shudder with brand new rotors

[nsx1164]

My mechanic installed new (F/R) rotors on my NSX. Turns out I only need to replace the rears, so I'll have the OLD front rotors put back.

Took the car for a test drive. Feels like there is shudder, even on light/medium braking. These are NEW rotors (2 piece 13" cross-drilled -- for the AP Racing BBK).

It feels like they are warped. Rotors are COLD at this point, and pads not yet bedded in.

Any suggestions ? I am about to return them to my vendor, to see what they can do.

------------------
Manuel C
93 NSX S/B #394
93 300CE
93 NH750

 

[sjs]

Any decent machine shop can check them. It can even be done reasonably well on the car with a simple dial indicator.

Did you replace the pads as well? There may have been a coating on the rotors which needs to wear off. Bed them in a bit before you yank them again.

Good luck.

 

[nsx1164]

Thanks

Pads and rotors BOTH new. I will check it more closely on Monday morning.

BTW, what is procedure to "burn off" this coating? I don't recall ever having to do this before, but this is the first time I've installed new rotors with this brake kit.

------------------
Manuel C
93 NSX S/B #394
93 300CE
93 NH750

[This message has been edited by nsx1164 (edited 09 June 2001).]

 

[Bruce]

These 2-piece rotors because the type of material used, tend to warp easier than the
1-piece cast rotors. Make sure the wheels are torqued properly(take lug nuts off and re-install with torque wrench...drive a little and re-torque) and that they are hub centric.Is the rotor hat a floating type?

 

[nsx1164]

Per my vendor, this is NORMAL.

Initially pad will "skip around" on the big rotor for a little bit whilst it seats itself on, particularly on light/medium braking. Which is where I noticed it.

Hard stops should be fine (for now, seem to be), and things should be fine once they're all bedded in (n hard stops with cooldown). Note that skipping on LIGHT braking may persist for as much as a month till things settle in.

I have about 400+ miles street driving and 3 days of track this weekend, so this should do it.

Thanks for all the responses, both in this forum and on private email.

- Manuel (with revised avatar)

 

[ScienceofSpeed]

The RM Big Brake kit that you own does not have floating rotors/hats. They do not allow movement for adjusting like floating rotors/hats.

Did you replace the hat with a new set as well?

It is possible that slight variances in the hub, or hat could casue shudder.

-- Chris

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www.ScienceofSpeed.com - Click for more info
www.NSXClassifieds.com - The internet's only exclusive NSX Classified site!

[This message has been edited by ScienceofSpeed (edited 17 July 2001).]

 

[NSXTech]

These are NEW rotors (2 piece 13" cross-drilled -- for the AP Racing BBK).

It feels like they are warped. Rotors are COLD at this point, and pads not yet bedded in.

Any suggestions ?

A common cause for brake shudder that feels like warped disc's but is not warped disc's,
is / can be rust or other debris on the hub surface. Anyone who has watched me install new rotors has seen me wire wheel the hub surface before installing the new rotors. The hub surface is almost always rusty, and if you disturb it when removing the rotors and now have a piece of rust or other debris
causing the hub surface to be uneven, you will have a vibration. I would remove the rotors and check, and would also clean the rust while you are there.
As someone else said, it is very easy to put a dial indicator on the rotor and find the bad part. I use an indicator stand that is magnetic, and attach it to the strut.

Good Luck,
Mark

 

[nsx1164]

shudder was on light/medium braking only; brakes worked fine on hard braking. Randy at RM advised me that this is normal for "new" rotors -- on his car it took over a month to go away

Took it to a 3-day event (Friday lapping day, Sat/Sun had driver-ed style run-groups) in mid-June and they worked fine. No shudder whatsoever on hard braking -- and was going late (only highly-modded racecars and open wheel cars could go deeper that weekend)

Last time I drove the car (30-June) there was still a little shudder on the street at light/medium braking... am told this is NORMAL for new rotors