Suspension Thoughts after 2000 Kilometer Alpine Tour + 10 hrs of intense twisties

[TheLion]

@BmacIL I think you will like it better than BG. After running BG in my oh so picky MT-82 that really did not like to shift into 2nd gear with any consistency, Ravenol was a God send for me as I was at the point of possibly having to take it in to the dealer to get them to start tearing into it. I don't believe there is anything damaged in my MT-82 from the previous owner or myself, but my 2nd gear syncro is just plain picky, it would frequently nibble significantly when cold and some times even kick hard but it never did pop out of gear like some have experienced. It also would completely fail to synchronize at times when cool or cold from 3-2 or even up from 1-2 if I was slow shifting in normal driving although that never happened when running car for performance driving. It would feel like it was completely in gear then I'd let the clutch out and it would just grind, so I'd have to pop it out of gear and back into 2nd then it would mesh, it never occured to me to try double clutching to get it to sync, but I shouldn't have to, it's a synchronized manual....

I also had to intentionally use extra force on 2nd gear, meaning I had to pull back firmly (not jamming it into gear, but consciously pulling harder to the rear left than I did with 4th or 6th). I don't have to do that now with the Ravenol fluid. Motul's DCTF is very similar and several are running that as well with very similar results. Ravenol is PAO based Group IV and Motul DCTF is Ester based Group V. However PAO's do have a slightly better cold temperature performance with nearly the same high temperature performance so after some R I settled on Ravenol as my issues were the worst when cold. Often Ester's are blended with PAO's and PAO's blended with Esters ironically as neither is perfect, so it's more like Brand A is more PAO and Brand B is more Ester, but both likely contain blends of both base oils.

But so far the Ravenol is far superior in it's performance in my MT-82 to BG, the transmission is actually shifting like it should for the first time. It's very smooth, it has almost a bit of a weighted feel or heft to it that I really love. I think you will be pleasantly surprised at how much better the MT-82 will shift and you'll no longer lament the fact that Ford chose Getrag for the regular GT's over Tremec (which they chose for the GT350 and it has some issues as well). Honestly we can't criticize Ford that much for using Getrag, Toyoda makes some very high quality cars, they are one of the top brands of common imports for quality (according to JD quality studies based on actual reported issues) and not many will argue that.

Toyoda uses Getrag as well, so it's not like Ford is using a horribly cheap Chinese piece of garbage, it's manufactured to their specifications, so if it's garbage by design it's Ford fault, if it's garbage my manufacture then I'd lay blame to the production plant in China. Most people don't realize that Getrag is literally the world's largest supplier of transmissions for passenger cars and commercial trucks although I will say they don't have a specific niche market focus on performance car manual transmissions like Tremec does if that matters. But with the right fluid and a good direct mount shifter setup OR the Ford Performance Aluminum Shifter Arm Bushings, it shifts like a dream. The MT-82 just has some high end tastes for oils is what it really comes down to .

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[TheLion]

You’re the third person, including myself, that has a vibration issue with the PP wheels at around 120mph. Seems like more than a theorized trouble at this point.

As far as pads, I’ll likely go to a ceramic pad when due. I don’t track the car (and thus don’t need anything intense) and I like the low dust/silent operation. I had PosiQuiets on my BMW and they were great.

On to sway bars: have you considered adjustable units? More expensive, yes, but the ultimate 20 minute dynamic change as opposed to ripping bars out.

As far as tires, thanks for the data. It looks like P4Ses will win the war unless something far less expensive can muster competition. I’ll also take a look into that trans fluid.

Regarding PP wheels, that's what it seems, but I'll have to wait to confirm that until next spring when I put PS4S's on my lightweight RTR Tech 7's. Only at that point with a full second set of wheels can I confirm it is indeed the PP wheels and not he drive shaft. 110~120 must be a resonant frequency. Maybe the PP wheels casting is just slightly skewed around the axis or maybe the are just a hair out of round and things resonate at that rotational velocity. Time will tell the tail.

Regarding pads, I'll have to give those a look as my stock pads are wearing fast. They have performed very well, so I have no problem with their performance, but due to all the high speed driving, which is what I bought the car for, they do tend to wear fast.

And onto sway bars, I'm very hesitant to use after market sway bars. Almost all of them are 35 to 36 mm tube diameters and are going to be overly stiff even on the softest settings for a car with a corrected roll center. I tend to agree with BmacIL in that the car does NOT need more bar, or at least not much. It's fairly well tuned in terms of sway bar rates from the factory. The biggest issues with the car's handling (Kelly at BMR also said the exact same thing to me on the phone) is the car's compliance in the suspension pivot points.

The GT350R front and rear bars are a nice intermediate and their torsional stiffness was tuned for S550's with a stock rate of roll couple. Many after market bars are stiffer than needed by design to help compensate for the fact that most lowered cars have more roll couple due to uncorrected geometries. Ford Performance did the same thing with their track pack and while it's a great kit, it's potential is not as good as the SP083 / FP Track Damper / GT350 Sway Bar setup with a corrected geometry. That setup in handling dynamics will be neck and neck with the GT350R as it's literally almost the same setup.

