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Suspension soft?

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The Shelby Magneride dampers are key to the whole thing. Without these, you don't have enough damping to control anything over about 300 #/in. Adding spring without the necessary damping doesn't work nearly as well. I think the Magneride Shelby dampers are about topped out with the 500#/in spring. I

So you are saying that increasing the stock spring rate is pointless in my Dark Horse with the stock Magneride?

BTW, the rear spring rate is 742 from the factory.
 
For the S550, there were two versions of dampers used on the Magneride car, The Shelby GT350R & GT500 got a 'high-force' damper and everyone else got 'normal.' When you use the normal damper controller with the higher force Shelby dampers, then you get a combo which feels like BMW damping.

The Dark Horse dampers are supposed to be the best yet in terms of what they do, but I don't know what actual forces they make, so it's tough for me to comment on what they can or can't match on spring.

This puts you down the road of an aftermarket controller. Ultimately, I guess I need to make one. That's a little easier said than done.
 
I have the GT500 dampers on my car now with 240F/850R FP springs, and have been very happy with this setup as a comfortable street and casual track day car. These spring rates are also similar/better than the GT350R, so I would consider it prime ford spec.

As of last month I now have an AJ hartman kit sitting in a box in my garage ready to install. Currently have 400 front and 1100 rear springs with my AJ kit.

As an alternative and a way to save you many hundreds of dollars, I have a friend who is selling his brand new, unused Ground Control coilover conversion kit with 400/1200 eibach springs(helper springs included). I would have bought from him instead of the AJ kit had I known he had an extra spare kit available. His price is $500 for brand new and unused GC coilover kit, and thats considerably less than the AJ kit, plus it's very easy height adjustability like a traditional coilover system instead of shims. That is a HUGE plus in my opinion.

EDIT: You will have to modify the stock struts with the Ground control kit.

1776209551255.jpeg

Here is the website to ground control coilover kit: https://groundcontrolstore.com/coll.../2015-mustang-s550-adjustable-ride-height-kit
 
Cool didn’t know anyone else made one. What are the helper springs for? Does it have a threaded perch for ride height?
 
Cool didn’t know anyone else made one. What are the helper springs for? Does it have a threaded perch for ride height?
Yes, I believe it has a threaded perch for ride height, just like a traditional coilover. This is a huge pull for me personally.

The primary purpose of the helper spring is to keep the main spring properly seated against the suspension upper or lower spring seat. This becomes particularly important when weight is taken off one or more corners of the vehicle. This is common when going into driveways or inclines at an angle. Typically, one corner will extend, or droop, and the helper spring will expand to hold the main spring in position. The helper spring does not affect total spring rate.
 
Got it makes sense. These springs must be more prone to falling out. That’s a cool deal as far as ride height. How hard is the strut modification?
 
Got it makes sense. These springs must be more prone to falling out. That’s a cool deal as far as ride height. How hard is the strut modification?

It is my understanding that the helper springs are nearly always fully compressed unless load is fully removed and/or suspension is fully drooped. Main springs would be prone to falling out without a helper spring to secure it in place.

I've never installed them, but Trent Musser, a mustang specialist out at sonoma raceway can modify it without issue. I believe its just trimming the metal OEM spring base around the strut.

Which camber plates do you have?
 
It is my understanding that the helper springs are nearly always fully compressed unless load is fully removed and/or suspension is fully drooped. Main springs would be prone to falling out without a helper spring to secure it in place.

I've never installed them, but Trent Musser, a mustang specialist out at sonoma raceway can modify it without issue. I believe its just trimming the metal OEM spring base around the strut.

Which camber plates do you have?
Depends on the spring. There are "zero" rate helpers that do fully compress when the car is on the ground but keep the main spring in position when the car is elevated or if it gets air on track. These do not impact the overall rate. There are also weighted helper springs that create a progressive rate depending on load. They can be had from 100 lb/in to 400 lb/in and free height is usually 3 inches.
 
