Brake issue

[Zapp]

I have noticed here lately that the brakes on my 87 have started to lock up really easily on wet surfaces. Like when I am just slowing down between stoplights I have to pump the brakes to get them to work. It sounds like it is the passenger side front tire locking up, however the tire itself is in good shape.
Also the brake pedal feels pretty soft, I can actually push it all the way to the floor without a lot of effort, but I have looked for leaks and cant find any.

I'm not sure if these problems are related or not, but if anyone has any advise on what I could do to correct them it would be great.

Thanks,
Chris

 

[ms07s]

Has there been any recent brake work done on the car? Is your car ABS equiped? Is the MC full of fluid? Is the Vac line to the Brake Booster good?

You should check for air in the brake lines, and for seized pins in the calipers (what the caliper slides on). Check for leaks at all four corners, lines and calipers with someone else pumping the brakes. Check the MC brake booster area as well.

 

[Zapp]

There hasn't been any recent work. Im not sure if the car has ABS or not, but I know it was an auto car that has been swapped to manual. The MC is full of fluid. The vac line is good.

I had my room mate pump the brakes as I laid under the car and looked for leaks. I haven't been able to pull the wheels off and check everything out just yet, It is cold and rainy here in Chicago and I don't have a garage.

 

[ms07s]

There hasn't been any recent work. Im not sure if the car has ABS or not, but I know it was an auto car that has been swapped to manual. The MC is full of fluid. The vac line is good.

I had my room mate pump the brakes as I laid under the car and looked for leaks. I haven't been able to pull the wheels off and check everything out just yet, It is cold and rainy here in Chicago and I don't have a garage.

Look under the hood. You will have an ABS unit on the passenger side beside the charcoal canister with lines from the MC to it at the fire wall if it is ABS equiped. Without ABS you can lock up regular brakes in rain if you don't pump them. Locked up brakes in rain makes you hydroplane.

Your spongy peddle could be cuased by air in the lines (leak or improperly bleed), seized pins on the calipers, or a dying MC. Could be as simple as removing and greasing the caliper pins.

 

[Zapp]

There is something behind my charcoal canister, it kinda looks like a bigger FPR, but I can't find any lines running to the Master Cyl.

I realize that it is possible to lock up the brakes on a non ABS car, I have actually never owned a car with ABS. However, the brakes on my car didn't used to lock up this easily, but now the lock up extremely easily, even when I'm not braking hard at all.

As soon as it warms up a little, I will disassemble my brakes and check them out, as well as bleed them.

 

[ms07s]

ABS unit is Big...Like a 6x6x6 box with steel lines. It is in the far corner and is as big as the Charcoal canister. Pins sounds like a likely culprit. If it is you will need: PB buster, brake pin greese, some new pin boots, and possibly a small torch if they are real bad.

 

[Zapp]

ABS unit is Big...Like a 6x6x6 box with steel lines. It is in the far corner and is as big as the Charcoal canister. Pins sounds like a likely culprit. If it is you will need: PB buster, brake pin greese, some new pin boots, and possibly a small torch if they are real bad.

The definitely isn't anything like that there, lol. I will be sure to replace the pins as soon as it warms up a little.

Thank you very much for your help,
Chris

 

[dumbo]

Is there air in your system? I would check the level and consider bleeding, master cylinder could have shit the bed.

 

[Keros]

http://www.cygnusx1.net/Supra/Library/TSRM/MK3/manual.aspx?S=BR&P=47

Have a look at that, it shows vaugly what the ABS unit looks like. Posting a picture of your engine bay would also help. Reasoning is that if you have ABS, the controller may be the source of your problem and I do believe there is a way to test it. If you do not have ABS, the sources of a problem you discribe are much fewer... basically air in the system, your caliper, or the master cylinder.

If the pedal goes to the floor that easily either there is air trapped in the system and being compressed... or the master cylinder seals are toast. Bleeding the brakes with new fluid is the best way to find out. If you bleed your brakes and the problem goes away, that was the problem. If you bleed them and can't get rid of the issue after you're sure you've flushed all the old fluid, then the master cylinder may be the culprit.

Good luck.

 

[dumbo]

Your spongy peddle could be cuased by air in the lines (leak or improperly bleed), seized pins on the calipers, or a dying MC. Could be as simple as removing and greasing the caliper pins.

Haha wow, I guess I should read before I write.

 

[ms07s]

Or you could see it as you reinforcing my theory.

Just check it out asap. Dont want to slide your baby into another car!

 

[Satan]

This is what I'd suggest/do... Assuming that your pads are good.

1. Bleed the brake system (properly)... while you are bleeding, you can also check calipers for signs of leaks, etc. Check your brake lines... especially the SS kind where there is a clear nylon tube around the braided piece of the line. I've had the lines leak, with the fluid remaining inside that nylon.

