to start this all off, i bought a set of hawk hps pads to swap on to my 91 civic si. they were the correct pads for my stock brakes and seem to work fine. i didnt notice any problems at all until just about a month ago, where the front end started shaking pretty hard. during this time, i needed to replace the master cylinder and the rear wheel cylinders, and i got new rear drums and pads. none of these things changed the dynamic of my brakes, or so i think. but recently i have gotten really violent shaking out of my front end, but ONLY under braking. and not just hard braking. soft braking and everything. so i just replaced the front rotors yesterday because the ones on the car were way out of spec for metal left so i couldnt get them turned. so i put my new rotors on, and the shaking is still there. so my next thought was the sliders that the calipers were mounted on hadnt seen any lube for a long time. so i tore the calipers apart today and lubricated the sliders really well. i did that and the brakes seemed not to shake under light pressure, but under heavy braking, the shaking came back, and now it does it on both low and high speed stops.

the very strange thing is that you can see where my brake pads are wearing on the new rotors, and right now the rotors seem to only be getting worn on the outer 1 inch radius. the inner one inch radius seems to still have the factory milling marks on it, while the outer edges on both sides look kind of burned. i am stumped, because ive heard the sliders can bind and cause strange problems. but that apparently was not it. i am just trying to decide where to go next. my alignment is good, i can let go of the wheel and it goes more or less straight over atleast 500 ft. the car is on what i assume to be a stock suspension. not lowered or anything. i am wondering if my front struts are really messed up, to the point where i am getting wheel hop under hard braking. the pads were bedded properly when i first put them on, and i have driven it enough to bed the pads on the new rotors and i even sanded the pads a little today, but both sides are exhibiting this strange wear patern on the rotors, and i am confounded.


cliffs notes: entirely new brake hardware on 91 civic si. still getting wicked shimmy in the front under all stopping speeds. new rotors, pads less than 2 months old, strange wear on the new rotors with outside radius getting worn and inside radius appearing unworn.

 

Did you remember to put the shims back in around the pads?

 

yeah the pads were shimmed when i put them in. thanks for the idea though.

 

well, today i put some pads i had laying around on, but not before i used a micrometer to measure the pad thickness and sand them so they were relativly even. and the shimmy is still there. i am beginning to suspect my rotors again.. but.. it just doesnt make sense to me at all.

 

it could be coming from rear ,test drive car and slow down using only the e-brake is it shakes you got an issue with the rears if not and shake when braking you got an issue with frt rotors or loose fr end suspension parts ..

 

yeah i am starting to wonder if it is suspension parts, because i have done everything i can think of with regard to the brakes to fix this problem. the shimmy is deffinetly coming from the front. the strange thing is that the car tracks fine left to right. im wondering if my castor could be way out and causing this.. but im not sure if castor could cause this .. and its only under braking. from 1 mph -100 mph there is no shimmy at all, except when the brakes are applied.

 

i had a similar problem with mine and what i noticed was that the axel nut that holds the axel when you take the tire off was loose causing the disc to vibrate like a bitch.

 

that is a very interesting idea. i have not even messed with the axle nut.. but i did have an axle that was clicking, and then it stopped clicking right around the time this whole problem started..

 

I have a similar problem except it does it during hard acceleration also.

for finding an answer.

 

somethings loose if its shaking. if everything it tight, and youre positive, it could be bushings, like the steering rack end bushing. feel around your tie rod arms. see if there is play. if there is, then you need to find the source of that and replace. it wouldnt be the SOURCE of the vibration, but it greatly increases the degree of shake if the suspension/steering has any vibration.

however, this is sounding like this guys problem.
https://honda-tech.com/zerothread?id=1313535

can you describe what the wear looks like on the BACK side of the rotor as well?




Modified by Tyson at 4:25 PM 7/29/2005

 

[QUOTE=sanimalp]the very strange thing is that you can see where my brake pads are wearing on the new rotors, and right now the rotors seem to only be getting worn on the outer 1 inch radius. the inner one inch radius seems to still have the factory milling marks on it, while the outer edges on both sides look kind of burned.

well this description tells me that the caliper piston might in a bind or got stuck

??????? when you put the new pads in how did you compress the piston to fit the new pads??????

