S197 help/suggestions

[MX621]

Hello all,

im new here and new to the s197 platform. I recently got a new to me s197 coyote car. It’s been detuned to 309 average whp for nasa st4 class @ 3540 w/ driver. I’m limited to a 282mm overall tire section width which lands me at a 275/35/18 Hoosier R7. My first outing in it was a few weeks ago and my first race was this past weekend at njmp thunder bolt. This weekend went pretty good, getting comfortable and confident it in. But I’m struggling with understeer.

car is on vorshlag MCS double remotes and 550/250lbs. I ditched the 250 for a 300 rear spring and it got better. Added the little 13mm rear sway and got a little better still. Played with shocks, still pushy. Rear is relocation brackets on a pan hard bar. The rear grip of this thing is pretty shocking actually. It’s really hooked up in the rear.

my thought process is either 500lb front. Or try 350 rear. I’m trying to read and learn about the platform. But was looking for suggestions and opinions from those who have walked this path before me.
Thanks!

 

[MX621]

Also: front Ford blue bar on soft and the rear vorshlag setup is spring at oem location. So I Havnt seen how the wheel rate is affected vs a true coil over.

 

[Mad Hatter]

When I passed my car to a friend (very hard to do), I had to warn him about understeer and get him to adjust his driving. For me the car is fastest with great corner exit which can bring lots of understeer. That you can fix with driver mods like late and trailing braking. Often braking right up to the Apex to rotate the rear then on the throttle for a quick exit. Oh, do you have the Torsen dif?? No having that can lead to unwanted understeer as well.

 

[MX621]

Ya I’m learning it wants a diff driving style that I’m adjusting/learning to. Currently it has a wave track diff. Which I can’t say I’ve really read anyone runs in these cars. I also realize a 275 is small for these cars but I’m bound by the class rules.

 

[Mad Hatter]

I raced my boss for years on 200 TW, 275's, do-able and quite fun!! With all that weight up front, you can use it when braking, load up the fronts with grip.

 

[Vettel-ish]

Do you have a watts system in the rear? Or some kind of management system?

 

[Vettel-ish]

I have 650 and 450 with ZERO understeer.

And yes @Mad Hatter is right these cars love trail braking. It helps to rotate the solid rear.

 

[MX621]

Do you have a watts system in the rear? Or some kind of management system?

KB upper/lower controls arms. Relocation brackets and adjustable panhard bar

 

[MX621]

I have 650 and 450 with ZERO understeer.

And yes @Mad Hatter is right these cars love trail braking. It helps to rotate the solid rear.

Yes I’m learning the car likes that.

Of the 3 things that I could try more to get more balance into the car. Would you suggest first?
1: softer front spring
2: stiffer rear spring
3: stiffer rear sway

 

[Vettel-ish]

Yes I’m learning the car likes that.

Of the 3 things that I could try more to get more balance into the car. Would you suggest first?
1: softer front spring
2: stiffer rear spring
3: stiffer rear

I have seen guys run no rear sway bar and see if that helps.

Are you able to do this and run the car or do you need to wait for an event. I only ask as its not an easy fix.

I would try stiff rear next then.

 

[SMGDHG]

Hello all,

im new here and new to the s197 platform. I recently got a new to me s197 coyote car. It’s been detuned to 309 average whp for nasa st4 class @ 3540 w/ driver. I’m limited to a 282mm overall tire section width which lands me at a 275/35/18 Hoosier R7. My first outing in it was a few weeks ago and my first race was this past weekend at njmp thunder bolt. This weekend went pretty good, getting comfortable and confident it in. But I’m struggling with understeer.

car is on vorshlag MCS double remotes and 550/250lbs. I ditched the 250 for a 300 rear spring and it got better. Added the little 13mm rear sway and got a little better still. Played with shocks, still pushy. Rear is relocation brackets on a pan hard bar. The rear grip of this thing is pretty shocking actually. It’s really hooked up in the rear.

my thought process is either 500lb front. Or try 350 rear. I’m trying to read and learn about the platform. But was looking for suggestions and opinions from those who have walked this path before me.
Thanks!

What is your front camber setting? You have aero on the car; is the understeer more or less severe at high speed corners? Toe settings?

I like your thought process of adding stiffness to the rear, you are headed in the right direction and sounds like you know the fundamentals to setting up a car!

As you've found, lots of rear grip in an S-197 usually means understeer up front. Lot's of grip up front means oversteer in the rear. It is time consuming to find that "balance", and what that sacred balance is depends on the driver, not what the internet says. Worse still, depending on the hardware you have under the car and your aero package, you may never actually achieve that "perfect" balance simply because you don't have enough adjustability. You can get close, say, 90%, but that last 10% to achieve perfection can be really hard to find. It took a long time to tune my car to the way I like it (slightly biased towards oversteer), as my personal handling preferences are unique compared to what others on TMO have recommended.

Since you have lower HP, you are at an advantage from a suspension perspective; you can tune in a more responsive front end because you're ~100whp down from a typical coyote car. This can be beneficial for achieving a neutral handling S-197 that doesn't oversteer. I have a much more responsive front end compared to other S-197's I run with yet I can be very aggressive with the throttle and not induce oversteer because I'm only 300whp.

