DPE

I've now been to the track in my 2010 GT and was honestly rather surprised how well it worked suspension-wise. From the comments I've read, clearly something changed between 2009 and 2010 in the chassis department, because I expected an understeering mule and got no such thing. Sure, it'll push steady-state, but it'll also rotate nicely under trail braking and under power at lower speeds. My car is a GT Premium, non-Track Pack. Also has sufficient brake mods for the track and GT500 wheels with 275/40 tires all around.

Don't get me wrong, there's some serious room for improvement. I guess my expectations were just a little low.

The common upgrade path for track day, non-racer folks appears to be a set of Koni Sports, Steeda springs, Steeda upper mounts for a bit more negative camber, some Strano swaybars, and perhaps a Watts link to really do it up right. I plan on doing most/all of that over time, but after driving the car on track the real weak link seems to be shocks. Certainly the body rolls and squats and dives, and I wouldn't hate a more solid feel from the rear end. But at the end of the day I left thinking that a good set of shocks would go a long way toward making that car really good on track. There's an initial compliance (softness) in the OEM shocks that seems to allow a lot of body motion, but once it takes a set they firm up reasonably well. Not enough, but not horrid. If one had a quality shock that got rid of that initial compliance and kept particularly the rear end from bounding about in high-speed, bumpy corners, I'd be pretty excited about that.

Obviously it makes a hell of a lot of sense to do shocks and springs at the same time, along with the upper mounts in front. But my question is has anyone ever JUST done shocks (Koni Sports in particular) and left everything else alone, and if so what are your thoughts? Looking more for the 2010-2011folks, but really any S197 owner who did this would be great to hear from. My thoughts are if I could just get shocks (and maybe upper mounts) but not lower the car, it might be a useful exercise to see what just adding shocks will do for the car on track. I'm sure springs would help even more and the car just plain looks nicer lowered, but I don't necessarily feel like the OEM springs are a 'problem' in the 2010 chassis.

As it is I've spent much to much on the car since buying it 2 months ago, so it'll be awhile before I invest in more suspension parts, but hey, maybe by the time I get around to buying, Koni Sports will be back in stock ?

Swoope

funny,

that was after reading so much and have not ordered the car yet my road..

get car, use track tires and wheels i own.. change shocks.. but i was just going with the koni str. as i am a 9/10s kinda guy.

then the strano linear springs, and sways..

beers :beer:

Sleeper_08

If you do the springs and shocks at the same time it is a big benefit at the front as then you only have to do one install and one alignment check/adjustment.

Of course if you are doing the work your self then this has zero cost other than your time.

With the Koni's on a 20% off sale this almost pays for the springs.

Norm Peterson

I'm not too much past "shocks/struts only" on my '08, and the better dampers will tighten up the transient body motions. The tail will still rise under braking, but doesn't seem to "lurch upward" quite as fast. I did add the Steeda HD upper strut mounts and Sam's adjustable bars at the same time (which I've re-adjusted once or twice), but I'm still on the OE springs. In terms of chassis dynamics, not every aspect that gets affected by lowering shows a gain when you do lower, and I haven't quite convinced myself that the net gain is worth it - or that I could reasonably do some further tuning to show a bigger net gain.

The car will understeer if overdriven, heavily if you're too hot going into a tight 180° auto-X turn-around. But it's not inherently a heavily understeering car otherwise, and doesn't really deserve by implication to be lumped in with its predecessors even in stock form as long as you can avoid that sort of driver mistake. That's my experience at least, though coming off a few seasons of autocrossing a FWD car and the alignment specs on my '08 GT being unusually aggressive as delivered may have had something to do with it.

You can clearly feel the difference that 1/4 turn on the adjusters makes from a ride quality standpoint, and even an eighth turn is noticeable. In street driving, I've got the Koni's about +1 turn from full soft, which is a pretty good setting most times. But it's about 1/4 turn too much for when my wife is aboard, and there is this one specific road situation that I encounter on a daily basis where I think +1 full turn in the rear is just a little too much anyway. I dialed out about half a turn in the rear for a bit of autocrossing earlier this year, out of concern that I might loop it (not having autocrossed a RWD car in several years and not at all in about a year). In hindsight I think I may have taken a little too much rear damping out, though I can't exactly complain about the results.


