Hi,

I have a 1989 Si and I recently replaced nearly every part of the brake system, new slotted rotors, new hawk pads, a reman driver caliper, new drums, new shoes, new hardware kit, and a new driver parking brake cable. I expected something like braking nirvana but instead I'm pulling out my remaining hair because the brake pedal now pulsates and the whole car shakes during light to moderate braking! It seems to smooth out under hard braking. I've checked and rechecked my work and have reapplied grease to the caliper slide pins, it seemed to help but it's still there. Does anyone have any advise?

Thanks,
John

 

I'm no expert but sometimes rotors come from the factory warped u just need to get them turned and it might fix the problem.

 

Thanks for your reply.

I'd hope Brembo would have better quality control than that but you do have a point. I'll add that to my list of things to check.

Thanks,
John

 

Where the slide pins do in could be worn if you take it apart there is actually plastic in there. Its most likely work out or completely gone. So the caliper has some wiggle to it now. Get some reman calipers they only are like $20 each. It should solve the problem

 

Thanks for your reply.

Although I've never seen any plastic sleeves around the slide pins, I agree the slide pins could be the problem. So if the upper caliper slide to too loose, the caliper is being pulled unevenly, the leading edge of the pad is digging into the slots, and causeing the shudder. I just received a replacement passenger caliper and will post my results if anyone is interested.

Thanks again,
John

 

Well, the passenger caliper is in along with new slide pins and plenty of grease. And??? The shudder is much less but not completely gone. I'm going to drive it for a week or so and see if it gets better. I did try pulling the parking brake handle and I think I felt a familiar shudder. So I'll look at the back brakes next. Stay tuned....

 

Well I dont know how violent your shudder is but when I put Baers crossed drill/slotted rotors I had a light shudder but thats because I didnt change da pads. (Pads were new). Now I have no shudder at all. And it is true that some aftermarket and even factory rotors come warped. so just resurface your rotors or check the run-out with a dial indicator to see if thats the problem.

 

faulty new rotors send them back cannot turn slotted rotors

 

it shouldn't shudder, but it will start to shudder when you reach in excess of 15,000 miles. Always try to change the pads and rotors at the same time.

 

u can turn slotted rotors...make sure u have the spacers on the slide pins. some times people take them out and forget. check the bracket bolts and make sure there on tight. also check the wheel bearings, u can do this by putting a a load on each side of the car while ur turning hard. good luck man

 

there called sleeves.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cr-x-91 &raquo;</TD></TR><TR><TD CLASS="quote">u can turn slotted rotors...make sure u have the spacers on the slide pins. some times people take them out and forget. check the bracket bolts and make sure there on tight. also check the wheel bearings, u can do this by putting a a load on each side of the car while ur turning hard. good luck man</TD></TR></TABLE>

Thanks for your reply.
The new rear drums seem to be out of round I'll have them checked. Sleeves are all new, rotors are new, pads are new, bracket bolts are torqued to factory specs. I'm not sure why the bearing would only misbehave while braking but I'll add that to my list of things to check.

Cheers,
John

 

Was the vibration immediately after the swap, and did you torque the lug nuts? If you didn't torque the lugs, the rotors can warp very quickly, which may just be a small piece of the puzzle if the slides were faulty as well.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by lessonsinspeed &raquo;</TD></TR><TR><TD CLASS="quote">Was the vibration immediately after the swap, and did you torque the lug nuts? If you didn't torque the lugs, the rotors can warp very quickly, which may just be a small piece of the puzzle if the slides were faulty as well.</TD></TR></TABLE>

Thanks for your reply.

Come to think of it I do remember a shudder during very high speed braking but I assumed
that was from the old nasty (and they were NASTY) warped rotor/drums. I did not torque the lug nuts but I didn't leave them loose nor did I put gorilla like torque through the wrench. I'm bringing the drums to the local brake shop to ask them to check/machine them. Wish me luck!

Cheers,
John

 

I also have a laser temp meter and I've checked them repeatedly during the bedding process and regular driving and they have not exceeded 250 F. So I'm fairly sure nothing warped due to heat but who knows.

I also want to add all the ball joints, outer tie rods, and bushings (front and rear) were replaced a few thousand miles ago and everything was torqued to factory specs.

I've also read that a worn steering rack could be also contribute to this condition. Is there a way to check for wear in the steering rack?

I was thinking of bringing the car to the dealer to check the rack because the service manual lists an adjustment procedure. Perhaps that will be my next step if all the above does not solve the problem...


Please keep the suggestions and advice coming.

Cheers,
John


Modified by johnb16a2 at 7:42 PM 6/29/2007


Modified by johnb16a2 at 7:45 PM 6/29/2007

 

Eureka! The mystery is solved! The new drums were the problem! They were machined by the great crew at Cole Muffler in Herkimer, NY and the car stops VERY smoothly now! I'll drive it regularly for a few weeks and post any developments. Thanks again to all who responded!

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by johnb16a2 &raquo;</TD></TR><TR><TD CLASS="quote">Eureka! The mystery is solved! The new drums were the problem! They were machined by the great crew at Cole Muffler in Herkimer, NY and the car stops VERY smoothly now! I'll drive it regularly for a few weeks and post any developments. Thanks again to all who responded! </TD></TR></TABLE>

nice find, glad you posted the solution!