Lots of people like to run S-197's with no rear bar and soft springs in the rear; this was a horrible setup for me. Feel free to DM if you want details of my setup, but at the end of the day all of our cars are different and our handling preferences are unique, so it's difficult to have a "one size fits all" perspective to race car setup

 

[blacksheep-1]

The general rule of thumb is a 18mm or no bar in the rear, the Ford blue bar up front, your spring rates are getting pretty close. The Phoenix Boss 302 is the gold standard for these cars and they were stupid simple. ( well except for the $10K Penskes, but there are alternatives) no relocation brackets and a stock upper link with Ford Performance non adjustable lower trailing arms. At least 3 degrees of camber and all the caster you can get. I've have a fair amount of experience on these cars with the 275s, and yes they are under tired. It does take a bit of learning to drive one quick. It looks to me that whoever sold you the car did you a solid on the suspension. BTW, what tire pressures are you running?

 

[blacksheep-1]

I just have to...take a look at the attitude of these cars.

 

[MX621]

The general rule of thumb is a 18mm or no bar in the rear, the Ford blue bar up front, your spring rates are getting pretty close. The Phoenix Boss 302 is the gold standard for these cars and they were stupid simple. ( well except for the $10K Penskes, but there are alternatives) no relocation brackets and a stock upper link with Ford Performance non adjustable lower trailing arms. At least 3 degrees of camber and all the caster you can get. I've have a fair amount of experience on these cars with the 275s, and yes they are under tired. It does take a bit of learning to drive one quick. It looks to me that whoever sold you the car did you a solid on the suspension. BTW, what tire pressures are you running?

Yea the car was pretty well set up by previous owner which helped the decision with buying it.
Camber is maxed on vorshlag plates. Caster is in the front holes ( oem location I believe ) should I move the caster back to the rear/max position? Jacking doesn’t come into play maxing the castor? The car is already decently quick. Qualified with in .1 from pole on my second weekend in the car. Race pace is about .5 off the leaders. Deff learning the way it wants to be driven. It just has to much of a push imo and would like to get closer to neutral.

 

[blacksheep-1]

Yea the car was pretty well set up by previous owner which helped the decision with buying it.
Camber is maxed on vorshlag plates. Caster is in the front holes ( oem location I believe ) should I move the caster back to the rear/max position? Jacking doesn’t come into play maxing the castor? The car is already decently quick. Qualified with in .1 from pole on my second weekend in the car. Race pace is about .5 off the leaders. Deff learning the way it wants to be driven. It just has to much of a push imo and would like to get closer to neutral.

You're looking for a phenomenon called " camber gain" when you roll it into a corner, maxing out the caster will help that in strut cars.

 

[stevbd]

Good responses here. If allowed by your rules and not already done, the only ways I can think of to increase front grip without compromising rear grip would be to either drill out the front shock towers to increase front camber even more (commonly done on these cars, can get up to ~4 degrees), or run spacers in the front to increase front track width. Beyond that, I agree with @SMGDHG that you should be increasing stiffness in the rear. He is fast and his car setup is probably pretty close to yours given your detuned Coyote, so he is a good reference point to start with. But like he said, a lot of this is personal taste.

Your combination of detuned motor, significantly lower rear spring rates versus front, huge rear wing (I doubt your front splitter is equalizing the downforce of that wing), divorced inboard oem rear spring location (lower effective rear wheel rate), tiny 13 mm rear bar, and maybe the KB relocation kit (some KB kits really drop the rear roll center), it's not surprising that your car is pushy. As a reference point, check out the spring rates thread here on TMO and you will see that all the OEM setups actually have proportionately more spring rate in the rear than the front, oftentimes by a lot and with huge rear roll bars. For Cortex coilovers (outboard rear coilovers with a higher effective wheel rate), it's pretty typical to have a 2-1 ratio of front to rear spring rate, obviously less rate without aero and more with aero.

As explained above, the basic secret sauce for going fast on track with these cars is to soften the rear dramatically, get all the front camber you can, get weight and grip on the nose on corner entry by trail braking to the apex, and drive off the corner on the outside rear tire using a good Torsen or similar rear diff. That definitely works but it takes a different driving style and it sounds like your car may be taking a good setup just a little too far. Your comment that the rear is "shockingly" well hooked up reinforces this impression to me. Personally I would cut the front shock towers, make sure front camber is truly maxed, add some front spacers, and then increase rear spring rates until the car feels balanced to your liking coming off the corner. With your detuned motor I don't think you need quite as much rear grip as you've got.

Good luck and welcome, it looks like you have a really nice car and you are driving it very well already.

 

[MX621]

Thanks for the reply. Shock towers are cut, camber maxed on vorshlag plates. 25mm spacers up front already. The wavetrac diff has me suspect if it’s worth upgrading. As black sheep suggested I plan to experiment with maxing the caster as well. I agree the g stream wing is Deff overpowering the poor excuse
Of a front splitter. I plan to maximize the splitter to the rule book soon.

I really appreciate the reply’s From you guys. Just the kinda insight I came looking for.

 

[stevbd]

@MX621 you refer to KB rear components, do you have the Kenny Brown rear grip kit?

REAR Handling Grip Kit 2005-2014 Mustang

High rear roll center has long been a primary issue with the Mustang's handling and traction characteristics. The Roll Center Relocation Kit is designed to dramatically improve the handling, grip, and control of your Mustang without compromising the ride.

kennybrown.com

 

[MX621]

Yes that’s in the car currently, minus the Pan hard bar it’s back ordered

 

[stevbd]

Yes that’s in the car currently, minus the Pan hard bar it’s back ordered

If you've installed the PHB relocation brackets that are part of that kit then you've significantly lowered the rear roll center, further adding to your understeer. I have no personal experience with that kit but my understanding is that some people who run it have increased their rear spring rates to compensate for the lower rear roll center. Hopefully others with direct experience will chime in.