Questions from new rotor install
Thread Starter
Drifting
Joined: May 2000
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From: Penfield NY
Questions from new rotor install
I installed a set of Sportbrake drilled & slotted rotors today. The install went well, no problems to speak of, but when I went out to test drive it I noticed a slight "wobble" in the steering wheel at 60 MPH. When I apply the brakes I get a slight pulsating from the front I think, almost like a set of rotors that were old and needed cutting. I think it's from the front end. It's not dramatic and is only slightly noticeable, but it's there. I'm using ceramic pads that have been on the car for less than 2,000 miles. Any ideas?
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Joined: Sep 2001
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From: Atlanta GA
Originally Posted by C5LOU
I installed a set of Sportbrake drilled & slotted rotors today. The install went well, no problems to speak of, but when I went out to test drive it I noticed a slight "wobble" in the steering wheel at 60 MPH. When I apply the brakes I get a slight pulsating from the front I think, almost like a set of rotors that were old and needed cutting. I think it's from the front end. It's not dramatic and is only slightly noticeable, but it's there. I'm using ceramic pads that have been on the car for less than 2,000 miles. Any ideas?
Did you bed your pads into your new rotors?
5-6 times from 70-20, then drive home without coming to a full stop with the pads stopped on the rotors. Let it cool off for at least 2 hours.
Thread Starter
Drifting
Joined: May 2000
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From: Penfield NY
I did bed the pads in in a similar fashion to what you suggest. I'll have more time tomorrow to drive around some and make sure all is well. I'll take the wheels off again and look things over. Hopefully I'll find something simple that I missed. Thanks!
Race Director
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From: Lynnfield MA
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You probably have a warped rotor even if it is new. I have experienced this issue in the past so I would have to suggest that you check the surfaces with a lathe or get an exchange. Taken them off again is a PITA for you I am sure....
Thread Starter
Drifting
Joined: May 2000
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From: Penfield NY
I couldn't get a torque wrench into the wheel well given the space limitation. I tightened the bracket bolts down as hard as I could and I'm a big guy, so I'm sure they're tight! I also used blue Loctite on the threads. I'm pretty sure everything is tightened down pretty well and I rechecked the wheel torque after driving yesterday. It looks like a nice day today, so I'll have time to get out and do some driving and see what happens. Hopefully the new rotors aren't warped. If so I'll just put the stock rotors back on and return the new ones - it's not worth all the work and the PITA to change them out again!
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Joined: Sep 2001
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From: Wilmington NC
Originally Posted by gmblack3
The area where the rotor contacts the hub may need to be cleaned up.
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That would be the first thing I would check. The rotor has to sit very very flat against the hub. Any rust there will result in uneven seating which is really magnified and will cause the problems just as you described them.
Advanced
Joined: Jan 2004
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From: Schaumburg IL
When I bought the same rotors from Speedbrake last week, the dude who took the order said the rotors will vibrate the first couple hundred miles until the Zinc plating wears off of the pad contact area.
Has anyone installed these and experieinced the same phenomena and not have the vibration resolve itself after a couple of weeks? It would be a bummer if they're selling defective product and pulling a fast one.
Has anyone installed these and experieinced the same phenomena and not have the vibration resolve itself after a couple of weeks? It would be a bummer if they're selling defective product and pulling a fast one.
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Le Mans Master
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From: Slave to the evil empire
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Originally Posted by vertte
When I bought the same rotors from Speedbrake last week, the dude who took the order said the rotors will vibrate the first couple hundred miles until the Zinc plating wears off of the pad contact area.
Has anyone installed these and experieinced the same phenomena and not have the vibration resolve itself after a couple of weeks? It would be a bummer if they're selling defective product and pulling a fast one.
Has anyone installed these and experieinced the same phenomena and not have the vibration resolve itself after a couple of weeks? It would be a bummer if they're selling defective product and pulling a fast one.
I have these same rotors and never had any vibration problems, I'm willing to bet you have excessive runout (warped) and one or both rotors need to be turned.
