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996GT3RS vs 996GT3 suspension comparison
I have a brand new set of 996GT3RS suspension components on hand and took a few pictures and measurements to compare with the stock 996GT3/2/Cup components. The RS has different front and rear uprights along with rear side members. These components were the homologation parts for the 996RSR. As such the RS uprights use the Motorsport castings but have pickup points machined roughly 12mm higher than the Cup/RSR units. The Motorsport casting are hollow and substantially beefier than the standard GT3 units. They use 6 bolt bearing retainers both front and rear, compared to 4 bolt on the standard units. While the 997GT3 cars (including the 4.0RS) use a 6 bolt pattern in the front, they still only use a 4 bolt street upright in the rear which is totally different from the Motorsport units. The front subframe pictured is a 996RSR subframe. The RSR subframe is identical to the standard version except the LCA pickup point is raised 6mm. The RS does not use this subframe, it uses the standard subframe. Cheers...
Front upright (This is the 380mm brake version used on 997.1GT3 PCCB cars. The 996RS uses a version machined for 350 brakes, same as those used on 997.1GT3 with steel brakes) Rear upright RSR front subframe The LCA pickup point on the RSR subframe is 6mm higher. You can see how the upper part of the subframe is milled to allow for clearance. Below is a picture of the comparison of the 996GT3RS upright compared to the standard units. The pick up points have been substantially lowered on the RS parts: Front: LCA: -60mm Tie rod: -55mm Rear: LCA: -30mm Toa arm: -30mm Upper arms: -25mm Front 996GT3RS v. 996GT3 Rear 996GT3RS v. 996GT3 (Note that the LCA pickup is correctly angled on the RS units unlike the stock units. The angle now matches that of the rear side member LCA pickup) |
fantastic documentation John! thanks for sharing!
Originally Posted by powdrhound
(Post 14746460)
I have a brand new set of 996GT3RS suspension components on hand and took a few pictures and measurements to compare with the stock 996GT3/2/Cup components. The RS has different front and rear uprights along with rear side members. These components were the homologation parts for the 996RSR. As such the RS uprights use the Motorsport castings but have pickup points machined roughly 12mm higher than the Cup/RSR units. The Motorsport casting are hollow and substantially beefier than the standard GT3 units. They use 6 bolt bearing retainers both front and rear, compared to 4 bolt on the standard units. While the 997GT3 cars (including the 4.0RS) use a 6 bolt pattern in the front, they still only use a 4 bolt street upright in the rear which is totally different from the Motorsport units. The front subframe pictured is a 996RSR subframe. The RSR subframe is identical to the standard version except the LCA pickup point is raised 6mm. The RS does not use this subframe, it uses the standard subframe. I will mention that the rear RS side members are the same as the standard side members. I could not discern or measure any difference between the two as all the pickup points measure identical. The only difference I could see was more machining in the area of the LCA pick up to create more clearance. If someone wants to convert their car to RS spec, I would not waste your money on the rear side members. Hope this settles some of the mystery surrounding the RS components. Cheers...
https://farm5.staticflickr.com/4759/...59922152_z.jpg Front upright (This is the 380mm brake version used on 997.1GT3 PCCB cars. The 996RS uses a version machined for 350 brakes, same as those used on 997.1GT3 with steel brakes) https://farm5.staticflickr.com/4768/...8c314119_z.jpg https://farm5.staticflickr.com/4721/...f182fa71_z.jpg Rear upright https://farm5.staticflickr.com/4767/...34906e4c_z.jpg https://farm5.staticflickr.com/4626/...4a015556_z.jpg RSR front subframe The LCA pickup point on the RSR subframe is 6mm higher. You can see how the upper part of the subframe is milled to allow for clearance. https://farm5.staticflickr.com/4628/...24530279_z.jpg Below is a picture of the comparison of the 996GT3RS upright compared to the standard units. The pick up points have been substantially lowered on the RS parts: Front: LCA: -60mm Tie rod: -55mm Rear: LCA: -30mm Toa arm: -30mm Upper arms: -25mm Front 996GT3RS v. 996GT3 https://farm5.staticflickr.com/4608/...fe043ec2_z.jpg Rear 996GT3RS v. 996GT3 (Note that the LCA pickup is correctly angled on the RS units unlike the stock units. The angle now matches that of the rear side member LCA pickup) https://farm5.staticflickr.com/4603/...84c4960a_z.jpg |
Originally Posted by 993GT
(Post 14746517)
fantastic documentation John! thanks for sharing!
