2007 Mustang GT in TTC questions

[Houstonnw]

I've been doing HPDE's at Texas World Speedway for 2 years now and am ready to try NASA Time Trials. I have several questions about modifying my 2007 Mustang GT.

 

1. Computer Tune

 

I found this in the 2009 rules under NO-POINTS MODIFICATIONS:

 

49) OEM ECU/PCM reprogramming or chip (must use OEM ECU/PCM box/housing/hardware)

 

So does that mean that a hand-held programmer such as a Diablosport Predator is a no-points mod?

 

 

2. Rear Upper Control Arm

 

I would like to take advantage of the no-points lightweight driveshaft but am concerned with vibration or long term damage to the rear end. The solution would be an adjustable upper control arm to set the pinion angle (the S197 Mustangs have a 3-link solid axle with panhard bar). These are the only related rules under SUSPENSION/BRAKES/CHASSIS that I could find:

 

7) Replace or modify control arms (other than plates, shims, slots, or eccentric bolts/bushings

for simple camber/caster adjustment only)(may have spherical/metallic joint(s) for

the connection to the spindle/knuckle) +4

 

9) Relocation of rear suspension mounting points +6

 

12) Changing the orientation or design of an OEM mounting point or pick-up point of a

control arm for a panhard bar or trailing arms +1

 

22) Non-OEM rear trailing arms (for stiffness only, no change in suspension mount or pick-up

points from stock) +1

 

None of these seem to apply exactly. If I use non-metallic bushings is this a free mod?

 

Edit to add: Nevermind, I would swear that a lightweight driveshaft was a no-points modification. Just as well, I didn't really want to mess with it anyway.

 

 

3. 2005-2006 vs 2007+ Base Classification

 

Any idea why the 2005-2006 Mustangs are in TTD and the 2007+ are in TTC? I don't know of any significant differences between the cars.

 

I currently have springs, Koni SA shocks/struts, caster/camber plates, and 275/40 Nitto NT555RII tires adding up to 14 points (I think). Any suggestions for the additional 5 points, dependent on the answers above?

 

Thanks in advance.

 

-Wayne

Edited February 4, 2009 by Guest

[kbrew8991]

1 - yup, thats a new free mod for this year - anything that can tweak the stock settings of the ECU is open as far as I know.

 

2 - the control arms are #7 - you need to keep rubber/poly/delrin/etc on the chassis side, but you can go full spherical/heim/metallic on the axle side if you wish. You're replacing the arms but not really moving the mounting points on the axle or chassis so #9 is out, same with #12, and you might have a case for #22 if they weren't adjustable but that could be stretching it. Good "Greg" question there on #22 vs #7, but I would bet a decent sum of $$ that its #7.

 

3 - good question there too, I'm curious as well

 

and I've got a 4th question to add to your list - would a lighter driveshaft need to be assessed points or is it considered just regular old weight reduction??

 

hope that helps some

[jason]

If clutches and flywheels are free, I'd think driveshafts would be too.

[kbrew8991]

I would as well, but it is a drivetrain part and the whole "if its not listed you can't do it" clause... etc

 

prob just an oversight or I'm misunderstanding something (wouldn't be the first time)

[Houstonnw]

If clutches and flywheels are free, I'd think driveshafts would be too.

 

I thought they were addressed in the rules and have edited my original post, thanks.

 

-Wayne

[TurboShortBus]

It seems to me that 7) could be interpreted to be worded as if it applies to front suspension, not necessarily rear suspension (for example, there are not a lot of spindles/knuckles at the back of a live-axle Mustang GT, but we do have front "control arms" that "connect to the spindles"). Is this the case (applies to front suspension only), or does it apply to the rear suspension as well?

 

Mark

[kbrew8991]

that solid axle just looks like a funny looking knuckle to me - ymmv

 

if its not #7, what is it?

