SCCA CAM-C Thread

[NightmareMoon]

I liked the Dual rates at ~350 in the stiff range, but now even a 500 lb spring feels soft in the front lol. They sure looked mostly loaded into the high rate when sitting, but whatever.

Going from 500 to 650 (at the same ride height) and my splitter bonks pavement a lot less because there's noticeably less dive on braking.

Sponsored

 

[WItoTX]

2nd the 500 probably too soft. I have 400s, and now have the decision of going to R dampers or just going coil overs.

Although that weight transfer on 400s is awesome.

 

[CobaltFilly]

2nd the 500 probably too soft. I have 400s, and now have the decision of going to R dampers or just going coil overs.

Although that weight transfer on 400s is awesome.

Trying to understand your guys' talk about spring rates is hurting my smooth brain.
I must learn more. If I am running Steeda non-adj shocks, and sport progressive lowering springs…and these springs are 145-225 front, 525-820lbs rear…then what should I expect to be different from your springs rates, and do I need something different due to being 200lbs curb weight lighter in the front then your gts?

(So far I am finding brakes and more seat time to be my limiting factors, this is purely a question to learn.)

 

[mavisky]

I liked the Dual rates at ~350 in the stiff range, but now even a 500 lb spring feels soft in the front lol. They sure looked mostly loaded into the high rate when sitting, but whatever.

Going from 500 to 650 (at the same ride height) and my splitter bonks pavement a lot less because there's noticeably less dive on braking.

Interesting. I'd been looking at the 500lb 2.5x7" Hypercoil springs for AJ's setup since he only offers a 400lb max spring offering.

He offers a 1200lb rear that I thought would be similar to the high end of what I've got at the rear from the Steeda dual rates.

According to Steeda these are the rates for the dual rates so this would significantly stiffen the front while keeping the rear about the same which should allow me to dial out a lot of front bar and dial up some rear bar.

Dual rate springs
220 - 350 - Fronts
800 - 1200 - Rears

Steeda competition bars
Front 1.5" bar vs Mustang GT bar
42% stiffer - 97% stiffer

Rear bar vs Mustang GT bar
23.6% softer - 13.1% stiffer

This month I ran these above rates and the Steeda competition bars at two events. First event was full soft on the bars front and rear (front bar can only be run at position 3 of 4 due to ride height sensors). Car was neutral, but felt like I was standing up in a canoe with all that body roll.

Last event I moved both bars to full stiff and the car had pronounced understeer almost everywhere. I couldn't really get the car to oversteer anywhere. I've dialed the front bar down to the middle notch for the next event while keeping the rear stiff to see how that works out.

You can see how bad the car was understeering in this event with the front bar so stiff, but the new shock programming feels much better on the DSC than the old Steeda DSC setup.

 

[WItoTX]

Trying to understand your guys' talk about spring rates is hurting my smooth brain.
I must learn more. If I am running Steeda non-adj shocks, and sport progressive lowering springs…and these springs are 145-225 front, 525-820lbs rear…then what should I expect to be different from your springs rates, and do I need something different due to being 200lbs curb weight lighter in the front then your gts?

(So far I am finding brakes and more seat time to be my limiting factors, this is purely a question to learn.)

The truth is, you gotta build the car around yourself. Once you start repeating the same position over and over (like top 10%), then figure out what the car is doing that you can't go faster. And even then, it becomes a question of driver or car set up that is the limiting factor.

Different springs change body roll, allow the car to be more responsive around corner, as they are pushing tires down. The goal is to keep the tires in max contact with the pavement all the time. Heavier springs allow this, with the trade off that often when you go to a heavier spring, it's rebounds less fast. This rebound rate can also be adjusted with shock tuning.

In other words, go as soft as possible, as stiff as necessary. And btw, someone will come along and tell you I am wrong. And it's entirely possible, but also a difference in how I want my car to feel to me, vs someone else. Just my opinion, but a stock M1 HP could win CAMC on any given day. So there's that.

