Help on J-55 HD rear rotors needed - ZR-1 Net Registry Forums

Sgreg · 04-29-2010

I need a little help. How thick are our ZR-1 factory J-55 HD rear rotors ? Seems replacements are really thin. I tossed mine some time ago and have regretted it many times. Calipers do not strike my new rear rotors properly and I believe it may be a thickness issue.

Aurora40 · 04-29-2010

They are 12x1.0" I believe. FYI the J55 just relates to the fronts. All 88+ cars had the same rear brakes.

Edit: I don't think that's right. Wilwood's site shows a replacement for the rear as 12 x 0.8"

http://www.wilwood.com/Search/PartNo...px?itemno=8314

Sgreg · 04-29-2010

[QUOTE=Aurora40;88530]They are 12x1.0" I believe. FYI the J55 just relates to the fronts. All 88+ cars had the same rear brakes.

Edit: I don't think that's right. Wilwood's site shows a replacement for the rear as 12 x 0.8"

http://www.wilwood.com/Search/PartNo...px?itemno=8314

Thanks for the info. I think .81 might be right. If there is no such thing as a J-55 rear rotor, should be a million of them out there. The ACD I purchased is less than .8 by a margin. I think that is contributing to a bad striking pad on my car. Rear caliper pistons are not long enough to press the pad down fully on the rotor.

04-29-2010	#1
Sgreg Join Date: Aug 2006 Location: Texas Posts: 518	Help on J-55 HD rear rotors needed I need a little help. How thick are our ZR-1 factory J-55 HD rear rotors ? Seems replacements are really thin. I tossed mine some time ago and have regretted it many times. Calipers do not strike my new rear rotors properly and I believe it may be a thickness issue.

04-29-2010	#2
Aurora40 Join Date: May 2005 Location: Leesburg, VA Posts: 2,704	Re: Help on J-55 HD rear rotors needed They are 12x1.0" I believe. FYI the J55 just relates to the fronts. All 88+ cars had the same rear brakes. Edit: I don't think that's right. Wilwood's site shows a replacement for the rear as 12 x 0.8" http://www.wilwood.com/Search/PartNo...px?itemno=8314 Last edited by Aurora40; 04-29-2010 at 10:27 PM.

04-29-2010	#3
Sgreg Join Date: Aug 2006 Location: Texas Posts: 518	Re: Help on J-55 HD rear rotors needed [QUOTE=Aurora40;88530]They are 12x1.0" I believe. FYI the J55 just relates to the fronts. All 88+ cars had the same rear brakes. Edit: I don't think that's right. Wilwood's site shows a replacement for the rear as 12 x 0.8" http://www.wilwood.com/Search/PartNo...px?itemno=8314 Thanks for the info. I think .81 might be right. If there is no such thing as a J-55 rear rotor, should be a million of them out there. The ACD I purchased is less than .8 by a margin. I think that is contributing to a bad striking pad on my car. Rear caliper pistons are not long enough to press the pad down fully on the rotor.