This is track mode. Seems like it still leans a bit much? Do i need white line or some other better sway bar? Factory magna ride. Or is is just a big heavy car thing

Mustangs are tragically undersprung on the front. Get AJ Hartman's Magneride kit with 400-450 #/in springs. It's a massive difference in driving and a lot less harsh than you'd think. Use the stock rear spring to start. A bigger front anti-roll bar from any of the normal suspects is fine. It just needs to be stiffer.

Ok great. Kinda what i was thinking. I’ll check out those springs

This kit i assume? Great site with lots of goodies but this with a stiffer sway bar should help a lot

That's the kit. He'll sell any spring you want. The 400 puts you back to stock ride height. A 450 puts you about 5mm higher than stock. Either works.

TeeLew said:

Mustangs are tragically undersprung on the front. Get AJ Hartman's Magneride kit with 400-450 #/in springs.

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What is the stock Ford OEM spring rate on the front of the Dark Horse with handling package?

According to this article:

MagneRide adaptive dampers with bespoke Dark Horse tuning are standard, as are bigger 33.3-mm front and 24-mm rear sway bars, though the Handling Package gets a solid rear bar for added rigidity. The spring rate is increased as well: the front spring rate is now 34 N/mm up front and 115 in the rear. The Handling Package ups the ante to 37 and 130, respectively, while also adding a redesigned rear spoiler and a bigger front lip for more downforce.

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N/mm. Got it.

So the internet gives me a formula that says the stock spring rate is only 211 #/in on the Handling Package for the Dark Horse. 742 in the rear.

Gunslinger55 said:

Ok great. Kinda what i was thinking. I’ll check out those springs

This kit i assume? Great site with lots of goodies but this with a stiffer sway bar should help a lot

View attachment 109584

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TeeLew said:

That's the kit. He'll sell any spring you want. The 400 puts you back to stock ride height. A 450 puts you about 5mm higher than stock. Either works.

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Does that work with a newer, S650 Dark Horse? It says 18-23 (S550).

Also, if it does work, please note that AJ Hartman says a maximum of 400 #/in. TeeLew is suggesting a range exceeding that, so you may want to check with the vendor prior to ordering stiffer springs.

Might as well do the Vorshlag camber plates at the same time if you are going to do this.

The vendor will tell him the same. And yes, 211 and 740. These were the Mach 1 spring rates as well. Early on, Ford kept stiffening the rear of the car more than the front GT, GT PP, GT350-350R-500 are increasingly more rear spring with minor changes on the front. Clearly, this was someone's favorite hammer in the Vehicle Dynamics department at Ford. With the Mach 1 and now Dark Horse it looks like they've learned just jacking the rear spring up doesn't really do what they want it to.

TeeLew said:

The vendor will tell him the same. And yes, 211 and 740. These were the Mach 1 spring rates as well. Early on, Ford kept stiffening the rear of the car more than the front GT, GT PP, GT350-350R-500 are increasingly more rear spring with minor changes on the front. Clearly, this was someone's favorite hammer in the Vehicle Dynamics department at Ford. With the Mach 1 and now Dark Horse it looks like they've learned just jacking the rear spring up doesn't really do what they want it to.

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I'm sure this spreadsheet has been floating around the internet for a long while now but lines up exactly as you said. All so soft.

Very interesting thanks. So the AJ hartman 400” conversion stiffer than anything on this chart by the looks of it? Do you leave the rest stock
or get a sway bar upgrade? Some go softer bar in the rear from reading on here it seems. In anycase good info

GAR444, thank you for sharing that chart.


If any of you have done this conversion, please tell me three things:


I watched the video on installing it, and it does not look too painful to do.

TeeLew mentioned in an earlier post it wasn’t bad on the street or i should say ride wasn’t terrible. I am not concerned about ride in this car

Junkyard Dog said:

GAR444, thank you for sharing that chart.


If any of you have done this conversion, please tell me three things:

(1) how is it on the street with the 400 #/in springs? That seems like a huge change. ​

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(2) Did this change, alone, reduce lap times, and, if so, by how much? ​

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(3) Did this change significantly reduce the need for so much negative front camber in the car? ​

I watched the video on installing it, and it does not look to painful to do.

