I just measured my front left pads and they are 5mm thick on both the outer and inner pad. I have not checked the other corners yet but will.

The pads are EBC green stuff put on 18,000 miles ago. At the time I had new front rotors installed and did not replace the rear rotors.

Anybody have any idea what % life is left in a 5mm thick pad and if its enough to do another autocross day? I am not set on attending yet but if I have time possibly...

Thanks,
k

 

I don't what other state's minimum thickness is to pass inspection but PA's is 2mm. 5 is getting close and probably will not last more than another year. For both performance and safety, I'd say switch 'em. The pedal will be higher and firmer as the piston will have less travel. For a good RoT, measure the pad thickness compared to the backing plate thickness. When the pad itself and backing plate are same thickness, it's time for replacement.

 

Thanks Hemihead,

I will plan on replacing in the next month or so then. Now for another question. Last time I had the front rotors replaced and not the rear. The front rotors have a small lip from wear. Can I get by without changing the rotors and only the pads? What is the minimum thickness for the rotors? I looked at the rotors but could not find it... Possibly on the back?

Thanks,
Kenny

 

Not exactly, the piston should adjust itself outward as the pad/rotor wears down. They only retract a few thou. That is why you need to compress the pistons back in when you change worn pads. It's a fun day when you have to rotor out and accidentally step on the brake. The pads are compressed against each other and getting the piston retracted is a PITA.

My factory rotors have a very noticeable lip on all of them. I'm not sure about their service limit. Good luck finding out.

 

I don't know about earlier models, but changing the rotors with the pads is recommended for the R56.

 

I found a post on here from an individual stating he was a Master BMW tech for 20 years. He stated the minimum rotor thickness as follows:

front 20.4
rear 8.4
pads start out at 12mm

I will plan on replacing my pads and rotors all around soon. Think 5mm of pad left is safe for a short autocross?

 

How can the piston adjust itself when it's a sealed system? The only way I see it adjusting is having the pedal compressed and adding fluid. Drive a car with very thin pads and then a car with fresh pads and I'll be willing to bet the car with fresh pads has a higher, firmer pedal.

 

You should be fine. If they start out at 12mm, you're just barely under half the original thickness. Pads somewhat insulate the caliper from heat but an auto-x shouldn't be putting lots of heat into the pads. I'd be more worried about a high speed road course.

 

Also a silly question about buying rotors. Do vendors price them in pairs (left and right) or individually? I have priced out zimmerman replacement rotors @ several auto parts web sites and I am pretty sure they are priced individually.

TSW upgraded rotors seem to be priced by the pair (I could be wrong) and are not that much more expensive than OEM.

 

Have you ever changed brake pads? Usually, the rotor will not fit back in with new pads because they are thicker and the piston has adjusted itself out. If they didn't adjust, the pedal would start going to the floor when pads are worn. The pads will retract a few thousandths of an inch from the rotor when pressure is released.

 

Plenty of times. Hell, more than I wanna know about. The piston moves out further because there's less pad material but I don't consider that to be self adjusting. I know what you're trying to say. You think that I mean that the piston fully retracts itself when you're not on the brakes which (as we both know) it doesn't. It's just that piston is further away from it's fully retracted position where it would be with a fresh set of pads.

 

Each vendor does it differently. If they do indeed start out at 12mm you should be fine with 5mm of pad.

 

Agreed.

 

Alright, now we're on the same page. Back to our original thread.

 

Rotors can be priced either way. Usually they say per pair or individually. The TSW rotors do look pretty good and I'm planning on using them when I need to replace mine.

 

I run Brembo blanks on EBC greens and have had issues whatsoever. Just my $.02 here but unless you want rusty rotor hats, tape off the swept surface and give 'em a coat or 2 of high temp engine paint. $40 each vs. $100+ for some others. Edit: Just looked with TSW, $119 for a pair of fronts, $100 for a rear pair or $200 for the whole set. Great value on great parts. Hell, if I would have seen that before I did mine awhile ago, I would have gotten those instead.

 

I look forward to your order, might also think about running the Carbotech pads too.

 

Thanks but I'm good with brakes right now. My Greenstuff's have plenty of meat on them and the Brembo's are still in good shape. But, when/if they go, that will probably be the route I go. Unless I feel richer than I am and go JCW coversion.

 

autocross isnt bad on the brakes at all when compared to a track day. 5mm is plenty to run, should go by the standards you hold for the road anyways, having to stop suddenly on the highway at 75 needs better brakes than the 60-30 slowdowns in autox.