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I have a 2013 991.1 Carrera Cab, that is going to need a full brake job soon. It currently has the Porsche OEM pads and rotors, but i think im going to swap them for Brembos all the way around. I already purchased the pads for front and rear, and the rotors are left. The front and rear rotors on the base 991.1 are the same size, thickness, width, etc. The only difference i see in the Brembo design sheets is that the front rotor height is 69mm and the rears are 75mm. Does anyone know what this means? If both front and rear rotors are 330mm in diameter, what is this "height" referencing? Forgive me this is my first 911, and i suck at wrenching, lol. Trying to learn though...
Take a look at dimension “A” in the diagrams. This is the height.
Ahh ok now that you pointed it out i looked at the more basic picture they have on the site and its the distance from the back of the rotor to the end of the center of the rotor, where the bolts screw in which is essentially the width of the entire rotor which i dont think matters when the difference is 6mm less. The only width that affects functionality/performance is the width of the part that goes in-between the calipers, right). So this is great news, it looks like it wont affect anyting besides the center of the rotor maybe sticking out a little less toward the rim but that def wont matter because since its lesser height it wont have risk of possibly sticking out too far into the wheel area or something like that (which would be the effect if we installed the front rotors on the rears since the part that bolts the rotor in sticks out 6mm more than spec maybe effect the fitment of the front wheels back on the car by 6mm but then a spacer would solve that problem or i just leave the wheels 6mm more in toward the wheel well.). The most important measurements that you need to be the same or it wont work is the bolt pattern, centering, and the thickness of the rotor that the caliper and pad hold on to which is all exaclty the same. It should not affect braking performance or functionality at all, if anyone wants to chime in and agree or disagree. I am def going to try i think the only thing it may affect is the placement of the wheel back on might be 6mm more inside the well cuz the center of the rotor that the wheel bolts on to is 6mm shorter than stock. Either way i am def going to just try when installing the pads and start by ordering 2, worst case i will just change out the rears then do the fronts another time.
I know this isnt a ton of money we are talking about here, but its ofcourse not about the money. Even though the difference between back and front is almost comical for the same exact freakin thing at the time of writing this brembo is charging $196 each for the front rotors, and $69 for the rears. I def think we get played by these car companies, and waste so much money on brand tax, That center part of the rotor is not doing anything besides holding the bolts who cares if it sticks out a little more or less especially a 6mm spacer would solve the problem anyways. But i dont think anything will be different or at least not noticeable. 6mm is literally about a 1/4 inch. I think this is all a ploy to just to make sure they get your money, as soon as they can when you change the front rotors cuz they know you are def going to change them and you might never change the rears!. Just a classic old ferrari part being the same exact thing as the Fiat part but added 900% brand tax cuz of the label. I forgot the name of it but its well known thing all auto and auto parts manufacturers do. They know they can get away with it and 90% of people aren't going to cross reference the part numbers or read the technical specs to see if there is any difference. Hell, Bosch literally makes probably 90 percent of all the shared parts between every german manufacturer and its so much less if you purchase directly from them, and noone thinks to just order from them directly, cuz its so easy to just go to the dealer or even if its not easier its what you know and are used to. One time i got a water pump from them for my BMW it was literally one quater of the price and all i did was need to know the BMW part number and they looked it up and sent me exactly what i needed. The markup is insane sometimes. Anyways, Thank you for pointing out the height, when i saw this picture below on the site, it clicked right away. I was only looking at the detailed diagram before and I couldn't see where they were showing A. The picture below shows exactly what measurement A is on the rotor.
Last edited by mikescayenne; 04-01-2023 at 04:10 AM.
The rear rotor likely includes an internal cylindrical surface and internal volume that houses a pair of parking brake shoes which engage with the cylindrical surface when actuated. The front rotors don't have this function. Hence the difference in height.
The rear rotor likely includes an internal cylindrical surface and internal volume that houses a pair of parking brake shoes which engage with the cylindrical surface when actuated. The front rotors don't have this function. Hence the difference in height.
Hmm, this for sure sounds like the correct reason. I totally didn't factor in the parking brake on the rear brakes. Do you think it makes a difference though if installed in the front? It looks like every dimension in between the caliper is the same (thickness of the rotor, etc)). The height difference is in the center part of the rotor where the bolts screw in.
Last edited by mikescayenne; 04-01-2023 at 04:45 PM.
LOL you are probably right but why??? i need an explanation!! Is it possible its only to make room for the parking brake caliper to fit around it and if you dont have a parking brake caliper up front to worry about, it wont matter?? I'm totally guessing here, and dont know anything about disc brake design, lollll. This is actually the first time i am replacing the brakes myself so im looking forward to seeing it all up close.
The rear rotor likely includes an internal cylindrical surface and internal volume that houses a pair of parking brake shoes which engage with the cylindrical surface when actuated. The front rotors don't have this function. Hence the difference in height.
I obviously haven't figured out how to use this forum yet. It keeps telling me that the token has expired. What is that? Never experience that on the Festool Owners' Group forum.
Anyway, I wanted to add this to my message in further reply to mikescayenne message #8: The offsets of the rotor surfaces relative to the plane on which they are fastened to the hub will cause the rub faces of the rotors to be incorrect if you use rear position rotors on the front, assuming they otherwise will fit. And that will put the rub faces too far inboard on the front positions to be centered in the caliper.
The rear rotor likely includes an internal cylindrical surface and internal volume that houses a pair of parking brake shoes which engage with the cylindrical surface when actuated. The front rotors don't have this function. Hence the difference in height.
I obviously haven't figured out how to use this forum yet. It keeps telling me that the token has expired. What is that? Never experience that on the Festool Owners' Group forum.
Anyway, I wanted to add this to my message in further reply to mikescayenne message #8: The offsets of the rotor surfaces relative to the plane on which they are fastened to the hub will cause the rub faces of the rotors to be incorrect if you use rear position rotors on the front, assuming they otherwise will fit. And that will put the rub faces too far inboard on the front positions to be centered in the caliper.
If you scroll up you can see every post you have made. You will see that you had already stated that sbove. That comment is actually what i originally quoted and responded to. Lets say what you are saying is correct, when i go to install it do you think it will fit, and if it fits do you think it will have an effect on functionality of the front brakes, and if so, what?
Ive never gotten a message on here about a Token expiring so not sure how to help you there.
03-31-2023, 04:19 PM
991.1 Base model brake rotor question