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On the front I've run 185 (stock), 220, 275, 450, 500 #/in springs. I've got a pair of 400's in my spring box. Every increase in front spring rate has given a step in performance. If I were tuning this car for Ford, I'd probably have 300's on the front and something like a 600/650 on the rear. If the change seems large, it's because Ford's chassis tuning is analogous to Vehicle Dynamics Malpractice. This would have a nice BMW-ish type of ride and be reasonable on a track. It would also have better traction than anything Ford has ever spit out.

My guess is that someone at the top of the ladder has a pet theory that the front needs to be soft and rear needs to be stiff, most likely to 'reduce understeer.' No one in the department has any real race experience, so they all do as they're told and it produces the sim and magazine numbers they want. There is a reason why so many of these cars end up in ditches. The chassis tuning from the factory is garbage. We are sold a car which has steady-state terminal understeer, but in transients, it has a nasty, unpredictable oversteer entry and exit. When driven like a car should be driven on a track, it's loose on corner entry. I don't care if Multimatic is involved here and there. They're using the same spring rates before and after Multimatic, so the influence can't be that big.

My 220# to 275# front spring was putting a spring rubber in between runs on a test/tune day on a 40 second course. We'd get 3 runs back-to-back, then be off for an hour. My first 2 sessions were learning the course/baseline. I played with pressure and DSC maps through most the day. Mid-afternoon, I put in a front spring rubber, which gave a stiffer spring rate and higher front ride height. The stock to 220# step seemed directionally right, but the car did all the same stuff as stock. It was like going from bubble gum to Play-doh...ya, there's a difference, but does it really matter? When I put the spring rubber in, I immediately picked up 1/2 second on next 3 runs. The biggest difference was more front grip in a long-duration, reducing radius sweeper that had a speed correction in the middle and better transistions in a slalom. I'd drive into the sweeper as deep as I had front to do, make my speed adjustment to pivot the car to the exit and then throttle off. I had more front end to go further into the corner before lifting than before and, when I did, I could keep the rear under me better than before. It was a win/win. With the slalom, I could make quicker inputs and get the car pointed earlier. I never took the spring rubber out for as long as I ran that spring. It was one of those changes that was a very obvious positive.

I'm on the Magneride dampers, so after that, I got a set of the Shelby valved struts and turned them into coil-overs to run any spring I wanted. It's similar to what AJ produced, but I use a threaded collar and can adjust ride height like any normal coil-over. My approach cost a lot more AJ's to make. His more simple approach is better for a sellable product.

My first spring as a coil-over was the 450. I ran that for over a year. It was an 8" spring, though, so I was having wheel/tire interference issues. I bought a 400 & 500 rates on a 6" spring, which eliminates the interference. I put the 500 in and haven't looked back. It's stiffer than a 'civilian' would want, but I like how it drives and it's not racecar stiff. I do think it's probably getting to the upper range of what street car dampers can control. My only complaints are on really rough roads, but around town or on the freeway, it's fine (for me).

Stiffening springs doesn't change the amount of static camber you have to run. I max out at -3.8* and that's what I run. It's a strut. Too much camber isn't really a thing until you start damaging the inner sidewalls of the tires. Springs have a bigger influence to the pitch of the car than the roll. Reducing brake dive by 2.5x and the increase in responsiveness is a big deal.

If I'm looking for negatives other than ride, then the only thing I'd say is that when you drive it in a way which induces understeer, it will understeer. For instance, If I go slow into a freeway on-ramp and then roll to throttle, it will pick up an understeer and the front will be my limiting factor. But, it won't do the big snap-loose. It just understeers to the exit. Having said this, you never drive into a corner like this on a track. You always approach a corner with brakes loading the front end. I use the front 1/2 of the corner when the front is loaded to rotate the car. When driven like this, it has a good front, even if my rear spring is a bit too soft for racetrack duty.

YMMV, but I've encouraged many people to go with AJ's kit. No one has been disappointed with the results. If you just can't live with the 400, then put something in that you can live with...300, 350 or whatever. The stock spring is like being at the South pole. Any direction you go is North.

On that spreadsheet, the Hurst Stage 1 looks interesting. I didn't know that existed. You can also mix and match front from one with the rear from another.

TeeLew said:

On that spreadsheet, the Hurst Stage 1 looks interesting. I didn't know that existed. You can also mix and match front from one with the rear from another.

