Hi
I am upgrading to the Boxster calipers. According to Rich Johnson I need the 24mm rotors on the front. I have the recommended 20mm on the rear. I currently have fairly new 20mm Zimmerman front rotors now. Havent tried installing the calipers yet but wonder if I can just stay with the 20mm front rotors? Or just spend more money?

David

Not sure, but off the top of my head but I think the offset is different on the rotor hat. Let some one else chime in.

IIRC the 24mm are much thicker. I don’t think the calipers will adjust for the difference. It will be obvious when you bolt them on. I did the upgrade like 20 years ago with Rich Johnson adapters.

My advice is get the right rotors. A few hundred bucks for the most important safety system in the car is a no brainer.

I agree I will just get the correct rotors. Thanks for the input.

David

I agree I will just get the correct rotors. Thanks for the input.

David

Also, just fyi, the 24mm rear rotors require some machining on the RJ adapters, otherwise the calipers won't be centered over the rotors.

See my post here for more info:
http://www.914world.com/bbs2/index.php?showtopic=170890

Hi Andy,
I have the 20mm rotors on the rear. Rich stated that I need 24mm for the front. I currently have 20mm on the front and believe I will need the front 24mm rotors?

Yes, that is all correct. 24mm in the front, 20mm in the rear is the normal setup.

I'm just pointing out that if you have/want 24mm on all 4 corners (like i did) you will need to machine the rear adapters to offset the rear calipers by 2mm so they will be centered over the rear rotor.

20 mm is SC and 24mm is Carrera. You do need the right size rotors to make the system work.

Exactly!

Technically you can use 20mm rotors, but when you get to the end of pad life and forgot you started with -2mm and the pistons extend past the seal and the brakes fail you will wish you had spent the $100 on 24mm rotors.

Thanks all,

Ordered the rotors from PMB today.

David

Holy smokes! My Boxster has the best braking of any car I've owned. Can't wait to hear how well the 'Whoa' pedal works for you when you're running.