Engine/Transmission (1998.5 - 2002) brake problems

[cmills]

Hi, everyone this is my first time actually posting anything on here so please forgive me if it looks like i don't know what i'm doing. I have a 99 2500 4x4 that has rear brake problems. The deal is that the rear brakes don't work at all in 2 wheel drive unless you have a very heavy load on it. If you have no load on it you can slam on the brakes all day long and the drums will never get warm at all, but the brakes work excellent when in 4 wheel drive loaded or unloaded. Any help would be greatly appreciated.

 

[jkern]

that is the way they are made...

first, welcome!! do alot of reading the posts and you will get a ton of info here. now on to your question... our trucks have a "rear brake porportioning valve" if you look under the left rear of your truck you will see a device that has some brake lines attached to it and an arm connected that is connected to the frame or some type of frame mount just under the bed. what this does is this: when you are running around empty, this valve is nearly closed thus reducing pressure drasticlly to the rear brakes, thus the "problem" that you describe. when you put a load on the truck this compresses the suspension, thus moving that lever and opening that valve to let more pressure to the brakes giving you much more braking power to the rear. this is the way that the engineers designed them, personally i hate it and have plans in the very near future to bypass that valve so that i have full braking to the rear all the time, not with just a load... plus it save wear on the front brakes too. hope this helps clear things up for ya, you will probably get some other replies as well. again welcome.



Jeremy

 

[jkern]

one more thing..

not sure what the 2WD or 4WD has to do with it, there is no correlation or link that i am aware of to braking and the transfercase. maybe just because it feels different because there is direct link to the front wheels that are doing all the braking when you are in 4WD. what i mean is when you are in 4WD the front brakes will slow the rear wheels too beacuse they are all hooked together by the transfer case. hopes this helps



Jeremy

 

[BroncoMarc]

If the transfer case is in 4wd it will stop the rear wheels with the front brakes. I experienced this with my 73 Bronco trail rig. I had a lot of problems with my rear drums. Could never get them adusted right. Looking back at it I think my wheel cylinders were bad.



If I had it in 2 wheel low, I could sit there on the brakes and my rear wheels would slowly turn... even on the road! Real fun on the trail... Sitting there at a stop and the rear end starts walking to the side.



But, in 4wl the front brakes did all the work and stopped the rear wheels thru the transfer case.



I've got rear discs on the Bronco now and they work great!

 

[cmills]

I do know about the rear proportioning valve but the thing is that these brakes have over 100,000 miles on them and are still over half there and and i do tow a lot, so I really don't think that this is the reason. I do know that the valve must be functioning do to the fact that the brakes do work slightly when loaded. By the way adjusting the brakes does not really make a difference. Thanks for the replys!!



Cory

 

[zap]

There is a TSB from Chrysler on this. They sell a hose which replaces the proportioning valve. I put one in and it made a pretty big difference to me for what it is worth . I think the kit is around 30 bucks.

 

[cmills]

Thanks Zap, do you have to get this kit at the dealer? I assume it is pretty easy to install, and do your rear brakes wear out real quick? Info greatly appreciated!!



Cory

 

[kluther]

does your truck have a height sensing valve off the rear axle?could be out of adjustment? ken

 

[VietDoc]

Cory,

I have about the same truck with fewer miles. I had to do a very emergency stop (going about 70 when a guy doing 15 decided to make a left turn from the right lane right in front of me. Then he looked in the mirror and saw a big Ram with the rear wheels locked up and smokin ( I have ABS too! They still locked, well I guess I would lock up too if I had a size 13 that far up my rear end ). He qucikly decided to very quickley get back in his lane much quicker than he got into my lane. Lucky he did or he and his family would have been toast... I was totally empty and couldn't have stopped.



I let off the brakes and cruised on through. The truck did start to swerve as the left rear locked up first, i corrected and then RR locked up and I had to recorrect. Sure glad the front discs kept turning!

I used to drive Ambulances and firetrucks so I am kind of used to folks pulling in front of me..... even with red lights and sirens they pull in front of you

But it took my wife over 5 minutes to talk and all she could say was "I'm sure glad you were driving!" About evety five to 10 minutes she repeated it about 3 times (See first line in Sig)



I don't suggest you try this to see if your brakes work. But I bet they will, they just don't seem to work in normal driving.

Richard

 

[Steve Campbell]

Two other options I have heard of...

put the 3500 wheel cylinders on your 2500.



The other is to put a turn-buckle in the brake proportioning valve and fine tune the front/rear brake bias that way. I chose this method... but keep in mind, you are altering a very important system on the vehicle. Choose wisely and be careful.



The resident brake "guru" on the TDR is Sam Petersen. Send him an e-mail, he may be able to help you out

 

[cmills]

Ken, I assume the height sensing valve you are talking about is the same as the rear proportioning valve, but i don't think you can adjust it.





Cory