[soundguydave]

My read is that the three parallel links between the chassis and the axle on the S197 chassis would be considered "trailing links." They do nothing but locate the axle in position, and unlike an SLA suspension, do not institute a camber curve under jounce and rebound conditions. They just keep the axle parallel to the body, and keep it from rolling under acceleration and deceleration. The Panhard rod keeps the axle centered under the chassis, and that's it. If the upper and lower arms aren't trailing links, then what, exactly, is a trailing link?

 

Trailing arm

From Wikipedia, the free encyclopedia

 

A trailing-arm suspension is an automobile suspension design in which one or more arms (or "links") are connected between (and perpendicular to and forward of) the axle and the chassis. It is usually used on rear axles. A 'leading arm' as used on a Citroën 2CV, has an arm connected between (and perpendicular to, and to the rear of) the axle and the chassis. It is used on the front axle.

 

Trailing-arm designs in live axle setups often use just two or three links and a Panhard rod to locate the wheel laterally. A trailing arm design can also be used in an independent suspension arrangement. Each wheel hub is located only by a large, roughly triangular arm that pivots at one point, ahead of the wheel. Seen from the side, this arm is roughly parallel to the ground, with the angle changing based on road irregularities.

 

A semi-trailing arm suspension is an independent rear suspension system for automobiles in which each wheel hub is located only by a large, roughly triangular arm that pivots at two points. Viewed from the top, the line formed by the two pivots is somewhere between parallel and perpendicular to the car's longitudinal axis; it is generally parallel to the ground. Trailing-arm and multilink suspension designs are much more commonly used for the rear wheels of a vehicle where they can allow for a flatter floor and more cargo room. Many small, front-wheel drive vehicles feature a MacPherson strut front suspension and trailing-arm rear axle.

 

Based on that, changing out the OEM pieces for aftermarket pieces would be a +1 mod, or +4 if he used spherical bushings.

[TurboShortBus]

if its not #7, what is it?

If not #7, then I'd definitely say #22 (in the case of a Mustang with non-OEM rear control arms). But, if #7 applies to rear suspension as well as front, then there could be a double-whammy of #7 (+4) and #22 (+1) just by switching to non-OEM rear control arms with "free" rubber/poly bushings, although both items seem to be saying the same thing in this case, and there's a big difference between a +4 modification and a +1 modification (and the sum of both items are nowhere near worth +5 in this case, IMHO).

 

Maybe breaking the suspension part of the rules down into 3 groups (front, rear, and general) could help to avoid misinterpretations.

 

Mark

[TurboShortBus]

They do nothing but locate the axle in position, and unlike an SLA suspension, do not institute a camber curve under jounce and rebound conditions.

There is definitely a camber curve with a live axle throughout its travel, especially if one side goes up (negative) while the other goes down (positive) on an uneven surface. I know I know, I'm aware of what you're saying...but we all saw My Cousin Vinnie...lol...don't take this particular reply too seriously...

 

Mark

[soundguydave]

They do nothing but locate the axle in position, and unlike an SLA suspension, do not institute a camber curve under jounce and rebound conditions.

There is definitely a camber curve with a live axle throughout its travel, especially if one side goes up (negative) while the other goes down (positive) on an uneven surface. I know I know, I'm aware of what you're saying...but we all saw My Cousin Vinnie...lol...don't take this particular reply too seriously...

 

Mark

 

Yeah, yeah, yeah, like you blend...

 

I think you understand what I was getting at, though. In some ways, I like your thinking on separating the front, rear and general sections, but there are just wayyyy too many possible suspension designs that could be mis-classified and inappropriately "taxed." Off the top of my head, for rear suspension, I can think of: solid rear axle, solid rear floating axle, independant rear axle, McStrut, SLA, wishbone, leaf-sprung, weight-jacked, coil-over, torsion bar, solid mounted... Perhaps breaking it down to steering axle, and non-steering? Also, we need to be careful with the definition of "OEM." I could conceivably see somebody with "millions and minions" searching through the junkyards to find the rear axle housing that was "improperly" assembled at the factory that provides some negative camber, as well as a bit of toe. Performance advantage over a "true" axle, even though they're the same part. Kind of like the Spec Miata guys auditioning computers on the dyno to find "the one" than gives them a few more horses.