Obviously the R has some advantages still, such as the Voodoo 5.2 engine, carbon fiber wheels, endless brakes etc. But in terms of geometry, springs, bars and dampers they are nearly identical. The GT350 also uses a corrected roll center as it rides just a hair less than 3/4 lower than a regular GT, hence the front hub knuckles are specific to that car, partly due to the unique brakes, but also in part to correct the geometry:

Do you notice how the aluminum hub knuckle on that GT350 above has ball joints that are off-set to a greater degree relative to one another? Now look at this standard GT cast iron hub knuckle and how much it is off-set (pay careful attention to the top of the lateral link ball stud nut and where it's at relative to the top of the other ball joint):

You can see that on the GT350 the lateral link height is not the same as on the regular GT. So obviously the geometry has been tweaked for it's ride height and it's a big part of what makes the GT350 a GT350 over a regular GT. The inner mounting point of the lateral link on the GT350 may be different than on the regular GT as well, but we can clearly see there IS a difference in geometry.

Knowing that, we can also conclude that the stock bars for the GT350 are also tuned for an optimized geometry instead of being overly stiff to compensate for increased roll couple that goes with a lowered suspension that has an uncorrected geometry. Most after market bars out there are for just that purpose, a little stiffer than they otherwise would be to compensate for increased roll couple that results from lowering. I would NOT want to use those types of bars on my GT as I have close to stock or possibly even identical to stock front end geometry, so my roll couple is noticeably less than lowered GT using the stock lateral links.

But I am running softer springs and dampers than the GT350 or SP083 / Track Damper combo and I actually really like the balance F/R right now (may change in the future), so I would need to add more bar up front and out back to further reduce roll but also avoid significantly altering the F/R balance. More bar up front gives you more steering and response, but too make will make the car over steer, especially on throttle = dangerous for a high speed car with big power. More bar out back will reduce steering (more push) which I also don't want because it's very balanced right now. So I need to add bar front and back and I don't want too much bar and make the car twitchy or possibly cause the car to be unsettled on bumpy roads either.

GT350R F/R Spring Rate Bias Ratio: 240 / 920 = 0.261
SP083 F/R Spring Rate Bias Ratio: 250 / 980 = 0.255
SP080 F/R Spring Rate Bias Ratio: 170 / 740 = 0.229

Higher ratio denotes more front spring bias, lower ratio denotes more rear spring bias. If I wanted more steering I'd add more front bar, if I wanted less steering I'd more rear bar, front or rear bars will both reduce body roll, but front bars much more so. If I want to reduce body roll and not upset the steering balance, I'd add more front and rear bar. It doesn't over steer and has a very mild push that corrects perfectly with throttle. It's an awesome balance in that regard and I'm lovin' it to quote everyone's favorite yellow arch company. So my next step will be 34 mm GT350/R (both R and non-R use same front bar) front bar and 24 mm GT350R rear bar.

My car will have maybe just a bit more under steer than the GT350R F/R balance due to the lower front spring rates relative to the rears. Obviously it wont' be as responsive due to the softer springs and dampers, but it's still very good, much better than stock and now actually handles like a true sports car and will only get better as I progress through my evolution of suspension modifications to the final result.

Where I'm at with suspension currently:

1. BMR CB05
2. FP M-5A460-M
3. MM Caster / Camber Plates
4. BMR SP080
5. Stock PP Struts
6. Stock 32 mm PP / Base front sway bar
7. Stock 22.1 mm PP rear sway bar

Alignment: -1.4 F Camber, 7.2 Caster, 0.03 F Toe Out, 0.20 R Total Toe Out, -1.25 R Camber

Where I'm going next year:

1. BMR CB05
2. FP M-5A460-M
3. MM Caster / Camber Plates
4. BMR SP080
5. Stock PP Struts
6. OE 34 mm GT350/R front sway bar
7. OE 24 mm GT350R rear sway bar

Alignment (no change): -1.4 F Camber, 7.2 Caster, 0.03 F Toe Out, 0.20 R Total Toe Out, -1.25 R Camber

Where I intend to finally end up:

1. BMR CB05
2. FP M-5A460-M
3. MM Caster / Camber Plates
4. BMR SP083
5. FP M-18000-F Track Dampers
6. OE 34 mm GT350/R front sway bar
7. Steeda 1/8 in rear Spring Spacers (gives the car a 0.5" rear drop instead of 0.75" and identical rake to GT350).

Alignment (will re-evaluate due to very slight change in ride height, but I don't see any reason it will likely change much): -1.4 F Camber, 7.2 Caster, 0.03 F Toe Out, 0.20 R Total Toe Out, -1.25 R Camber

 

[BmacIL]

@TheLion more front bar increases front response off center but will decrease front grip and thus increase understeer. Bars decrease roll on the end of the car they're on and shift balance to the opposite.

 

[Roadway 5.0]

It has been about a year since originally posting this, so it’s overdue for an update:

Needs Improvement:

Long sweeping turns at speed (60mph or higher) is the Achilles heel of my setup. There are no issues concerning traction and I never lost control (or even close), but the LACK of roll and/or feel of transition in my setup actually gives me an uneasiness when steering the way. Yes, this is probably odd to hear if you are a seasoned racer, but I was actually yearning for a bit of roll/feel of transition to ease into these long sweepers.

