Caliper Locking up Options

[Euphoria]

Hey, For a while now my passenger side rear caliper has been locking up under hard braking, no leaks anywhere and it bled fluid out both sides fine. I rang up for rebuild kits and they were all $120-95 a side! so last time I was in the wreckers I got a caliper for the side that wasn't locking, still the same problem! today I re-greased the 2 outer caliper bolts but its still doing it, any ideas?

Anyway the passenger side rear caliper is working TOO well?

thanks.

[barterj]

Is the other rear caliper working? Is the piston stuck in the passenger caliper?

[Euphoria]

How do I tell if its stuck?

[bccentaur3]

Are you lhd or rhd? depending on where the master cylinder located tells which caliper gets the fluid first. When you bleed the brakes you do the farthest away from the MC first. Try adjusting the brake pedal first. You might barely hit the brakes and getting too much pressure the the caliper causing it to lock up.

[azian_advanced]

Use a big C-clamp and push it back in. Be sure to grease inside the piston rubber seal and remove the brake fluid reservoir cap before doing so. If the piston won't slide back in, then you know its stuck.

If you replace the caliber again, it would be a good idea to flush and fill with new brake fluid.

[Euphoria]

It only locks on hard braking, slow braking is fine.

Piston goes back in fine, I was unsure what baterj meant.

I already bleed the entire system, as you HAVE to when changing a brake caliper as it gets air in the system.

Also re-greased the sliders and they work on both sides.

I'm gonna have to buy a rebuild kit from the US as they are $100 a side in Australia (yes $100 for 2 pieces of rubber) but I can't find any that ship worldwide

[bccentaur3]

well try adjusting the brake pedal. If you look at where the brake pedal mounts to the brake master cylinder you can adjust there for pressure. Back it off I bet its in too tight.

[Euphoria]

Also It only does it when it gets hot, another reason why I don't think its that, but I will check it out, thanks.

This post has been edited by Euphoria: Oct 7, 2010 - 10:18 PM

[bccentaur3]

Because its happened to me before.

[Euphoria]

and you had one side only locking? because I thought It was only one line going the master cylinder.

[bccentaur3]

yes. Well one line goes to the MC but then it branches off to the calipers. The farthest caliper away from the MC will get the fluids first.

[Euphoria]

well the car is a right hand drive and its the passenger caliper that is locking...

I don't understand how loosening the line to the master cylinder would do anything, wouldn't it just let air in the system?

[bccentaur3]

NOOOOOOOO!!!! not loosen the line fool. Okay you are RHD. The passenger rear is locking meaning it is farthest away from the master. If you look inside the car where the pedals are you'll see an adjustable nut where when you press the pedal it pushes the rod into the MC to give pressure. On that rod theres a nut you can adjust.

[Concept69]

Check for restrictions in the brake lines like pinches or bent lines preventing brake fluid from returning. Pressure may allow to flow towards the caliper but will hold pressure causing the brakes to drag

[Euphoria]

Yeah there is no way its the brake pedal adjustment, hence why I was confused.

I had spare calipers so I took them apart and cleaned them up (they weren't too bad) and then I put them in and bled the whole system, still exactly the same...only now the brake light is on.

Its not leaking, the lines aren't pinched and I've had 2 seperate calipers on that do the same so what else could it be?

Brake light was on as the fluid was too full .

This post has been edited by Euphoria: Dec 15, 2010 - 1:04 AM

[blackthunder]

hrmm, I seem to be having a similar problem. I have a RHD and my left rear caliper seems to be sticking? I just replaced the pads since the ones I had on were worn down to almost nothing (thank goodness for squeaker indicators)! I was able to press in the caliper with a c-clamp so the caliper is not totally stuck. I can tell something is up because I have no problems braking and the car doesn't pull to one side or the other under normal braking. After a short drive with normal breaking I can park and literally feel the heat radiating from the brakes (I have pretty open 5-spoke wheels) and all the other brakes are pretty much warm to even cold to the touch. Any thoughts or ideas on this? Living in Japan ATM so the language barrier is kind of tough when taking it to a shop...

Sorry, not trying to hijack the thread but I have a similar problem and why waste board space?

[Euphoria]

Yeah I'm in a similar situation, I don't have the money to take it to a shop, I'm still clueless on what it could be.

[mkernz22]

Maybe your system just applies too much pressure on one side...

[blackthunder]

Well I made an appt. for the shop next week. I will post up what they found and what they did and if it was fixed at all to try to help anyone else out.

[nsxtypeR]

Maybe the proportioning valve is at his end. It's the number 2 in the schematic:

[Spider77]

That sounds reasonable, since there are two separate line for the rear.

[Euphoria]

Thats probably what it is, how do you tell if you have a faulty proportioning valve, everyone says they rarely break.

[Spider77]

[Spider77]

I think there is a different way to check the valve its self as well, pretty much the same though, but instead of hooking up at the calipers you hook up at the valve.

[Euphoria]

thanks! might be worth trying if they are not too expensive.

[nsxtypeR]

47150 VALVE ASSY, PROPORTIONING
47150‑20240 ST204 (12/1994 - 07/1999) 1 $256.72
47150‑20290 ST204 (09/1993 - 06/1994) 1
47150‑20380 ST204; W(ABS) 1

Price is not actual price, but only a guideline

[Euphoria]

Holy **** lol, think they sell them after market?

[Bitter]

Have you replaced the rubber brake hose yet?

[Euphoria]

I haven't but it bleeds fine so I don't see how it could be blocked.

[blackthunder]

well took her to the shop and they found that it just needed a rebuilt caliper. Did that and it works like a dream now. Although I'll keep an eye on it to see if the problem comes back at all. Sadly they also found a torn CV boot, ugh, had that replaced too!

[Euphoria]

Ah dam, looks like you got out the easy way, im 99% sure its not my calipers.

[Euphoria]

Well I've rebuilt both pistons at the back, still have the problem...

So I'm gonna replace the pads and possibly get discs machined and see what happens from there.

Best off rebuilding master cylinder after I've done the other things?

[Euphoria]

Well I put on a used disc I had there and the problem seems to be gone /facepalm.

But saying that, it was really rusted and old so maybe thats why it won't lock haha.

[brenton1919]

u might have air in the line.... are u sure its not the wheel bearing locking up ? ive seen that happen once

[Euphoria]

It was only under braking, wheel bearing would be constant, I had a bearing seize in the past aswell.

And you'd know if you had air in the line because the pedal would be soft and lack feel.

Hopefully this will stay good, I took it for a good drive today and it was so much safer under hard braking.

[brenton1919]

It was only under braking, wheel bearing would be constant, I had a bearing seize in the past aswell.

And you'd know if you had air in the line because the pedal would be soft and lack feel.

Hopefully this will stay good, I took it for a good drive today and it was so much safer under hard braking.

alright that sound great.. remember tho u can get little air bubbles in the line it can be hard and go soft and then go back hard. that is also a sign a a whole somewhere or a leak... maybe even a bad brake booster. but you should of had the brake seize after u had replaced the piston, that just seem funny i have never heard that before, i have heard of a blockage. but hmm make sure u keep a eye on that, would wanna be going down the road with no brakes or at a high speed and they lock up lol...... i just remember something i was working on a cadillac on time and her brakes kept locking up a line from her abs rub against her tire, and she had a whole in it which made the abs keep locking up. replaced that line and she was all good to go