TeeLew
Well-Known Member
- Thread starter
- #1
Here is a little documentation on the what and why of my spring changes and choices.
-------------------------------------------------------------------------------
TL;DR
Iāve played around with springs a bit and would like to share what Iāve found. None of these choices were made based off calculations, just my feel, which is suspect at best.
First, the car is an Eco HPP, which means Iām a little lighter on the nose than a V8 car, but I donāt think this appreciably changes anything Iāve found. The other caveat I have is that itās on the Magneride dampers. If anyone can use this info, great. If you have any questions, Iāll try to answer. Mostly, itās just for general information.
I think these cars start out at the ānormalā PP spring rates (I've never seen for certain), which are 165 #/in on the front and 728 #/in on the rear. I didnāt drive it long on these rates, but I felt that the front felt significantly softer than the rear. I picked up a set of Vogtland springs, which were 220 #/in on the front and 880 #/in on the rear. I installed the fronts, but the rears werenāt for a Mag car, so I had to stick with the stock rear springs. This meant the car had the front ride dropped about 25mm with the stock rear ride height. Even with the slightly stiffer front spring, the car was *very* loose in the Auto-X I did this way, particularly on corner entry. Iād get an early over-rotation and then it was just a balancing act to corner exit. I was not particularly fast.
I knew that rear spring options were going to be an issue, so I installed Mike Maierās rear spring weight jacker kit so I could choose whatever I wanted. I borrowed a pair of 2.5x5ā ā 950 #/in rears to start. I like using the longest spring I can for any given application, and this was a little short, but I used them anyway, because it allowed me to drop the rear ride. With these rear springs, the tail of the car felt a lot stiffer and lacked a bit of grip from middle-out, but lowering the rear ride height allowed for much more stable entry characteristics. I donāt think the rate improved the car nearly as much as the lower ride height. I ended up buying the same rate as a 6ā spring and ran that for a while. At this point, my 4-banger was reasonably competitive with the other Mustangs in CAM-C in my area, so it couldnāt have been too bad. About this time that I really started tuning the DSC controller for the Magneride, so a lot of my track time was centered around that tuning.
Prior to a test/tune day, I installed a 20mm rear anti-roll bar (was 24mm factory) to help with corner exit rear grip. During this day, the car was still loose pretty much all the time, but it was easy to over-drive the front as well. About 2/3rds of the way through the day, I installed a polyurethane spring rubber in the front spring. This raised my front ride height about 10mm and stiffened the spring from a 220 to somewhere in the region of 280-300 #/in. I went about a second faster on the very next run and maintained that time gain the rest of the day. It was a big gain and that gain came primarily on the front of the car. The stiffer front had a lot better response and would accept load in a way which the softer rate would not. STIFFENING THE FRONT SPRING DID NOT INCREASE UNDERSTEER.
So, I was a little skeptical about the rear spring rate at this point. Maier told me that he runs very stiff on the rear of his car (well over 1000 #/in), but there was nothing I felt that was pushing me in that direction, so I decided to drop it 100# as see what that did. At the same time, I installed the Hyperco hydraulic spring perches to reduce the bind the spring sees. I dropped the rate to 850 #/in, but I did so with a 7ā spring. The combination of a longer spring and the fancy spring perch meant the rear was a little too far in the air again. I drove this combo for quite a while. I tuned the DSC on it, but for ānormalā driving, I use the stock Mag controller. I can make the DSC go significantly faster than the Ford tuning on the track, but I canāt match the stock Ford ride characteristics. Theyāve got that part pretty dialed. I had an Auto-X outing which was complete crap for various reasons, none of which had anything to do with chassis tuning, but it did mean that I never got a really proper track evaluation. After driving it on the street in this form, though, I came to understand it.
The biggest issue with the 280/850 combo was loading the front of the car. It was still difficult to load the front of the car appropriately. I had to turn into corners relatively early and with slow hands because I couldnāt turn the steering wheel at the rate I wanted. If I turned in slow and early, Iād keep the car gripped up, but Iād arrive at the apex with too much turning left to do, wash the front and get the rear loose on power (which was a product of the mid-corner understeer). If I turned in later and with more aggression, Iād lose the rear early in the corner. That front spring rubber had helped this about 25%, but I was going to need more.