RECOMMENDED FIX: I am strongly considering the Steeda progressive or dual rate springs for next year's Tour.

Low and behold, that correcting the roll center and adding a bumpsteer kit resolved these stated issues. Prior to installing the Steeda roll center/bumpsteer kit, I had an uneasy “tilt” occurring in the front of the car. This is now gone. I am still running Ultralites and ProAction fixed dampers, and couldn’t be more impressed/satisfied.

180 degree elevated hairpins caused a touch of chirping with the inside rear tire; my aggressive rear camber or the extra stiff rear sway bar is probably the root cause. Either way, I drive these types of turns often in the mountains so I'll have to dial-in a fix.

RECOMMENDED FIX: drop the rear sway bar one notch; if that doesn't work then dial back the rear camber a half-degree from -2.0 to -1.5 or so.

Dropping the rear swaybar to the softest setting rid the car of the switchback chirps.

2nd gear pulls are weak: my car is untuned, in fact it has zero engine modifications. The lack of low-end grunt in the factory tune is VERY apparent when at 6000-7000 feet and pulling a 180 degree elevated turn at 20mph. Damn this car is heavy. Anyway, 20mph is a touch too fast for 1st gear, and bogs in 2nd. RECOMMENDED FIX: I'll be considering a 93 octane tune in the future to give some pizzazz into the low end.

I added a K&N drop-in filter and I pick up just enough oomph to satisfy me. I still have no tune; I probably won’t do one as my traction-to-power ratio is too damn good right now.

Well known fact, but I'll reiterate, the factory wheels are far too heavy. I need to lighten these up to allow the suspension to react even faster and to make rotation a touch easier on the engine.

MRR wheels at about 24lbs a piece, plus lighter, low profile MPS4S tires, made a monster difference in off-the-line feel and ride quality. Unsprung weight reduction is an unsung hero.

And there it is; all updated and my Mustang has been untouched for a good while now. These few improvements really aided the car to become a more feel-some and enjoyable drive.

Thanks to Steeda and MRR for the quality parts; see you all in the Smoky Mountains this fall,

-Mike

 

[ModularKid21]

It has been about a year since originally posting this, so it’s overdue for an update:



Low and behold, that correcting the roll center and adding a bumpsteer kit resolved these stated issues. Prior to installing the Steeda roll center/bumpsteer kit, I had an uneasy “tilt” occurring in the front of the car. This is now gone. I am still running Ultralites and ProAction fixed dampers, and couldn’t be more impressed/satisfied.




Dropping the rear swaybar to the softest setting rid the car of the switchback chirps.



I added a K&N drop-in filter and I pick up just enough oomph to satisfy me. I still have no tune; I probably won’t do one as my traction-to-power ratio is too damn good right now.



MRR wheels at about 24lbs a piece, plus lighter, low profile MPS4S tires, made a monster difference in off-the-line feel and ride quality. Unsprung weight reduction is an unsung hero.

And there it is; all updated and my Mustang has been untouched for a good while now. These few improvements really aided the car to become a more feel-some and enjoyable drive.

Thanks to Steeda and MRR for the quality parts; see you all in the Smoky Mountains this fall,

-Mike

Any more info on this Smoky Mountain trip? A link or a pm would work so I don’t take this thread off topic. Great read and good info/feedback here

 

[Bluemustang]

@Roadway 5.0 - Glad the car has improved even further! You have found as several of us have - adjusting the roll center does some good magic. To me it feels like it's restored to stock, but better than stock could ever do. Which MRR wheels did you end up going with and offsets? I am glad to hear that softening the rear sway was positive. I'm sure those P4S tires are treat to drive on as well.

 

[BmacIL]

@TheLion more front bar increases front response off center but will decrease front grip and thus increase understeer. Bars decrease roll on the end of the car they're on and shift balance to the opposite.

Correcting myself a bit here. Because of the improvement to front geometry, load distribution, the net effect of a stiffer front bar with these heavy, McPherson strut cars has NOT been understeer. If anything, it's the opposite. It increases front grip on turn-in and to the apex, and adds more stability in the exit phase, giving you confidence to get on the throttle earlier and more. It's not just me, either. @kz @Bluemustang @Rebellion

 

[Roadway 5.0]

Any more info on this Smoky Mountain trip? A link or a pm would work so I don’t take this thread off topic. Great read and good info/feedback here

PM sent

For the masses, I’ll be in the Smokies for Columbus Day weekend to review a couple of roads. Feel free to join-in on the fun; foliage and scenery should be perfect!

@Roadway 5.0 - Glad the car has improved even further! You have found as several of us have - adjusting the roll center does some good magic. To me it feels like it's restored to stock, but better than stock could ever do. Which MRR wheels did you end up going with and offsets? I am glad to hear that softening the rear sway was positive. I'm sure those P4S tires are treat to drive on as well.

I scooped the FS02 wheels in 20x10 +35 and 20x11 +50. I love these things...just hard to clean lol. Here’s a shot:

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