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+1 Great job John. Thanks for your contributions to the community!
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Great info. The bigger question though. at what ride heights do these really begin to become an advantage vs toe arms with bump steer correction. I do realize one is a band-aid and one is a proper solution but still curious on your take. |
An archetypal post.
Thanks for sharing the photo's and information. Cheers Craig |
If one wants lowered rear subframes, the RSR is the solution. OEMs may be hard to find, but one can always mill (12mm in my case) std parts to RSR style. This with solid bushings moves Carrera's/turbo's suspension arm pickup points about 21mm (IIRC, have to check from my archives) up (=lowers chassis 21mm down). On GT3 solid bushings are already used, so drop is less.
https://cimg4.ibsrv.net/gimg/rennlis...8a1de6ca93.jpg |
According to the homologation document the RSR's rear subframe mounting points are only machined 10mm down at the face. The fixing holes are moved up: Upper arms 9mm up, LCA 8mm up, Toe link 10mm up.
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Very interesting stuff - curious as to what the parts cost to make the 996 GT3 suspension into a 996 GT3 RS suspension.
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Originally Posted by AudiOn19s
(Post 14748246)
Great info. The bigger question though. at what ride heights do these really begin to become an advantage vs toe arms with bump steer correction. I do realize one is a band-aid and one is a proper solution but still curious on your take. With that said, I would caution against blindly using Cup/RSR components on our cars. While it may sound cool, you may actually be going backwards. The 996RSR runs a ride height of 80/100 using 27.8” tall rear tires. As such, the upright pick up points are another 12mm lower and the subframes are mover closer to the body to account for this. Keep in mind, the 996GT3 uses 25.2" tall rear tires and a higher ride height (I am running 7.2Cup tires which have 27" rears). I think running the RSR subframes and rear side members would work in conjunction with the stock 996GT3 uprights as it would raise you roll centers by a moderate amount. I would not recommend using the RSR subframes in combination with the RS wheel carriers components, especially if you are running the RSR LCAs which allow you to raise the roll centers further on the outboard side. Might sound cool at the water cooler but that's about it. Just my $0.02. There are a lot of variables that go into optimizing each set up. The most important thing is working with someone that is intimately familiar with setting up these cars. It's oftentimes hard to make things better, and easy to make them worse. |
Fantastic, thank you for sharing!
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Originally Posted by powdrhound
(Post 14749306)
The most important thing is working with someone that is intimately familiar with setting up these cars. It's oftentimes hard to make things better, and easy to make them worse. |
Very cool parts. Just so I understand the big picture: you're upgrading these parts to maintain correct suspension geomtery (specifically roll centers) to better accommodate larger wheels sizes and/or get a lower CofG (aka faster car)?
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Originally Posted by mistermct
(Post 14752821)
Very cool parts. Just so I understand the big picture: you're upgrading these parts to maintain correct suspension geomtery (specifically roll centers) to better accommodate larger wheels sizes and/or get a lower CofG (aka faster car)?
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Originally Posted by powdrhound
(Post 14753712)
It's not really an issue with larger wheel sizes. I'm running 18x10x13 currently with the stock uprights. The RS parts will actually make a little harder to fit the same sizes but it can be done. Yes, the geometry is greatly improved with the RS parts and they are much stronger. On top of that, the current uprights are no longer available from Porsche with none worldwide and no ETA on if and when they will be available. Neither are the RS front uprights (the 350 versions) actually. None worldwide. Luckily a couple of pair of the the 380 versions were available in Europe so I grabbed the whole set. Spares are becoming very hard to source for these cars and it's only getting worse. I'm not sure what the hell Porsche is thinking when it comes to spares for these older cars.
I just realized my last post may not be clear but I was thinking OD wheel diameter per your 26 in comment. big wheels raise it up so you'd lower it back with coils and correct geo with RS parts. I'd be pissed if I had to replace an upright and I couldn't source one.. I guess be careful is the motto! |
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