Shimmy when braking but only around 55 mph and other Brake questions!!

99 Sport 4x4, Michelin LTX M/S 225/75x15's on the stock steel wheels and all suspension stock too. I have the usual/characteristic minor shimmy when at the 55mph area while crusing. I know that my front rotors are not super true and it seems to be hard to get any rotor that I have tried to keep from warping when I get more than 6k-8k miles on them. Anyway, I know that I need to have the front rotors replaced or turned (again), but the only time that the shimmy is above a tolerable level is when braking in the 55mph range. You can feel a very light vibration when braking at 90 all the way down to 60 then it gets kinda bad from roughly 60-50 and then it gets very minor from 50 down to zero. I am thinking that the characteristic 50's shimmy is just exaggerated by the less than perfect rotors, but I thought that my stock (never been replaced) steering stabilizer might be adding to the problem. I have had the shimmy from un-true rotors before, but I have never noticed it so much worse in this speed range before. Also, any rotor and brake combo's that anyone else out there has tried that have remained true for an extended period of time? I am getting tired of having the rotors turned or replacing the rotors every 6k-8k miles. Also, can the factory 99 rotors be turned? I still have them in a box at home, but was told by a brake shop that 99's have some type of composite rotor that they can't turn because it will only chatter on their brake lathe

I had same exact problem I installed new rotors and is smooth again. I have full cast rotors not the cast composite rotors. The rotors I replaced were the originals at 55,000 miles. There are some companies out there that make rotors that are of a much higher quality but the price will be two to three times as expensive. I have a 99 WJ (grand cherokee) and I have to replace those rotors every 5,000 miles or so. Not to mention that Jeep knows that this is problem so I have had three front caliper replacements and rotors and pads have been changed out four times. Still same problem, so I know the frustration. Good luck.

Joe

Yep, I have some aftermarket cast rotors on their right now myself, I am going to have the stock (composite) rotors turned and put them back on and see how they do. I would be really pissed off if the pads and rotors were not so easy to change out, haha. Oh, I have heard conflicting reports of weather or not the composite rotors can be turned or not. I was told that the rotor lathe would only chatter and not cut by the local brake shop, and was told that they could be turned by another local shop. Anyone know if either is true?....Rusty

I work at a shop and there is no reason why you cannot turn composite rotors. The only thing I would say is that when you turn them you are taking away more metal which is going to make it even easier for the rotor to warp again. If you are tired of changing the rotors out because they keep on warping then turning a warped rotor is a very temporary fix. If the rotor warped once it will only do it again but even quicker if it is turned. Just my personal experience after replacing thousands of brake rotors, pads, drums, shoes, calipers wheel cylinders etc.

Joe

Well I got the Jeep with 19,500 miles on it and it had the factory rotors and it definately had some shimmy then. It didn't take long for me to change the rotors out. I am now at about 73,000 and am using my 2nd set of cast rotors right now. What I am thinking about doing today is just taking the old factory composite ones to the shop and having them turned. One other question..I have heard some shops say that you always want to have a brand new rotor turned before using it but I don't know if that is true or not. It always seems that a hot rotor wants to seem more warped than a cool one too. I guess heat really brings out the worst in rotors. Is there anything out there at all that is reasonably priced that will last 30-40 thousand miles? My wife has a 99 Corolla with 75k miles on it and it still has the original pads and rotors too and it is smooth as silk. Pretty frustrating and embarassing when I can't keep the shimmy down on my jeep for over a few thousand miles. I still wonder if I need a new steering stabilizer since it seems right now even the normal 55ish mph nonbraking shimmy is a little enhanced right now. Tires are fairly recently balanced and rotated but they are getting worn. How can you tell (without taking the steering stabilizer off) if is is bad or going bad, aka what are it's symptoms?.......Thanks for all the info....Rusty

Same problem. I also was told that they couldn't turn composite rotors. Bought some from NAPA and them were warped before the 1 year warranty expired so I returned them. Now less than a year and probably 20K later.....warped. Somebody told me that my rear brakes could not be working properly and maki9ng the fronts work harder, meaning more heat, meaning warpage. Could be. I will try and see if I can get NAPA to replace rotors (gift of gab). And then I will have a buddy that owns a brake shop look at the whole system.

Well the first thing is to look and see if any of the seals are blown n the steering stabalizer which I am sure you would have noticed just by looking at it. On my first 87 XJ the steering stabalizer was shot which caused a death wobble problem. You could not tell it was shot by looking at it but once removed it was obvious it could not make up its mind if it wanted to be in or out. It acted like a pogo stick. So in that case you could not tell it was bad untill you removed it but they are really simple to remove and replace. One of the best rotors out there that I have researched are frozen rotors. They guarantee not to warp at the tune of about 100.00 a piece for cast rotors. I do not remember the web site at this moment but if you do a search on yahoo under frozen rotors and it will pop right up. You asked for reasonable price and I do not think that this is reasonable but I do think it would solve your problem. I just replaced my factory rotors and I run 32" tires. To be honest I don't think that they would have had to be replaced but I got in a rush when I last rotated the tires and I did not torque the lug nuts properly I just spun them on with the impact on the lowest setting. I think that it caused them to warp. I am at work and got to go. Just make sure that your lug nuts are torqued properly.

Joe

I was curious, 4wd hardware offers TRW brake rotors vented and cross drilled for $86.00 does anyone know if they are worth it?

I installed cross drilled rotors from summitracing, hawk hps pads from tire rack.com, and rear disc conversion from 4 wheel supply, I think I could outstop a Bimmer. I have had the front rotors for over 100,000 miles with no warpage, wonderful. I had rotors on there before warp monthly. Not any more. Cross drilleds are definitely worth it, one of the best investments for an XJ. Rear disc conversion is also a profound improvement, but expensive and a pain in the ass.

Jackhill442 said:

I installed cross drilled rotors from summitracing, hawk hps pads from tire rack.com, and rear disc conversion from 4 wheel supply, I think I could outstop a Bimmer. I have had the front rotors for over 100,000 miles with no warpage, wonderful. I had rotors on there before warp monthly. Not any more. Cross drilleds are definitely worth it, one of the best investments for an XJ. Rear disc conversion is also a profound improvement, but expensive and a pain in the ass.

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I realize this thread is quite old, however i'm starting to have the same braking problems on my 2000 XJ with about 46k miles on it.

I like the idea of new, drilled rotors and soft composite pads, like the setup you describe above. Could anyone further comment on brands or otherwise that has helped in this matter?

I'll definitely keep my rear brakes as drums... but i would definitely like to improve my braking system up front, along with get rid of the mysterious 55mph brake shake.