 

As for the original post in this thread, I would consider the rear control-arm/drag-link/whatever-you-call-em a +1 mod, unless we can get a regional or national level honcho to comment... IMO, though, the biggest issue with lowering the S197 isn't the pinion angle, it's the fact that your anti-squat% goes south fast without relocation brackets, which are quite pricey at 6 points. I would lobby for a "change from OE angle or orientation," since we're already paying for the lowering with points on springs. I know, wee-ing into the wind...

[Greg G.]

OMG, quit playing with words unless you want to get caught up in a problem with a TT or Race Director deciding whether your win turns into a D/Q. The poster asked what points he would take if he changed out the rear upper control arms. It is +4 points, and +3 more if there are spherical/Heim joints on the inboard side, just as Ken originally stated. Trailing arms are perpendicular to the axle as the Wiki article posted stated.

 

The newer Mustang has a lower base weight, and a higher base class.

[soundguydave]

OMG, quit playing with words unless you want to get caught up in a problem with a TT or Race Director deciding whether your win turns into a D/Q. The poster asked what points he would take if he changed out the rear upper control arms. It is +4 points, and +3 more if there are spherical/Heim joints on the inboard side, just as Ken originally stated. Trailing arms are perpendicular to the axle as the Wiki article posted stated.

 

The newer Mustang has a lower base weight, and a higher base class.

 

Greg, seriously, no offense intended, but the Mustang 3-link on the S197 IS perpendicular to the axle, and is letter-exact to the Wiki article referenced, so I'm trying to figure out where they would be considered a control arm. They seem to fit the definition, to the letter, of a trailing arm/link. Am I incorrect in thinking that essentially "control arm" is equal to "A-arm?" These are definitely NOT "A-arms." My issue is really whether the links should even be called "control arms" in the first place.

 

In automotive suspension, a control arm (sometimes called a wishbone or A-arm) is a nearly flat and roughly triangular member (or sub-frame), that pivots in two places. The broad end of the triangle attaches at the frame and pivots on a bushing. The narrow end attaches to the steering knuckle and pivots on a ball joint.

 

Two such devices per wheel make up double wishbone suspension, while one control arm per wheel makes up a part, usually the lower part, of MacPherson strut suspension or of various other configurations.

 

That is the exact Wiki definition of a control arm. On the S197 chassis Mustang, the links are flat/tubular, not triangular, and pivot in only one location per end, but that end is able to articulate in pitch, roll, and yaw axes, unlike a control arm which only moves in one axis. On the S197, unlike the older Quadrabind (which did NOT mount perpendicular to the axle), if ANY ONE of the three links or Panhard rod were to be disconnected, the car would be 100% undrivable.

 

Honestly, I'm not trying to be combative, or question your call, I'm just trying to clarify exactly what the points cost is of replacing a flat stamping/rubber bushings with a tubular piece with poly or rod ends. To the best of my knowledge, there is no aftermarket manufacturer offering replacement bushings for the control arms (a no point mod) as the cost on replacement pieces is relatively negligible. $99 if you know where and how to shop. So that I can fully understand the difference, what cars have trailing links that are not considered control arms? That may help me to "get it."

 

Respectfully,

 

Dave Lowum

[Greg G.]

This discussion is worthless without photos. My comment was that he asked about replacing "upper control arms", and got the answer that they are trailing arms. The "arms" in many multi-link suspensions are generally considered "control arms". I have seen where the terms "trailing arm" and "control arm" have been used interchangeably on the Internet.

[Houstonnw]

Here is the rear suspension on the S197 Mustang, however mine doesn't have the pretty colors :

 

 

Edit to add: It seems that they have the previous gen suspension on the left side of the mirror, notice that the spring is on the lower control arm rather than on the axle.

[soundguydave]

Here's the upper link (adjustable rod end version) The "fork" at the end slips over the bushing mounted on the top of the differential.

 

 

And the lower link (also adjustable rod end version)

 

 

Obviously, if the rod-end versions were installed, that would add +3 to the points tally.