Teelew runs a very similar car to you I believe, and is a wealth of information.

 

[CobaltFilly]

@TeeLew I will be heading down your way next week for the whole week, any events going on in SoCal?

 

[TeeLew]

@TeeLew I will be heading down your way next week for the whole week, any events going on in SoCal?

I don't really know. I have a work thing in New York for the next week. July gets busy for me as well. I generally don't get a chance to play much in the summer.

 

[TeeLew]

Interesting. I'd been looking at the 500lb 2.5x7" Hypercoil springs for AJ's setup since he only offers a 400lb max spring offering.

He offers a 1200lb rear that I thought would be similar to the high end of what I've got at the rear from the Steeda dual rates.

According to Steeda these are the rates for the dual rates so this would significantly stiffen the front while keeping the rear about the same which should allow me to dial out a lot of front bar and dial up some rear bar.

https://www.resuspension.com/catalog/product/view/id/1237/s/spring-2-5-x-7/

I don't know where this will put your ride height. AJ uses a shim adjustment and with rates over 400, you might just be raising the front of the car. Even if you just went with the 400, that increase in rate, and the fact that it's just linear, would be a big difference.

I don't think stiffening the rear of the car is the most effective way to reduce understeer, but opinions vary, so salt to taste.

 

[webspoke]

Interesting. I'd been looking at the 500lb 2.5x7" Hypercoil springs for AJ's setup since he only offers a 400lb max spring offering.

He offers a 1200lb rear that I thought would be similar to the high end of what I've got at the rear from the Steeda dual rates.

According to Steeda these are the rates for the dual rates so this would significantly stiffen the front while keeping the rear about the same which should allow me to dial out a lot of front bar and dial up some rear bar.

Dual rate springs
220 - 350 - Fronts
800 - 1200 - Rears

Steeda competition bars
Front 1.5" bar vs Mustang GT bar
42% stiffer - 97% stiffer

Rear bar vs Mustang GT bar
23.6% softer - 13.1% stiffer

This month I ran these above rates and the Steeda competition bars at two events. First event was full soft on the bars front and rear (front bar can only be run at position 3 of 4 due to ride height sensors). Car was neutral, but felt like I was standing up in a canoe with all that body roll.

Last event I moved both bars to full stiff and the car had pronounced understeer almost everywhere. I couldn't really get the car to oversteer anywhere. I've dialed the front bar down to the middle notch for the next event while keeping the rear stiff to see how that works out.

You can see how bad the car was understeering in this event with the front bar so stiff, but the new shock programming feels much better on the DSC than the old Steeda DSC setup.

You will likely want to go back to the 24mm steeda rear bar. I use the 1.5" front in the stiffer settings and it overwhelms that skinny 19mm rear comp bar. While I only track the car, I needed that rear stiffness to make the car neutral mid corner in the 40-50mph range. I use the same steeda springs and square nankang 325's.

 

[NightmareMoon]

Last event I moved both bars to full stiff and the car had pronounced understeer almost everywhere. I couldn't really get the car to oversteer anywhere. I've dialed the front bar down to the middle notch for the next event while keeping the rear stiff to see how that works out.

You can see how bad the car was understeering in this event with the front bar so stiff, but the new shock programming feels much better on the DSC than the old Steeda DSC setup.

I've never liked the 35mm bars on full stiff, let alone the bigger steeda competition bar. I'm not sure what spring rate or race car would need that bar on full stiff. Maybe an M1 Abrams tank.

 

[mavisky]

https://www.resuspension.com/catalog/product/view/id/1237/s/spring-2-5-x-7/

I don't know where this will put your ride height. AJ uses a shim adjustment and with rates over 400, you might just be raising the front of the car. Even if you just went with the 400, that increase in rate, and the fact that it's just linear, would be a big difference.

I don't think stiffening the rear of the car is the most effective way to reduce understeer, but opinions vary, so salt to taste.

