brake help!!!

[maro2nv]

I just finished getting my car back on the road. I put the ridetech level 2 coilover kit with wilwood 6piston 2 piece rotors and 4 piston on the rear. First drive out when I slow down it makes a knocking sound over and over again while I'm on the brakes but it's only in the front. I went back and re shimmed the calipers but it did nothing still has the same sound. The clearance between brake pads and the Pistons is all the same so I know the caliper can't too out of line. Any ideas will help. I will try anything. I just want to drive it!!!


Thanks
Josh

[kevmurray]

What's hitting? See any witness marks?

[maro2nv]

I can't see anything hitting. I looked over everything and re-tightened everything on the front end but still does it. The only thing I noticed is on both front rotors if you turned them by hand they would turn free but on about 1/4 of the rotor they would drag a little.

[minendrews68]

are you sure you have the hub tight? I know it sounds funny but...

[kevmurray]

I can't see anything hitting. I looked over everything and re-tightened everything on the front end but still does it. The only thing I noticed is on both front rotors if you turned them by hand they would turn free but on about 1/4 of the rotor they would drag a little.

Are these hat rotors? Maybe a rotor bolt is too long? Take it apart and have a look in behind. What hub are you using?

[maro2nv]

Yea there a hat rotor. The hubs are the ones that wilwood sent with the kit. It's there superlight kit. I will take a look again and see but I looked over them a few times and everything was good. The rotors spin fine without the calipers on there.

[maro2nv]

So I talked to wilwood today and they told me to re-clock the rotors. They said they have had them have a little wobble in ones they have installed so they would re-clock them and it fixes it. I hope it works!!

[kevmurray]

Those FNSL brakes use a fixed caliper so if it only rubs with the caliper in place then you must have a rotor problem. Let us know if re-clocking them helps. Are you able to measure the lateral run out?

Edit: If so measure the hub run out too. I'm curious what the source is.

[maro2nv]

So I re-clocked them and it helped a little. So I took it out for a ride and that knock is still there. If I barely touch the brake I don't notice it but the harder I push the worse it gets. I don't feel any pulsing in the pedal though. I can't feel it on the steering wheel either.

How do you measure the lateral run out and hub run out. Sorry first time having to deal with this. I've put a couple of these kits on friends cars and I've never had a problem before.

[kevmurray]

Lateral run out is the side to side wobble of the rotor as it's turning. It can be measured with a dial gauge. It's odd that you feel nothing in the wheel or pedal though. A change in thickness would be felt most in the pedal and a wobble would be felt most in the steering wheel.

Here is a link to a youtube vid showing how it's done for brake rotors. You may want to check it at several clocked positions of the rotor to see if it's a combination of hub and rotor run out. It should be worse at one position and better 180 degrees from there.

https://www.youtube.com/watch?v=6SbWB2CNqio

If the lateral run out is ok then I'd move on and look into other possibilities. Are there any witness marks on the calliper? Maybe it's not centered well and minor lateral run out (that would ordinarily be benign) is giving you a rub?

[maro2nv]

Ok so drivers side rotor has .007 and the hub is .003

Passenger rotor has .005 and hub is .002

[Hydratech®]

Theoretically, you want to see zero readings, but in the real world you will likely always see some readings. Are the rotors slotted? If so, I have experienced noises of your nature until we have taken the vehicle out and pounded it thoroughly. Seemingly never a problem with just drilled rotors, but have experienced noises with slotted rotors, thinking that maybe the slots in the rotors are pushing the pads up / down due to the diagonal angle of the slots in relation to the pads biting into them.

Sometimes it becomes a case of no repairs needed, just a few thorough thrash sessions to get everything happy. How does that saying go? Fix it 'til you break it, then fix it again 'til it's fixed? Or something like that...

I don't think you have anything to lose by putting it through a "spirited pound session". If it is what I think it is, it will quickly go away (as everything burnishes in with use, and a heavy pound session brings that into play in an accelerated fashion).

Just my .02, FWIW

[maro2nv]

There slotted and drilled. A thrash session always sounds fun to me!!! I will give it a go tomorrow after I get home from work and see how it goes. Thanks for the responses.

[maro2nv]

So no luck on the brakes. Tried everything. I put a dial indicator on the top of my rotors and I was getting about .018 growth on them so I tried the rotor hat and was about .010. I took a video of it and sent it to wilwood so we will see what they say.

[kevmurray]

Is the noise more of a "tick, tick.." or a "swish, swish..."? There may be material displaced by machine work hitting the pads. Like the slots. Try turning the rotors by hand to find the exact section that hits and mark it out with a sharpie. Then turn that section away from the caliper and search both rotor faces for burrs or other crap that hasn't come off yet. Mention the .007 runout if you talk to Wilwood.

[maro2nv]

Sorry for the delayed response. So I looked over them and couldn't find anything wrong. So I took them off and sent the hubs, rotors and calipers back to wilwood. The only bad thing is they told me it would be 4 weeks till they could give me a answer which I think is a little excessive for just buying the brakes. I will update the thread soon as I here something. Thanks

[maro2nv]

Alright been a while but here is the update. Wilwood kept my old brakes to test them and figure out the problem and sent me a new set. I drove them around for a day and they were fine till I started bedding them. They started making noise again. So I just waited till this past weekend at hot august nights at the autocross to allow them to hear this noise in person. They noticed after I ran the autocross that there seemed to be chatter marks on the rotors. So the took pic and notes and are working on trying to find out what the issue is.

[pist0lpete]

Appreciate you keeping us posted, it seems Wilwood is working to make this right. Let us know what happens.