[TurboShortBus]

So, let's say that a set of these showed up on a Fox/SN95 (1979-2004) Mustang with rubber/poly bushings on all ends:

 

Or a set of these on an S197 (2005+) Mustang with rubber/poly bushings on all ends (I couldn't quickly find a photo of a fixed-length upper Mustang arm with poly bushings, but let's say that it's included):

 

then 7) would apply for +4 points per Greg's post above ("Replace...control arms"), but what about 22) for +1 point ("Non-OEM rear trailing arms (for stiffness only...)")? Would one or the other apply for either +4 or +1, or would both apply for a total of +5?

 

The mention of camber/caster adjustment and spindles/knuckles in 7) could lead to the interpretation that 7) is talking about front suspension (especially as it applies to Mustangs, since none of that occurs in the rear of Mustang GTs), so I could see a Mustang driver skipping right past 7) and its +4 points and assessing 22) with its +1 point and possibly winding up with a points and class discrepancy (honestly, that's how I read it, although I still have OEM control arms and bushings back there, so it's a non-issue for me at this point).

 

And my Mustang buddies and I interchangeably call them control arms (UCAs, LCAs, etc.) or trailing arms (they sure do seem to me like they trail, as opposed to an IRS setup) as they apply to our Mustangs, so I won't contest the choice of vocabulary, as I don't see a problem with it.

 

Mark

[soundguydave]

I read it exactly as you did... I could see the previous generation being considered control arms, as the springs ride on them (weight jackers) and not on the axle itself, and also that at least the uppers are pretty angled, but none of that holds true for the S197 design. To my thinking, the front control arms are flexible in the vertical axis, but not in the lateral, longitudinal or torsional axes. The rear "pieces" in the S197 are flexible in vertical, lateral, and torsional axes, but not in the longitudinal, essentially ONLY providing positioning for the axle in one direction. They are in no way triangulated, like the front control arms are, or like the previous generation Quadrabind, where you could drop out an upper link (or just pull the body-side bushing) and still have a fully functional suspension.

 

I don't want to sound like we're being a bunch of guardhouse lawyers here, but it STILL sounds to me like the rear suspension parts should fall under the "trailing link" rule. Especially since the control arm section specifically allows spherical bushings as part of the change, but only where they connect to the knuckle. As there IS no knuckle, that would seem to invalidate the description altogether. It would seem to me that either the rear links are considered control arms, in which case the spherical bushings (Heim joints) should be not be assessed points, no matter where located, OR they are trailing links, for 1 point with rubber/poly bushings, and 4 points with Heim joints. Let's face it, the reason we're replacing the arms on S197s is strictly for bushing material and for stiffness of the part, which certainly sounds like the description "Non-OEM rear trailing arms (for stiffness only, no change in suspension mount or pick-up points from stock) +1"

 

Since we're not entirely clued in to the classing process, I think we just need to wait for an official ruling. I'm planning on being in TT this year (with an S197, go figure...), so this is certainly germane to me, but there's no way that replacing the OEM arms/links as a +4 mod, AND an additional +3 for the Heim joints would be worth the same on-track performance as moving from street tires to R888 or NT-01s for any car that I could think of. They're just not equivalent, as the point assessment would suggest they are.

[TurboShortBus]

so this is certainly germane to me

"THE GODDAMN GERMANS GOT NOTHIN TO DO WITH IT!" -Sheriff Buford T. Justice

[skitzmix]

I've been doing HPDE's at Texas World Speedway for 2 years now and am ready to try NASA Time Trials. I have several questions about modifying my 2007 Mustang GT.

 

1. Computer Tune

 

I found this in the 2009 rules under NO-POINTS MODIFICATIONS:

 

49) OEM ECU/PCM reprogramming or chip (must use OEM ECU/PCM box/housing/hardware)

 

So does that mean that a hand-held programmer such as a Diablosport Predator is a no-points mod?

 

-Wayne

 

FYI the TTD base class for 2006 +14, so tires put's it in TTC.