 

the wear on the back side of the rotor is the same. the outer radius of the brand new rotors have deffinite wear from the hawk brakes, but the inner radius has no wear at all. both left and right side and inner and outer sides of the rotors.

as for compressing the piston, i actually compressed it by hand. i didnt use any tools.. just pushed on it hard with my thumbs until it sank, but it didnt need to go very far at all.

a discovery i made today is that the shims on the hawk pads are glued on with some strange glue, and the shim had shifted a little bit on one of the 4 pads. the other 3 seemed ok. i used a bench grinder to get the glue cleaned off the shim, but i will probably reinstall the hawk pads tonight after i level them and check them with a micrometer.

i will check the pistons tonight to make sure they arent bound up but i really dont think i will find that they are, as i was able to hand compress the pistons on both sides, and im not leaking any brake fluid at all. thanks for the help all, and keep the suggestions coming. its a good thing i have 2 weeks off to figure this all out.

 

you must have strong thumbs....

ive never been close to being able to compress my pistons by hand. a decent adjustable pipe wrench works fine tho.

 

Had the alignment checked lately. This is usually the culprit in front end vibration. Unless you have a stuck caliper, your brakes as you've described them seem fine.

 

well, it looks like the "new" rotors i bought are warped.. i am going to take them back tommorow and see if i can get some that arent warped out of the box. i used a micrometer and found that on one edge of the rotor, the reading was .850in and on the opposite side of the rotor, the same distance from the center it read .844in and .842in at another point the same distance from the center, and honda specifies .004in variation at any point on the rotor as the runout limit. so these are crappy rotors. i will take them back tommorow because they have a 1 year warrenty, and either exchange them or just get my money back.

 

I don't know. That's a difference of 0.006 inches, which really isn't much. I really don't think this is your problem. Have you inspected all your suspension components and made sure they're tight. When was the last time you got an alignment? Have you made any changes to the suspension since your last alignment?

 

.006" of runout shouldn't be a problem. That's a pretty acceptable figure. The pins and bushings on your caliper could be seized and it may not be sliding. This could also leave the caliper is a weird position causing strange rotor wear. Try lubricating them and slide the caliper back and forth in it's full travel w/ the rotor off. See if that cures your problem. (Good Luck)

 

You should change new pad when changing/regrind rotors.
You probably need to regrind your rotor and buy new brake pads.

 

thanks for the suggestions. i did grease all the slider bolts profusly a couple days ago.. i removed all the sliders and bolts and hit them with a wire brush to get all the old grease off, and then repacked the sliders and rubber boots with a pretty good amount of hi temp brake grease. tommorow i am going to take the rotors off and take them to a machinist to see if they are really out of specs. yesterday i sanded down my pads that i have, the hawk pads, and used a micrometer to make sure they were as level as possible for the new rotors, and it still vibrates.

i have a feeling i will figure this out tommorow, because i am going to tear the brakes apart again and figure this all out. i havent had an since i have owned the car.. so that still leaves me skeptical. if this issue isnt resolved by changing rotors tommrow, i will get an alignment.

none of my suspension components seem worn. my upper and lower ball joints seem to be in good condition, there is no play in the steering rack, and i tested the ball joints grabbing 12 and 6 on the tire and seeing if there was any movement, but it was solid, and no tears on the boots or anything. the suspension doesnt have any broken parts, while i was under it there was nothing that showed any sign of being broken. ill update this tommorow after i tear all of it apart again.

 

Maybe you have bubbles in your brake lines? Did you try re-bleeding the brakes? (Doesn't hurt to try)

 

I'd like to contribute that I cheaped out on my rear drums and had all sorts of problems..by cheaping out I mean really inexpensive..like $8 per drum..

Went and paid just a little more, now everything is fine.

Did someone mention bushings? Make sure the rubber is still attached to metal.

good luck

 

i mentioned the steering rack end bushing. its plastic, not rubber. it significantly contributes to the ride quality of the car, surprisingly so. because its plastic, it deteriorates quickly, along with the ride quality, including brake vibrations.

https://honda-tech.com/zerothread?id=1117870

 

Should be interesting to hear the end of this one..

BTW, slightly OT..what's the company that makes the upgrade steering rack for the ED/EF series?

 

quaife.

youll need a DX/HF steering rack for the EF for it to fit properly. its (improperly) designed to use a DX rack, not an Si.

(quaife goofed and used the wrong rack to model their part....)

 

Ah yes, right on. I was thinking of the fellow who goes by 'Del' on one of these boards who got a new rack and did the quick-ratio upgrade.

As long as I'm at it..and if you know offhand, but is the STD rack the same P/N as the DX or HF? I would assume that to be the case..

Thanks