Project STX update and 13/14 April Solo event After Action

[c_reber]

Can you guys come to Vegas/socal area and let me ride with you? I need some pointers/experience!

 

[Whiskey11]

I can certainly see it removing a wear item from the car!

However, I don't see how it's going to actually reduce the push you get around the turns. If anything, I'd expect it to increase the grip you get in the rear because now you're more properly balancing the power to the rear wheels.

My neophyte impression, for what it's worth, is that push (understeer) versus oversteer is always a question of which end breaks traction first. Nothing more, nothing less. If you dial in less understeer, you wind up dialing in more oversteer automatically. You may wind up also increasing the total amount of traction you get before something breaks loose, of course, and that's desirable, but in the end, once you get to the limits, one end or the other is going to let go.

You may end up having to give up a little traction in order to gain a bit of extra controllability. Ideally, you'd gain both simultaneously. I don't think a Torsen is going to accomplish that. It seems to me that you need to do something to increase the grip at the front end while keeping it the same in the rear. The Torsen should help with grip in the rear when powering through and out of corners, but won't help with grip in the front. Indeed, it may actually slightly reduce your grip in the front.

My reasoning behind that is that by more properly distributing the torque between the two wheels, the wheel on the outside is going to be getting more torque than it did before. That will cause the outside front tire to lift a little more, and thus to break traction a little earlier than it did before. Hence, I would actually expect more push with a Torsen than with the Traction Lok, both because the rear won't break loose as easily (thus, higher grip in the rear) and because the front will lift just a little more as a result of the greater amount of torque in the rear and, especially, on the outside.


Be interesting to see if my thinking on that is correct...

One thing you are leaving out is the thrust capabilities of the tires with a Torsen. When the wheels move at different speeds but off throttle the diff is "open" and when you apply throttle it will start to torque bias. Basically the outside wheel is going to receive more torque because it can support more torque and it will grab and move the car around the corner because the outside wheel is seeing greater power than the inside and is making less grip than the inside. With the clutch based diff it resists this motion so you'll get power on push (due to the added grip) all the way until the inside tire gets enough power to spin and then it will try and lock both together causing throttle oversteer.

I have yet to hear someone say a Torsen causes the car to understeer but I have heard quite a few times that it will help the car power around corners without adding push to the car.

I can see how a Torsen on a stockish sprung car would cause a problem but we are talking about a car that isn't that softly sprung, comparatively. I would think this would already be a problem if it was going to be present with the Torsen since I don't see it "adding" or "realizing" more grip than what is currently there, just better managing it.

I could be wrong, we'll see when I get it, I just know that everyone I've talked to has said that a Torsen under power is far more neutral than a clutch based diff which always understeers under power or on entry if it is setup to be tight enough on coast and drive.

 

[csamsh]

One thing you are leaving out is the thrust capabilities of the tires with a Torsen. When the wheels move at different speeds but off throttle the diff is "open" and when you apply throttle it will start to torque bias. Basically the outside wheel is going to receive more torque because it can support more torque and it will grab and move the car around the corner because the outside wheel is seeing greater power than the inside and is making less grip than the inside. With the clutch based diff it resists this motion so you'll get power on push (due to the added grip) all the way until the inside tire gets enough power to spin and then it will try and lock both together causing throttle oversteer.

I have yet to hear someone say a Torsen causes the car to understeer but I have heard quite a few times that it will help the car power around corners without adding push to the car.

I can see how a Torsen on a stockish sprung car would cause a problem but we are talking about a car that isn't that softly sprung, comparatively. I would think this would already be a problem if it was going to be present with the Torsen since I don't see it "adding" or "realizing" more grip than what is currently there, just better managing it.

I could be wrong, we'll see when I get it, I just know that everyone I've talked to has said that a Torsen under power is far more neutral than a clutch based diff which always understeers under power or on entry if it is setup to be tight enough on coast and drive.

