My rear brakes still lock up before the fronts...

Matt90GT · Mar 5, 2004

custom89stang said:
STILL.... his rear brakes shouldnt lock up first. the reason the front does 90% of the braking is cuz the suspension on every car leans forward and all the weight is on the front, thus the fronts usually lock up.

First off understand the physics happening. When you apply the braking force, your weight shifts forward on the car. Thus unloads the rear tires, thus making them easier to lock up. That is why the rear is proportional in pressure to the front.

BlackFox5.0 said:
I have a very good pedal, I already got all the air out of the rear calipers, my struts are still good, they kept going back down when I was trying to hold them up while doing my spindles. I also have stiff springs, and almost no nose dive. Even if I am going under 5mph, they still drag.

I have 245/45 17 tires all around

If they drag, you probably do not have the brackets shimmed properly so the calipers are centered on the rotor. You have to check and double check this measurement!

Also if you use to aggressive of a pad compound on the rear with that setup, you will never get enough front bias dialed in with the off the shelf valves. Go buy some organic pads for the rear or super aggressive front pads.

87gtconv · Mar 5, 2004

Matt90GT, if I go with less aggresive pads in the front can I get my right front to stop locking up before left front does????

Matt90GT · Mar 5, 2004

87gtconv said:
Matt90GT, if I go with less aggresive pads in the front can I get my right front to stop locking up before left front does????

uhh, no.

Common issue with the 3 port MC bastard.

87gtconv · Mar 5, 2004

I can sure vouch for that!!

bhuff30 · Mar 5, 2004

sorry to get back on topic here, but if your pads got any brake fluid or oil on them, they get very grippy, and tend to lock up.
Sounds like you need to find a different master cylinder to fit your application though.

87gtconv · Mar 5, 2004

Agreed but his sig says he is using the SVO MC and I thought that was the correct one for that set up!! Sorry about my digression!

Maryland Stang · Mar 5, 2004

On the front vs. rear lockup issue my 95 F-150 has rear anti-lock brakes and not the front. Ford would rather have the fronts lock than the rears.

BlackFox5.0 · Mar 5, 2004

I have the top prop valve in this link

http://www.wilwood.com/products/valves/valves.asp

I adjusted it all the way out, to FULL line pressure, so it's like i don't even have the adjustable prop valve.

Matt, I have stock brake pads in the back, I used the ones from the junkyard calipers I used for cores. They still have a lot of pad left so I figured I'd use them, and of course I sanded them flat before I used them.....

I appreciate all the discussion, but it's not really helping to solve the problem...What could be wrong with my setup?

It feels like the rear is locking up way before the fronts are even close to locking.

And Matt, my Cailpers are pretty centered over the rotor, How would it affect the braking if they weren't?

91BlckGT · Mar 5, 2004

BlackFox5.0 said:
I have the top prop valve in this link

http://www.wilwood.com/products/valves/valves.asp

I adjusted it all the way out, to FULL line pressure, so it's like i don't even have the adjustable prop valve.

Matt, I have stock brake pads in the back, I used the ones from the junkyard calipers I used for cores. They still have a lot of pad left so I figured I'd use them, and of course I sanded them flat before I used them.....

I appreciate all the discussion, but it's not really helping to solve the problem...What could be wrong with my setup?

It feels like the rear is locking up way before the fronts are even close to locking.

And Matt, my Cailpers are pretty centered over the rotor, How would it affect the braking if they weren't?

I just got done debugging and fixing a brake locking issue with my car. I had a similar problem like you. Although I'm sure my prob was slightly different, it turns out that my particular issue was that i had the adj. piston in the brake booster adjusted OUT too far. So when ever I drove, the brakes would end up groaning and eventully lock up as the rotors heated up. Not fun. I backed in the nut about 1/16" and that solved my problem.

When your brakes heat up, how much pedal travel do you have before they start to catch? If you have worn pads in the front, and fresh pads in the rear, that might explain it.

Another thing about the prop valve. We have the same one. I have mine adjusted out 5 turns from fully open. Stupid question, but did you mount it correctly? It should look like this:

Matt90GT · Mar 5, 2004

BlackFox5.0 said:
I have the top prop valve in this link

http://www.wilwood.com/products/valves/valves.asp

I adjusted it all the way out, to FULL line pressure, so it's like i don't even have the adjustable prop valve.

Matt, I have stock brake pads in the back, I used the ones from the junkyard calipers I used for cores. They still have a lot of pad left so I figured I'd use them, and of course I sanded them flat before I used them.....

I appreciate all the discussion, but it's not really helping to solve the problem...What could be wrong with my setup?

It feels like the rear is locking up way before the fronts are even close to locking.

And Matt, my Cailpers are pretty centered over the rotor, How would it affect the braking if they weren't?

Are you not listening to what I post? I am giving you solutions. If you dont like them, tough. Get over it and start wrenching on your problems.

If the calipers are not centered, they will drag like you have stated. Go back and reshim the brackets.

Then go buy some CHEAP organic rear pads for the rear brakes. Who would use "used" pads off a junkyard car??? for $9 you can get new ones. Bad idea since you have no clue what pad compound these pads are.

bhuff30 · Mar 5, 2004

Maryland Stang said:
On the front vs. rear lockup issue my 95 F-150 has rear anti-lock brakes and not the front. Ford would rather have the fronts lock than the rears.

this is because of the varying loads that your truck will be carrying, which greatly affects the amount of braking that can be done by the rear tires.

BlackFox5.0 · Mar 5, 2004

91BlckGT,my prop valve looks exactly like that, I know it works because I have had to adjust it before....

I just checked my calipers, and the rotors are not centered with the hole in the top of the caliper, should this be where it's centered?

Also how, and where do I shim it? Do I shim the bracket or caliper?

Also when I checked the calipers, the slide pins were sticking out from the caliper about 1/2"

91BlckGT · Mar 5, 2004

I had to reshim mine (granted, it's a different kit, but you can see here where the shim went). I put in on the anchor place that holds the caliper to the mounting bracket. On one side I had to use a 1/8" shim, the other side 1/16" was plenty. It varies by vehicle because ford usually didn't weld up the axles flanges nice and true.

BlackFox5.0 · Mar 5, 2004

I can't shim it like you did, because there is no caliper bracket like yours. The caliper sits on slide pins, and is held in place by being clamped over the rotor.....the only thing I can think about is the bracket on the axle. But if I put it on the opposite side of the flange, then the caliper doesn't come even close to fitting over the rotor....

speed1972 · Mar 6, 2004

You stated that you have it adjusted all the way out for full line pressure... Is that full line pressure to the back or front? If it is to the back, that is your problem... you need more in the front

My rear brakes still lock up before the fronts...

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