Brake shake with freshly machined rotors?

Discuss your situation with a *quality* shop and go from there.

If you take your car in and ask them to machine the rotors and they dont ask you why, never go there again! A *good* shop will ask a ton of questions before service to determine what will fix your car, and a *good* tech take the

75 or 80 seconds it takes to toss a mag base on before he tears it down.

Finding a brake shimmy is auto shop 101 freshman year. Dial indicator on the rotor, hub if necessary.

So many shops and customers are their own worst enemies...

HTH Ben

Reply to
ben91932
Loading thread data ...

Also... there is a tsb that says that rotor runout must be .002 or less... Sounds like an on-the-car brake lathe would be best...

TSB # is 00-05-22-002L

HTH, Ben

Reply to
ben91932

Wow... This post sums up the sorry state of the industry quite well...

Reply to
ben91932

I agree, in my particular case I am limited to two shops, if I take it anywhere else I pay out of pocket. just wanted to post to see if anyone had any other things to check just out of curiosity.

I will see if I can take it back on Wed. while I am in a meeting at the office...

nate

Reply to
Nate Nagel

Somebody needs to give me the theory behind this phenonomon. The rim itself has nothing to do with it. The only device which comes into contact with the rotor is the caliper and pads. The piston side of the caliper should move with fairly little pressure so scratch that idea. The whole caliper should move if there were pressure on the outer side. Besides it would take a fair amount of pressure to bend the rotor. Only if the rotor were loose and something got behind to cause wobble after tightening then yes. The run out of the rotor would wear the rotor surfaces on opposite sides and opposite diameters, with consequent uneven thickness. Most of the rotors take some effort to remove after a few years of service so I don't see tire service causing problems. Finding a hub improperly machined from the factory is very unlikely given today's manufacturing standards. Removing a rim for tire service is not going to change the dynamics of the rotor.

Somebody has to show me an actual case before I'll buy it. I've been around too long.

Reply to
labatyd

It has everything to do with 'it'... Remember, this is with alloy wheels, not steel ones. There's a reason: steel rims are rather flexible, alloy ones are not, the center hub is much more rigid.

Oh, not in 99% of the vehicles on the road. Almost all have the rotor sandwiched between the rim and the hub. Check yours, and you'll see it. Exceptions are very exotic ones such as the Hummer H1 (inboard brakes on all for corners), the vette, some Jaugar models, and some high-end sports cars. Most common vehicles have rotors sandwiched just as described.

Humm...

Virtually everything above is either outright wrong, or misstated.

How long you have been around is insignificant if you stopped learning at 15. But, hell, in your world everyone else is wrong and you are right.

Reply to
PeterD

OK so how does a rim affect the rotor in either case? As you state most are sandwiched between. Forget exotic vehicles. How many of us drive such things anyway?

I know that.

You don't say WHAT's wrong.

On any of the common wheels most of us drive I've not seen it yet.

Reply to
labatyd

I've had it happen to an ordinary audi with alloy wheels about 15 years ago. I had new tires installed and the shop had hammered the wheels back apparently on full blast with the impact wrench, and I had a terrible shimmy.

I tried to torque the wheels properly at home, but could not get the bolts on one of the wheels loose. I cracked a socket trying to undo the bolts.

I went back to the shop and with the long hose they had on the IW they could not get the bolts loose without waiting for the compressor to build full pressure in the tank. When they torqued the wheel properly the shimmy was gone.

I always hand torque the wheels after this and I have never had a problem with it again.

Reply to
Thomas Tornblom

Obviously the wheel was mounted crooked. But the rotor wasn't damaged and that's my point. But any reasonable person on a wrench should know enough not to tighten one bolt to extreme. It doesn't require a torque wrench IMHO. Of course as I've pointed out earlier in the thread any jockey may do the job using a torque wrench and it relieves the shop of any consequences.

