RCE SS-2 for '23, spring rates ?

[lutfy]

Originally Posted by ZDan

Yeah, expect all of those would have a more profound effect on handling and handling balance than the difference between 7kg all around vs. 7kg front with 9kg rear springs.

Surprising, I would not expect a huge difference really. FWIW when I went from 11/11 spring rates on the FD to 11/13 (Ohlins) I noted barely any difference in handling balance.



Then again 400/400 spring rate biases stiffness to the front.

Honestly I don't think it's going to make any profound difference in handling balance. I'm just trying to mitigate understeer, I still expect to get some. I will be *very* surprised if 7F/9R results in an oversteery car but we shall see.

Will go over this with RCE, but plan to lower the car something like 32F/25R. RCE SS-2 include rear top mounts which I *think* increase bump travel so less worried about bottoming the rears too soon which could result in unexpected oversteer.

Ex COMSCC member, say hi to Marc Epstein from me.

Having tried multiple spring rates, rake, alignment etc here are my .02 cents.

I would not go below 400lbs in the front. Under braking, there is a fair amount of dive. If you could run 450lbs front and rears, that would be somewhat ideal for street/track.

I went with 550/550 with full aero and the car pushed a fair bit on high speed sweepers. Went 650 rear and it was too much. 600 worked out fine.

The 50lbs delta was due to a large wing at the back (and front splitter). Square setup worked very well for me without aero.

The gentleman who posted .25 high rear rake is correct. Mine is almost even after corner balance but that was the starting point. Anything more, the car would skate under braking (my observation) and I couldnt get the desired rear camber.

For years I ran -3 f and -2.2 r negative camber. It was not enough and I would tear up the Hoosier R7 but was limited to class rules.

Now that I am running -3.8 f and -2.8 r, during testing day, I was able to drive with the steering and throttle and its a different car all together.

Testing with Goodyear SC3R they liked -3.5/-2.5 and anything less than that, I was eating up the outside (f/r). The only way to get the f camber is through camber plate maxed out and camber bolts at the bottom (in your case).

Also smidge toe in at the back helps a lot at high speed sweepers. I tried 0 toe and the car was a touch sketchy on fast downhill corners. I suspect there is some toe change during rear wheel travel.

Good luck!

[strat61caster]

Dynamic toe is pretty linear and negligible in the typical working range of the suspension, you have to completely unload the rear to get measurable toe change. That’s not to say you weren’t feeling something, there’s a lot of variables but I agree there’s no real reason to run zero rear toe unless you’re band aiding a pushy setup.

[ZDan]

Originally Posted by lutfy

Ex COMSCC member, say hi to Marc Epstein from me.

OK, will do! Will he know you as "lufty"?

I would not go below 400lbs in the front. Under braking, there is a fair amount of dive. If you could run 450lbs front and rears, that would be somewhat ideal for street/track.

Yeah, I did pretty alright for years on more street-oriented springs/dampers (4.4F/5.3R with Bilstein B8s), slaying the competition in my class, but now a hotshoe is driving one of the NCs I usedta kill and took my class last year (I got 'im in mixed conditions at NHMS last month though)! I don't wanna leave anything on the table, so bumping up the suspension to be a bit more track-oriented.

I went with 550/550 with full aero and the car pushed a fair bit on high speed sweepers. Went 650 rear and it was too much. 600 worked out fine.

Huh, I would expect aero changes to be a lot more effective at addressing high-speed balance than modest changes to rear spring rate?

The 50lbs delta was due to a large wing at the back (and front splitter). Square setup worked very well for me without aero.

Could still try 7kg/mm "square" spring rates, but always important to note that that is very UNsquare as far as wheel rates. 90% going to go 7F/9R right off the bat based on experience with the '17.

The gentleman who posted .25 high rear rake is correct. Mine is almost even after corner balance but that was the starting point. Anything more, the car would skate under braking (my observation) and I couldnt get the desired rear camber.

Cool, definitely will be running at least 0.25" rake.

Testing with Goodyear SC3R they liked -3.5/-2.5 and anything less than that, I was eating up the outside (f/r). The only way to get the f camber is through camber plate maxed out and camber bolts at the bottom (in your case).

Plan to run max negative camber via the oval upper holes where strut mounts to upright/hub assembly, and adjust up top to -3.5 front which worked great with the 17, should be even better with stiffer suspenders.

Also smidge toe in at the back helps a lot at high speed sweepers. I tried 0 toe and the car was a touch sketchy on fast downhill corners. I suspect there is some toe change during rear wheel travel.

Was gonna go zero rear toe but will amend that to 0.1 degrees total rear toe-in. And zero up front.

