I was doing a brake job for a friend of mine who has a Mercedes S500. Guess what, the S500 has the same size offset rotor a the S4 928 and Its a full 13" diameter. (330mm). PLUS, they are made by zimmerman, are the same thickness. Will they work? One problem, the bolt pattern is a little smaller. (about half a bolt circle.) that could be easy to fix by just drilling the proper holes in them. possible option?

mk

 

yikes.

 

Are my shade tree antics really showing now?? Its the economy. Its driving us all crazy!!!

 

Drilling the holes how exactly? Assuming that's done right, the rotors are hub-centered. Is the hole in the center exactly the same size?

 

Why not get another set of spindles from Mark A for prototyping?

 

mark,

I don't understand your fascination with zimmerman. Zimmerman is an aftermarket rotor and is far less quality than the Porsche OE manufacturer. I have seen their rotors fall apart under hard use and although they look the same the veining in the casting is not the same design and offers less air flow. We actually cut one of each apart for a brake demo. The zimmerman cut easily and the OE was much harder to cut. this might be why the have a tendency to groove more than the OE rotors. I was told but could be wrong that the holes are drilled not cast.

 

So, it would be possible to change rotors and change our bolt pattern? Does this open us up to the possibility of a wider range of rims to use?

 

He's talking about drilling out the rotor to match our bolt pattern, not the other way around.

IMO the front offset is the limiting factor of rim choice, not the bolt pattern. You are not going to find many (if any) Mercedes rims with a et65+ offset.

It would be cheaper to order a custom set of HRE or Fikse wheels than trying to change the bolt pattern on the car.

 

These Mercedes rotors had the same offset a our rotors which I thought was interesting.

the hole is smaller and I will check to see if it clears the wheels bearing area, but certainly the 928 rotor are not hub centric. drilling holes that match our bolt pattern will not be that difficult and are on a larger bolt circle than the mercedes. (mercedes looks to be like the BMW pattern)

cooling vanes are smalller or narrower, but mostly longer. heck, that could be good or bad.

I certainly didnt see any issue with porsche OE vs zimmerman having totally abused the zimmerman in racing for over 10 years now.

Here is a pic.

 

Pic of the holes that need to be drilled for the wider bolt pattern added. By the way, same thickness, same offset.

 

You can safely drill rotors for a new pattern. You just offset the new hole in between the old holes. Do not elongate the old holes.

 

I don't see why this wouldn't work. Just drill 5 new holes offset from the current ones and enlarge the center hole. If you can do it precisely, it should work fine.

Dan
'91 928GT S/C 475hp/460lb.ft

 

I understood that he was referring to the mounting holes. I was speculating on whether it was possible to use alternate rotors and be able to use alternate rims. If it's time to change your rotors, then custom rims would not be cheaper at all. It's only speculation.

I wonder what rotors are available with the appropriate mounting hole pattern.

 

I'm not sure I understand your connection between rotors and wheels? The rotors just have holes that the wheel studs in the hub go through. If your wheel stud spacing is 5x130mm, your rotors must match this and so must your wheels.

Dan
'91 928GT S/C 475hp/460lb.ft

 

That's smarter. I just thought it would be more accurate to use the existing hole to make sure you were centered.

This does open the door for more variations of rotors. These are a lot cheaper too. I wonder if they are as strong as the porsche design, even though both are made by the same copycat OEM manufacturer, Zimmerman.