I recently bought an 88 CRX dx that already had the rear disc conversion from an Si. When i'm dirving down the road the from brakes start to gradually lock up and I have to pull over and bleed them. This happens about twice a day. Somebody please point me in the right direction. I recently installed stock power booster, one way valve in the vacuum line, front calipers, 40/40 proportioning valve and the 15/16" master cylinder off the 91 ex (I put the 10.2" rotors and itr calipers up front when I changed out the calipers). Not much left to change out and the problemis the same after all the new parts. HELP!!!

 

wow...wtf.

thats weird...

seems like fluid is going but not coming back...

you check all of you lines make sure they arent pinched at all...?

 

What does bleeding the brakes have to do with them locking up?

Locking up the brakes from what I understand is when you hit the brakes and the wheel stops spinning and you slide to a smokey halt. What are you talking about? Are you saying that once you let off the pedal the wheel won't move? Calipers don't stick in the on position, they stick in the off position.

And I don't understand what bleeding has to do with this at all. You bleed the brakes when there is air in the lines. You would only need to bleed them if there is air in the lines and nothing happens when you hit the brakes. This is the complete opposite of them locking up.

However, in my experience big brakes on small cars make the brakes lock up easily if you're not really progressive. I have 11.75" rotors with wilwood calipers and those things will lock instantly if you slam on the brakes. This has nothing to do with bleeding and means the system works fine, except for the lack of ABS.

 

And if the caliper sticks in the on postion, it usually just overheats, it doesn't lock the wheel. This is a weird description of what is happening.

Do you mean to say the brakes get soft as you drive the car. This would mean they are not properly bled, which is a huge issue when swapping calipers and/or lines. Takes forever to bleed. I did a gravity bleed for a half hour to get all the air out of mine, that is after bench bleeding the M/C again.

 

Actually, as I brake more often the pedal gets harder. After bleeding off pressure the calipers release and I can move again. The brakes do get harder and harder until the car will not move, so yes they do lock up. I was told they soft brake lines are collapsing. Any comments on this. I will changing out the front lines today and will post the results later.

 

make sure your lines arent twisted too...

 

I sounds to me like you have a master cylinder issue. Your master cylinder may pushing fluid out but its not allowing it to suck back in. You might have a plugged vent ports which allow the brake fluid to expand from the heat and flow back into the resevoir to release the pressure. Also, what is the brake pedal like. Is it spongy at all or lower then normal?

 

The master cylinder is a brand new Nissin 15/16" from Honda. A guy I know said the power booster, rebuilt, may be bad, not sure. Keep the ideas coming, this is driving me crazy.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by scar066 &raquo;</TD></TR><TR><TD CLASS="quote">Actually, as I brake more often the pedal gets harder. After bleeding off pressure the calipers release and I can move again. The brakes do get harder and harder until the car will not move, so yes they do lock up. I was told they soft brake lines are collapsing. Any comments on this. I will changing out the front lines today and will post the results later.</TD></TR></TABLE>

This is the strangest brake problem I have ever heard of, Wow. So, you've got pressure building up in two directions at the pedal and at the calipers... weird. I have no idea. Last time I saw a rubber line collapse it cause the caliper not to grab as the fluid couldn't get to the caliper. Couldn't hurt to replace them with some steel braided ones, as you've already replaced everything else. Don't know anything about brake boosters, still running my stock one, never messed with it.

 

Brake lines didn't fix it. Trying a different power booster tomorrow. Still need input, please help.

 

i will bet its your booster NEVER! rebuild these just buy a new one the only time u rebuild theses is if they don't make them anymore

 

It was a reman. from Napa, but I've heard bad things about remanufatured ones also. Thanx. I will post after it's the parts are on. This one is from a salvage yard, but it looks in good shape. Keep up the suggestions.

 

WOW.... I've never heard of a brake problem like this before. Usually brake problems are completely the opposite. Please keep us updated as to the condition of your problem & the results from replacing parts.

 

Changed the power booster out. It may be fixed. Have to drive it more to find out for sure. Also found a vacuum leak at the throttle body. Hope this is it.

 

Well, the brake pedal getting harder makes perfect sense if the booster is bad, but usually that means it's harder to stop the car. One time I was towed and it took some serious effort to brake without the booster helping.

 

I noticed you said ", one way valve in the vacuum line" check it to make sure it is pointing in the right direction. The booster holds vacuum when the oneway valve is wrong. and will apply brake pressure because the pressure when you apply the brakes has no where to go and builds up.

 

One way valve is in correctly. Gravity bled the brakes and it seems to be working, still need to put more miles on it to make sure. So it looks like the reman. brake booster was no good. It still needs some tweeking to be right on the money though. Thanx for all the suggestions and ideas, any more comments are still welcome.