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That's actually very close to what I run, 650F 1000R, not a daily but still a full interior road car. The fronts line up very close to my 944 track car on a rate per weight ratio. If you are tracking a car i'm sure you don't expect limo ride charactistics, I don't think it's road manners and ride are bad at all. Obviously it's going to bang over potholes etc but we want track manners. My biggest stock complaint was feeling the rear steer as the bushes flexed, that unnervered me. Easy fix with spherical bushes, but noisy / clunky. At least I now know what all the clunks relate too. I'm now back to -4F & -2.75R so really starting over again with where the car is balance wise. Initially the spring package with my ST coil overs was in the 270ish front rate and the nose dive under brakes was massive, wear marks on the fender liners but it was quick on track. I lost camber going to 11s up front but have matched my times from then with about -2 on the front with the 11, I'm sure they will drop again with the camber gain.
Getting @ajhartman rear adjustable spring platforms was key to rear spring options being able to run standard 2.5' race springs. Swap to your heart's content with readily available parts

GAR944 said:

Initially the spring package with my ST coil overs was in the 270ish front rate and the nose dive under brakes was massive, wear marks on the fender liners but it was quick on track. I lost camber going to 11s up front but have matched my times from then with about -2 on the front with the 11, I'm sure they will drop again with the camber gain.

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I thought the coil overs were smaller diameter than the standard strut and spring and made more room for larger tires and increased negative camber? Could you explain for me in a little more detail what happened and what you did to now to give yourself more negative camber?

(PS - forgive me if what I wrote sounds like ignorant gobbledygook. I am just reading and watching videos on how to replace the stock strut with the AJ Hartman coil over and then regurgitating here what I thought I had learned).

Seems like a coil over conversion should give you more room. In any case the AJH kit is reasonable in price.

Junkyard Dog said:

I thought the coil overs were smaller diameter than the standard strut and spring and made more room for larger tires and increased negative camber? Could you explain for me in a little more detail what happened and what you did to now to give yourself more negative camber?

(PS - forgive me if what I wrote sounds like ignorant gobbledygook. I am just reading and watching videos on how to replace the stock strut with the AJ Hartman coil over and then regurgitating here what I thought I had learned).

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I built my own 'coil-over' Shelby Magneride struts. They're completely custom. I use a body off of a 3" King Shock as an outer sleeve. The spring is 3" ID x 6"L. If I lower the spring perch too much, it can contact the tire. That was with the 8" front spring. As it is, I can run about any spring I want and have room to spare. If spring travel were an issue, I could use a tapered spring 3.0 on once side and 2.5 on the other, for another 5mm. It hasn't been an issue.

To get the camber, I have plates, bolts and an offset bushing on the tension link. I can get quite a bit.

@Junkyard Dog
Stock setup has in simple terms "the most clearance with the least adjustability". The photo is a stock 255 on a 9.5R19. Small amount of clearance between strut leg and tyre. Tyre sitting under the stock spring platform.

When compared to our target 305, the 305 would sit slightly closer to the strut leg. 19x11 ET52 to allow front and rear swapping, front with 1' spacer to get correct offset.

Going to an "adjustable coilover" as the stock strut is a "coil over shock absorber assembly". Depending on the spring rate will determine how long the required spring is as the softer the spring the more compression in length before it holds the car up. The more compression requires more length to avoid coil bind, "the spring coils hitting the one adjacent". Not a good thing. Longer spring requires the lower spring platform to be lower on the strut leg which could interfere with the tyre. Worse off than stock. Usually you are going up in spring rate and can step down in spring length and keep the lower spring platform above the tyre just like stock.


The benefit of an aftermarket strut is they usually come with a slotted upper hole for the knuckle bolts and the ability to run standard race springs of any rate. This allows us to add camber by angling the knuckle relative to the strut. With a narrow tyre we can also space the wheel out with the addition of longer studs and get maximum camber adjustment at this point.
With a 1' spacer the stock arrangement has way more room to be cambered at the hub compared to the 305.


Certain strut manufacturers also have the option of spacing the mounting holes further out to allow more clearance for larger width rims.
Excerpt from Apex Wheels




Where there is no adjustment on a standard strut the upper hole can be filed to a slot like an aftermarket version or camber bolts used which have an offset shaft. Small amount of camber gain with the wide rim.
This is all relatively easy because i don't have magnaride and can swap struts to my hearts content.
Maximum total camber then becomes what can be gained at the top of the strut tower with camber plates plus what achieved at the knuckle.
I got mine back as previously mentioned by going all out on the strut top.
FP350s/GT4 style camber plates.
As you push the limits of size EVERYTHING must be taken into account as clearances get smaller and smaller. Look long term where you want to end up first.