 

When you mod your ECU, keep in mind that you will start being affected by the min HP to Weight requirement for TTC of 12.0:1, so a 375HP car for TTC must weigh 375*12 == 4500lbs. for a 3356 base weight + driver of say 200lbs, I think the highest you can go is ~296HP. Anything more than that and you are TTB/A. Say you were putting down 345hp @3356lb car+200lb driver - that would be TTB - based on the way I read it...

 

Example: 2001 Ford Mustang, with OEM transmission, on DOT approved 295 tires, weighing

3201 lbs, with 365 rwhp, and TT competition class TTA by base class and mod points:

3201/375 = 8.50 (Car bumps from TTA to TTU)

 

I believe you'll find the ratios in section 6.1.2; so yah it's free to a point.

 

ken brewer reminded me of this last weekend when we were talking about form submission for Texas Region.

 

JK

[TurboShortBus]

When you mod your ECU, keep in mind that you will start being affected by the min HP to Weight requirement...

Also, keep in mind that the "free" ECU modifications can be used to decrease horsepower in order to avoid being bumped up a class. I'll be taking mine to the dyno in the next couple of weeks to see what kind of power it's putting out, and if it's making too much to keep me in TTD (I know that it's going to be pretty close), then I'll just throw a tune in there to take some power out and record the changes. It's quicker and easier than screwing around with various diameters of restrictor plates.

 

Mark

[Greg G.]

The upper arm is definitely considered a control arm, regardless of the fact that it doesn't connect to a spindle or knuckle. I have discussed the issue of the lower arms with JWL as they are more controversial, and they are still also considered control arms. As well, almost all of the sites selling the aftermarket arms call them control arms. This really goes back to the general assumption that the arms on multi-link suspensions are all considered control arms as well. Also, there are some of these lower arms that apparently have offsets, which is fine since the car is being assessed +4 for control arms. But, some of the brackets for them relocate the suspension mounting points. Care should be taken when assessing points for these aftermarket suspension pieces.

 

Lastly, the rule regarding control arms is meant for any control arm, not just front.

[TurboShortBus]

Well, at least that determination has been made. IMHO, aftermarket arms are a waste of 4 points on a Mustang if you aren't trying to run in the faster TT classes. Oh well. If it's any consolation to the S197 guys, the Koni Challenge Mustangs run the stock upper arm with aftermarket lowers, all with poly bushings (per the rules; Heim joints not allowed).

 

Lastly, the rule regarding control arms is meant for any control arm, not just front.

At any rate, I feel that this statement about control arms needs to be clarified in 7) in order to eliminate any confusion; maybe a revision/rewrite is in order.

 

With that being said, what is a trailing arm as it applies to rear suspension? Please give an example of a vehicle type with trailing arms, as we apparently do not have them on our Mustangs. 23) takes care of the FWD crowd, so where would 22) occur?

 

Mark

[soundguydave]

Thanks, Greg, it looks like we have an official clarification. That works for me, although I obviously wish it went the other way. Resolution is good, though, any way you look at it. As Mark mentioned, a re-write of the part description would be in order. I'm a former ASE-certified Master Automotive Technician, and my reading led me to a conclusion that is inconsistent with the intention of the rule.

 

Information only, the offset that you are referring to is present on the OEM rear lower control arm, in that the bushing at the axle end is not symmetrical with the axis of the stamping.

 

To clarify, if I were to (theoretically) replace the upper and lower control arms with rod-end pieces, I would be assessed +4 for the control arms, and +3 for the rod ends? Or would I be assessed +4 for the upper, +4 for the lower, and then +3 for the rod ends? Or, would the +4 cover the two fronts, AND the three rears all at once?

 

I'll admit to curiosity as well, concerning the trailing link application. What vehicle(s) was this rule aimed at?

[Greg G.]

Control arms are +4 for as many as you want to switch out, front or rear. Yes, you would take the +3 for metallic replacement bushings/spherical/Heim joints if they have them. Again, they are +3 for Heim joints at any/multiple locations.

 

There are older live axle cars that have true trailing arm suspensions. There are also FWD vehicles that have rear trailing arms. I know that the Neon does (and no, I haven't replaced mine and don't plan to).