996GT3RS vs 996GT3 suspension comparison
#31
Rennlist Member
Thanks powdrhound--all these years I've assumed the 6RS to be pretty much the same car as the 6.2 GT3 save for the carbon fiber bits, LWFW and cage... and you've set it right!!
#32
RL Community Team
Rennlist Member
Rennlist Member
CRex,
The 996 GT3 Rs was the homologation platform for the RSR. Lots of things changed including heads, a few other engine / tranny parts - I had compiled a list some time ago: https://rennlist.com/forums/996-gt2-...rs-thread.html
Ray
The 996 GT3 Rs was the homologation platform for the RSR. Lots of things changed including heads, a few other engine / tranny parts - I had compiled a list some time ago: https://rennlist.com/forums/996-gt2-...rs-thread.html
Ray
#33
Rennlist Member
Great stuff, thanks!! Cool to know these cars run bits that aren't even in the 6 Cup!
My front suspension's developed a leak and soon I'll be testing how easy (or difficult) it is to source parts for these cars...
My front suspension's developed a leak and soon I'll be testing how easy (or difficult) it is to source parts for these cars...
#35
Rennlist Member
Thread Starter
#36
Former Vendor
-sits 6mm higher in relation to chassis. (But 6mm less than 996 GT3RS LeMans racer)
-upper control arms' attachment points are 5mm (front) and 10mm (rear) higher and some 5mm outwards
-track rod's attachment point is 17mm higher and the bolt is in different angle (front of the bolt is pointing upwards) and there's just one 12 mm hole, no eccentric adjustment.
-LCA's attachment point is 7mm outwards and 10 mm higher than 996's eccentric in it's most inboard position. Again just one 12mm hole, no eccentric adjustment. OTH if 996's LCA is completely pulled out, it'll be 6mm more out, ie 13mm out (actually slightly less, because of the angle of that eccentric hole) and some 5mm more downwards.
I'll post a pic or two later.
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lordpantsington (01-09-2024)
#37
Racer
I did some highly unscientific measurements this afternoon, after recieving my new parts. Compared to 996's (GT3) rear subframe this 997 Cup/R/RSR one (These numbers are very inaccurate, just for giggles/general info!)
-sits 6mm higher in relation to chassis. (But 6mm less than 996 GT3RS LeMans racer)
-upper control arms' attachment points are 5mm (front) and 10mm (rear) higher and some 5mm outwards
-track rod's attachment point is 17mm higher and the bolt is in different angle (front of the bolt is pointing upwards) and there's just one 12 mm hole, no eccentric adjustment.
-LCA's attachment point is 7mm outwards and 10 mm higher than 996's eccentric in it's most inboard position. Again just one 12mm hole, no eccentric adjustment. OTH if 996's LCA is completely pulled out, it'll be 6mm more out, ie 13mm out (actually slightly less, because of the angle of that eccentric hole) and some 5mm more downwards.
I'll post a pic or two later.
-sits 6mm higher in relation to chassis. (But 6mm less than 996 GT3RS LeMans racer)
-upper control arms' attachment points are 5mm (front) and 10mm (rear) higher and some 5mm outwards
-track rod's attachment point is 17mm higher and the bolt is in different angle (front of the bolt is pointing upwards) and there's just one 12 mm hole, no eccentric adjustment.
-LCA's attachment point is 7mm outwards and 10 mm higher than 996's eccentric in it's most inboard position. Again just one 12mm hole, no eccentric adjustment. OTH if 996's LCA is completely pulled out, it'll be 6mm more out, ie 13mm out (actually slightly less, because of the angle of that eccentric hole) and some 5mm more downwards.
I'll post a pic or two later.
#38
Former Vendor
Actually I did plan to do this with uprights next winter, but was forged to change subframes now because the other one broke. So uprights next and then it's done. I promise....not... Still with 996 GT3 uprights and 2-piece LCAs, adjustable upper control arms and track rods.
About that breakage. If someone plans to use LCA inner solid/uniball bushings, be sure to remove eccentrics and install locking plates right away! I did run one summer with eccentrics and they did not hold. So they moved around and apparently ate both brackets and spacer bushings, which become slightly hemispheric. After installing locking plates the large/noticeable movement went away, but they did continue to grind themselves all the time, for three seasons. And I did not remove and replace them at any point, which was a mistake. So now with big rubber the load to LCAs increased, RH uniball moved a bit too much, spacer bushings jammed and snapped RH forward bracket while braking on track. Which was not fun, rather scary actually. Slow point fortunately, I stayed between white lines and no other damage was done.
#39
RL Community Team
Rennlist Member
Rennlist Member
Hi Pete,
My measurement data for the 996 RSR parts are here: https://rennlist.com/forums/996-gt2-...n-der-gt3.html
Ray
My measurement data for the 996 RSR parts are here: https://rennlist.com/forums/996-gt2-...n-der-gt3.html
Ray
#40
Former Vendor
Hi Pete,
My measurement data for the 996 RSR parts are here: https://rennlist.com/forums/996-gt2-...n-der-gt3.html
Ray
My measurement data for the 996 RSR parts are here: https://rennlist.com/forums/996-gt2-...n-der-gt3.html
Ray
997 GT3 Cup/R/RSR rear subframes. Solid steel bushings permanently installed.
Above 996, below 997. Subtle changes in details.
Above 997, below 996
Above 997, below 996
#41
Rennlist Member
Thread Starter
Hey Pete,
I have a pair of used 996GT3/Cup rear wheel carriers (side members) if you need a set. Again, I would be very cautious of blindly using Cup/RSR carriers or uprights as they are based on a car running 27.8” rear wheels at super low ride heights.
I have a pair of used 996GT3/Cup rear wheel carriers (side members) if you need a set. Again, I would be very cautious of blindly using Cup/RSR carriers or uprights as they are based on a car running 27.8” rear wheels at super low ride heights.
Last edited by powdrhound; 05-15-2020 at 12:09 AM.
#42
RL Community Team
Rennlist Member
Rennlist Member
Hi John,
Other than adding compliance, why does the size of tire matter? The ride height is keyed off a mark on the chassis?
Thanks
Ray
Other than adding compliance, why does the size of tire matter? The ride height is keyed off a mark on the chassis?
Thanks
Ray
#43
Tire OD matter as the taller the tire the 'lower' the suspension needs to be to obtain the same chassis height
#45
Rennlist Member
Thread Starter
One thing I would do as a starting point if trying to optimize a suspension is to take a look at an RSR or a Cup car and carefully measure the degrees of inclination/declination of both the front and rear LCAs, thrust arms and upper control arms at static ride height with weight on wheels. Best way to do this is on an elevated alignment rack. If one is not looking to do a highly sprung race set up, then looking at these items on the late generation 997GT3s is also beneficial if you are looking to get a starting point of a dual purpose track/street car that runs similar ride heights to our cars. I would then shoot for those numbers as Porsche spent a lot of R&D getting the suspensions dialed in on the late gen GT cars like the 3.8RS or the 4.0.
Last edited by powdrhound; 05-17-2018 at 01:49 AM.