azrampage

OK, I've tried the Vogtland springs more than a few times in an autocross events (STX class, I keep very good records), and found them to be .......inadequate. I'm seeing no significant (if any) improvement in times over stock springs (2007 Pony Pkg). Along with the Vogtland springs, I also have an Eaton limited slip, camber bolts, Steeda intake with Brenspeed tune, adjustable PHB and Steeda/Strano sway bars F/R.

Problem seems to be the abruptness with which the progressive springs seem to take effect; like when they kick in it is enough to upset the balance mid-corner. Fine for the street and daily driving, not good for serious autocross. NOT a smooth transition IMO.

Being a penny-pincher, I don't want to go to coil-overs, but would like a competitive set of linear springs that have significantly higher spring rates. All I see that looks close to that is the Steeda race springs, and even then the rates seem a little soft. That, and Sam says that they typically sit a little high in front.

I'm puzzled with the popularity of 05+ Mustangs that there isn't a better selection of aftermarket autocross/race springs that are directed at the competitive crowd, and not the "I want to lower my car so it looks good" crowd.

I suspect that many Mustangs that are road-raced with different sanctioning bodies nationally are limited to original seat springs; surely not all have to go to coil overs.

So where can I find such springs? Anyone out there know? Please share what is known with contact info if you can.

Thx,

Sam Strano

Sorry, you've reached critical mass. Steeda Comps aren't really any stiffer, in fact they are softer in the rear... If you want stiff, then it's H&R Race, which are a lot stiffer @ around 325/290... and progressive (though like the Vogtlands, the soft end is pretty much never in place it's dead from the get-go).

Or, time to move to coil-overs to do what you want.... Sorry, not what you want to hear, but probably the move you need to make.

As for the lowering springs not mattering, I find that hard to believe as they run about 30-40% stiffer than stock, similar to Eibach springs vs. stock springs (to put a perspective on it based on the Shelby vs. my '07 GT).

azrampage

Could some of the issue be less suspension travel? The Vogtlands lower the car about 1.3", so perhaps it's the bump-stops I'm feeling? Firebird has a fairly uneven lot with it's share of bumps.

Tried the car first in Sierra Vista with only VGL springs and new rear adjustable bar. Next event was Marana with Eaton differential added, and last weekend at Firebird with the Steeda intake and BrenSpeed tune.

Despite the changes, I would expect some gain vs my "benchmarks", and found....none. And....it also may be that I just need to get used to things more, but still

Symptoms - Starts into a corner well, front starts to bite, and then the front seems to lose feel and washes out as a little power is applied (think snowplow). The rear feels a little "twitchy" at different times while cornering (front bar and rear bars both at middle hole). I was assuming the spring progression effect creating that feel.

No?

And NO ONE makes stiffer linear stock seat springs? Really?

(Love the Eaton Truetrack for the 7.5 rear BTW; very smooth and consistent).

Sam Strano

That tells me you might well be tire limited... because frankly adding a diff that works where there wasn't one before certainly didn't hurt you and neither did the power.

Seeing no difference to speak of, just does not add up unless the the tires were holding you back before (and still).

Rubrignitz

I'm with Sam, coilovers are probably the way you want to go. I thought I'd hit paydirt when I located hyperco 2.5x12'' for the rear in rates from 150 all the way up to 600 in 25lb increments but the fronts are a problem. I thought a 5''x12'' pigtail type would work, which are available in rates from 150 to 300 in 25# increments but Sam said no. The steeda\hyperco fronts are custom made for the S197 to steeda specs.

azrampage

OK, I'm beginning to think it wasn't the springs.........

I *was* running My Pony Mustang in G Stock Street Tire class, and after a few years of learning had it very dialed in. I was turning 940-960 Pax times on my Direzza 245/45/17 street tires against some National-level local drivers (Peters, Zust, more). I had the SA Konis on full hard, Steeda front bar on full stiff, and 4-5 pounds more pressure in the rears than the fronts, and -2.5* negative camber. On our smaller lot/courses this worked very well. Note this was with an open rear differential.