With weight on the car they fully compress and become a solid spacer when using the very light spring weight ones as shown in the kit from @Rodpwnz
Just see the layers of compressed helper spring at the top in the photo below. As we have mentioned before, as spring rate goes up you can get away with a shorter narrow diameter spring which gets the lower spring plate above the tyre again for max clearance. As everyone has mentioned they become fully floating when the suspension goes into full droop so the secondary spring keeps that in check.
IMG_20240404_211152831.jpg
Same springs as i run. Mine are 600F 1100R
2024-04-04 13.45.55.jpg
AJ's rear setup look like this installed. Well with the rear spring more captive as my cradle was hanging in these photos.
You have to clean up the lower arm casting to get a flat mounting surface for the adjuster base.
2024-04-28 16.22.17.jpg2024-04-27 13.18.23.jpg
Just confirm that the kit for sale is for magnaride. I think it is as the photos show the lower adapters to be 2 different directions. Different lower mounting arrangement to AJ's. My understanding is the stock coil springs wind opposite direction between left and right on magnaride arms. I'm sure someone will confirm.
 
Second thing first: Unless you're running GT3 car in big-boy racing, if you're driving a Mustang at the track, you're the broke guy in the crowd. That's just how it goes. If you even think you have money, you're in a different car. That's just reality. "Stop being poor" would be great advice for any of us.

On to springs. If I were a chassis guy for Ford, I'd have chosen something like 300/550 for the base GT. If you want a good dual purpose compromise, the 400 front is a good start, but you'll want more front spring if you spend more time on the track. I feel like the stiffer front gets over a lot of bumps better because of the reduced travel. Stock spring rates are less comfortable to me because the damn thing moves too much. I have a bigger problem with rear rates going up than front for ride.

I feel like the stock rear spring rate is what controlled the entire setup at Ford. It feels like to me that the rear spring stiffness was as stiff as the engineers felt they could go for each model and maintain whatever ride metrics they use. The base model should be on a 550 rear. PP, maybe 650? Keep in mind, this is with the stiffer front. You could keep the overall stiffness level about where it is and proportion it to the front. I know what they're trying to do, but it works a lot better on the computer screen than the street or track.

If you run a 400 front and a stock rear, I think you'll have a good street/track comprise. The advantage of AJ's kit with a 750 over stock (same basic rate) is being able to adjust rear ride height. That's a very powerful tuning tool.

The Shelby Magneride dampers are key to the whole thing. Without these, you don't have enough damping to control anything over about 300 #/in. Adding spring without the necessary damping doesn't work nearly as well. I think the Magneride Shelby dampers are about topped out with the 500#/in spring. If I go stiffer, it has to be on a real damper. They are not designed in a way to give high enough damping forces with small piston motion. I think that's an issue with the passive cars, too. They don't have dampers which will really control the stiffness they need without spending some cash. All the 'sport' type dampers are limited by architecture as much as the actual valving.

So there's my guess 400/750.


P.S. The bullish!t spring differences that Ford made from model to model tells me they aren't great on car tuning. They have these 10-20#/in steps that are just meaningless, especially considering how far out of the performance window they were. If someone told me they wanted a 10#/in spring change at the track, I'd laugh at them. FFS, we're talking about a 2-ton car, not a 1/4 midget.

Tomorrow, I am having AJ's front conversion kit put on the car with 400lb spring rate. I currently have FP M-5300-W with 250lb spring rate so it will be interesting to see the difference. The car is on shelby GT500 Magneride dampers with OEM PP1 magneride tuning. For now, I am not changing anything else suspension wise on the car except slightly more front camber(-2.3 to -2.75). Later on, I plan to eventually install the rear AJ kit too once I figure out if I need more rear spring rate or less than the current 850lb(I will refer with feedback to the experts here on what I've felt after next HPDE). The AJ kit also allows me to adjust front/rear ride height because the car is raked as it sits, and I want the car to sit flat with neutral rake - this is because I superficially like the way flat looks better and more importantly, others here and Kenny Brown have stated its better for S550 platform.

