Proper brake fluid pressure at rears ?

[JohnW63]

In my never ending quest, to get my rear brakes working right, on my 95, ATX SHO, I've replaced one of the rear flex lines. ( I would have replaced them both, but the other line looked less than new, so I'm going to call the on-line vendor and exchange it. )Of course, bleeding the line was in order. Once fluid began flowing, I was under whelmed by the flow. Yes, I had the car on the ground , so the bias block would not reduce the flow. I would say that the fluid only arced about 3/4 of an inch before heading ground-ward. The fronts showed a lot more strength.
Is this the right amount of flow for my SHO ? Other , and older cars I've done, would squirt a foot or two.


JohnW

 

[Deaks2]

Rear calipers usually have less pressure going to them. If you think your is unusually low you should check your brake proportioning valve.

 

[JohnW63]

What exactly should I check for with the proportioning valve ?

What amount of pressure SHOULD I see at the back ?

JohnW

 

[89 black SHO mtx]

a few of questions here. How much pressure was on the pedal when bleeding? and, is the control arm for the porpotioning valve still intact and properly adjusted? Where the pads all the way against the rotor? All of these are factors when looking at the hydraulic pressure. ride height also plays a part in the porpotioning valve as well. but if you had a good stream out of it and no air try driving it and see if it pulls the other way.(one grabbing harder than the other) this is always the best test and the easiest. unless you want to spend around $300 for a brake pressure tester(mainly for abs anyway).

 

[luigisho]

You probably need to put pressure on the rear wheels with a jack to simulate a large amount of weight in the rear. The valve opens wider as the weight in the rear of the car increases. Put the rear on stands and use the jack to push the rear wheel/hub up.

 

[JohnW63]

Firstly,

As I mentioned, the car was on the ground, so the bias valve was NOT limiting the flow. I will need to cut a piece of tubing to .69 inches and see if it is adjusted to specs.

My wife is the designated pedal pusher, and I would have to guess she pushes the pedal down with about the same pressure each time I ask here to do it.

The car is not running when we do this.

I was hoping for a general answer, like: The fronts usually shoot twice as far as the rears. Or they should be close to the same. Or, WOW, they should squirt farther than 3/4 of an inch !.

JohnW63

 

[pjtoledo]

Since you are in Ca we don't have to tell you to pull the bleeders out and scrape the rust out of the little passages. I always put a hose on the bleeder, so no squirts, just fluid in a jar. Thats the proper way, so you don't suck air back into the caliper. The rears being smaller, expect only about half the amount of the fronts.

Perry Toledo,Ohio

 

[pete c]

You got a 3/4 inch squirt? Lucky bastard. After replacing my rear left caliper, I get a very slow dribble. With the bleeder open, the pedal is still very firm. It does go down, but very slowly.

A little history on the problem....

I bought this car, 93 mtx, 89K, last summer. Right from the start, the rear driver side stuck on occasion. I replaced the sliders, bracket and pins. They were pretty whooped.

This spring I noticed that familiar odor of rear caliper roasting. I suspect it was caused by the wife driving with the e-brake on. She never sets the damn thing fully and therefore drives away with it on. There is no dash light thanks to fords wonderful switch gear quality. Why can't ford just buy all their switches and connectors from honda?

I digress.

The sticky caliper comes and goes. The wife (of course) was driving it about a month ago and was pulled over by a state trooper because of the smoke trail she was leaving behind. I drove the car home without incident. I have been driving it to work and back since, without any problems.

Yesterday, I finally got the time to take a look at it. The caliper was leaking and the piston and slide boots were partially melted. The pad surfaces were completely gone. There should have been a hellacious grinding noise, but, there wasn't.

I replaced the caliper with an AZ rebuilt. I attempted to bleed that brake but there basically no flow. The pedal remains firm with the bleeder open.There is some flow, you see the fluid level in the clear tubing rise veeerrrrrryyyyy slooooowwwwwlllllyyy.

I then found (here ofcourse) that this is normal with the suspension unloaded. So, I replaced the tire, lowered the car and tried again. Same problem.

Since there was a slow leak in the bad caliper (I had to add fluid twice over the last month) could this have caused a problem with the master cylinder? Is my proportioning valve shot?

I am about ready to bring it to ford and let them handle it, but, I am afraid they will just farg it up and lighten my wallet a few hundred bills.

Any recommendations would be appreciated. Recommendations of reputable brake service folks would be equally welcome. I am in Ellington Ct about 20 minutes up I-84 from hartford.

Thanks,

Pete

 

[projectSHO89]

pete

Replace the brake line on that side, it's probably swollen shut under that metal piece that mounts it to the strut. That will keep pressure from getting to the caliper. It will also cause the caliper to stick (pressure can't bleed back to the M/C once applied) and roast your brakes.

Brake line should be around $20-25 bucks at your local parts house.

Steve

 

[pete c]

Thanks Steve. That is just what the ford wrench I talked too said. How much more are the SS by the way. Doubt I would splurge for them, but if the price diff isn't too bad.....maybe.

 

[Xs SHO 1]

the stainless steel brake lines from jegs.com is $87+shipping= around $97. i replaced my rear hoses today since i was having the same probs as u. since i didnt have anyone to help me in the brake bleeding, i used a craftsman bleeder kit with a little vacuum pump.

the first 20 mins of using the kit, i couldnt get any fluid flow. then finally, i had some nice flow in the lines. i will rebleed the rears again after i finish replacing the front hoses and just to be in the safe side.

everything in the rear brake system is new, new calipers, pads, rotors, brackets, slider pins, brake hoses and even the e-brake. if i still have my rear left brake sticking, it will probably be the proportioning valve. i hope it isnt but its possible. i took it for a ride and everything feels fine. my rear left white wheel looks a little yellow due to this sticking prob.... headbang

<small>[ May 08, 2003, 09:07 PM: Message edited by: xssho1 ]</small>

 

[Xs SHO 1]

i bled the brake fluids on the fronts and rears today with a second person as a brake pedal pusher. i am currently getting lots of flows on the rears as well.... thumbup

my preference would be the "two person" method compared to a little manual vacuum pump. i cant even feel my forearms! squint

 

[jeffrey138]

dont be concerned about how much or how far fluid shoots out of the bleeder. it is the air you want to be concerned with, if there is fluid coming out of the bleeder and not air i think you can sit back and be proud of a job well done thumbup