Contemplating FRS for track car

[GrandSport]

Originally Posted by cjd

If the shocks (spring rates/damping/etc) can't handle slicks, you're in for a rough time either way.



Maybe I'm in the minority, but I'd take a well tuned suspension setup over stickier tires any day.

Yeah, that's really more your springs, not the shocks. Base model and Z51 corvettes have this problem. Anything even resembling a track day tire is too much for them whereas the GS, Z06 and Z07 springs are just fine on substantially larger slicks. My friend's Z51 practically endos on the brakes on 265 RE71 whereas my car would be 100% fine on 315 slicks (and I have much stronger brakes too). We both have the same mag-ride shocks. He dialed his up to max stiffness and it didn't do much.

[Joesurf79]

Originally Posted by cjd

If the shocks (spring rates/damping/etc) can't handle slicks, you're in for a rough time either way.

Maybe I'm in the minority, but I'd take a well tuned suspension setup over stickier tires any day.

I agree - It's hard to maximize any amount of grip being provided by the tires (and balance it's at-the-limit-allocation for steering/braking/acceleration) through each phase of a corner, on a poor suspension.


You aren't maximizing any tire's traction capability without a quality suspension setup. Slicks may cut 2 seconds off the bat with bad suspension and a driver that wasn't maximizing the previous tire's potential anyway... but that doesn't mean either tire was anywhere near being used to it's full traction potential.


Not making any judgements on anyone's driving skills at all here. Just saying that good suspension DOES make a big difference - especially with stickier "slicks" or any tire that has a "peakier maximum friction zone". With those it's even MORE important that you get maximum chassis communication at the limit.

[Joesurf79]

Originally Posted by GrandSport

Yeah, that's really more your springs, not the shocks. Base model and Z51 corvettes have this problem. Anything even resembling a track day tire is too much for them whereas the GS, Z06 and Z07 springs are just fine on substantially larger slicks. My friend's Z51 practically endos on the brakes on 265 RE71 whereas my car would be 100% fine on 315 slicks (and I have much stronger brakes too). We both have the same mag-ride shocks. He dialed his up to max stiffness and it didn't do much.

It's allllll a system, it's not just spring rate.


What's the spring rate delta between the stock/Z51 and the GS? *EDIT* think I found it - for the C7 stingray with the Z51 package and the C7 GS, it looks like the front spring rate was 2% stiffer and the rear was 8-ish percent. Not exactly a huge rate difference - i'd be surprised if I could feel that difference all things being equal. Not saying the suspension action and car performance you describe wasn't occurring - his car may have been nose diving like a mutha - but it wasn't due to a massive spring rate disparity

[tony_r]

Originally Posted by GrandSport

Yeah, that's really more your springs, not the shocks. Base model and Z51 corvettes have this problem. Anything even resembling a track day tire is too much for them whereas the GS, Z06 and Z07 springs are just fine on substantially larger slicks. My friend's Z51 practically endos on the brakes on 265 RE71 whereas my car would be 100% fine on 315 slicks (and I have much stronger brakes too). We both have the same mag-ride shocks. He dialed his up to max stiffness and it didn't do much.

I'm willing to bet that a good set of shocks with proper low-speed control will mostly fix the stock soft springs. Magna-ride stuff is not good enough. Recent C7's in SSR changed significantly with custom dampers.

[Icecreamtruk]

Is nobody going to say anything about that 2s difference between slicks and street tires? Because my experience and everything I see on track (time attacks) points towards a fairly larger difference than that (about double actually).

[cjd]

Originally Posted by Icecreamtruk

Is nobody going to say anything about that 2s difference between slicks and street tires? Because my experience and everything I see on track (time attacks) points towards a fairly larger difference than that (about double actually).

What course length? I think 2s is likely accurate for some tracks, but certainly not all.

[Icecreamtruk]

Originally Posted by cjd

What course length? I think 2s is likely accurate for some tracks, but certainly not all.

Anywhere from 3k to 5k long, the difference is around 3 to 4 secs, depending on how twisty the track is, at least for our cars is, maybe that changes when the weight/power ratio changes drastically. Unless we are talking about little 1k to 2k tracks that are around 1min lap, there it is around 2s per lap, but there arent many tracks like that down there, are there?

[CSG Mike]

Originally Posted by GrandSport

Man, I don't know. The difference from street tires to slicks is like 2.5 seconds. Super Sports to Cup2 was a bit under 2 seconds for me. You ask any racer would they rather run slicks and crappy shocks or the best shocks and street tires, and the answer will be very unanimous.

I'd bet there's a strong correlation for the tire preference with driver skill. A more experienced/skilled/confident driver would take the shock that enables them to exploit their skill, rather than go the "safe" known of a stickier tire.

