problems with new Hawk brakes
 

This week i have been working on installing RP SS brake lines, replacing the OEM brake pads with Hawk HPS pads all the way around, and repainting the calipers. I had some prevous noise coming from the FR rotor/pad so while i was at it i had the front rotors machined.

The problem:

-first off, the front pads wear was uneven; inside pad had about 5% remaining and outside pad had about 50-60% remaining.
Possibly need to rebuild the caliper

- replaced the pads and the FL caliper is stuck on the rotor. It is as if there is a small amount of force applied to the rotor (like it should to stop). i went for a quick drive and there was a considerable ammount of heat from the FL brake/rotor and burning smell after my drive.
??????????????????????????

- the new pads on the rear were too large for the caliper to fit over. i even broke down and bought the brake piston tool to turn the piston back into the caliper, and it I was about 1-2mm short of clearing the new pads. i checked the # on the pads and should be the right pads for the RX8. so i used one hawk pad on the inside, and one OEM pad on the outside (still cosiderable life left) so i could get back on the road.
I had the wrong pads for the rear. Correct pad for the rear is HB378F.565; I had the HB378F.626 (thicker).

-In addition, the pedal still feels a little soft, and the car does not brake like i thought it should. i bled all 4 calipers till there was clean fluid coming out, is it a possibility there is still air in the lines or what?
Thoroughly bleed brakes, make sure there is no air in entire line

Thanks in advance...

Before...
http://i214.photobucket.com/albums/c...P1010001-1.jpg

After...
http://i214.photobucket.com/albums/c...P1010012-2.jpg

http://i214.photobucket.com/albums/c...P1010013-1.jpg

It seems to me that you might need to replace the LF caliper or at least rebuild it only if you know how to do it and there is a kit available to do such job.

Question. Why did you have to bleed the lines if you were only replacing pads ?

Turning the rear caliper piston back in is absolutely necessary to get the new pads to clear. Did you leave the master cylinder cap off when pushing/turning the rear piston back in? If not, the piston(s) probably did not go back flush.

Mix/match of different pads on the same rotor is probably not the best idea either.

Bleed the brakes once again. You should definately have a firm pedal once the proper procedure is done. Finally, bed the new pads in using Hawk's recommended bed-in procedure.

I replaced the lines with SS brake lines

Yes, i did leave the cap off the M/C. i was able to push it back quite a bit, but then i got to a point where it would not go in any further. the piston was not flush with the caliper b/c there is a rubber gasker that surrounds the piston. should it be flush like the fronts?

I did bed the pads as per the procedure, and not currently driving the car till i figure all this out.

could have been that (cap on) or just open the bleeder valve and try to push the piston back in, you already on the way to bleed them again anyway , right ??

STOP DON't do this.

Take off cap, use syringe to remove some fluid or bleed some fluid out first.

Then turn the calipers back in.

Otherwise you may over flow the fluid at the MC and make a mess.

I trust that you know how to bleed the wheels correctly. But you need to bleed the Master cylinder also. 2005 has a bleed screw doesn't it?

05 does not have a bleed screw, i looked for it, and searched but from what i have found is that 05-06 does not have MC bleed screw, not sure about the newer.

yes, i have bled breaks before, i might not have done it enough though, did at least 5 cycles each (pump pedal, open bleed valve, depress pedal, close valve). i had clean fluid coming out without any air bubbles

Hmm, interesting, might be that the old pads left bad residue on the rotors and it needs to be taken off with some sandpaper or the new brakes need to be bedded in.

is the rear piston supposed to be flush with the caliper? i only need about 1-2 mm more clearance to get the caliper over the pads. i got the piston as far in as i could; there is a rubber gasket that gave me some issues at first, and was able to push it in, but it is not flush with the caliper.

the fornt and rear calipers are single piston sliding type, the slide pins need to be clean and greased or they can bind and cause uneven wear

there's a small pin sticking out on the back of the rear pads, you must align one of the four slots in the rear caliper piston face to slide down over the pin

My 05 MC has a bleed screw, but you should never need to touch this unless you run the MC reservoir empty and get air in the MC

but the most likely thing to check is that the rear HB378 pad pattern comes in two pad material thicknesses; 0.565" and 0.626". The RX-8 uses the thinner pad material. If you received the thicker pads they'll never go on. I had this happen with some custom pads.

excellent reply - all hail team :bowdown:

Thanks Team, i checked the pads for the rear, and i have the wrong pads. I have the HB378f.626. they are too thick for the caliper that is why they wont fit over them.

The MC Brake Bleed valve should be right here, correct? or am i just crazy and cant find it?

http://i214.photobucket.com/albums/c...scott/MC-1.jpg

TeamRX8 brings up a good pont. Make sure the nipple of the pad backing plate slides into the groove of the piston, which needs to be turned in alignment to receive the metal nipple of the pad. If the alignment is correct and you still can't shut the caliper closed, then the mentioned thickness disparity would be the only culprit left as reason for the problem.

Thanks, i know about the rivet in the pad that must align with the piston. my pads are too thick for the caliper to fit over, the rivet being a problem was never an issue as i never that the caliper down that far.

I had the HP+ pads. I hate Hawk pads.

That's why I stick with the OEM pads! :)

If you were using them for street only use, you were using the wrong pads.

I had the car towed to the dealership today and They told me that I need to replace the LF caliper and rotor at $905!!! I will post more info as i get it tomorrow when the work on it. All I know so far is that the caliper is locked up and it warped my rotor beyond machining. Service tech mentioned that when i painted the calipers it #@*&% the caliper up, just that one. WTF?!?!?!?

Looks like a good reason for a brake upgrade :D:

$900 will pay a good chunk of some new calipers for the front....

You could also get a stock replacement caliper (possibly used from one of our sponsors), a replacement rotor, do the install yourself and save more than half of that amount in price.

Heck, for that price, purchase a complete front kit from RacingBrake.