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Demon Coyote
Well-Known Member
- Joined
- Jun 24, 2014
- Threads
- 37
- Messages
- 711
- Reaction score
- 134
- Location
- Naperville, IL
- Vehicle(s)
- 2015 Mustang GT
- Vehicle Showcase
- 1
Definitely love my setup, wouldn't even think about going back to my previous setup lol.
Bluemustang
Well-Known Member
You’re running the SP083 and FRPP track dampers no?
TheLion
Well-Known Member
Yah it's in his sig if you read through it. I'm going to go with that same setup, SP083's (3rd revision 250 lbs/in fronts and 980 lbs/in rears) with FP Track Dampers and at least a 34mm GT350/R front sway bar. I'm also contemplating throwing in a set of the steeda roll center correcter lower front links. They are designed to correct front roll center on lowered cars. The GT350 sits about 3/4" lower than the regular GT and it DOES have a different front end geometry for that ride height.
The Hub knuckle is different I believe even if the links are the same, so it lowers the roll center over the standard GT. Steeda's are a work around that's cheaper than replacing the entire hub knuckle in the front (and a lot less work to boot). I think that with some Aero eventually along with my current tweaks would be one amazing street / HPDE dual purpose car and hard to beat at the price point I paid for the car (27k with only 5,600 miles on it, 100k power train warranty and Corsa already on it).
Cost wise, we're talking $100 front the front GT350 sway bar and hardware, $270 for the springs, about $500 for the FP Track Dampers and $335 for the Steeda Roll Center & Bump Steer Correction Kit. So in total about $1200 for an amazing suspension setup, not bad!
TheLion
Well-Known Member
In fact, I honestly would pair steeda's 555 4915 roll center and bump steer correction kit with SP080's / PP struts which is already a decent street / causal track setup. Also I've seen some reports of people using the GT350's 34mm front and 24mm rear bars with SP080's / PP struts with very good results.
The car doesn't need a LOT more bar, but PP cars do need a LITTLE more bar. The front to rear spring ratio bias on the SP080's is fairly close to the GT350's and SP083's.
PP GT (and SP080) Front / Rear Spring Rate Bias: 0.229
SP083 Front / Rear Spring Rate Bias: 0.255
GT350R Front / Rear Spring Rate Bias: 0.261
Ford Performance Track Springs Front / Rear Spring Rate Bias: 0.272
Higher bias number indicates more front spring vs. rear spring rate, so interms of anti-roll you may want a little more rear bar along with the increase to a 34 mm front bar, but then again maybe not. The GT350 runs a 22.2 mm rear bar and 890 lbs/in rear springs (softer rear in general) while the GT350R runs a 24 mm rear bar and 920 lbs/in rear springs. Both run the same 34 mm front bar. So I'd expect the R to just slightly understeer compared to the regular GT350 unless the differences in tires affect the steering that much.
I believe the offset of the GT350R's carbon fiber wheels is larger than a PP GT, which uses 45 mm front off set and 52 mm rear offset, so that slight understeer may compensate for the increase in scrub without making it twitchy. You get feedback and yes it R's do tramline on street, but not necessarily twitchy. Since I'll be running a fairly aggressively offset +33mm RTR Tech 7 lightweight wheels, I'd still want some mild understeer for stability.
Given how close the GT350's and SP083's are, I still think there might be a benefit to running the R's 24 mm rear bar with the SP083/FP Track Damper/34mm Front Bar combo setup, but one could easily swap it back out for a 22.2 mm PP rear bar if it's too much rear bar.
But given how the stock PP GT's under-steer too much, I can see why a full set of R bars would give it a really good balance as the R bar front / rear roll stiffness ratio I think has a little more front bar bias than rear despite the fact that both increase roll stiffness and PP front / rear spring bias ratio is a bit softer up front so it balances out the anti-roll a little more. But right now I'm mostly lacking good tires, so we'll see how my current basic setup works once I get tires and where it needs some tweaking.
I'm leaning more towards an incremental set of changes by doing GT350R bars and the steeda roll center / bump steer kit first with SP080's / PP struts then doing the springs and struts the following summer once I've gotten some miles on that setup. It gives me time to critique the car, keeps cost spread out over several years and I"m not wasting good parts by just replacing them before they have some wear and tear on them and I also can appreciate the progressive increases in handling dynamics as the car gets better and better.
The car doesn't need a LOT more bar, but PP cars do need a LITTLE more bar. The front to rear spring ratio bias on the SP080's is fairly close to the GT350's and SP083's.
