vaclavg

hi
when I drive at highway speed and press the breake, my front (seems) vibrates quite a bit.
I do not think I have this problem at lower speeds.
I put new rotors in front, had rear ones machined, tires are new and fairly well balanced.
not sure what to check/replace next. anyone has ideas? I need help
thanks, Vaclav

AcuraTL

You've got warped rotors.....again Either get them turned or get new ones.

twopointtwo

I am not trying to be the know it all "new guy" but I had this same problem and ordered new rotors and pads (all 4 wheels) and got everything installed and it had the same problem! Turns out it was the caliper sticking on the pins that it was supposed to slide on. It would stick on the rear one only causing the pulsating. (this was on my STS cadillac, I just got my Acura friday so I am not sure of how the calipers work on it... but I will by the end of the week, 'cause I just order drilled rotors and ceramic pads off of E-bay!) Hope this helps...

AcuraTL

The reason I said it was the rotors because he said during highway speed. When you brake a highway speed, your rotors will heat up much faster and if they are warped already, you will feel the vibrations when you brake.

AJē06

Sometimes I heard it was the balljoint? Can anyone verify that?

twopointtwo

I would start with lubing the pins. I looked at mine and the calipers slide on two pins just like on my STS. That was the same problem I had with that car, at higher speeds with low pedal pressure the caliper would only slide on one pin and it would pulsate (I guess it was actually fluttering on the rotor). If I jambed on the brakes it would be enough pressure to move the caliper on the sticky pin. There was an article I read a while back by a brake manufacturer who said that a rotor very rarely warps on a street car. If I can find it, I will post a link. I am pretty sure it was on the "Stoptech" web-site.

vaclavg

thanks guys for the inputs
the culprit is in the rear - I checked the rotors run out and found
1 mil at both front rotors (new ones)
and 2 mils on the left rear and 5 mils on the right rear
the limit is 4 mils, but I think it is too high. 1-2 is more like it.
both rear disks were machined, but I did not check the run out before or after. I am not sure if this is a machinist problem or disks go out of face too
quickly.
I have new rotors and they are going in today.
I hope this will solve my problems

AcuraTL

I hope that was your problem, but having warped rear brake rotors are usually not the problem that would cause the vibration. It is usually the front rotors.

vaclavg

hi guys again
I am back in square one.
with the run-outs of 1 mill or so on all rotors, I still have a problem. I verified my dial indic on my other car and had also 1-1.5 mil. but only CL vibrates.
The pins are greased and show no sign of sticking. I added new grease for a good measure, but there is no change.
I do not think calipers are sticking - the car does not pull to one side. Front just vibrates at over 55 mph or so.
The reason I paid attention to the rear disk is my experience with E300D I had in the past - one of the rear disk was warped and caused front shaking. the problem went away after machining bad rear rotor.
Could this be ABS? I have no alarm (ABS light works and it goes OFF few seconds after start of the engine). I do not hear any noise indicating ABS in action (like it happened when I tested ABS in the snow, but at low speed)
If I disconnect the ABS cables, will the alarm clear after putting them back? Or will I need to reset some codes at the dealer's place?
what do you think?

AcuraTL

Do you feel vibration when you go over 55mph or when you step on the brakes over 55mph? What about going a long downhill when you step on your brakes, does it vibrate? Do you feel the vibration on the brake pedal (like a pulsating feel) or on your steering wheel?