My Torsen got rid of a lot of push, it made the car rotate unbelievably well. I almost drove into the curb leaving the shop that installed it because I wasn't ready for how the steering was going to feel. No mod I've done has had more of an impact on how the car feels and behaves than the Torsen. All the other stuff is incremental, shock y is better than shock x, spring y is better than spring x, etc, but they all perform the same function. The Torsen is a completely different feel from the posi. The most noticeable thing is the ability to put power down in an autocross setting. You can get on power before an apex in some cases, and it's great coming out of 180 degree turnarounds. You pretty much get the car lined up and just mash the gas, or just mash the gas early and apply a little countersteer. It's stupidly easy to hold a drift with the Torsen. See below videos:

 

[Norm Peterson]

When the outside rear tire is actually carrying more torque than the inside tire, its forward traction is greater than the forward traction of the inside rear tire. This produces a net yaw moment about the car's CG (as seen in plan view) that is specifically in the same direction that you're trying to turn in. The Torsen doesn't have the "push" between turn-in and throttle-on, which I guess is something you just sort of adapt to in a regular clutch/cone type LSD.


Norm

 

[kcbrown]

One thing you are leaving out is the thrust capabilities of the tires with a Torsen. When the wheels move at different speeds but off throttle the diff is "open" and when you apply throttle it will start to torque bias.

Ah, you're right, I hadn't considered that the Torsen will place a torque on the car about the vertical axis of the car due to the torque differential.

So I guess whether that effect outweighs the (probably slight) increase in lift on the front and the subsequent reduction of maximum grip there depends on the setup, but now that I think about it further, I would expect the torque differential to dominate the equation in the general case.

 

[Whiskey11]

Decided to retorque suspension fasteners and play with the new GoPro Hero 3 Black Edition:





Front wheel camera is frightening on hard braking how much fore/aft movement there is. Terry was right!

What does this have to do with STX and my car? Well, not a whole lot. I recently received word that one of the localish Police Departments wants to hire me and the next academy class is in April so the chances of my car being at either Spring Nationals or Nationals next year is very slim. The academy is 4 months long (ok, 16 weeks) and would cross over both dates. What events I will be making it to next year I will probably carry on with my current wheels/tires until they are done and I doubt anyone will care if I run in STX even if the cars get moved to STU (which is seeming less and less likely judging by the number of people now writing in against the move).

For the 2015 year, assuming I haven't bought into the new S550 cars (Ecoboost 4 banger at 3100lbs PLEASE!), I will run my 09 in ESP. I think I've carried this torch plenty far to know that the car doesn't stand a PRAYER in STX and we already know it wont in STU. Yes, it sucks for those who were wanting me to take the time to run in STU but I think it's time to move on. The only things really left for the car are suspension bushings (which the front obviously needs really bad and the rears are WIP), differential, power, and weight. None of those will make up the 6 second deficit to trophy in STX and definitely wont close the gap on the boost buggies in STU. None of those will cover the 8 second gap to win STX either and I doubt Sam, or Heitkotter or whatever alien you chose could pilot it there.

If I'm in the next gen Mustang then, expect an ST build, wherever it gets classed in ST, because I like the ST formula and I think if the rumors about the Ecoboost 4 cylinder are true for power and weight, then I think the car might have a slight hope of doing well in either class.

Anyway, nothing is 100% for certain that I am getting this job. They can't make a conditional offer until October 1 and I have to complete the conditions of the offer to get the job so until that is done, nothing is officially changing. No big major changes in car prep and set up, just continuing to run what I've got.

 

[NDSP]

Well here's hoping that your get the job. So good luck with that.

I'd be curious to know what the people writing in to block the move to STU are saying. I'm mean what is their beef? That we'd be 2 fewer seconds off the pace of winning times?

 

[Whiskey11]

Well here's hoping that your get the job. So good luck with that.

I'd be curious to know what the people writing in to block the move to STU are saying. I'm mean what is their beef? That we'd be 2 fewer seconds off the pace of winning times?

"The cars are more competitive in STX than STU" is the most common one I've heard, but they don't stand a chance in either IMO. One reason alone that makes the move worth it is not needing to buy another set of wheels when going from ST to SP...

 

[Justin_H]

Well if you do get the job, you can drive faster to Lincoln with 'professional courtesy'.

I think the cars are capable of a trophy at nationals in STX, but it'll take top notch driving and maybe the right course. We definitely don't gain enough speed on 285s to be more competitive in STU, but I am in favor of it- many street Mustangs ride on wheels more than 9" wide. If we don't go STU, I guess I'll stick to CP on street tires.

