powdrhound

Any of you guys know if the 997.1Cup front 380mm rotors offsets are the same as the street (non center lock) 997.1GT3 380 PCCB rotors offsets? In other words, will the street 997GT3 PCCB 380 rotors directly bolt onto a 997.1Cup which is using uprights 997.341.157/8.92. The street uprights are the same part number with the last tow digits a .94 (instead of a .92) but I think the only change is a a different wheel speed sensor mounting pattern as the Cup uses the old 996 sensors while the 997GT3 uses new style 997 ABS sensors. Thanks!!

Tom@TPC Racing

Offsets are the same between 997.1 GT3 street PCCB, 997.2 GT3 steel and PCCB, and 997 Cup rotors.
I think the drive pin diameter might be different. Might have to drill out the holes slightly to fit over Cup drive pins.
Cup uprights have raised axle centerline compared to street uprights. Depending on year the difference can be ~30mm higher.

powdrhound

Thanks Tom. The drive pin diameter is of no concern as my plan would be to use the 997Cup upright with 5 lug hubs instead of the center lock. I spoke with a local guy that is using 997GT3 PCCB 380 rotors on his 7.2Cup without any issues. He just had the holes enlarged for the drive pins but that was it. That's why I thought the brake rotors offset was the same but what threw me off was a thread by this buy that did the conversion and claimed that the cup rotors was offset slightly more toward the inside as in his post #2.

https://rennlist.com/forums/997-gt2-...onversion.html

The only thing that I would think could make the offset slightly different is a different offset on the Cup hub compared to the street 5 lug hub. I can't imagine the upright has a different offset as that would require a different casting or the bearing race machined deeper. That doesn't make much sense as the castings between the street and cup parts are basically the same except the speed sensor block which is machined differently on the .92 and .94 part due to the different type of speed sensors, the old style 996 sensor on the 997Cup .92 upright and the 997 ABS sensor on the 997GT3 .94 upright.

Are you 100% sure the Cup uprights have a raised axle centerline (or conversely lower LCA mount) when compared to the 997GT3 parts? I am not sure the LCA mounts lower on the 997 Cup carriers than on the 997GT3 carriers as it's the same casting, it looks the same in pictures but hard to tell for sure. The RSR pieces are lower for sure..

The reason I'm trying to figure all this out is that I'm looking to swap out the front and rear wheel uprights on my 996 to the 996GT3RS parts which were the homologation pieces for the 996RSR and later the parts used on the 997GT3/Cup/RSR. I could use the 996GT3RS front uprights but they are for 350mm brakes and my car runs the 997GT3/Cup 380Front/350 rear brakes. As such I was looking into using the 997Cup front upright as they appear to be the same thing as the 996GT3RS part except for the 380 brakes. Hope that makes sense. Thanks Tom!

Tom@TPC Racing

Yes I am sure. I did the measurement because at one point in time I wanted to swap uprights(kind of still do but low priority for me at this time). For some reason the 997.1 GT3 street uprights(which is OEM replacement for 996RS street) have higher axle centerline than on 997.2 GT3 street. Perhaps the .2 street upright wasn't homologated for RSR...I have no idea. To me the higher centerline of the .1 street is a racier geomety. I couldn't believe it but the measurements are facts. I took photos to proof, don't remember which folder I put the photos right now.The 997.1 street uprights have a closer axle centerline to the Cup than the 997.2 street.


I have a 997.1 GT3 street car factory equipped with 350mm steel brakes. I too craved to the have 380mm front brakes. I looked into swapping to .2 street uprights, that prompted me to visually noticed and then measured that the .2 street has lower axle centerline than .1 street. Thus, I didn't end up buying .2 street uprights. I did the 380mm front brake conversion using OEM brackets for 997/991 Turbo S. My other option was to buy 997.1 street PCCB uprights which has same centerline with 225mm brake caliper mounting pattern. The brackets were a lot cheaper.
See post #585 and #587
https://rennlist.com/forums/997-gt2-...07-gt3-39.html
I ended up machining the brackets and worked fine all year. I also made a drawing to CNC machine an improved bracket for later.

powdrhound

That's good info on the differences Tom. If you come across the folder with the comparison pictures or measurements, please post it up or PM it to me please. I would be particularly interested in the difference of the axle centerline between the 997.1GT3 and the 997.1Cup upright. In other words, how much lower is the LCA pick up on the Cup upright compared to the 7.1GT3? Based on comparing pictures, it appear to be about 10mm lower.

The OEM brembo brackets that you mention above is what I've been using for years on my 996GT3/Cup uprights. They work well. Ideally I would use the PCCB 997.1GT3 uprights but I need to use the 996 ABS sensor which won't work with the 997GT3 uprights. As such the 7.1Cup upright would be ideal but the LCA pick up may be too low at my front ride height of 98mm. My other option is the use the 996GT3RS upright in conjunction with the 380 brackets but I'd rather not use those if I could avoid it.

