Front End Shakes After New Pad/Rotor Installation

Hi, I need some suggestions with this problem I encountered today -- I'll
provide as much information as I possibly can!

Stats:
1998 Accord V6 4-dr Sedan
162K mi
New pads: OEM 45022-S87-A01
New rotors: Wearever YH145232 (used previously on this car with success)
Torque/Technical source: Helm Manual

I've spend much time looking up past posts in the newsgroups and it looks
like usually when a car has front end shaking while braking, it's
recommended to check the rotors. But mine are new and didn't appear to
arrive damaged in any way.

Usually I just use Bendix pads (D503) on my car because of the lifetime
replacement, but this time I wanted new shims for the pads (the old ones
cracked after multiple reuse) and decided to buy OEM pads from my dealership
since they come with the grease and shims already. As I said, I have used
the Wearever rotors on both the front and the back previously with success.
I prefer to change the rotors with the brake pads since they only run about
$35 each here and it has always seemed to greatly improve my stopping
distance even though it adds cost.

I've done this all before a number of times... Removed the caliper, caliper
mounting bracket, and the rotor. Replaced the rotor, using new disk-to-hub
screws. Cleaned the caliper mounting bracket quite thoroughly and all
copper brackets. Reinstalled the rotor and caliper mounting bracket
(torqued to 80 ft-lb as stated in both helm and haynes), cleaned caliper
thoroughly (including greasing the pins with grease Honda recommended I buy
from Car Quest next door) along with carefully cleaning the exposed piston
before pushing it back into the bore. Installed the pads, with grease as
specified, and torqued the caliper bolts to 36 ft-lbs. Disks rotated fine,
no hangs or anything abnormal. Turning the rotor by hand and applying the
brake worked fine to stop rotation. Wheel installed and torqued to 80
ft-lbs. Everything I can think of was fine and exactly the same as I've
always done on this car.

The only difference that I can think of is that I have not used the wearever
rotors in conjunction with OEM pads (always Bendix before). I noticed the
OEM were *slightly* thicker and appearing more durable (which is
understandable), but not any significant difference.

Now details on the vibration. It occurs only over 55-60 MPH when braking
with medium force. Stronger force does not seem to cause vibration. There
is no pull to the left or right either when braking or cruising. The
vibration is similar to a strong ABS feeling. The vibration is mostly felt
in the steering wheel rather than the brake pedal, and it is also audible
(like ABS chatter).

I gave the brakes what I believe to be adequate brake-in driving around town
and the freeway, etc. The vibration may have slightly let up in my 50 mile
adventure, but not enough by far. I did not brake so hard that glazing
might occur, rather, let the brakes heat up to see if they needed to be
seated. But no success. In terms of braking power, it seems great and very
strong.

So I'm looking for any suggestions. I'm out of ideas really. I'll look
again tomorrow in the day and see if there is anything amiss. This thought
had crossed my mind though... Is it ever possible that ABS would come on if
the front brakes were significantly more powerful than the rear? I mean,
the speed sensors (which looked clean by the way) would have to get
different front/rear readings. But I've never had this happen before with
the same identical replacement in the past. The only reason I thought ABS
had anything to do with it is because there is no pulling and the chatter
sounds familiar. But never this strong in the steering wheel.

Thanks in advance.

 

1.
a. Check tire inflation pressure.
b. Has the car been over any bumps or had anything happen to it such that it's
possible a wheel rim (or maybe another suspension or steering component) became
bent?

2.
Any chance you can put the old brake pads and shims in place (leaving the new
rotor in place) and see what happens then?

3.
From Wearever, can you get the specifications for the following?

3a. rotor thickness (for OEM 1995 Accord V6 sedan = 0.91 inch)
3b. allowable rotor thickness variation (probably around 0.0006 inch)
3c. allowable lateral runout (for OEM 1995 Accord V6 sedan = 0.004 inch)

Then can you get a micrometer and dial indicator gage to measure rotor thickness
and runout?

I understand that brand new, yet defective, rotors do appear now and then.

In the same vein, an article on runout in this month's issue of "Brake & Front
End" (an automotive trade magazine) observes: "Never take for granted that the
newly installed or freshly machined rotor is free of runout."

4. Disassemble. Carefully assemble and re-torque everything to spec. Maybe you
missed something the first time around?

Updates welcome (to help others in the future).

Good luck.

 

I didn't even read your posting. The title says it all.

All new rotors should be turned, on the car, per Honda specifications.
Otherwise, you get the shakes.

 

I think it's fixed...

Thanks Elmo. I had seen this comment before in this newsgroup, but I had
also seen on a number of occasions that the rotors should not be turned on
Hondas as they will warp much, much faster. But I think I see what you mean
if they are new, the turning should only be slight enough to bring into spec
and not cause warping... At least that's my interpretation of what you mean
and I'll be sure to check this out the next go-around.

Caroline, thanks for the comments. Yes, it had been on gravel roads here in
the DC area on Friday riddled with large potholes (avoiding Friday traffic
on the Interstate), so I'll have to keep an eye on the suspension and
related parts. I had a four-wheel alignment about 5Kmi ago, and I adjusted
the PSI about a week ago. But after 162K mi...things are probably getting a
bit worn.

Anyway, I think you were both right. The new rotors must have been out of
spec/warped. After (1) disassembling and reassembling everything -- no
luck; (2) Trying different pads/shims -- no luck; finally (3) placing the
old Wearever rotors (sanded to remove glaze) back on and the new OEM
pads/shims, it seems to be working fine! I plan to buy a runout gauge and
micrometer today to keep handy for the next time and to check current/future
readings.

Thanks for all the advice. It seems to have solved the problem. I'll keep
my fingers crossed in the mean time and be prepared to check these
suggestions in the future.

Rousseau

 

That's exactly right.