I have height to work with to an extent as the splitter is only about 3" off the ground with the 295/35 Yokohamas it has on it now but could always go to a 6" Front spring instead of 7" and use his shim setup to get some height back if it becomes a problem.

You will likely want to go back to the 24mm steeda rear bar. I use the 1.5" front in the stiffer settings and it overwhelms that skinny 19mm rear comp bar. While I only track the car, I needed that rear stiffness to make the car neutral mid corner in the 40-50mph range. I use the same steeda springs and square nankang 325's.

I actually misspoke and only have the 1-3/8 front bar. Got confused by rhe part number being 555-1015 and thinking that meant 1.5", but it may be appropriate to step up to their larger setup, especially given that my car is full weight.

 

[TeeLew]

I needed that rear stiffness to make the car neutral mid corner in the 40-50mph range.

Which it does. The question is whether this is the best way to make it happen.

I tune to mid-corner balance last. Corner entry is where all the heavy lifting is done. If you can get a good initial point and are able to start the rotation of the car early and aggressively without going loose, then you're doing the lion's share of the work with some level of brake load in the car, which is what the front tires want. In long duration corners, the understeer is just physics. The weight distribution is what it is.

Generally speaking, making a car have a neutral balance in a steady-state corner will make any corner where you have to load the front loose. Further, GT cars make their lap time by getting turned and getting to throttle, so if rear stiffening does anything that might hurt traction, it's gain will be muted. There are some racetracks that you have to go this direction, because it has a lot of long duration corners. Most of the time, the payback you get from reducing understeer is limited, because of the inevitable compromises.

I'm not trying to convince you of anything, but just cautioning that *every* change you make is a compromise. There are no free lunches.

 

[NightmareMoon]

Which it does. The question is whether this is the best way to make it happen.

I tune to mid-corner balance last. Corner entry is where all the heavy lifting is done. If you can get a good initial point and are able to start the rotation of the car early and aggressively without going loose, then you're doing the lion's share of the work with some level of brake load in the car, which is what the front tires want. In long duration corners, the understeer is just physics. The weight distribution is what it is.

Generally speaking, making a car have a neutral balance in a steady-state corner will make any corner where you have to load the front loose. Further, GT cars make their lap time by getting turned and getting to throttle, so if rear stiffening does anything that might hurt traction, it's gain will be muted. There are some racetracks that you have to go this direction, because it has a lot of long duration corners. Most of the time, the payback you get from reducing understeer is limited, because of the inevitable compromises.

I'm not trying to convince you of anything, but just cautioning that *every* change you make is a compromise. There are no free lunches.

Love it. I have used rear shock rebound to tune for some corner rotation on entry and then you can still have compliant rear suspension for putting power down on exit. I fully agree that too much rear bar in an attempt to balance entry or mid corner will hurt your corner exit.

I like some rear bar, just to keep body roll and rapid transitions fast enough, and to overall balance the car well for throttle steer in the longer corners. Salt to taste.

 

[mavisky]

Love it. I have used rear shock rebound to tune for some corner rotation on entry and then you can still have compliant rear suspension for putting power down on exit. I fully agree that too much rear bar in an attempt to balance entry or mid corner will hurt your corner exit.

I like some rear bar, just to keep body roll and rapid transitions fast enough, and to overall balance the car well for throttle steer in the longer corners. Salt to taste.

This has been my preference as far as driving style. A dominant front end with early corner neutrality to oversteer and then a smooth transition to a compliant rear on corner exit. The car on the steeda competition bar setup on full soft exhibited this balance, but with loads of roll. So trying to match that "balance" with more roll control.

 

[TeeLew]

I liked the Dual rates at ~350 in the stiff range, but now even a 500 lb spring feels soft in the front lol. They sure looked mostly loaded into the high rate when sitting, but whatever.

Getting any real info out of Steeda is impossible, but I'm going off of what the guy said that chimes in every once in a while. I could easily be wrong.

Sponsored