Correct me if I am wrong but aren't you running a square setup....?

You just posted exactly what I am trying to do..... I have already chosen the dampers (hint they are the stock ones.....). Now I am looking for a spring that improves performance and also lowers the car compared to stock. I will also be putting in some different bushings throughout the car so the spring selection will reflect that change. I will fine tune it with adjustable swaybars and endlinks...

If I am in left field in my suspension planning please let me know!

 

Yup... and once I get it dialed in (stock dampers, and springs (don't have to tune those) and swaybars, it will rock.

Once I change the dampers and springs (ride height as well), it will all have to be dialed in again. But that's what I enjoy.

Not in the nose-bleeds, but be forewarned that the stock dampers are designed to work under a prescribed spring rate over a prescribed range of travel. If you increase the spring rate, the dampers most likely will not keep up. If you decrease the ride height, the dampers will not have the same range of travel. All of these can lead to less than desirable handling characteristics.

Shorter springs require shortened dampers to maintain the same travel. Stiffer springs require higher damper rates to maintain the same ride quality.

 

I thought it was dialed in from the factory?

 

Hopefully this is not a hijack, as I feel it is relevant to the selection of springs.

I'm wondering if this is purely a shock control issue. One thing I've wondered about with the stock spring rates is how mismatched they are front to rear.

Specifically, the fronts are much softer relative to the weight on the front wheels than the back.

This means that the natural frequency of the front suspension will be significantly lower than the natural frequency of the rear suspension.

I think this may be contributing to what you're feeling.

For any of the experts on this forum: Why would Ford tune their suspension this way? Aftermarket springs seem to be considerably harder in front relative to the rear - Not to the point of matching the rear (primarily due to the larger amount of weight on the front wheels), but at least getting much closer.

Here's a reference I found from the internet: ". . . there is a good reason not to have equal frequencies. The inputs are experienced at the front wheel and then some time later at the rear. If you have equal frequencies then there will be mismatch in the phase of the damped curves, driven by the velocity of the car and the wheelbase length. This will force a pitching motion. To avoid this, the rear frequency is generally higher by some multiple of the front. Guideline values from Olney, Milliken, and SAE references support a range of 1.2 to 1.3 times the front frequency to achieve a flat ride." (from: http://www.timskelton.com/lightning/...on/springs.htm)

 

The spring rated on the fron of the Boss are really soft...hence why the front sway bar is bound or preloaded to make up for the rate... whers Sam Strano when you need him?


BTW I am working on JRZ's for mine...I loved them on my SM STi

 

Huh front sway bars are not preloaded or bound up. If they are you have a problem. Lowering live axel cars also entail adj panhard rod or watts type linkage to center axel and also you will need to adj pinion angle.

Peter

 

Has anybody actually measured the spring rates on their Boss? I have not I have measured the actual spring rates of a bunch of stock Mustang and aftermarket springs and not one set had lighter springs on the front. I also asked Rehagen racing and they said the quoted spring rates for the Boss was a typo that the stiffer spring was in the front and the softer spring in the back. If you tell me you actually put them on the scale and press and measured them yourself I'll believe if you quote some press release from some advertising hack at Ford I won't.

 

I haven't. What were the rates that you actually measured and from which year Mustangs? Were they McPherson strut Mustangs?

The aftermarket springs are definitely quoting higher rates in the front, which is what seems strange to me.

Here's a table of spring rates quoted for all of the current versions - they're very consistently quoting the higher rates in the rear (since it appears that they did a separate interview of various Ford Engineers, I'm assuming that this is separate corroboration from the spec sheet):

From: http://www.mustang50magazine.com/tec...2/viewall.html

This post corroborates the base mustang spring rates (see point #5): http://www.sccaforums.com/forums/for...e/posts#396690

 

Ulrich, I have to say thanks for the tech on suspension frequency. Very informative.

Tob

 

Peter, I hear what you're saying and agree (previous page's posts). Not knowing Adam's level of experience with suspensions, I wanted to warn him about how complex and expensive it can get to get a car well set up after merely changing one component of the suspension. Completely agree that the car is not track perfect, otherwise it would likely be a beast to drive on the street.
Mark

 

The front will stay the same height. The rear will come down about an inch so the car will be more level.

 

I don't have the info at hand. I'll see if I can dig it up.

Here is what I was told.
"Dean from Rehagen says "I have not seen the specs you're talking about, but the front rates should be close to double the rear. The Boss 302S car is going to be something close to 500 front, 325 rear."

I say that Ford mixed up the spring rates in the Boss supplement. 26nm is 148pound/inch which is slightly higher than 142pounds/inch of the stock rear and far less than the stock front. 32.4nm converts to 185 pounds/inch which is slightly higher than the stock front 165pounds/inch. For the LS they lowered the rear to 24nm or 137pounds/inch which is even less than stock. But raised the front to 33.5nm or 181pounds/inch. Swapping heavier springs to back makes no sense and is not what they did."

 

Peter - Not to disagree with you, but the swaybar on my Boss was in fact bound up in the stock bushings. I noted it when I installed my camber plates and again when I replaced the front sway bar with a strano unit. Heck, I think they glued the bushings to the bar as I can't even move them now that it's off the car.

I actually asked this of Todd when we were at Hastings... didn't really get an answer, but if you think about it, that's one way to increase front spring rate.

*Note: If you order a strano bar, you end up talking to Sam... and he'll also note that the boss 302's he's worked on also had the front bars in bind.

 

It is... for a staggered wheel setup. I went and jacked it up with a square setup. I can barely back out of the driveway without snap-oversteering into my neighbor's yard

 

Exactly. Then you have to ask yourself, what's the gain versus the compromised ride quality/streetability. The Boss is so well setup that I'm guessing the incremental gains of changing the suspension are going to be small. To get those gains, you're going to spend a lot of $$$$$$$$ and have a lot of before getting it all sorted out. I for one am going to be happy with the added camber, better brake pads/rotors, wheels and tires and TracKey for now. I wouldn't be surprised if Ford Racing doesn't come out with a well sorted out option for upgrading the suspension at some point that's been tested and proven to work. Great topic though!

 

LMAO

 

You forgot to add "spinning off into oblivion"

 

I wasn't going fast enough as my backing skilz don't permit me to reach 'oblivion' speed limits

 

My experience and knowledge seems to be a lot less compared to some of these guys based on their posts... I guess I find it hard to believe that all these "great and knowledgeable" companies would sell a lowering spring that is advertised to do everything that they are said to do, but in reality may do the opposite and wear out other items in the suspension prematurely....

For me this car is turning more into a track car. Ride quality is not the number one priority. However I don't want to be driving around in bulldozer.......

Yes the stock suspension is good. I think the general handling characteristics and feel of the car is great! However the performance could be better for an often tracked car and that is an obvious statement. Look at all of us that track the car often and we are changing stuff already. From simple caster camber plates and doing a square setup, to a full coilover setup.

I am not talking about going crazy. I just want to lower the car, have a little less body roll, and produce more grip. All with some simple changes and adjustments. Is that to much to ask.... Wouldn't a spring, swaybar, endlink, bushings, and adjustable panhard bar package meet these requirements? If need be throw in a better single or double adjustable damper in there..... This is nothing more than what every other platform sees or what is done to most track oriented cars. Is it really that complicated????

 

I have known Sam for years from autox when we ran the GT3 in SS. If the front bars are bound up that is still a bad thing and something that needs to be corrected. If it was designed that way then shame on Ford. Guess that is another thing I will need to add to the list.

Peter