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Joined: Jan 2004
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From: Schaumburg IL
Originally Posted by runamuk
I gotta call I have these same rotors and never had any vibration problems, I'm willing to bet you have excessive runout (warped) and one or both rotors need to be turned.
I have these same rotors and never had any vibration problems, I'm willing to bet you have excessive runout (warped) and one or both rotors need to be turned.
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Joined: Sep 2001
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From: Wilmington NC
Originally Posted by vertte
Runamuk, if you didn't have any issues, then Speedbrake is probably selling rotors that have been improperly machined and warped during the process. Damn! I was going to install them this weekend, too!
I do not think this is the problem. Warped rotors will not cause the wobble, while driving, Lou described. I'm betting he has a rotor that didn't seat fully on the hub. This is caused by not getting the hub really clean (rust and crud) before installing the new rotor.
This has been discussed frequently, but I don't think I have ever seen a truly warped rotor on a C5.
http://www.stoptech.com/whitepapers/...otors_myth.htm
Thread Starter
Drifting
Joined: May 2000
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From: Penfield NY
I went out for a drive this morning and the "symptoms" seem to have disappeared. I drove for probably 50 miles with various stops at lights and stop signs. I may jack it up today and make sure there's no problem with the rotors not sitting flush with the hubs, but I don't think I'll find anything. My car has never been driven in the rain or snow, so the hubs are like new. It kinda sounds like maybe the theory of the zinc coating needing to wear off might be correct! Thanks for everyone's responses! 
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Joined: Sep 2001
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From: Wilmington NC
Originally Posted by C5LOU
I went out for a drive this morning and the "symptoms" seem to have disappeared. I drove for probably 50 miles with various stops at lights and stop signs. I may jack it up today and make sure there's no problem with the rotors not sitting flush with the hubs, but I don't think I'll find anything. My car has never been driven in the rain or snow, so the hubs are like new. It kinda sounds like maybe the theory of the zinc coating needing to wear off might be correct! Thanks for everyone's responses!
I would guess a rotor seated the rest of the way on the hub. You might want to redo you the lug nuts in case there was a slight gap. Zinc coating would not cause the wheel to wobble while driving as you described earlier.
Drifting
Joined: Apr 2004
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From: CT
I installed a set of SportBrake slotted/ dimpled with Hawk HP+ pads ss brake lines and DOT 3 fluid on my 2000 FRC this spring and now have about 4000 miles on them. I experienced the same pulsation for the first 200 miles or so until the zinc plating wore off at the pad contact area and also had a lot of brake dust during this period. According to my tuner, this is normal for any zinc plated rotor. Once the zinc wears off they should be fine.
In addition, you may notice that initially the pads may not make 100% contact with the rotor surface. This also is normal and they will eventually wear in to full contact area. Hope this helps, I'm very satisfied with mine and would not hesitate to buy them again.
In addition, you may notice that initially the pads may not make 100% contact with the rotor surface. This also is normal and they will eventually wear in to full contact area. Hope this helps, I'm very satisfied with mine and would not hesitate to buy them again.
Thread Starter
Drifting
Joined: May 2000
Posts: 1,769
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From: Penfield NY
Originally Posted by HRDTOPC54FUN
I installed a set of SportBrake slotted/ dimpled with Hawk HP+ pads ss brake lines and DOT 3 fluid on my 2000 FRC this spring and now have about 4000 miles on them. I experienced the same pulsation for the first 200 miles or so until the zinc plating wore off at the pad contact area and also had a lot of brake dust during this period. According to my tuner, this is normal for any zinc plated rotor. Once the zinc wears off they should be fine.
In addition, you may notice that initially the pads may not make 100% contact with the rotor surface. This also is normal and they will eventually wear in to full contact area. Hope this helps, I'm very satisfied with mine and would not hesitate to buy them again.
In addition, you may notice that initially the pads may not make 100% contact with the rotor surface. This also is normal and they will eventually wear in to full contact area. Hope this helps, I'm very satisfied with mine and would not hesitate to buy them again.