Brake Rotors - Dial Indicator needed

[a1amap]

My current brakes have have what can best be described as break judder. I have a 2000 Mitsubishi Eclipse V6 3.0L. I have herad from a couple friends that are into there cars (also google) that the factory rotors on Mitsubishis are inferior. After about 12K miles the factory set of pads started to do it a bit. I replaced the pads at 20K and had the rotors turned. This seemed to fix the problem but after 10K miles it was back. This has been a problem for the past 2 years but has become more violent recently. I purchased new rotors and pads and was going to replace the both when I was reading one of the warnings about checking for runout. I am familiar with a micrometer to determine thickness but was not familiar with runout. I don't want to replace the brakes only to have the tolorance off by more the .003" and then have the judder start because the runout was unacceptable. The rotors list .003" as a max.

After doing some homework I found rotor runout can be measured by placing a dial indicator against the face of the rotor and turning the rotor. Easy enough but I don't have a dial indicator. Anybody have one and would lend it to me for this Saturday? I hope it is just bad rotors but there are fixes if the runout is bad(shims). Anyone seen Mech0255?

 

[kaptken]

Are you saying your disk brake rotors are causing a pulsating shudder as they warm up and apply the brakes? My old suburban had that problem for many years. new pads, turned rotors, many new pair of rotors from all the turning. and still they shuddered. turns out the rotors were a two piece system that had to be bolted together, not assembling them properly was one problem. another turned out to be the pad material type. they required high temp semi metalic pads to wear and grab correctly with the heat load. othewise the rotors warp and get ripples in them which causes the shuddering.

check the specs again. I have had no problems since i have taken it to PRO TRANS on rte. 40 for brake, axle and trans work. I don't know what they do, but they seem to do things right. and my brakes have been smooth and straight ever since. axles and trans rebuild too.

 

[a1amap]

Not as they warm up, it is a constant vibration when applying the brakes. I have new rotors and pads to be put on the car but after doing some reading I found that either my original rotors were inferior and warped from the heat (most likly) or the rotors/hub have an unexceptable "runoff" which causes the rotor to develope high spots or hard spots and gives a judder when breaking.

 

[4n4sd4]

another thing that can cause the brake pulsation is warped rotors from improperly tightening the lug nuts when you put the wheels back on. If you don't evenly torque the lugs it can cause the brake rotors to warp as well. Wish I could help you with the runout gauge but I, nor anyone that I know has one.

 

[mburke]

Brake pedal pulsation

Brake pedal pulsation

Usually it is rotor runout. While the causes can be many the only time we have seen hub problems they were quite obvious.(rust built up around studs,a bent hub due to accident,or an improperly manufactured hub(not surfaced all the way). Most likely cause is improperly torqued lug nuts,corrosion build up on the hub or back side of aluminum wheel or aggressive driving.
Mike

 

[kaptken]

in the younger days of my 21 year old burban, i was going thru new rotors and pads every 15,000 miles. which means something was wrong with the rotor castings or installation. torquing could have done it too. but after finding some good repair shops, no problems. either they got better, or parts got better, or both. 6 sets of rotors in 187,000 miles. mostly in the first 100K. I bought it used with 27K on it in 89. not sure if the first owner replaced them once, too.

 

[coralnut99]

My Sierra went through it's first set of rotors at about 30K. After a lot of yelling and screaming at the dealer, all I could get out of them was the front rotors for free. I wouldn't pay them $250 each for the rears. I went and bought slotted rotors for $110 and they've been on the truck for over 80K now. OEM brake parts should always be looked at with great skepticism especially if they wore prematurely. As Mburke noted, overtorqued lugnuts are a prime cause. Rotors are so razor thin out of the box, that it doesn't take much. I've been through this so many times, I make a point of telling tire shops I want the lungnuts hand-tightened, and tell them to write it on the service ticket. Even then I'll take the car home and double check. If I can't get a lugnut off by hand, it goes right back to the shop. Also, ceramic pads don't cost that much more and run much cooler.

 

[a1amap]

I bought sloted rotors and ceramic pads. I put the brakes on and had problems with the one wheel being too tight. I had the tire replaced about 6 months ago and I guess they put it on way too tight. Had to use a pipe on the lug wrench to get extra length for extra torque.

 

[coralnut99]

For me, the worst part of overtorqued lugnuts is not being able to get them off when you have a flat. I try to keep full size spares in all 3 cars, but they'd be useless if I can't get the lugnuts off. Depending on where you do most of your driving, a flat could be no big deal, cost you a good piece of change, or scare the daylights out of you waiting for help. I had a flat on I80 in January, and I was right back on the road in 15 minutes flat.

From what you describe, I think your brake shimmy is at least partially due to overtorqued lugnuts. The darn things are so thin nowadays, you'd be amazed at how close together the pass/fail spec. is.

 

[a1amap]

I keep a 8" pipe in the trunk with my spare. That extra 8" on the end of a lug wrench make all the difference with torque

 

[mburke]

Lug nut to tight

Lug nut to tight

Another thing we religously do here at the shop is add a dab of white litium grease to all the studs before installing the nuts. If you have ever wrestled a lug nut off by hand that screeched the whole way off you can appreciate this. (tried never seize that was just too messy)To many low budget shops do not hire techs that treat your vehicle as their own and rush thru the job to get the next one in the door because they are usually being paid flat rate or piece work. I insist on it, my techs are paid hourly with a bonus at certain production levels but if something comes back not done right it is on the tech. I have lost several high producers due to this but I will not stand for not doing the job correctly and the way I want it. The joke in this business used to be treat my (client's car) as if it were your own. What a joke all the vehicles that pass through our doors are treated as family vehicles unless the owner does not want that. Sorry for my rant just needed to vent
Mike