To be honest, I am still a bit unsure about how front 400lb spring rate will feel, especially since I am on PP1 OEM magneride tune. I may feel a bit more sure if I had the DSC, but thats another $1000+ and potential world of headache/tuning to deal with. I also want to maintain or improve road ride ability if possible and I've heard DSC sport cannot accomplish that, and is even worse than ford street tuning. Ford street tuning, much like you feel Teelew, I feel like I am bouncing and rebounding around everywhere without enough damping.

Tomorrow I'm also installing OPmustang front hubs with extended studs, DSUNO pads and DBA slotted rotors up front too(upgrade from OEM front). Rears will stay OEM rotors and pads. I am planning on running 19x11 with 305/30r19 square Yoko AD09 for next track day compared to the 275/40r19 square Conti ECS02 I've run the last few HPDE. I hope to make it to SCCA TNIA June 18th at Thunderhill.
 
Tomorrow, I am having AJ's front conversion kit put on the car with 400lb spring rate. I currently have FP M-5300-W with 250lb spring rate so it will be interesting to see the difference. The car is on shelby GT500 Magneride dampers with OEM PP1 magneride tuning. For now, I am not changing anything else suspension wise on the car except slightly more front camber(-2.3 to -2.75). Later on, I plan to eventually install the rear AJ kit too once I figure out if I need more rear spring rate or less than the current 850lb(I will refer with feedback to the experts here on what I've felt after next HPDE). The AJ kit also allows me to adjust front/rear ride height because the car is raked as it sits, and I want the car to sit flat with neutral rake - this is because I superficially like the way flat looks better and more importantly, others here and Kenny Brown have stated its better for S550 platform.

To be honest, I am still a bit unsure about how front 400lb spring rate will feel, especially since I am on PP1 OEM magneride tune. I may feel a bit more sure if I had the DSC, but thats another $1000+ and potential world of headache/tuning to deal with. I also want to maintain or improve road ride ability if possible and I've heard DSC sport cannot accomplish that, and is even worse than ford street tuning. Ford street tuning, much like you feel Teelew, I feel like I am bouncing and rebounding around everywhere without enough damping.

Tomorrow I'm also installing OPmustang front hubs with extended studs, DSUNO pads and DBA slotted rotors up front too(upgrade from OEM front). Rears will stay OEM rotors and pads. I am planning on running 19x11 with 305/30r19 square Yoko AD09 for next track day compared to the 275/40r19 square Conti ECS02 I've run the last few HPDE. I hope to make it to SCCA TNIA June 18th at Thunderhill.

Please report back on how it is. I have been interested in AJ's magneride front conversion kit, and I am curious how much the front springs change things, both on track and driving on the street.

As for the DSC, can you install it for the track and take it out for the street?
 
Please report back on how it is. I have been interested in AJ's magneride front conversion kit, and I am curious how much the front springs change things, both on track and driving on the street.

As for the DSC, can you install it for the track and take it out for the street?
I will report back with details on install if I can, and on how the 400lb springs compare to the 250 front.

As for DSC install/removal, it sits behind the trunk subwoofer. I’ve replaced my rear taillight so accessing the DSC area takes 15-20 minutes iirc. Not too bad, but I think most keep the DSC in there 24/7 for street and track without swapping.
 
I will report back with details on install if I can, and on how the 400lb springs compare to the 250 front.

As for DSC install/removal, it sits behind the trunk subwoofer. I’ve replaced my rear taillight so accessing the DSC area takes 15-20 minutes iirc. Not too bad, but I think most keep the DSC in there 24/7 for street and track without swapping.
If you don't like it, allow me to apologize in advance, but you'll like it. The Shelby dampers and the PP1 tuning works well together. A DSC will never be as good on the street as the Ford controller. It can be better on the track.

Lowering the rear is a good thing, but do it before you get an alignment, because it will throw camber and toe off when you drop the rear.
 

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