Brake vibration above 60mph stops, run out problem?

[Tonyfeb14]

I installed 4 new slotted discs, aftermarket. Checked runout and have total .002 " on each front disc, or what I would interpret as +/- .001 ". Stopping is smooth with hard stops tested below 60mph, but when I hit the brakes at 65 mph or higher, I get a vibration until I get the speed down to 60mph. I saw in other thread on the forum that BMW runout tolerance was .1mm, so .004", so this looks like it is well within acceptable tolerance. I had a 4 wheel alignment at dealer, and rebalanced all four wheels. Runs smooth at 80mph and straight, but this vibration on braking at any speeds above 60mph has me stumped.

I will recheck suspension is tight (seems fine and should have been caught on the alignment at dealer if a problem) so posting here on the forum if a knowledgable BMW mechanic can comment on disc runout and if that might still be the cause. Open to recommendations.

BTW, 2003 X5, 4.4, only 66k original miles.

[TwinTurboGTR]

That may not be a run out problem. Normally warped discs or discs that are out of tolerance will will create a shake throughout vehicle speed. I mean even if it was .005 out, you probably still wouldn't notice it.

Looking at the info, you have an 03 with 66k miles... hows the suspension? People experience vibration in the higher speed ranges and then dissipates when the speed drops below a certain value. That is normally attributed to a suspension component. Normally at higher speeds, the Swing control joints are shot, causing instability. Also the Tension strut could also be to blame. While they make look good, internally, they may be shot.

Hope that helps.

[TwinTurboGTR]

That may not be a run out problem. Normally warped discs or discs that are out of tolerance will will create a shake throughout vehicle speed. I mean even if it was .005 out, you probably still wouldn't notice it.

Looking at the info, you have an 03 with 66k miles... hows the suspension? People experience vibration in the higher speed ranges and then dissipates when the speed drops below a certain value. That is normally attributed to a suspension component. Normally at higher speeds, the Swing control joints are shot, causing instability. Also the Tension strut could also be to blame. While they make look good, internally, they may be shot.

Hope that helps.

[Tonyfeb14]

I will dig deeper into the suspension as I have time to work on it. Thanks for the ideas. 66k miles is not really very many miles these days, but will go over it carefully.

[Tonyfeb14]

Ok, so I pulled out my Bentley Publishers BMW X5 Service manual, and found a big note in the section on Front Suspension as follows: NOTE Steering wheel vibration during braking (usually at road speeds of 50 to 60 mph) are often caused by faulty suspension arm bushings, not out-of-true brake rotors.

It looks like this was written for me . I will check out the suspension. Looks like my rotor lateral runout can be eliminated.

Thanks for pointing me back to check the manual.

[TwinTurboGTR]

Not a problem. Hopefully you can straighten that out. Just curious, was the shaking there before you did the rotors?

In any case, 66K isn't a lot of miles, but the rubber is 10 years old. Since the car has such low miles, it has probably done a lot of sitting, causing settling and strain on the suspension. On my 4.4i, the entire front suspension was shot and the vehicle only had 72K on the clock. These vehicles are heavy considering their platform is based on a 5 series sedan. Adding all that extra weight puts more strain on the rubbery parts.

[Tonyfeb14]

I didnt notice the shake before the rotors, but on the other hand, after any change you are more aware and thinking about it. It could have been there since it only happens with hard braking >60mph. Need to spend some quality time under the car.