Good luck!

Thanks, I'm really looking forward to Palmer June 3! Holy crap that's coming right up...

[lutfy]

Originally Posted by ZDan

OK, will do! Will he know you as "lufty"?

Yeah, I did pretty alright for years on more street-oriented springs/dampers (4.4F/5.3R with Bilstein B8s), slaying the competition in my class, but now a hotshoe is driving one of the NCs I usedta kill and took my class last year (I got 'im in mixed conditions at NHMS last month though)! I don't wanna leave anything on the table, so bumping up the suspension to be a bit more track-oriented.

Huh, I would expect aero changes to be a lot more effective at addressing high-speed balance than modest changes to rear spring rate?

Could still try 7kg/mm "square" spring rates, but always important to note that that is very UNsquare as far as wheel rates. 90% going to go 7F/9R right off the bat based on experience with the '17.

Cool, definitely will be running at least 0.25" rake.

Plan to run max negative camber via the oval upper holes where strut mounts to upright/hub assembly, and adjust up top to -3.5 front which worked great with the 17, should be even better with stiffer suspenders.

Was gonna go zero rear toe but will amend that to 0.1 degrees total rear toe-in. And zero up front.

Thanks, I'm really looking forward to Palmer June 3! Holy crap that's coming right up...

Yeah he knows me by Lutfy

The rear spring delta was more on slower speeds, the 100lbs delta was too much and I couldnt power out as effectively/agressively. Square setup with the rear wing and I could feel push over 40-50mph hence the 50lb delta I know I have. But this is based on my personal experience.

Cheers,

Lutfy

[ZDan]

Update: Finally got to track the car at NJMP Lightning last Mon/Tue with COMSCC! Overall had a great time! The car was very well balanced, definitely less understeer than previous setup on the '17 Still got some understeer carrying speed from 2 into 3, very easily could tighten the line to make T3 apex with little taps on the brakes. Could either throw it into Turn 9 (extended banked right-hander) and get it to rotate a bit and scrub speed, or brake a bit more and carve around T9, either could crank steering in to make late apex without undue understeer. Nice! Definitely glad I went with the 9kg/mm rear springs, THANKS @NoHaveMSG ! Seems to work quite well with my car. Won T50 class by 1.4s! Sweeet...

Time-trial setup:
3120 lb. (3107 lb. minimum for class) with '17 spare tire + 100 lb. ballast in spare tire, full tank, 53.5%F/46.5%R
RCE SS-2 coilovers, 7kg/mm front 9kg/mm rear springs, 12 clicks-out front, 10 clicks-out rear
330mm hub to fender all around (-35mm front, -30mm rear)
-3.15F/-2.5R camber, 0 front and 0.1* total rear toe-in
245/40-17 RE71RS on 17x9 +42 wheels (borrowed from Doug F., THANKS!)

Ran 1:16.29 time trial despite screwups each lap. FWIW Doug's 245/40-17 RE71RS with +40 lb. more ballast were nearly 1s faster than my 225/45-17 RT660 :O

https://www.comscc.org/events-result...s/#third-event

[Racecomp Engineering]

Originally Posted by ZDan

Update: Finally got to track the car at NJMP Lightning last Mon/Tue with COMSCC! Overall had a great time! The car was very well balanced, definitely less understeer than previous setup on the '17 Still got some understeer carrying speed from 2 into 3, very easily could tighten the line to make T3 apex with little taps on the brakes. Could either throw it into Turn 9 (extended banked right-hander) and get it to rotate a bit and scrub speed, or brake a bit more and carve around T9, either could crank steering in to make late apex without undue understeer. Nice! Definitely glad I went with the 9kg/mm rear springs, THANKS @NoHaveMSG ! Seems to work quite well with my car. Won T50 class by 1.4s! Sweeet...

Time-trial setup:
3120 lb. (3107 lb. minimum for class) with '17 spare tire + 100 lb. ballast in spare tire, full tank, 53.5%F/46.5%R
RCE SS-2 coilovers, 7kg/mm front 9kg/mm rear springs, 12 clicks-out front, 10 clicks-out rear
330mm hub to fender all around (-35mm front, -30mm rear)
-3.15F/-2.5R camber, 0 front and 0.1* total rear toe-in
245/40-17 RE71RS on 17x9 +42 wheels (borrowed from Doug F., THANKS!)

Ran 1:16.29 time trial despite screwups each lap. FWIW Doug's 245/40-17 RE71RS with +40 lb. more ballast were nearly 1s faster than my 225/45-17 RT660 :O

https://www.comscc.org/events-result...s/#third-event

- Andrew