So (think STX class), I added the Vogtland springs, Steeda intake with Brenspeed 91 tune, Truetrak differential, and Sam's larger rear bar. Added the springs and sway bar first, then the diff, then the tune and intake.

Yep; I'm slower or at best no faster. Four events to date. Seems I've pretty much destroyed the balance I had before, and am really struggling with finding new settings that will work for me and this car. I need experienced advice please.

I now experience understeer under acceleration from corners. Can't put much power down without plowing. Upon doing some research, I'm beginning to think that I need to rethink my bar settings to account for the new-to-me limited slip. Whereas a stiff front setting before made up for the lack of a posi, now it may be hurting me. My best result so far used a 2-2 (middle/middle) sway bar setting (3 = full hard, 1 = full soft). Do I need to go full soft in the front perhaps?

Last event I put back in the stock Pony springs with bars at 3-1, and was still unimproved (at Marana very fast and open course), and although it felt better, still not faster (against my "benchmarks"). I use raw times for comparison, not Pax numbers.

No doubt I need to "land" and stick with stable settings for a while and just learn the darn car (again), but I need an opinion on a good starting point with the sway bars given the above info.

Thanks.......

908ssp

Rehagen racing..."The Boss 302S car is going to be something close to 500 front, 325 rear."

Sam Strano

Change begets change... The diff would have made the car tighter. I assume by "not being able to put power down" you mean you can't get to the gas due to understeer, right???? not that you fry the inside tire (that should be much better than stock).

As for spring rates, first 500/325 is pretty bone jarring on a street car and the front to rear ratio will be even more front high than what you already have.

I'd soften the front bar, but I'd also talk to Brian Peters if you can get with him about some tips on driving the car as setup. He is proven, fast, won in RWD stuff with power, and has a Shelby clone too. I don't see anything, ANYTHING in your list that should make the car a plow pig (other than street tires), but those same tires will also make the car much more easy to rotate with power too.

If you keep changing and changing it's an indication that it's not the setup. But if you want to loosen the car up, soften the front bar, and stiffen the rear some more.

azrampage

First, thanks for taking the time to offer suggestions. Very much appreciated.Right. Likely too many changes at once, and the great prior balance has been lost. Doesn't take much around here to lose a lot given our level of competition locally.

I am just looking for stiffer stock seat springs and nothing exotic. Not sure I trust/like the progressives, but first things first.

I'll call Brian, and agree about the front bar. I've found a few articles that implied a LS Diff did promote understeer under power. That, and STX limits me to a 265 size (next up on my list).

The plan was to put the STX stuff on and go a little faster, and then begin the tuning process. Blew me away that it has been no faster, so I'm back to stock springs with the diff, intake, tune, and rear sway bar.

Following your suggestions, and once I've got a handle on it and have some confidence in it, I'll try the Vogtland springs again.

Thanks again.

azrampage

OK, time for an update.

Summary - Added an Eaton TrueTrac to a 2007 Mustang Pony Pkg; stock was an open 7.5" diff. Added other things pretty much at the same time (see list above) and lost the previously great balance.

I returned to the stock springs to try to figure out what was going on and found the following: Adding a limited slip tends to promote understeer. Totally changes what sway bar and shock settings from those used with an open diff (duh). I didn't realize how much.

So now that I have found a good balance with the Eaton, CAI, and adjustable rear sway bar, I'll try the Vogtland springs again.

I *believe* I've found out also that with the stock springs (rear sits higher), that I may be "unloading" the rear suspension in tight corners, and perhaps while not totally lifting the inside rear, seriously unloading it, which some have suggested, might "open" the Eaton (gear) diff. They say if one wheel becomes unloaded with that type diff that it might act like an open rear? Agree?

So I'm hoping the Vogtlands will help prevent that possibility and keep things planted better. Stay tuned.