 

[Whiskey11]

Well if you do get the job, you can drive faster to Lincoln with 'professional courtesy'.

I think the cars are capable of a trophy at nationals in STX, but it'll take top notch driving and maybe the right course. We definitely don't gain enough speed on 285s to be more competitive in STU, but I am in favor of it- many street Mustangs ride on wheels more than 9" wide. If we don't go STU, I guess I'll stick to CP on street tires.

I guess I'm a bit jaded because of my experience, but I don't think either the new 5.0's or the 4.6's have a prayer in STX. Waaay too much going against the car in comparison to the rest of the class, even in the lightest of the light trim we are talking about 400+lbs to the nearest competitor in weight and the tire rules are the same for everyone. Combine that with torque of a V8 and you pretty much are left, pardon the pun, spinning your tires. J-Rho doesn't even think he can get it done within the framework of the rules and he is at 3100ish for weight.

There is an alternate solution to this and J-Rho certainly is going to be a major factor in it. In his "not official STAC" opinion, an STPony class would have a ton of success. Basically making it ESP on Street tires. I think that it has merit, but we are looking down the barrel of a gun with this. The BoD meeting is next month and that is when things get "rubber stamped" into the rule book. The chances of anything, anything at all making it to them this year is slim to none BUT, I suggest that if we want to have an ST class that we can be competitive in, we take J-Rho's thought process and put our weight behind maybe a provisional class for pony cars in ST.

 

[csamsh]

I guess I'm a bit jaded because of my experience, but I don't think either the new 5.0's or the 4.6's have a prayer in STX. Waaay too much going against the car in comparison to the rest of the class, even in the lightest of the light trim we are talking about 400+lbs to the nearest competitor in weight and the tire rules are the same for everyone. Combine that with torque of a V8 and you pretty much are left, pardon the pun, spinning your tires. J-Rho doesn't even think he can get it done within the framework of the rules and he is at 3100ish for weight.

There is an alternate solution to this and J-Rho certainly is going to be a major factor in it. In his "not official STAC" opinion, an STPony class would have a ton of success. Basically making it ESP on Street tires. I think that it has merit, but we are looking down the barrel of a gun with this. The BoD meeting is next month and that is when things get "rubber stamped" into the rule book. The chances of anything, anything at all making it to them this year is slim to none BUT, I suggest that if we want to have an ST class that we can be competitive in, we take J-Rho's thought process and put our weight behind maybe a provisional class for pony cars in ST.

Yup. STPony would be great. Rules: (not that the SCCA would ever go for this...)

1. Minimum 200TW DOT approved tires
2. Minimum weight 3200# (maybe? seems like an ok-ish target to be inclusive of lots of generations of pony cars)
3. No cutting or welding

 

[Whiskey11]

Yup. STPony would be great. Rules: (not that the SCCA would ever go for this...)

1. Minimum 200TW DOT approved tires
2. Minimum weight 3200# (maybe? seems like an ok-ish target to be inclusive of lots of generations of pony cars)
3. No cutting or welding

Frankly I think we could do without the minimum weight and go for something a long the lines of average car curb weight determining tire width.

Working down it seems the S197 chassis has an average of around 3400-3500lbs between the heaviest coupe and the lightest coupes. Give cars over 3400lbs whatever tire they want, the SN95's seem to average around 3300ish, give them 285's, the Foxes around 3000, give them 275's, and anything with a lighter than 3k average gets 265's. It would take a little tweaking to get correct but I don't see any reason it wouldn't work.

Or you could just take ESP's rules regarding fenders and let them run what they brought. Basically making ESP on street tires and without UD/BD or limited UD/BD.

Personally, here is what I'd want to see added to the current ST rules outside the tire issue:
-Relocation Brackets as I wrote the letter
-Rear lower control arms
-Gear swaps

I think I could live with the rest.

 

[Justin_H]

I would be all for RWYB street appearing American RWD 200 TW excluding Corvettes&kit cars, even though my closeout tires are marked 140 TW.

We have a strong ESP class locally thie year, not sure if they'd give up the purple crack though.

 

[phoenix335]

I would be all for RWYB street appearing American RWD 200 TW excluding Corvettes&kit cars, even though my closeout tires are marked 140 TW.

