Front-wheel shimmy when applying the brakes

brakes

#1

1997 Dodge Grand Caravan, only 60K miles. Stripped model - only features are A/C and radio. 3.3L engine. Front-wheel brakes.



At times when I apply the brakes, I get a pulsing in wheels. It gets worse at highway speeds – it triggers a shimmy in the front wheels that shakes the steering wheel and the front-end of the car.



I put new (inexpensive) rotors on the car a year ago, and new pads on a month ago.



I suspect the rotors are warped. Or – it is possible the calipers are sticky. When I bought the car, ONE of the two calipers was extended almost entirely, and had ground the rotor to paper-thin.



Ideas?


#2

My best guess is that those inexpensive rotors are already warped because they were…inexpensive. In the long run, this is not something where it pays to try to save money. Rather than trying to have these rotors machined, it would probably make sense to have them replaced with OEM rotors or a well-respected aftermarket brand.

Incidentally, if your Caravan really has brakes only on the front wheels, then you REALLY have a problem. I am going to assume that you meant to say that it is front wheel drive. If I am incorrect in this assumption, please post back!


#3

Its really not unusual to have a shimmy right after putting on new pads. It is part of bedding in the new pads. If you take it out and do a couple of moderately hard stops from about 60, not to the point of lock up but just short, and don’t come to a complete stop, let up at about 5 mph. You will find that the shimmy will disappear. It may come back in a few months, just repeat the procedure again. You may have to do it a few times over the next year.


#4

You should also check out the calipers again. One of the things that can create problems with rotors - especially the cheap ones is sticking or otherwise improperly operating calipers. If they stick a bit the rotors get overheated and for various reasons this can create unevenness on the surface - thus the pulsing.

So I would take the brakes down again, and make sure that the caliper slides are clean and well lubricated. Also, I have a '95 Caravan, the model changed after '95 but the brakes are likely quite similar. I had a situation where my inside pads wore much faster than the outside b/c of a wear point that hangs up the caliper. I was told this is very common in Dodges. It never caused mine to stick or any rotor problems, but in essence, the inside pads were doing most of the braking work.

So take the brakes back down, and fully inspect the calipers. After that I would be tempted to turn the existing rotors and put those back on. But certainly a better pair (middle-expensive rather than least expensive) wouldn’t hurt.


#5

go to NAPA ask for the made in USA rotors. they cost about 6 bucks more than the cheapys and they last. and they dont rust as bad as the china rotors do.

next time get the mid grade or the best pads.

prior to pushing the caliper pistons back in, clean all the gunk off the pistons. (but don’t cut the rubber bellow boot) if the gunk get shoved back in it jams the pistons which will make them not let go, and will cause these symptoms too. a hanging caliper will chew through the brakes in a couple of days or so.

get some brake parts cleaner. use it liberally. clean all the brake dust off the whole rotor, calipers, and pads and get all the finger oils and grease off the whole thing before putting the tire on. that will eliminate alot of the brake noise while the pads are seating in.


#6

I did mean “front-wheel drive”. There are rear-brakes also, the standard drum brakes.

Thanks all to your advice. I’ll work over the brakes again, and use better-quality parts this time.


#7

These fans are fairly hard on brakes because the brakes didn’t get appreciably bigger as the vans got heavier with each generation (yours is a third generation). It is therefore vital that the rear brakes do their share, small as that share is. A frequent problem with this generation van is the rear brakes going out of adjustment. Unlike most other vehicles with rear drums, they do NOT self-adjust when you apply the brakes with the van moving in reverse. Instead, using the parking brake adjusts them.