So for a little while now i've been getting brake shakes.

-brand new tires, mounted last week.
-calipers, good.
-pads, new
-rotors, new (2 different sets)
-radius arm bushings, new
-lca bushings, new.
-got decent steering rack from the wrecker, no play in rack bushing that i can tell. my old one did.

pedal feel is good, no pulsing in the pedal.
all the problem pertain to highway speeds.
i do not feel it in my seat, i feel it all in the wheel.

lets say i'm decending down a long hill here in the mountains. the first time i brake all is well, the second time i go to brake i get shakes. I know this is typical of rotors heating up and warping. so i changed my rotors 2x. just got in from my test drive on the second set and it still does it. If i don't use the brakes for a long after the shakes, they go away and then come back next time.


When it does shake, say i'm braking from 100kmh (60mph) it will shake badly and even makes a sort of thudding sound down till 80kmh and then slowly goes away until 65kmh and then returns all the way down to about 30kmh. it's definitely has a rhythm to it and sounds/feels like it's coming from the front right side. THUD THUD THUD THUD thud thud thud thud... ..thd.. ... thud thud THUD THUD THUD THUD.

could it be the booster? pedal adjustment nut to booster adjusted to agressively
? m/c? bad fluid? axle? i get no clicking and boots are lookin good.

 

aftermarket rotors? i have gotten a few sets of rotors from places like autozone and napa that are warped straight out of the box.

 

i tried 2 different brands.


i should also mention i get a slight wheel shake at 70mph which worsens when i turn left.

 

my buick did that, and it turned out it was a motor mount. the only thing other than that i can think of, is a tire out of balance. does it do it at high AND low speed braking though?

 

also,check rack play even if ya got "decent" one (lil plastic bushing on gear end wearz out,15.00 or so @ dealer) Tightened my shiz right up tite...

 

I second this, tire may be out of balance and/or too much radial force variation (http://en.wikipedia.org/wiki/Radial_Force_Variation). Seen this on a Chevrolet Equinox. Had a brake pulsation when at freeway speeds, but brakes had less than .001" runout. No play in suspension/bearings/steering linkage. Tires were nearly bald. Seen this with brand new tires too, using a Hunter GSP9700 balancer.

EFing8: Try putting the left front tire on the right rear, and vice versa and see if the vibration returns. If it does, I'd look at the brakes heating up while going down the hill. My Si does that a lot down one hill I drive down so I usually just let it coast in neutral.

 

hmmm possibly motor mount. 2 days ago i disconnected the main relay and had someone crank the car over (it won't fire but it will give a lot of engine movement to see what's going on). The tranny mount under the battery seemed to move more than the rest, and it is on the pass side, so that would go along with the way it feels. It doesn't seem to be bad enough to cause my problems though. How can i tell if a motor mount is bad or not.

i just took it for a drive and really tried to narrow down what's going on.

- first stop from 100km - 0, no shakes, but it does feel a bit loose.
- 100kmh cruising, slight shake starts. it gets worse when i turn left.
- 120kmh cruising, it's slightly worse.
- if i start braking at anything under 65kmh it does not shake.
- if i start braking at 100kmh, and stay on them, they will shake all the way down to about 35kmh. the shaking is accompanied by a thudding which sounds like it's coming from the front right.

my old rack had noticeable end play, my wrecker replacement does not have any. bushing is good.

I had an alignment done a few weeks ago, afterward it was still pulling all over the place until i changed my radius rod bushings last week. now it is nice and straight, but still shaky. it's the exact same shake before and after the alignment/bushings so i don't think another alignment will fix it. i've also changed both knuckles with good wrecker units with nice bearings. i don't get any bearing noises at all. there is no play when i get outside and shake the wheels around.

 

Ok, this is what i have to say about my tire situation.

- rotated tires, no change.
- tried my winter tires & steelies. no change! i was surprised.
- got some nice looking tires from the wrecker, no change.
- bought 2 brand new front tires, no change.
- had another shop balance them, the shaking while cruising has lessened, but the braking remains the same. this is all within the last 5 weeks.

 

After installing all the parts and throughout all of this have you ever gotten an alignment done?

 

how old are your wheel bearings?

 

did you guys even read the follow up posts?

 

Check the rack end bushings, wheel bearings, and the front and rear crossmember bolts.

 

i'd check wheel bearing. mine does that too.

 

Have you considered cv axles at all? If all these parts have been replaced you should start looking at all parts to the system. Worn cv joints sometimes make weird sounds and oem shafts have a weighted damper on them, which will break loose after some time and jump around. Also you should check ball joints upper and lower and outer tie rods. I know you said you replaced most of this stuff but its worth looking at while the car is on jacks and apart. Last thing I can think of, I have a LS in my 90 hatch with a 4-1 header and the first time i notched my front crossmember the header would hit when the motor moves. But i went to some stiffer mounts and trimmed the x member more and its good.

 

Wheel barrings, busted axel, and check the tie rod too

 

He would know if it was axles tho because his wheels should be dirty as hell and usually there is a clicking noise. I'm going with wheel barrings.

 

ya. just replaced my wheel bearing. perfect.

rides like a lexus. only kidding. ls's in a crx don't ride that nice. they ride better. hahah

 

tie bars?

 

X2