doh!), but I should jack up that wheel and see how it feels when the brakes are. The caliper slides are alright; they had stuck before but I worked them free and packed them with grease (the rubber boots were intact), and they were sliding fine when I put them back on the car.

Which brakes share a circuit from the master cyl? Is it both fronts and both rears, or a front and the opposite rear, and vice versa? If one of the pistons were stuck, wouldn't the other one in it's circuit therefore be locking up more quickly?

I should clarify, the wheel that locks up soon is only doing it when I push the brakes semi-hard. Harder than you would in normal driving, but definitely softer than you'd need to in a panic stop. When the brakes aren't pushed, all the wheels spin freely.

[Bitter]

you could have air caught in one caliper causing it to NOT apply when the other is. re-bleed. if that doesn't help then replace both with brackets. I recommend Hawk HPS brake pads for street use with liberal use of CRC rubber brake anti squeal.

[toplessFC3Sman]

I thought it might be the bleeding as well, but the only brake that I seemed to have a problem with was the drivers rear; I used almost half a bottle of brake fluid waiting for all the bubbles to come out. Both fronts pushed out new, un-bubbly fluid very quickly. I'm going to try it again, and check the wheel rotation with brakes applied too.

I didn't know that Hawk made the HPS for the '91 celica; they don't list it on their site. Do the ones from the corolla fit? I picked up some generic ceramic pads from o'reilly auto parts for the warranty and price, since the car is my gf's, is rarely subjected to aggressive driving, and has fairly low treadwear (high numerically) tires on it. For my project/fun car, an 88 Mazda RX-7, I love the HPS's on it though

[Bitter]

Ah I didn't see if they made them for your car or not. I was just generally stating. It's very possible the other side is seized up and not applying which is why the one side locks up. If you're sure its not an air issue then grab a pair of loaded or semi loaded calipers and replace them. Often the time you save in doing that is well worth the cost.

[toplessFC3Sman]

Before replacing any calipers, I'm going to try to bleed it one more time, and bleed the master cylinder separately beforehand. What is the thread size for the brake lines where they screw into the MC? Does anyone know which two wheels are on each circuit of the dual-circuit braking system?

[Bitter]

I think it's diagonal split.

[toplessFC3Sman]

Diagonal would make sense from a dynamics standpoint. One other question, unrelated to the brakes. How can I tell which transmission is in the celica? It's a '91 GT with the 5SFE, 5 spd manual.

[RobMilkshakes]

That would be the S53 trans.

[toplessFC3Sman]

Ok, re-re-bleeding the brakes seemed to help a lot; that one wheel is still locking up a little sooner than the other side, but its considerably better than it was. All of the brakes do clamp down when the brakes are pressed & the car is in the air, and all release when they aren't pressed.

On another note, the driver's side front suspension has a clunk & rattle whenever going over bumps (or bouncing the car on that corner) that none of the other corners exhibit. Everything feels solid, and when the car's up on jack stands with the wheel off, I can tug on the strut, brake rotor (if I put the lug nuts on to keep the rotor from coming off the hub), tie rod, roll bar, or anything else down there, and nothing makes a noise or seems to move. I've replaced the steering rack (what a PITA), as well as both driveshafts to fix other problems within the past year.