PP GT (and SP080) Front / Rear Spring Rate Bias: 0.229
SP083 Front / Rear Spring Rate Bias: 0.255
GT350R Front / Rear Spring Rate Bias: 0.261
Ford Performance Track Springs Front / Rear Spring Rate Bias: 0.272
Higher bias number indicates more front spring vs. rear spring rate, so interms of anti-roll you may want a little more rear bar along with the increase to a 34 mm front bar, but then again maybe not. The GT350 runs a 22.2 mm rear bar and 890 lbs/in rear springs (softer rear in general) while the GT350R runs a 24 mm rear bar and 920 lbs/in rear springs. Both run the same 34 mm front bar. So I'd expect the R to just slightly understeer compared to the regular GT350 unless the differences in tires affect the steering that much.
I believe the offset of the GT350R's carbon fiber wheels is larger than a PP GT, which uses 45 mm front off set and 52 mm rear offset, so that slight understeer may compensate for the increase in scrub without making it twitchy. You get feedback and yes it R's do tramline on street, but not necessarily twitchy. Since I'll be running a fairly aggressively offset +33mm RTR Tech 7 lightweight wheels, I'd still want some mild understeer for stability.
Given how close the GT350's and SP083's are, I still think there might be a benefit to running the R's 24 mm rear bar with the SP083/FP Track Damper/34mm Front Bar combo setup, but one could easily swap it back out for a 22.2 mm PP rear bar if it's too much rear bar.
But given how the stock PP GT's under-steer too much, I can see why a full set of R bars would give it a really good balance as the R bar front / rear roll stiffness ratio I think has a little more front bar bias than rear despite the fact that both increase roll stiffness and PP front / rear spring bias ratio is a bit softer up front so it balances out the anti-roll a little more. But right now I'm mostly lacking good tires, so we'll see how my current basic setup works once I get tires and where it needs some tweaking.
I'm leaning more towards an incremental set of changes by doing GT350R bars and the steeda roll center / bump steer kit first with SP080's / PP struts then doing the springs and struts the following summer once I've gotten some miles on that setup. It gives me time to critique the car, keeps cost spread out over several years and I"m not wasting good parts by just replacing them before they have some wear and tear on them and I also can appreciate the progressive increases in handling dynamics as the car gets better and better.
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Bluemustang
Well-Known Member
I’ve considered the Steeda lateral links (I already have their bumpsteer kit), but I am holding off on that. I do think there is most likely more positives than negatives to doing this but I don’t want to go through the whole bumpsteer correction thing again right now.
I’ve got the car pretty much the way I want it now. I’m planning a 2018 intake manifold and LU47 injector install soon.
Maybe next year on the Steeda lateral links.
I’ve got the car pretty much the way I want it now. I’m planning a 2018 intake manifold and LU47 injector install soon.
Maybe next year on the Steeda lateral links.
wildcatgoal
@sirboom_photography
Fun times at Road Atlanta with Gridlife, all Steeda suspension. 20mm spacers on the front--spacers acquired from OPMustang.com because they're BLACK in color and high quality. Went faster than this video but this is the fastest time video I have.
TheLion
Well-Known Member
Understood. But since I have an aggressive drop in front presently (1.2" front, 0.5" rear) and I plan on in the future using SP083's w/FP Track Dampers, corrected front end geometry will provide better handling, especially with wide off set wheels like my RTR Tech 7's. Reduces tramlining / twitchyness from road imperfections due to incorrect roll center and bump steer.
The SP083's run a 7/8" drop in the front and 3/4" drop in the rear, so still a fairly aggressive drop. That's something that IS unique to the GT350. The front hub's mounting points for the lateral and tension links are further down from the hub bearing to give it correct roll center as the ride height in the front is roughly 3/4" lower than a standard GT. I'd imagine the tie rod ends also have corrected bump steer for that ride height.
So you could 1. Convert to GT350 front end parts and that would get you where you want or 2. You could use steeda's kit which as the same strength as OE parts but also corrects roll center and bump steer. I'm in favor of option 2 when using wide off set wheels with aggressive ride height. Weather using the SP080's or the SP083's, my ride height has dropped more than 1/2 inch so there is some benefit to a corrected roll center and bump steer.
How much one would notice it in actual use I'm not sure, but I don't see any downside other than added cost. The front end seems less sensitive to geometry changes than the rear, however it's not immune. Here's a great read up on roll center (gotta scroll down about 1/2 way): https://edfishjr.com/author/edfishjr/
By correcting roll center you get the benefits of a lowered center of gravity aka less weight transfer, camber gains (with caster / camber plates), obviously for some the looks and finally you negate the increased leverage on the suspension with works against the camber gains and lower center of gravity.
By correcting bump steer you rid the car of excessive toe angle changes when subjected to cornering loads. Consequently the gains in roll center also reduce bump steer inherently because they reduce body roll by decreasing the momentum force lever arm.
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