At this point, I had to make a decision. I could use race springs on the back of the car, but the front was restricted to OEM style springs. I needed coil-overs, but I wanted to stick with the MR suspension. Thatās when I got the idea of converting Magneride struts to coil-overs. Tractive is a company that produces very nice MR racing dampers, but they were out of my price range. What I was able to do buy the Shelby 350R struts, which have about double the damping forces of the standard Mag struts (which is on every other model, even if the programming varies). I knew I wanted to throw some spring rate at the car and this was only going to happen if I could match the rate with additional damping. So starting with these struts, I made a pair of coil-over which accepts a 3ā ID springs. I wanted to use 2.5ā ID springs, but the Mag struts are just a little too big in diameter to accept those. Anyway, 3ā ID springs do kind of limit my choices, but itās really not that big of a deal.
With the coil-overs built, now was time to put it on the car. I knew based on the front spring I was using that I wanted a big step stiffer, so I went up 50+% to a 450 #/in spring on the front. As usual, I tried to use too long a spring (8ā) and got bit. The front ride height is OK, but unless Iām running big wheel spacers, the inside of the tire makes contact with the lower spring perch. So, all I should have to do here is use a shorter spring (6ā) which will allow me to move the spring perch out of the way of the tire. The problem there is they only had a 400 or a 500 in stock. There was no 450 available. Which will it be? Why stop at Chicago on your way to New York? I got the 500. As of right now, I havenāt installed these. Mostly because I like the 450ās, but think an extra 10% stiffer might be a little much.
Remember, at the time I changed the front spring, the rear was at 850 #/in. I drove the car only a couple hundred miles that way. The 450ās on the front has really quickened up the front end of the car and I wanted to get the rear ride lower so it wasnāt so quick on the front. I also wanted to soften the rear a little as the 850ās still felt stiff to me. So I put in 2.5x6in 750# springs. A false start with an unnecessary tender spring aside, this allowed me to lower the rear ride a little over an inch. The ride is improved with the softer rate and so is on-throttle rear grip.
Handling-wise, itās a little hard for me to give you great feedback, because I havenāt been in any competitive scenario; itās all subjective. The biggest change is the front end response. Iām not talking about a twitchy on-center feel, but more of a thing where follows my hands at the rate I really want to turn the wheel. When I would try to ask too much of the softer front end, it kind of used to trip over its own feet like if you were to try and turn a tricycle quickly. Now the front is able to respond at a quicker rate which allows me to turn a little later into some corners and combine loads without upsetting the car. My real issue here for evaluation is that I think it feels pretty good, but I canāt promise itās faster. The reduction in brake dive alone has to be a gain. Is there any more understeer than before? Not that I can feel during city/highway driving. I have corners which I regularly hustle the car through. Initially, I took those corners a little cautiously, but now Iām starting to explore it a little. The car feels pretty stuck.
The Shelby 350R damping with the stock controller works surprisingly well with 450#/in front springs. Itās a hodge-podge, but it works. I havenāt played with the DSC controller, yet. I would say that these are good enough that I think any Magneride owner that just wants to run stiffer OEM-style springs should buy these. This extra damping feels like how they should have made them all.
Thereās been all sorts of talk about choosing springs via the flat-ride concept on this board. Iāve said that I donāt use this concept to choose spring rates and, clearly, these choices demonstrate that. Iāve got probably 1500 miles on the 450/750 combo. I was on one road for a couple miles which I kind of felt a little of the pitchy ride thing, but that was a POS road and no performance car would have felt particularly good on it. I know my choices run completely counter to the conventional wisdom here. It could be that Iām wrong and, if so, Iāll change it. For now, though, Iām just going to go off my feel for the car and see where that leads me. I can tell you that Iād be a little more apprehensive if I didnāt watch the Runoffs from Indy. The Mustang winners there seemed to have a similar approach. At the very least, the group here knows I put my money where my mouth is and it doesnāt hurt to have someone sail past the āThar Be Dragonsā sign on the map from time to time.
-------------------------------------------------------------------------------
TL;DR
- I have tried several spring packages. 165/220/~280/450 have all been used on the front and 728/750/850/950 have all been used on the rear. Present combo of 450 front and 750 rear feels promising, but has not seen an autocross for a real evaluation.
- Rear ride height is a big tuning tool. Specifically, if itās too high itās common to experience corner entry instability/oversteer which is detrimental to carrying speed into a corner.
- Raising the front spring rate has not seemed to increase understeer and has perhaps reduced it through increased responsiveness and a better overall chassis stability.
