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Wheel imbalance causing braking vibration?

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Old Sep 5, 2007 | 09:18 PM
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Default Wheel imbalance causing braking vibration?

i recently finished installing Baer Extreme Plus 6-piston monoblock 14-inch system front and OE Brembo rear on my touring to have more fun on track days. i've had too many track days where i had to limp the car home from boiling fluid, worn down pads via standard brakes on the touring model.

i've seasoned the rotors and bedded pads per Baer's instruction - Baer had a very specific, a little tedious, procedure that was a little more involved than my usual bedding procedure. i havent had much time driving the car other than my 1.5 mile commute(lol ) and everything was gravy.... until i drove my car from LA to vegas and back past wknd.

on the highway speed (65-85mph), when i brake, i get a vibration. it only does it on a "high" speed and never around town. i did notice one of my front wheels had wheel weights missing. i think they fell off. could this be causing this vibration?

i am getting the wheel balanced this week. but i figure, if a wheel was not balanced, wouldnt it do it all the time? i am just frustrated and hoping that getting the wheel balanced will solve the problem.... i have a track day scheduled this wknd.
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Old Sep 5, 2007 | 09:52 PM
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yes, thats one of hte main reason to balance a tire.

get used to wheel vibration, you will get them as you chunk the pads
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Old Sep 6, 2007 | 12:04 AM
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I would think that if your wheel was off balanced, that it would vibrate a certain MPH like most cases. If the wheels vibrate while applying the brakes, that would usually indicate a warped rotor. My cars begins to vibrate over 80mph or so, and I suspect that to be because of my wheels being off balance.
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Old Sep 6, 2007 | 04:33 AM
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if your running a bbk now, then your brake temps are much higher then before. its not uncommon for a stick-on weight to lose its adhesiveness when the wheel gets hot. I slung off 3 of 4 weights first time out this year with my track tires/pads. now, as you will notice at events, most sticky weights are taped on as well. I know mine are.

a balance issue can happen at any speeds, normally higher speeds its just noticed a lot more.

having new pads/rotors their are a couple things that can come into play as well if you have a BRAKING vibration. Pad deposit would be my first guess. Second would be a warped rotor but doubtful considering your BBK upgrade. Thirdly, uneven tightening procedure with a high impact gun on the wheel lug nuts.

just some things to consider. gl
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Old Sep 6, 2007 | 04:43 AM
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The old racer trick is to tape the stick-on wheel weights with metal duct tape which will keep the weights on the wheel where they belong. Some, but not all, tire service trucks at the track do this for us, but we keep a roll of the tape in our trailer and always check the weights before first mounting.
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Old Sep 6, 2007 | 07:47 AM
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A wheel vibration is typiclaly felt all the time while uneven brake pad deposits are felt when the brakes are applied.
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Old Sep 6, 2007 | 03:20 PM
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Originally Posted by tmak26b
yes, thats one of hte main reason to balance a tire.

get used to wheel vibration, you will get them as you chunk the pads
chunking pads? You mean chunking tires? I chunk my street tires from time to time, but that doesn't cause vibration while braking.

BetaMotorsports is right. You most likely left pad deposit from insufficient bed-in. I usually get if I don't bed the race pads in enough. Since it's so difficult (or nearly impossible) to bed race pads on public roads, I usually do so on my first track session. Often, on brand new pads, I'll get pad deposit after my first couple sessions, no matter what. It eventually goes away, and never comes back until I put another brand new set of pads; Could be something to do with incompatible pad deposit on the rotor when swapping between different compounds.
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Old Sep 6, 2007 | 09:37 PM
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thanks for all your replies. i am going to bed them some more on the street and use the first session of track day this wknd to really get it done.
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Old Sep 6, 2007 | 09:42 PM
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chunk the pads, it can happen
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Old Sep 7, 2007 | 06:31 AM
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I agree with the uneven pad deposits. You can get that from not cooling down the brakes enough before you come to a stop too, not just the bed in procedure. If your brakes are too hot when you come to a stop then the pad will leave an imprint of itself on the rotor. The hardest part of bedding in pads on public roads is not stopping for 10 min when you cool the brakes down.

This happened to me on my Evo when I was at the track. I was running with an organization who thought it would be a good idea to wave the checker about 3 turns before pit entrance. Obviously three turns does not offer a sufficient cool down lap and a lot of us got uneven pad deposits from it.
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Old Sep 7, 2007 | 07:14 AM
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Originally Posted by tmak26b
chunk the pads, it can happen
Yeah, I guess it can. My windshield is chunked from all the pebbles big rigs pick up.
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Old Sep 7, 2007 | 09:09 AM
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Originally Posted by dnguyent
Yeah, I guess it can. My windshield is chunked from all the pebbles big rigs pick up.
that's good, hope it destorys it too.

check a non brembo z after a hard track event, then you will know what it is to have pads that are chunking off.

yes if you do chunk a tire off or flat spot it, you can get vibration too
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Old Sep 7, 2007 | 04:01 PM
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Originally Posted by tmak26b
check a non brembo z after a hard track event, then you will know what it is to have pads that are chunking off.
I've had it on my Brembo's too ... with the OEM pads .
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Old Sep 7, 2007 | 06:59 PM
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The joy of owning a fat cow
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Old Sep 8, 2007 | 11:07 AM
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Missing wheel weight can lead to uneven tire wear. I bet that can be felt as a vibration when that tire is loaded.
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