i searched some post but found nothing similar to the problem.

when i brake test from 55mph it slows smoothly and quickly when applying more than normal pressure, as it slows down to under 5mph it locks up all four tires and then unlocks right before coming to a complete stop. other issues are when braking normally right before stopping the rear drums will lock up and then again unlock right before coming to a complete stop. when rolling from a stop if you press on the brakes it locks them all up.

checked the fluid, it is clean and correct level. checked lines and appear to be leak free. i'm thinking maybe the master cylinder but wanted to see any other suggestions. don't mind tearing into things to find the problem, but sometimes ya'lls wisdom could have helped in the first place. thanks guys

 

BUMP _____

still having the issue of the breaks locking up below 5 mph when brake testing. also, if stopped and let off the break and start to roll, if i hit the break again it clamps down hard and comes to a very quick stop. it's almost as if your either breaking or your not, there is no in between. it either lets the calipers lose, or its clamping down on the rotors too hard.

 

i had a similar problem with a car while i was in college, i think it was a proportioning valve. might be stickin, roll ur truck at about 10 mph n slam that brake pedal with everything ya got. how old are the metal lines?

 

do you have abs ? rear only abs ? abs lite on ?

 

Ive heard thats pretty common with the duallies of that generation. I never had it personally happen to me, but its something to do with crappy rear abs or not having abs or something that makes the rear axle lock up very easily.


Come to think of it, I may have locked up the duallies a few times but I wasn't going very fast, and as soon as I locked them I let off.

 

it does have abs. no abs lights on. i pulled the rear abs and and the front right abs and took it around the block, as expected the tires that were unplugged locked up but the front driver which was still plugged in did not lock up. i don't know how well of a test that was, but it made me think that maybe the abs is working properly. it's not just the rear brakes, in fact they seem to be working correctly, only when really braking do they lock up which is common on these trucks. it's the front that seems to be giving me the most trouble. i mean the calipers really bite down. like i said, when at a rolling stop and pressing on the break normally it slams on the rotors and comes to a quick stop, almost jerking the truck. also as mentioned, when testing the brakes from 55, at 5mph the brakes lock up for 1 second and then unlock to come to a stop. it's as if there is no braking action at all. it's either no breaking or sending too much pressure to the calipers. theres hardly any the more you push on the pedal the harder they clamp

 

have you just bought this truck? Because my 12v brakes were VERY catchy as well. It didn't take much peddle to make this thing slow down.

 

i just bought this one, but sold my 97 a couple of moths ago. i know it ain't supposed to locking up like that i hate to do it, but it looks like i'm gonna start changing parts on it till i get somewhere.

 

Is this your first dually? Or was your '97 a dually?

 

97 dually, this one not