[GrandSport]

Originally Posted by Icecreamtruk

Anywhere from 3k to 5k long, the difference is around 3 to 4 secs, depending on how twisty the track is, at least for our cars is, maybe that changes when the weight/power ratio changes drastically. Unless we are talking about little 1k to 2k tracks that are around 1min lap, there it is around 2s per lap, but there arent many tracks like that down there, are there?

ya, obviously the car, what street tire and what slick you're going to. In my case it was a good street tire (Super Sport). Obviously if you're going from an 80k mile hard economy tire to a michelin soft on a super technical track that is very long, it will be more than 2s. Kind of related: Strangely, I have very similar lap times with R888R and MPSS (ZP). MPSS get greasy and lose traction much faster and cost a lot more though. R888R are 40mm wider in front too.

Typical call it 2.4 mile-ish track going from a street tire you'd do a track day on (R888R, NT01, MPSS, etc) to a Slick/semi/cheater slick you'd do a track day on. I'm not trying to go from one extreme to another extreme.

Originally Posted by CSG Mike

I'd bet there's a strong correlation for the tire preference with driver skill. A more experienced/skilled/confident driver would take the shock that enables them to exploit their skill, rather than go the "safe" known of a stickier tire.

I'm not sure about that. I think virtually every driver would take slicks every single time. I'd be really surprised if one coilover system to another resulted in 2 second difference in lap time, assuming both are setup right. Suspension as a whole (geometry, spring rates, shocks, etc) can do a lot, but just one shock brand to another? Eh.

[CSG Mike]

Originally Posted by GrandSport

ya, obviously the car, what street tire and what slick you're going to. In my case it was a good street tire (Super Sport). Obviously if you're going from an 80k mile hard economy tire to a michelin soft on a super technical track that is very long, it will be more than 2s. Kind of related: Strangely, I have very similar lap times with R888R and MPSS (ZP). MPSS get greasy and lose traction much faster and cost a lot more though. R888R are 40mm wider in front too.

The R888R should be faster in basically any scenario on track, except in soaked track or more wet. A look at data should show why you're not going faster on the R888R.

[GrandSport]

Originally Posted by CSG Mike

The R888R should be faster in basically any scenario on track, except in soaked track or more wet. A look at data should show why you're not going faster on the R888R.

Unfortunately, I lost my Solo. Well, it's in my house somewhere. Maid cleaned up and it is gone. First world problems.

Could easily be conditions from one day to another, but I expected to be flying on 888R. At least close to my Cup2 times given I had another 30 or 40mm of rubber up front (and it doesn't need more in the rear). My biggest problem with PSS is that they are greasy by the second full lap.

[Racecomp Engineering]

Laptimes with a skilled driver aside...good shocks are just a lot more fun and confidence inspiring IMO. That also tends to translate into more consistent times for a newer driver.

There are plenty of time attack cars on crappy shocks and sticky tires that can put in a good lap. But watch the in-car video and it's a battle with thin margins. Not always fun or consistent lap after lap (without even mentioning shock fade). The cars with good shocks and enough travel and a nice balance make for a happy driver and longer lasting tires and drama-free consistent lap times.

Anyway, really love my MPS4S and the older MPSS on the street but it's less of a track tire and more of a tire you can track if you need to.

- Andrew

[Joesurf79]

Originally Posted by GrandSport

Unfortunately, I lost my Solo. Well, it's in my house somewhere. Maid cleaned up and it is gone. First world problems.

Could easily be conditions from one day to another, but I expected to be flying on 888R. At least close to my Cup2 times given I had another 30 or 40mm of rubber up front (and it doesn't need more in the rear). My biggest problem with PSS is that they are greasy by the second full lap.

If your tires are full on greasy on the 2nd full lap, are you sure you aren't just flat over-driving the snot outta the car? Running too much cold pressure ? What hot pressures are you getting right after you pit out? I run with a few people in grand sports on NT01s and they are super sensitive to a few pounds of cold pressure either way...

That could explain the lack of gain from the R888R - any tire can be over driven and once it's out of its operating temp range, it's a losing battle until you back off and cool the tire back to its happy place

[GrandSport]

Originally Posted by Joesurf79

If your tires are full on greasy on the 2nd full lap, are you sure you aren't just flat over-driving the snot outta the car? Running too much cold pressure ? What hot pressures are you getting right after you pit out? I run with a few people in grand sports on NT01s and they are super sensitive to a few pounds of cold pressure either way...

That could explain the lack of gain from the R888R - any tire can be over driven and once it's out of its operating temp range, it's a losing battle until you back off and cool the tire back to its happy place

Grand sport is heavy with power and good downforce (for what it is). It's pretty easy to get them greasy within a few laps. Maybe it's the third full lap rather than second (I haven't run them since I went though them so fast).

Haven't run NT01 on the GS yet, but R888R are VERY pressure sensitive as well, as you might expect. I can't remember the numbers right now, but I want to say they were good at 33 and worthless at 36 or so. Might be off on those numbers- this was 4 months ago.

edit: and yeah, obviously I was over-driving them