- Reducing the rear spring rate seems to have improved forward tire grip and ride quality.
- At this point, I tend to think that most of the ācannedā spring packages available right now are too soft on the front and too stiff on the rear.
- If concerned about performance with OEM style springs, I think the front springs from BMR (300 #/in) or Steeda (350#/in) are the best choices.
- At this point, I donāt see it mandatory to be over about 800 #/in on the rear spring and I see stiffnesses over about 1000 #/in as a detriment, at least on anything even resembling a street tire.
- If you have the Magneride suspension, get the Shelby GT350R shocks and struts. Their higher damping forces works surprisingly well with stiffer springs, even if youāre just using the stock damper controller.
Iāve played around with springs a bit and would like to share what Iāve found. None of these choices were made based off calculations, just my feel, which is suspect at best.
First, the car is an Eco HPP, which means Iām a little lighter on the nose than a V8 car, but I donāt think this appreciably changes anything Iāve found. The other caveat I have is that itās on the Magneride dampers. If anyone can use this info, great. If you have any questions, Iāll try to answer. Mostly, itās just for general information.
I think these cars start out at the ānormalā PP spring rates (I've never seen for certain), which are 165 #/in on the front and 728 #/in on the rear. I didnāt drive it long on these rates, but I felt that the front felt significantly softer than the rear. I picked up a set of Vogtland springs, which were 220 #/in on the front and 880 #/in on the rear. I installed the fronts, but the rears werenāt for a Mag car, so I had to stick with the stock rear springs. This meant the car had the front ride dropped about 25mm with the stock rear ride height. Even with the slightly stiffer front spring, the car was *very* loose in the Auto-X I did this way, particularly on corner entry. Iād get an early over-rotation and then it was just a balancing act to corner exit. I was not particularly fast.
I knew that rear spring options were going to be an issue, so I installed Mike Maierās rear spring weight jacker kit so I could choose whatever I wanted. I borrowed a pair of 2.5x5ā ā 950 #/in rears to start. I like using the longest spring I can for any given application, and this was a little short, but I used them anyway, because it allowed me to drop the rear ride. With these rear springs, the tail of the car felt a lot stiffer and lacked a bit of grip from middle-out, but lowering the rear ride height allowed for much more stable entry characteristics. I donāt think the rate improved the car nearly as much as the lower ride height. I ended up buying the same rate as a 6ā spring and ran that for a while. At this point, my 4-banger was reasonably competitive with the other Mustangs in CAM-C in my area, so it couldnāt have been too bad. About this time that I really started tuning the DSC controller for the Magneride, so a lot of my track time was centered around that tuning.
Prior to a test/tune day, I installed a 20mm rear anti-roll bar (was 24mm factory) to help with corner exit rear grip. During this day, the car was still loose pretty much all the time, but it was easy to over-drive the front as well. About 2/3rds of the way through the day, I installed a polyurethane spring rubber in the front spring. This raised my front ride height about 10mm and stiffened the spring from a 220 to somewhere in the region of 280-300 #/in. I went about a second faster on the very next run and maintained that time gain the rest of the day. It was a big gain and that gain came primarily on the front of the car. The stiffer front had a lot better response and would accept load in a way which the softer rate would not. STIFFENING THE FRONT SPRING DID NOT INCREASE UNDERSTEER.
So, I was a little skeptical about the rear spring rate at this point. Maier told me that he runs very stiff on the rear of his car (well over 1000 #/in), but there was nothing I felt that was pushing me in that direction, so I decided to drop it 100# as see what that did. At the same time, I installed the Hyperco hydraulic spring perches to reduce the bind the spring sees. I dropped the rate to 850 #/in, but I did so with a 7ā spring. The combination of a longer spring and the fancy spring perch meant the rear was a little too far in the air again. I drove this combo for quite a while. I tuned the DSC on it, but for ānormalā driving, I use the stock Mag controller. I can make the DSC go significantly faster than the Ford tuning on the track, but I canāt match the stock Ford ride characteristics. Theyāve got that part pretty dialed. I had an Auto-X outing which was complete crap for various reasons, none of which had anything to do with chassis tuning, but it did mean that I never got a really proper track evaluation. After driving it on the street in this form, though, I came to understand it.
