Hi guys. There's a 32 page service bulletin for this problem. In later years it has been affecting more than just Dodges but it only applies to the 2500 and 3500 series with heavier engines, particularly the diesel engines.
The bulletin involves checking 31 pages of things that turn out to not be the problem, then on the final page they finally get to the brake rotors. They have to be EXACTLY the same thickness and speed of cut on the brake lathe. I know you said it has new brake rotors but a lot of mechanics take a light cut on new ones in case they were dropped in shipping. I was involved with two lemon-law buybacks that no one else could solve because they didn't read the service bulletin. The district rep. Brought one to our shop on his monthly visit and insisted it had to fixed regardless of cost, then it would go to an auto auction. After checking all the other stuff, I found.007" difference in the thickness of the two front rotors. That's the thickness of two sheets of paper on a rotor that's well over an inch thick. I took a light cut on the thinnest rotor, then I took enough off the thicker rotor to match the first one with the same speed of cut with an on-car brake lathe. That solved the pull.
By the way, the secret is the pull is never there until the brakes get hot. Normal city driving on a summer day is enough heat buildup to cause the problem. Braking will be fine one stop and tug the steering wheel out of your hand on the next stop.
If you have the brake pull when the brakes are still cold, you'll need to check the other things in the service bulletin. There are four different front brake calipers for each side. There's some with 80mm pistons and some with 88mm pistons, and there's the standard calipers and low-drag calipers. Measure the 3" wide (approximately), mounting surface where the caliper rests on the mounts. If the width is the same on both sides, the pistons are the same diameter.
Look at the four control arms that hold the front axle in place. There's standard duty and heavy duty. That has absolutely nothing to do with the weight of the truck. All you care is all four are the same. They will be unless someone replaced one from a salvage yard and wasn't aware of the difference. Look at the metal sleeves the rubber bushings are pressed into on each end of each arm. One side of that sleeve has a raised lip all the way around. Look at that lip or run your finger over it. One type of bushing has two small dimples along the edge of that lip. If you find them, all the bushings must have those same two dimples. If some arms do have those notches and others don't, the composition of the rubber is different and the arms will flex differently causing a brake pull.
The district rep. Thought I was a genius for fixing that first truck so a month later he brought me another one. That one had.020" difference in the rotor thickness, again, after someone had done a perfectly fine brake job. Two hours later and on-truck rotor machining, and it was solved.
Also be aware there were a real lot of problems with steering wander that can also show up as a brake pull, but the additional clue is it might not always pull the same way. The biggest offender is the track bar. That is the long bar attached to the frame near the steering gear box with a ball and socket, and to the right side of the axle with a rubber bushing. The ball and socket develops a little wear and leads to steering wander. To identify that, have a helper turn the steering wheel from about the 10:00 to 2:00 o'clock position about twice per second with the engine running, then watch the movement between the ball and socket very closely. If you see any up and down movement, replace the track bar. Under warranty, Chrysler allowed no more than.080" movement when checked with a dial indicator. None ever got that bad because by.020" play, which is just enough to see, the truck was tiring to drive. At.020" play, new track bars solved the complaint.
Related to that is slop in the steering gear box where the pitman shaft comes out the bottom. While your helper is turning the steering wheel back and forth, watch if there's movement between that shaft and the gear box housing. Rotational movement is what you want to see. If the shaft moves sideways first, bottoms out, THEN starts to turn, the play is excessive. That can not be adjusted out. The bushing in the bottom gets hammered out. That usually goes unnoticed until the movement is great enough for the shaft to move away from the rubber lip seal and power steering fluid leaks out. A new seal will not solve that leak for very long.
Also notice if there is a pull while NOT braking. It's normal for the truck to drift a little to the right due to road crown, but if you have to keep tugging on the steering wheel to make it go straight, there are other fixes for that. Caster and camber are the two alignment angles that affect pull and they're both not adjustable. Actually, caster is adjustable but only by rotating the entire axle housing which affects caster equally on both sides so the net difference between the two sides can't be changed. I solved a pull on two trucks by grinding the spacers between the rear leaf spring and axle housing, then shifting one side forward or rearward to correct a seemingly insignificant thrust angle. I did that on out-of-warranty trucks. When they're in warranty, you can get a set of stainless steel spacers but three of them cost $450.00. That's why we didn't go that route when customers were paying the bill. If the truck always pulls right, you install the 5.0mm spacer between the left wheel and hub to move the tire out a little. That changes the "scrub radius" which affects how hard each tire wants to turn out from rolling resistance. If the pull is gone, you're done. If it pulls left now, you install the 3.0mm spacer instead. If it still pulls right, you install the 8.0mm spacer. If the 8.0mm spacer helps but you still need more, there is a 10.0mm spacer available separately but you must also install longer wheel studs.
Saturday, April 14th, 2012 AT 10:42 PM