As Sleeper mentioned, it's a lot easier to justify splitting up the installation of struts and front springs if you can do the work yourself, and particularly so if you can do your own alignment and aren't completely reliant on the car being the sole means of transportation.

Out of curiosity, do you know how much camber you've got?


Norm

DPE

Thanks for the responses. And I should have clarified that; yes, I'll do all of the work myself. So it's just a time issue. And the wife can grudgingly drive the minivan to work if the Mustang is down for a few days (I have a company truck). As for negative camber, I haven't bothered to measure what I got from the factory. My eyeball says something between -0.5 and -1.0 degree, but that's obviously not the most accurate measure . Once I have some parts to install, I'll do baseline readings before I tear it apart.

Reminds me I need to figure out how to measure toe on this car. On any other car I've had (with an IRS), you can use strings on jackstands and get a parallel line to measure toe from assuming you know the front and rear track. With the Mustang I guess the axle can shift, thus being off-center, thus making that kind of measuring potentially flawed since the rear track can vary a bit. Something to read up on I guess. At least I don't have to worry about rear camber or toe!

Norm, it sounds like we're on the same page; lowering doesn't always help in every way, and while I like the look and the cost is minimal I'm just not sure I need it for what I do. And I'm at a point in my modding life where I like doing one thing at a time and evaluating the result rather than throwing several things on at once and having to guess which part had which effect. Not to say that's a 'bad' thing to do as there are well-proven sets of mods for this car that make sense to do at once and just plain work, I just wouldn't mind trying one thing at a time. And, it gives me more excuses to be out in the garage, which is always a plus.

Norm Peterson

No problem.

Quote:

Originally Posted by DPE

Reminds me I need to figure out how to measure toe on this car. On any other car I've had (with an IRS), you can use strings on jackstands and get a parallel line to measure toe from assuming you know the front and rear track. With the Mustang I guess the axle can shift, thus being off-center, thus making that kind of measuring potentially flawed since the rear track can vary a bit. Something to read up on I guess. At least I don't have to worry about rear camber or toe!

It's not the track dimension that varies, just the centering. Although the potential error won't be as big as a stick axle with a PHB, even with an IRS you can't really assume that the rear wheels are perfectly centered.

What you really need to do is plumb the strings ahead of and behind the car and make the distances across equal. Then make them equidistant from the front wheels, keeping the parallelism (and expect this to involve going back-and-forth between distances and parallelism). Your strings may not be parallel to the car's centerline, but you'll be close enough that the toe measurements will still be good enough. Half an inch of axle "off-centeredness" is about a quarter of a degree that you'd have to steer the fronts to make a zero toe setting line up, and over that quarter degree the Ackermann effect isn't going to influence your toe measurements enough to matter on a car with compliant control arm bushings. At worst, a test-n-tune session might suggest a little tweaking, which you might want to do anyway.

Or, you might tweak the line spacing off the rear wheels for a sort of lowest-overall error considering string parallelism vs rear wheel toe measurements (don't assume zero here, measure) and lateral position vs axle centering, and let the front spacing off the wheels "float".



Norm

DPE

Good info there Norm. I had thought of the twin parallel strings on either side and squaring them up on the front wheels after getting them even to each other, but thought that may still be too inaccurate. I suspect you are right though; it would be close enough. I'll have to experiment and see how it comes out when the time comes.

Norm Peterson

Even if you're rushing things and the strings end up being a rather sloppy 1/8" out of parallel - at ~200" or so between the parallelism measurements that's still only about 1/64" (0.036°) toe error taken over the diameter of the tires, or 0.01" at the rim flanges where your toe measurements are more reliable. I've never seen a ruler graduated any finer than 0.01", so you could have half that much string setup error and never be able to even tell that it was there (never mind how much it might be).


Edit - mostly just for grins, you ought to actually measure the rear axle camber and toe. Due to tolerances, there is no real guarantee that they will be precisely zero. You may not be (easily) able to adjust those parameters, but that's not the same thing as them being "perfectly zero'ed". Never mind that a little negative rear camber can be a good thing even with a stick axle.


Norm