I have an unsettling issue with my truck, its a 2000 Ram 1500 Sport 4x4 with the 5.2l V8. I have been having a problem with the rear brakes locking up and slipping when braking hard. So naturally I pulled the drums, found one leaking cylinder, worn pads, and out of spec drums. I replaced the one cylinder, shoes and drums. My rear brakes seem to work better, but during the rain or when the truck is cold, my rear drums lock up and skid my tires with the slightest tap of the brake pedal. This normally happens when leaving for school in the morning and leaving school in the afternoon. Gets very annoying... Im thinking the proportionality valve but im not sure. anyone have any input?

 

Maybe starwheel adjusters sticky or bad?

 

i just posted on the same issue and dvaughan said his did the same thing, so im guessing its normal. it only does it for 2 maybe 3 taps of the pedal, rite?

 

does your truck have 4-wheel ABS or RWAL (rear-wheel anti-lock) brake system?...i would look into that system if your rear brakes are locking up when they really shouldn't...also, have the brake lines been bled properly?...if not, then air in the lines would give you braking issues by contaminating the brake fluid (which the fluid is essential to your brakes functioning properly)

 

Ok, it is normal for your drums to lock up when you first take it out in the morning. Especially when it is damp. That happened to me and my Father in Law (a mechanic) said that was normal.

That has not happened since I had both shoes replaced and the drums turned, AND had the hardware kit replaced (springs)

I would change the shoes on both sides and have the other drum turned. Brakes are like armpits, you don't wash just one.

I think you actually need to get them TURNED and THE HARDWARE replaced. Those rusty and worn springs make a WORLD of difference when replaced. I had the same problem as you (locking brakes with the slightest tap). Replaceing the shoes, getting the drums turned and replacing the hardware kit fixed that.

You fixed the lockup and slipping with replacing the cylinder.

 

Also gotta keep in mind, that the rear brakes are designed to stop the truck when it is FULLY LOADED. If you are driving around with an empty bed, the brakes are significantly over-powered for the weight they are trying to stop. Thus, they lock easily. On some of the newer trucks, there was a proportioning valve, with a lever arm attached to the frame, that varied brake pressure by the perceived weight in the bed. Check and see if you have one, and if it is hooked up properly.

 

Mine locked up on my one time and it only did it in gravel for the first stop of the day in gravel. So if I went to the end of the driveway and got up to about 5mph and hit the brakes lightly the brakes would lock but not after I took off down the road and hit the brakes on the pavement.

On my truck it was a leaking wheel cylinder.

It hasn't done it since replacing that wheel cylinder.

I did have everything fall apart in one of the rear wheels one time too, half of the springs and the star adjuster were ground to dust so I replaced those too. I don't remember if that happened on the same side.

 

Well I have replaced both side shoes and both drums, I will replace the other side cylinder and adjust the starwheel and see if it helps. Today It was raining heavy and my rears were locking up downhills and at hard stops..

 

The master cylinder may be causing it also, if it is not completely releasing the piston in its bore. This happened to me. My rear wheel cylinders were leaking, changed those, changed shoes both sides, had both drums turned. Still did it. Master cylinder was keeping some pressure on the brakes when they were not applied (very slight pressure). I replaced the mc and now all is good.

 

have a 96 ram 2500 that started locking up. had s good guy replace rear drums/shoes and it did it from then on - wet/dry, warm/cold. he said it likely was proportioning valve. cannot find new one so finally found used & replaced. eventually changed master cylinder as well with no change. works fine with 500 lb or so but locks at slightest touch when empty.
have looked around back drums but see no valve there and doubt a 96 had abs. i think it is a simple thing i am missing cannot find anyone who is familiar or seen this before to say "ah! it is ....." anybody know?