We have a strong ESP class locally thie year, not sure if they'd give up the purple crack though.

I think u run Wdcr. Was wondering why you run in prepared class (xp and/or cp). I'll stop by and say hi if you run in the xp heat.

 

[Justin_H]

Yep WDCR. Come say hi next time we're both there, ride along if you want. I run P classes right now because I have/can make the class letters easily, don't care about trophies, and want to run early to get home sooner. Next year maybe I'll get some STU letters- the car will be legal there if the BOD has ink for their stamp.

Justin

 

[sholzer]

I can't wait to join you all up there in WDCR next season/year. Much better competition than BRR

 

[phoenix335]

Yep WDCR. Come say hi next time we're both there, ride along if you want. I run P classes right now because I have/can make the class letters easily, don't care about trophies, and want to run early to get home sooner. Next year maybe I'll get some STU letters- the car will be legal there if the BOD has ink for their stamp.

Justin

I've been driving Larry's Cobra in xp most of the summer. I'll look for you next event. I totally get wanting to be in the morning sessions. Can be a long day otherwise.

I can't wait to join you all up there in WDCR next season/year. Much better competition than BRR

Are you moving back to the area. We have the last event on the 6th come on up. ESP is going to be growing over the next couple of hears in dc due to the street class.

 

[sholzer]

Are you moving back to the area. We have the last event on the 6th come on up. ESP is going to be growing over the next couple of hears in dc due to the street class.

Yep, I am graduating in May and will be moving back to NoVA. But that's what I've heard about ESP growing. This past weekend I had David Wampler co-drive with me and he was telling me about all the people up there that are planning on building ESP cars. I can't wait to get up there

 

[Vorshlag-Fair]

Decided to retorque suspension fasteners and play with the new GoPro Hero 3 Black Edition:





Front wheel camera is frightening on hard braking how much fore/aft movement there is. Terry was right!

That first video gets interesting at the 3:15 mark, when he gets on the brakes. And yes, the fore-aft movement of the wheel relative to the wheelbase is staggering. And this is mild braking, with street tires.

The second video didn't show much visually, but the audio tells the tale - lots of clanking and popping from the metal rod ends on the Watts. That's why I'm not a fan of that style for a street or dual-purpose car. I won't beat a dead hose so I will leave it at that.

These two videos from Whiskey11 are inspiring - so much so that I am going to do some similar videos on a couple of our S197 cars here, both in street driving and on track, with poly LCA bushings vs OEM rubber up front, and WL Panhard vs WL Watts out back. Look for similar videos in my build thread here shortly.

Oh, and good luck on the job front. Sorry if the timing precludes you from a more serious 2014 autocross campaign, but a job is important.

I cannot understand what nit-whits are writing in opposing the S197 move to STU. I would wager that it is likely from people THAT DON'T EVEN DRIVE S197S. It would be "So SCCA" for them to bar the STU move for this chassis based on letters from a gaggle of Miata drivers.

J-Rho finally got the message I was giving him 2 years ago - that anything with more than 350 whp in STX is a joke, and will never ever work on skinny street tires. Even with 500 fewer pounds and a more serious build than our own, he finally came to the same conclusion. I also begged him to LEAVE THE SCCA with that car, and go have fun running with ASCS, Goodguys, Optima Challenge, and the other muscle car autocross competition groups. Which he seems to now be realizing makes more sense for that car.

And sure, his ST-Pony Car idea has merit, but it has a snowball's chance in HELL of ever flying in the SCCA. I was for the ST-P class for a long time - and actually helped create this class for a local club back in 1991, that is still hugely popular 22 years later in this club. But I knew that something this logical and popular would never fly in SCCA, so instead we pushed for the "easy" move from STX to STU. Since so many other Pony Cars are already in STU (anything over 5.0L of displacement). But no, they seem to be screwing that up, too.... (shakes head)

 

[2013MustangGT]

Just spoke with Jason @ Vorshlag (modernbeat) and ordered the WL watts for my car after seeing this video. I was thinking of going with the Fays2 because I wanted to keep my differential cover. The differential cover on my track GT has heat sinks to help keep differential fluid cool. Might just have to put the differential cover up for sale now.