The biggest issue with the 280/850 combo was loading the front of the car. It was still difficult to load the front of the car appropriately. I had to turn into corners relatively early and with slow hands because I couldnāt turn the steering wheel at the rate I wanted. If I turned in slow and early, Iād keep the car gripped up, but Iād arrive at the apex with too much turning left to do, wash the front and get the rear loose on power (which was a product of the mid-corner understeer). If I turned in later and with more aggression, Iād lose the rear early in the corner. That front spring rubber had helped this about 25%, but I was going to need more.
At this point, I had to make a decision. I could use race springs on the back of the car, but the front was restricted to OEM style springs. I needed coil-overs, but I wanted to stick with the MR suspension. Thatās when I got the idea of converting Magneride struts to coil-overs. Tractive is a company that produces very nice MR racing dampers, but they were out of my price range. What I was able to do buy the Shelby 350R struts, which have about double the damping forces of the standard Mag struts (which is on every other model, even if the programming varies). I knew I wanted to throw some spring rate at the car and this was only going to happen if I could match the rate with additional damping. So starting with these struts, I made a pair of coil-over which accepts a 3ā ID springs. I wanted to use 2.5ā ID springs, but the Mag struts are just a little too big in diameter to accept those. Anyway, 3ā ID springs do kind of limit my choices, but itās really not that big of a deal.
With the coil-overs built, now was time to put it on the car. I knew based on the front spring I was using that I wanted a big step stiffer, so I went up 50+% to a 450 #/in spring on the front. As usual, I tried to use too long a spring (8ā) and got bit. The front ride height is OK, but unless Iām running big wheel spacers, the inside of the tire makes contact with the lower spring perch. So, all I should have to do here is use a shorter spring (6ā) which will allow me to move the spring perch out of the way of the tire. The problem there is they only had a 400 or a 500 in stock. There was no 450 available. Which will it be? Why stop at Chicago on your way to New York? I got the 500. As of right now, I havenāt installed these. Mostly because I like the 450ās, but think an extra 10% stiffer might be a little much.
Remember, at the time I changed the front spring, the rear was at 850 #/in. I drove the car only a couple hundred miles that way. The 450ās on the front has really quickened up the front end of the car and I wanted to get the rear ride lower so it wasnāt so quick on the front. I also wanted to soften the rear a little as the 850ās still felt stiff to me. So I put in 2.5x6in 750# springs. A false start with an unnecessary tender spring aside, this allowed me to lower the rear ride a little over an inch. The ride is improved with the softer rate and so is on-throttle rear grip.
Handling-wise, itās a little hard for me to give you great feedback, because I havenāt been in any competitive scenario; itās all subjective. The biggest change is the front end response. Iām not talking about a twitchy on-center feel, but more of a thing where follows my hands at the rate I really want to turn the wheel. When I would try to ask too much of the softer front end, it kind of used to trip over its own feet like if you were to try and turn a tricycle quickly. Now the front is able to respond at a quicker rate which allows me to turn a little later into some corners and combine loads without upsetting the car. My real issue here for evaluation is that I think it feels pretty good, but I canāt promise itās faster. The reduction in brake dive alone has to be a gain. Is there any more understeer than before? Not that I can feel during city/highway driving. I have corners which I regularly hustle the car through. Initially, I took those corners a little cautiously, but now Iām starting to explore it a little. The car feels pretty stuck.
The Shelby 350R damping with the stock controller works surprisingly well with 450#/in front springs. Itās a hodge-podge, but it works. I havenāt played with the DSC controller, yet. I would say that these are good enough that I think any Magneride owner that just wants to run stiffer OEM-style springs should buy these. This extra damping feels like how they should have made them all.
Thereās been all sorts of talk about choosing springs via the flat-ride concept on this board. Iāve said that I donāt use this concept to choose spring rates and, clearly, these choices demonstrate that. Iāve got probably 1500 miles on the 450/750 combo. I was on one road for a couple miles which I kind of felt a little of the pitchy ride thing, but that was a POS road and no performance car would have felt particularly good on it. I know my choices run completely counter to the conventional wisdom here. It could be that Iām wrong and, if so, Iāll change it. For now, though, Iām just going to go off my feel for the car and see where that leads me. I can tell you that Iād be a little more apprehensive if I didnāt watch the Runoffs from Indy. The Mustang winners there seemed to have a similar approach. At the very least, the group here knows I put my money where my mouth is and it doesnāt hurt to have someone sail past the āThar Be Dragonsā sign on the map from time to time.
Sponsored