Reply to
labatyd

Just for the hell of it I'm going to take off (in turn) each front wheel of my vehicles with disc brakes and retighten the rim to try to achieve what you guys are telling me. I'll be watching very closely for any changes. I don't expect any.

Reply to
labatyd

No it was not. Just properly tightening the bolts one at a time to the proper torque was enough to fix the problem. The wheel was not removed, which would have been needed had the wheel been put on crooked.

Reply to
Thomas Tornblom

If you retighten with an ordinary socket and BO bar, you probably wont. The human brain and sense of feel will give an even slightly experienced person some control.

Slam it on with an impact wrench, all rotored wheels, as if you were a tire monkey. Watch it for a month or two. You may be lucky and you may not.

Reply to
HLS

  1. Goto barn.
  2. Door was left open.
  3. Check horse
  4. Horse missing.
  5. Close door.
  6. Problem solved!

Not much of a test, there is nothing that says that the warpage would correct itself if you did that. Only some evidence that in some cases it helps.

Reply to
PeterD

Not true. It would only require to loosen each lug nut a bit and retighten them. I agree with labatyd - your experience is not the same as what is being discussed.

Reply to
Mike Marlow

Yeahbut that's not what's being discussed here. That's an extreme. I realize you say you've seen this and I take your word for that, but I haven't. Here's another side of this discussion - just the other day I had to have a tire replaced. The mechanic threw the wheel back on the car and ran it up with his impact - "hammering" each lug. But... his gun is set very low, so the torque being applied to each lug is well under the torque spec. To hear it, it sounds like he's just hammering the lug nuts on. He grabbed the torque wrench when that was done and proceeded to get around a quarter turn (or maybe a bit less), on each lug nut.

Those of us that don't use a torque wrench (I have used them, but do not use them on any regular basis), have put them on with our impacts, and then drove problem free for more than a month or two. That's the point of this discussion - lots of folks don't use a torque wrench and have no problems, either short term or long term.

Reply to
Mike Marlow

Where does the warpage come from? You're sandwiching steel between steel. There is nothing to give or bend. No gasket material between like installing a head on an engine. If something got between then I can understand the claim.

Reply to
labatyd

They can both bend. When you tighten a lugnut to 100 ftlbs, it can apply thousands of PSI to the rotor/hub, more if using an impact wrench. Steel, cast iron etc all bend easily under such forces. HTH Ben

Reply to
ben91932

The torque applied to the lug nuts does not have to bend /warp the rotor. All it has to do is apply uneven pressure to the rotor. After that heat will finish the job much the same as heating a metal plate or rod while applying pressure to it. With the materials they are using today it doesn't take a bunch of panic stops to do it. Heavy traffic, coupled with the driver riding the brakes could well cause the problem.

My Safari started showing signs of warpage after the first aftermarkrt brake job. I think I will buy all new OEM parts and do the job myself. New rotors, drums, pads and shoes.

Reply to
Anyolmouse

My theory:

You are sandwiching aluminum between steel. My guess is that the hub flange gets warped when the studs or threaded holes are pulled with excessive force into the fairly soft aluminum. The aluminum between the holes does no bend and thus the flange, and rotor warps slightly.

Steel rims are not susceptible to this as it is much softer between the holes.

Reply to
Thomas Tornblom

Uneven clamping forces in the assembly, along with the natural stretch of fasteners, along with the thermocycling (especially extreme changes like water puddle quenching or pad bake at the end of a really long stop and mashing the pedal down for a long time, which causes localized hot spots and pad material transfer). The three things you can control as a driver are 1) driving through less puddle with smoking hot brakes

2) not holding the pedal down hard after a long hot stop - creep a few inches a couple times and lightly hold the brake pedal instead 3) torque your own wheels to spec. The only thing a tech can do for your car is #3.
Reply to
Toyota MDT in MO

MotorsForum website is not affiliated with any of the manufacturers or service providers discussed here. All logos and trade names are the property of their respective owners.