Yesterday my friend and I completed our second ever brake pad & rotor install. I have a 93 Civic Si coupe (EX for the American people) and put in new Brembo blanks and Performance Friction Carbon Metallic pads (originally had Hawk HPS but ended up being wrong pads).

The install went off without a hitch... just like the one we did on my buddy's 94 coupe the week before. However, after properly breaking in the new pads and rotors, and after a short cruise with some of the guys from the car club, I headed back down the freeway to my place. I hit about 120-130 km/h and started to notice shake in the wheel that wasn't there before... and it was quite pronounced shaking.

I slowed down, got back to my apartment and proceeded to take off the wheels to inspect the rotors. (BTW, we had torqued everything down to factory spec.) I spun the hubs while I had it up on the jack and it spun fairly freely (there should be some resistance from the differential right?). The pads were making even contact on the rotor from the marks I could see on the new rotors so I don't think it was that. I summed it up to be badly torqued wheel lugs and put the wheels back on.

After that, I took the car out onto the freeway again and gradually brought it up to 120 km/h and beyond with little to no shake apparent. However, after coming back from a day of autocross, back on the freeway it started to shake.

I'm really at a loss as to what the problem could be... I'll admit I'm a novice when it comes to this kind of work but considering that myself and a buddy managed to install his new pads and rotors the other week (same setup) without problems really bugs me. Before I go dismantling the brakes again (or going to a mechanic) does anyone have a suggestion as to what the problem might be? I keep wondering if maybe I just threw a wheel weight or something but I can't see any evidence of that.

All suggestions or advice anyone can provide is greatly appreciated.

 

wheel weights would not effect it all that much, they balance the tire so it wear evenly. Id check your suspension out and make sure those are all torqued correctly, but other than that, look at you tire wear and make sure its even all the way around..huh all i know bout that wish i could help more.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by drumking15 &raquo;</TD></TR><TR><TD CLASS="quote">wheel weights would not effect it all that much</TD></TR></TABLE>

they sure as hell can, if you have ever used an old mechanical on-car balancer, the way you balance the tires is feel the fender for vibrations, its crazy how much an unbalanced tire can throw the front end around.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mr.Saturn &raquo;</TD></TR><TR><TD CLASS="quote">

they sure as hell can, if you have ever used an old mechanical on-car balancer, the way you balance the tires is feel the fender for vibrations, its crazy how much an unbalanced tire can throw the front end around.</TD></TR></TABLE>
Listen to this guy. If your wheels are off balance they can make your car vibrate badly depending on how far off weight the wheel/tire are. Get them rebalance if you are sure you did your brake install perfectly.

 

Thanks for the replies guys!

Takeoff &gt; I'm not 100% sure that I did the brake install properly but there's definitely zero shake/vibration coming through the brakes... it's all through the steering wheel when at speed (no brakes applied). When the brakes are applied, it's smooth and consistent pedal feel.

UPDATE:
I took the advice offered in a Popular Mechanics article one of the guys in the local car club sent me and went through everything I could do with what I had... the CV axles are fine and the boots are in great shape, the tie arm is solid, and there was no play in the wheel when I had it off the ground and shook it.

I took the wheels off, inspected them to see if any wheel weights had come off but there was no evidence of that. There weren't any wheel weights on them or evidence of it anywhere.

I put the wheels back on and took it for a run. The vibrations only appear at around 130 km/h+ under acceleration or just coasting which leads me to believe it's an improperly balanced wheel.

Another friend had this to say: "Could be a coincidence that the shimmy happened after the apparently simple brake job (these coincidences happen all the time!).

I had the same problem on both Civic and BMW. Shimmy at speed, with no brake input. Problem both times was the caliper grabbing. The Honda problem was many years ago, the BMW problem very recently. Both times, the caliper needed replacing.

BMW forum guys suggested rear tie arm, warped rotor, tie rods, or ball joints. No one suggested a caliper."

His suggestion of a problem with the caliper is a possibility. Is there any way to visually inspect that? I can't feel the pad rubbing against the rotor when I drive (still coasts fine) but you never know.

I did take the car down a few streets littered with all way stops and did some threshold braking to double-check that there was consistent grab on the brakes and to my butt-meter it feels perfect. I'm on a very limited budget right now but I guess it's time to go see a mechanic.


Modified by ryanhook at 6:33 PM 5/4/2003


Modified by ryanhook at 6:34 PM 5/4/2003

 

Balacing the wheels should take about 20 min or even less if you dismount + remount

 

probably balance, how are the tires?

 

PROBLEM SOLVED! I took the car in to the local tire shop today and got the wheels balanced... turns out somewhere between the Friday I installed the brakes and the Saturday when I was at autocross that I threw the front wheel weights. The wheels were so dirty that I couldn't see that there had been wheel weights on there previously.

I'm relieved... I was worried I did a crappy brake install.

 

Makes a huge difference huh