Attention J&s Teg

hey i drove my car last night and the car drove fine for about fifthteen mins. then the car started slowing down by itself like the brakes where draging. Do you think the proportioning valve is real bad and if i is do they go out if they where not used for a long time.

i have changed out alot of things on the brakes system like the brakes lines, rotors, pads, and the master cylinder. The brake petal feels soft and good at first then when the car starts slowing down by itself the petal feels hard like it won’t go down no more.
so what do you think it could be


Man, this is getting interesting! First, I do not think that you have a bad prop valve. They are either plugged or not. I believe that this design does not have any moving parts. Besides, if it was bad, it would be bad ALL the time not intermittent like you mention. So, just to sum up everything to make sure I understand…(let me know if I’m wrong). You get in your car initially and all works great. You can apply and release the brakes like everything is normal. After a bit of driving(i.e. 15 min), the first thing you notice is that the car begins to slow down on its own. This is then followed by the fact that the pedal gets hard to push. Because the brakes work well at first eliminates the booster and the adjustment rod.
Here are next steps (a little homework):

  1. Check that all bolts are still in place on all the calipers and they are not loose. Make sure that the slider bolts are greased well.
  2. Use this diagram to make sure that the prop valve is installed correctly.
  3. try and repeat the process with the engine running but do not drive it anywhere. If or when the pedal starts getting hard, try and see if the pedal is up or is it hard because you are already at max. travel down. This way we can know for sure if the booster or master cylinder is bad.
  4. Raise the car onto jack stands, have the engine running, and pump the brakes a few times and release. Try to see if ALL wheels are hard to turn or just one. Repeat as necessary to see why the car is decelerating when the pedal is not applied. This should help to see if the problem is at a particular wheel end or if the whole system is getting the effect.

Let me know the results. Good luck hunting. (did you think this was going to be easy?)

Hey thanks alot for the help I just hope that i can get everything done right this time. So you don’t think the brake booster is not the problem right, because the dealer told me they were different parts numbers and they are different and other people say that they are the same and it shouldn’t matter about the booster.

i’m going to do what you told me to do and see if that will get it to work. So it cant be the booster they are all the same? What would make the car do all this could it be because of thestupid conversion

Thanks again

hey i did do all of that like make sure the caliper bolts where tight and made sure the slider bolts where greased good but i just and the prop valve is on the right way. but i have not jacked the car up to see which wheel is not turning so im going to double check on all the things you posted.


ok we jacked up the car and we put it first gear and saw that the driver side was not spining and had a little resistance. Then we drove the car for about ten or fifteen mins and the car was slowing down a little bit not as much as it did before.

We put it back in the driveway and jacked up the front again. We bleed the driver side without pumping the brake and fluid came out like it would if you were bleeding the brakes.

For some reason there is still presure in the line on the driver side that is causing the caliper to squeeze the rotor. The presure is not releasing on the driver side

good. At least we now know that it is a specific corner causing the problem not the master cylinder and booster. Now we can start to define the actual problem. Lets start from the highest point and work our way down to the wheel. Do the same test and make sure that the right rear wheel can turn free. If the wheel has no resistance, we can eliminate the master cylinder, the line that goes to the master cylinder and the prop valve. “nosense” may be right in the fact that the flex line may be acting like a check valve. I have seen this once before too. When the pressure is held at that wheel, gently squeeze the length of the hose with pliers to and see if the pressure is released and the wheel turns freely. Is the line new? Otherwise you have a sticking caliper which you will need to replace. Let me know what you find out.

so you think its not the brake booster and it wouldn’t matter anyway cause the boosters on intergra are all the same.

Ok so what can be making the car do all of this the lines were from a junk yard car but the car would not bleed as good as the did when we bleed the brakes. Something is not letting presure release in the brake line. Does the check valve work with the brakes too and if it does could it be bad.


oh do you think the push rod has to do with somethink too.

Because the boosters have a different part number, they are obviously not the same BUT this has NOTHING!!! to do with your problem of pressure release. It looks like the overall diameter of the boosters are different. The larger booster (WHICH YOU HAVE SINCE IT WAS ORIGINALLY AN ABS VEHICLE) will generate more force. The reason for the booster change is for “pedal feel”. The OEMs want a certain “pedal feel” for a vehicle for marketing reasons. A larger booster means that a customer does not have to push the pedal as hard to get the same output force to the master cylinder for pressure build. Also, a improper length push rod will either require more pedal travel to start pressure build (too short) or it will ALWAYS have a little residual pressure built in the system (too long) The reason I do not think it is the problem is that in either case, it is “ALWAYS”, not just some of the time like the preblem you have. ( you did mention that it works fine for the first 15 min.) . The push rod would be something good to check since it is easy. Do it if you can.

Now, lets get back to your main problem. I am not talking about the vacuum check valve that goes to the booster. What we are saying is that one of the rubber lines that go to your caliper has a tear on the inside liner which can “flap closed” causing the brake fluid to be trapped in the caliper and not get returned to the master cylinder. Until you do the second set of tests that I listed I cannot help you. Also, I need some clarification from you on two comments you made:

  1. From another post (which is making it hard to keep track of everything): “But for some reason they switch for side to side in the front like they take turns slowing the car down.” What do you mean? Do you have a problem with both fronts? I thought you decided that it was only the driver front giving you problems.
    2)“lines were from a junk yard car but the car would not bleed as good as the did when we bleed the brakes.” What?

I’m almost thinking it would be best to take your car to a brake shop and let them fix it for you. You need to get this fixed soon. Aren’t you driving the car everyday?

Ok there could be a hole in one of the lines and if there is one would it be visable?

What i ment was that is what it feels like to me like the front brakes are swithing sides maybe its just me, and on the lines i got the lines from a junkyard car and i was saying that if those were bad that they would no bleed as well as they did.

So you think i should take it to a brake shop and let them deal with it cause i have had it i just can’t figure out the problem with it. But they have told me that my brake booster is out that might be causing the problem think so?

Thanks alot for the help

It’s not a hole and it is not visible. It’s like a tear. Either way, just take it to a good brake shop. Let them diagnose it.

Thats what im going to do and i’ll let you know what was the whole deal with the brakes. Thanks for the help and time