Basically, by doing a thorough bleeding, you will also inspect most of the brake system's components. If this is ineffective, go to #2.

2. Rebuild the master cylinder... it really is very straightforward and costs less than $20. make sure you have the right grease to use (don't need much). You can get a rebuilt one for about $50.

3. Still a problem? If your pads are good, then it's time to just pull the wheels off and check out the calipers more closely. If your pads are low, this is the best time to replace 'em and refresh the brake system all at once.

4. The calipers are also easy to rebuild, for about $10 each, if ya need to go there.


There are a bunch of variations, etc. However, by just doing the bleeding you will have removed the air out of the system and see if the problem recreates itself after a while.. indicating a slow leak of some kind.

I have a 1990 Supra, which has undergone all of this work and still has spongy brakes. I have a new set of lines and will also replace the proportioning valve if necessary. That's another project, for another time.


Good luck!

 

[Zapp]

I defiantly don't have anything that resembles that abs unit, and my car is a base model. So I'm gonna assume I don't have ABS.

It looks like we are gonna have a fairly nice day here on Saturday. So I'm gonna try to bleed my brake system then...Fingers crossed

 

[ms07s]

Sounds like a plan. Check the pins, pads, and lines while you have the wheels off.

 

[Zapp]

Sounds like a plan. Check the pins, pads, and lines while you have the wheels off.

Will do, hopefully I don't have to replace too much, lol. Being broke sucks.

 

[ms07s]

Will do, hopefully I don't have to replace too much, lol. Being broke sucks.

Lines are pricy, but brake fluid is like 3$, brake pin greese is 1$ per pack (or get the 7$ jar of it like me and never run out), and pads range from 30-70$. Cheeper than a front end!:biglaugh:

Yes brokeness is the sucks

 

[InFrnt0fU]

Sorry to thread jack, but I just swapped out my leaking MC with a pretty new MC and booster from a RHD clip that had less than 30k on it as well as installed Earl's SS lines.

My car is 89 and is ABS equipped. I did not have a new "paper" gasket for the MC and booster and just reused the old one(I'm putting on a new MC-Booster gasket Sunday)

The brakes probably need to be bled a couple more times cause pedal feel is still a bit too soft and inconsistent. We first vacuum pump bled the brakes then bled them old school till about 1:30am last night.

Questions:
The vac line that comes off the booster is still the stock one and possibly could be leaking, could this be adding to the problem?
or
Is the worn old gasket causing issues?
or
Do I just need to put some more time into bleeding them to get all the air out of the system? I've read that it takes a considerable amount of time with ABS equipped vehicles.

Any input is appreciated, thx.

 

[Satan]

I've seen some ABS unit bleeding procedures in the MKIV TRSM, but am not aware of that being necessary in the MKIIIs. It may explain the perpetual sponginess I've had in my 1990. But, I never had to bleed the ABS in any other of my MKIIIs and they were fine.

However, with a used MC, you may never be sure of the condition it was in, before it was removed. The rebuild kit is quite inexpensive and easy to install.

I'd look for any ABS bleeding procedures and if that does not work, I'd make double-sure of the master by just rebuilding it.

 

[InFrnt0fU]

I've seen some ABS unit bleeding procedures in the MKIV TRSM, but am not aware of that being necessary in the MKIIIs. It may explain the perpetual sponginess I've had in my 1990. But, I never had to bleed the ABS in any other of my MKIIIs and they were fine.

However, with a used MC, you may never be sure of the condition it was in, before it was removed. The rebuild kit is quite inexpensive and easy to install.

I'd look for any ABS bleeding procedures and if that does not work, I'd make double-sure of the master by just rebuilding it.

The front clip it came off had less than 30k miles on it so that doesn't worry me.

 

[87tomanymods]

first check the system for contamination and leaks. to check for contamination take a cup of water and put some of the fluid from the master in the watter with a drinking straw then stir it up if it seperates after a few seconds (like oil and vineger would) its contamonated if not your ok . if it is contamonated you will need to replace everything that contains rubber (calipers hoses master and prop)before pulling the wheels make shure the wheel bearings are all tight then move to the slider pins .to check the sliders pry pistons back on the calipers with a flat head and make shure all 4 slide easily by hand. once you have done that pump them up and bleed them start at rr then lr then rf and last lf .go around a few times make shure you have no air bubbles (and make certain the master never goes empty if it does you have to start all over again) .also check the booster vac line (and dont use silicone it will cave in) . if it still does it use line clamps on all 4 hoses and check the pedal (you may have to start the engine) if its still spongy or sinking its most likely the master cy . if the line clamps make it go away take them off one at a time and recheck after each one . if after taking the clamp of one of the lines it starts again thats the bad corner. if none of that helps most likely a prop valve good luck and godspeed