my brakes seem weak !!!! - Ford Forums - Mustang Forum, Ford Trucks, Ford Focus and Ford Cars

351w · 09-15-2003, 19:52

ok guys here is my problem, some of you know i have an 86 F-150 that eats other trucks (89's especially) and quit a few cars for breakfast.
but for the last yr or so i have been thinking my brakes have been a little weak.
so now in an attempt to remedy this i have replaced the front calipers with reman calipers and also replaced the rear wheel cylinders to find no difference so i broke down and bought a reman booster and master cylinder also and still the brakes seem weak, so now after replacing all the components and all the fluid in the system the only thing left is the proportioning valve. is there any way that this valve could be restricting my pressure to the calipers. when the fronts are bled i have no problem drawing fluid out.
more specifically i can lock up the back tires if i jam the brakes on so i know they are getting plenty of pressure and about 3 yrs ago i had jammed on the brakes and locked up the fronts as well.
i have no spongy pedal or problems stopping it just seems that whenever i tow something i have to stand on the brakes to stop and i recently rented a chipper to grind brush and got scared when i had to stop on a hill while pulling that and didnt think i was gunna stop at all. (i even dropped the trans to nuetral just to be sure the engine wasnt pullin)

if i do a line pressure test on the front calipers can anyone tell me what would be a good PSI number to look for.

89F150 · 09-15-2003, 23:44

pfffft brakes are for wooses!!!

Are you still running the stock rubber brake lines, try stainless steel lines.
They help increase pressure in the braking sytem.

big1 · 09-16-2003, 05:47

The valve can diffenently restrict fluid flow. I came upon this same problem. I got rid of the factory valve and replaced it with an aftermarket adjustable valve . That way you set it to feel right for you.I got mine from http://www.summitracing.com
.

351w · 09-16-2003, 20:45

thanks big1 thats really all i needed to hear cause i already have been thinking about replacing it. i know summit very well, just didnt know about the brake valve.

89f150 the rear is all steel lines but when i tried to put steel lines on the front they kept breaking off when i went around a corner.

the only place that isnt steel is the 6" flex that runs to the front calipers.
i never used stainless but i am pretty sure it takes a special flaring tool that i dont have.
something along the lines of a different degree flare.

351w · 09-16-2003, 20:53

who copied my post and put it in the garage ?
i had one in there already.

Fat F100 · 09-28-2003, 22:45

Got a mate with a '79 F100 who put a '89 F350 brake booster into his truck. The only problem is that shaft is a bit longer which he got cut to the correct length. He reckons that this improved his braking 100%.

351w · 09-29-2003, 19:28

thats a strange thing to hear i didnt think there was any difference in the booster except for the rod length.
ill check into that at the parts store though it might be an idea.
my brakes really are crappy i towed a trailer load of wood home the other day and you got to stand on the pedal to stop.

Fat F100 · 10-06-2003, 22:03

Yeah, the rod length was longer, but the overall diameter of the booster is smaller & it's almost twice as thick. Still working well last I heard.

351w · 11-23-2003, 17:36

hey guys i finally got the problem fixed with my brakes.

i had to order the brake differentiating valve from ford and replaced that.
now the brakes seem pretty strong again, i have no problem locking up the wheels with no load in the truck.

i couldnt go with an aftermarket proportioning valve because the factory valve also does the distributioning as well.