KMR-RSR 001 > development and rebuild.
11-22-2013, 05:40 PM
#92
As I understand it the factory RSR's back in the day were running about 1700lbs which is what someone I know has in his. He describes it as too stiff and will be changing to softer springs. This factory RSR owner drove my car at a recent Road America test day and found the set up to be much better than his car. After my car is finished and testing begins we'll start where we left off with F=1,100 R=1,200 and experiment up to about 1,400lbs but no more.
235 to 286 N/mm fronts w/ 30N/mm helpers(1342 to 1633 lb/in)
270 to 350 N/mm rears w/ 30 N/mm helpers(1542 to 1999 lb/in)
GT2 Evo ran
270 to 320 N/mm fronts w/ 30N/mm helpers(1542 to 1827 lb/in)
296 to 350 N/mm rears w/ 30 N/mm helpers(1542 to 1901 lb/in)
11-23-2013, 05:44 PM
#94
Race Car
You have to remember these rates were what were used on the much smoother tracks in Europe.
I remember when the RSR's and GT2's came into Australia in the '90's, the first thing they changed were the spring rates because the tracks in Oz, like the US, were not as smooth and the cars with European spring rates would be bouncing all over the place, no grip at all.
I remember when the RSR's and GT2's came into Australia in the '90's, the first thing they changed were the spring rates because the tracks in Oz, like the US, were not as smooth and the cars with European spring rates would be bouncing all over the place, no grip at all.
11-24-2013, 12:33 AM
#95
Rennlist Member
Matt, the seat/slider mount fabrication was done by Kelly Moss after I bought the car. I wanted something ergonomically better and safer. Yes, the mounts are quite a lot lower than standard. For me as a driver the ergonomics are now much better with the location of the seat, adjustable AP pedals, height adjustable steering rack and shifter. I wanted to improve in car safety while we were doing all the other work so now I'm looking at the new Recaro P1300 GT seat and slider. With an easy mod to the seat/slider mount in the car this can be installed. Everything I have read and heard about this new seat and slider says this set up is a huge safety improvement and very comfortable.
11-24-2013, 09:28 AM
#96
Race Director
11-24-2013, 10:26 AM
#97
Rennlist Member
Boxer engine -> the longer the stroke the wider the engine...
edit: well, of course you could then use shorter rods... I guess. Must be something else...
11-24-2013, 10:42 AM
#98
Rennlist Member
A ton of great info here, lots of fun to read. 
11-25-2013, 02:46 PM
#100
Racer
Thread Starter
Join Date: Jun 2013
Location: Hong Kong
Posts: 294
Likes: 0
Received 0 Likes
on
0 Posts
Thanks for the spring rate info Bill. The factory RSR's I have seen use a tensioning device mounted in the spring which changes the spring rate. Do you know if this achieves the spring rate range in your spreadsheet or were there different springs available depending on customer preference?
porsche993gtrsr there are too many variables to be able to answer your question > tires, ARB, shocks, driving style/experience, track, etc. The only way to determine what spring rates work best is to test. Personally on an RSR type car running on Michelin or similar slicks I would suggest a range of 1200-1400lbs in the rear with the front 100lbs softer to establish a baseline. Then try softer and stiffer set ups to find what works best. Maybe on a GT2 you might want to go a little bit higher because of more weight at the rear of the car?
Quadcammer the 4.0l is being achieved with bore and stroke. I'm out of my depth trying to explain the "wide" engine... But as I understand it these "wide" engines improve angles inside the high hp/displacement motor, improving reliability and service life. A lot of parts need to be custom to do this. As it turns out Gamroth (Rothsport Racing) has decided not to do this and will now stick with a conventional configuration. The new engine will still achieve the target HP and service life intervals.
Falcondrivr sorry, I wish we could be at Sebring in January. But it looks like the car won't be finished by then. And the plan is to test for 2-3 days (likely on the west coast) before racing. I'll be at Road America for the labor day weekend for sure and maybe COTA. Other events TBD.
porsche993gtrsr there are too many variables to be able to answer your question > tires, ARB, shocks, driving style/experience, track, etc. The only way to determine what spring rates work best is to test. Personally on an RSR type car running on Michelin or similar slicks I would suggest a range of 1200-1400lbs in the rear with the front 100lbs softer to establish a baseline. Then try softer and stiffer set ups to find what works best. Maybe on a GT2 you might want to go a little bit higher because of more weight at the rear of the car?
Quadcammer the 4.0l is being achieved with bore and stroke. I'm out of my depth trying to explain the "wide" engine... But as I understand it these "wide" engines improve angles inside the high hp/displacement motor, improving reliability and service life. A lot of parts need to be custom to do this. As it turns out Gamroth (Rothsport Racing) has decided not to do this and will now stick with a conventional configuration. The new engine will still achieve the target HP and service life intervals.
Falcondrivr sorry, I wish we could be at Sebring in January. But it looks like the car won't be finished by then. And the plan is to test for 2-3 days (likely on the west coast) before racing. I'll be at Road America for the labor day weekend for sure and maybe COTA. Other events TBD.
11-25-2013, 03:02 PM
#101
Racer
Thread Starter
Join Date: Jun 2013
Location: Hong Kong
Posts: 294
Likes: 0
Received 0 Likes
on
0 Posts
Fabrication continues on the tunnel to incorporate the 996 Cup gearbox/shifter cables and front air jack mounts with shrouds to protect the lines are complete. Brace to tie the front suspension and chassis together has been finished.
11-25-2013, 05:25 PM
#102
Thanks for the spring rate info Bill. The factory RSR's I have seen use a tensioning device mounted in the spring which changes the spring rate. Do you know if this achieves the spring rate range in your spreadsheet or were there different springs available depending on customer preference?
.....
.....
11-30-2013, 12:40 PM
#103
Nice work !,
But I have a question, what is the benefit of the brace for the front suspension ?, do you need this because you are missing some original parts and need this as reinforcement ?
I Found this picture:
where you can see that a original gt2 did not have this, just like to know the thoughts behind this piece of engineering
But I have a question, what is the benefit of the brace for the front suspension ?, do you need this because you are missing some original parts and need this as reinforcement ?
I Found this picture:
where you can see that a original gt2 did not have this, just like to know the thoughts behind this piece of engineering
11-30-2013, 04:43 PM
#104
Steering brace
I originally saw this done by Geoffrey Ring on his 964.
https://rennlist.com/forums/964-foru...eferrerid=4234
https://rennlist.com/forums/964-foru...eferrerid=4234
11-30-2013, 09:24 PM
#105
Racer
Thread Starter
Join Date: Jun 2013
Location: Hong Kong
Posts: 294
Likes: 0
Received 0 Likes
on
0 Posts
porsche993gtrsr I was told by Kelly Moss this was done to improve the front end (suspension and steering). Apparently some privateer teams made this modification to the factory RSR's and GT2's. It seems Geoffrey had the same idea with his 964. I'll ask Kelly Moss for more info and let you know.
Hood and ducting have now been finished. Work has begun mocking up the fuel cell which will be made by ATL in the UK.
Hood and ducting have now been finished. Work has begun mocking up the fuel cell which will be made by ATL in the UK.