Tom@TPC Racing

Found the photos. Sorry, not a very scientific way to measure but you can also see the ball joint relative to the bottom edge of the 380mm rotor. Here you go-

997.1 GT3 street (also 996 GT3 RS street).


997.2 GT3 street.


997 Cup.


996 World Challenge.


Another 997 Cup.

powdrhound

That helps a lot Tom. Thank you! Honestly, it looks like the 997.1GT3 and the 997Cup are identical. Does it look that way to you? The 997.2GT3 definitely has a higher LCA pick up, looks to be about 20-25mm higher.

powdrhound

Tom,
Just looked at this closer. You label the first pic a 997.1GT3 but the brake rotor appears to be an OEM Cup rotor, the LCA is a Cup part, and the upright is marked with a .92 which indicates a 997.1Cup upright, NOT a 7.1GT3. The third pic down you marked as a 997Cup but it is definitely NOT a 997Cup part as it has a 996 part number (ending in a 9F) which indicates a 996RSR upright. Can you verify which pic is which? The second picture is correct as a 997.2GT3 upright. Thx..

pete95zhn

Interesting...very interesting indeed. I've bought earlier a set of 997 GT3.1 uprights and recently a set of 991 GT3 brakes, and I was wondering if those brakes would fit to those uprights. Just had to...they were cheap...you guys saved my day! My uprights have 225mm caliper's bolt holes but also castings for 142mm calipers. So far I've seen these, ones with only 142mm spacing and ones with 225mm spacing and 142mm casting (the other one) milled away. I think that mine indeed are early 997.1s, made with same casting than 996 RS. Then again 997.2 ones don't have the possibility to install 142mm calipers by machining 225's mounts off, plus the axle centerline is different.
My intial plan was to remove 225 mm mounts off and get 142mm mounts machined. (Thanks Tom for measurements!) Fortunately we only got this idea to planning/measuring stage before my 142mm 6-piston calipers were sold with old uprights and I maanged to find a complete set of 991 GT3 brakes.Complete means calipers, Pagid pads and Brembo 2-piece rotors F&R.
My uprights are compatible with 996's ABS speed sensors. See pic for details. They were soda blasted last week, I might get them powdercoated.

Rickard 993 Turbo

Yes there is diffrence between the street and the cup upright

Tom@TPC Racing

The photos are as named in my folder. I originally measured and took these photos for personal use so sorry if there's any discrepancy.
We do install Cup parts on street cars frequently so LCA and rotor doesn't always depict the car.
You are correct on the 9F being 996RSR. Thanks for pointing it out. This was removed from a 997.1Cup that was Grand Am spec which uses RSR upright. Sorry I didn't think of that.
I will measure a 7.1 GT3 street again for you as soon as there's one in the shop. I remember the measurement being 105-110mm which is why I didn't buy 7.2 GT3 street upright.
For now here are photos of 7.1 street and 7.2 street. The 7.1 street is closer axle centerline to Cup.

997.1 GT3 street (my car, with brake adapter bracket and 380mm rotors).


997.2 GT3 street.


997.1 street and 997.2 street side by side.


Sorry for posting street car stuff in Cup forum.

powdrhound

Good thread Tom. Thanks for contributing. Your pics have shed a lot of light on this. One thing I've realized is that each upright has a part number etched into the flat area (ahead of the lower caliper attachment boss). The last two digits of the number identify the upright so you can visually verify which is which. The 997.1/.2Cup upright is marked with a .92 as pictured below. The 997.1GT3 is a .93 for the car with 350 brakes and the 997.2GT3 is a .95. Both of these are side by side in the second picture below. A 997.1GT3 with 380 brakes is a .94 but dimensionally the same as .93 except for the brake caliper mounting lugs. RSR upright will have a 9 with a letter instead of two numbers. With that said, the LCA pickup point of the 997Cup upright appears about 10mm lower than that of the 997.1GT3 and probably 25mm lower than that of the 997.2GT3. If you get a chance, it would be great if you could put a tape on the .93 upright on your car in the same way as pictured below on the .92 upright. This would give us a pretty accurate number for comparison. This will help me decide which would be the optimal upright for my ride height on my application. There is a lot more to this that simply slapping on an upright if you want to do it properly. Thanks again!


997Cup (.92)


997.1GT3 (.93) vs. 997.2GT3 (.95)

powdrhound

Hey Pete,
Can you make out the part number on the long vertical rectangular area (under the digit 9 on the tape measure). I'm curious what exact upright that is. None of the 997GT3 uprights are compatible with the 996 speed sensors which are used on the 996GT3RS and 997Cup/RSR uprights. Can you take a picture of the speed sensor mounting boss? I also believe that some of the RSR upright also have different (taller) 225mm caliper mounting bosses when they were used with the anodized billet Brembo brake calipers instead of the normal 380 street/cup calipers. You can see the difference in the picture below indication that different calipers are used.

pete95zhn

I will, when I get back home...now 5000 nm away...

lordpantsington

The 996 RS Homologation pdf has some of the differences in the RS to RSR upright. http://historicdb.fia.com/car/porsche-911-gt3-rs