AST 4150 installed

[ArizonaBOSS]

^great post. I agree but I'm not sure how to maximize front end grip anymore?! So I increase the rear bar to reduce understeer

Assuming you start with a neutral setup:

Making the rear bar stiffer reduces rear grip, which means that while your front grip has stayed the same, you've reduced the rear grip and now the car is comparatively more loose.
Conversely, if you make the rear bar softer, you increase rear grip compared to neutral, and now the car is more prone to understeer because there is comparatively more rear grip available.

Same thing follows for front bars. Soft = more grip, stiff = less grip.

However, soft also = more roll, so ideally you want your springs to be able to compensate for that. In roll or turning situations, the swaybar acts as a spring.

Running Strano's adjustable front 35mm and rear 22mm (smaller diameter--softer than stock), I really like the way the car feels at full soft in the front and "middle" in the rear, with the spring rates I'm running, on a square setup.

 

[ArizonaBOSS]

zzzyzxxyzzz is right on the money

 

[Grant 302]

I agree but I'm not sure how to maximize front end grip anymore?!

More tire. Front suspension geometry. Two places to start.

 

[VoodooBoss]

Interesting discussion. When several of us were at Chuckwalla last month three of us rented their academy cars. We got to drive a stock 2013 GT track pack car, one with modified Eibach suspension and another similar but with the rear sway bar disconnected. The first day I drove the stock GT. The next day I drove the modified GT and was amazed to see my lap times drop by at least 2 seconds a lap. Then after we broke the cars they brought out the one with modified suspension and the rear sway bar disconnected. I could immediately tell the difference in rear grip and was amazed how much sooner I could get on the gas with the rear staying planted. Keep in mind I'm a novice and Gary has a lot of track experience. We swapped notes after driving both back to back and Gary liked the modified car better than the modified car and no rear sway bar. I liked the one with no sway bar better. Why? The one with no sway bar had a slight push in the front end. That felt fine to me but Gary didn't like it and given our experience levels that was not surprising.

That's the reason why I started the Watts Link vs. Kenny Brown roll center relocation kit thread. Steve if you have any thoughts on the other thread please post in it.

https://trackmustangsonline.com/index.php?topic=4237.0

 

[DD GT3 RD]

I agree but I more refer to understeer on big sweepers to judge. Like how how does the car behave in a steady state of turning.

I have the Hotchkis sways and have the front on the softest setting. Running AST coilovers 550f/250r spring rates. Camber is around 3.25 I had rear bar on softest and felt mild understeer so raised it to middle setting after the track so will see how it behaves next track day

 

[Jimmy Pribble]

My "spaghetti-sized rear swaybar" hyperbole isn't very useful, so here's a pic:



Yes, the end-links are thicker than the swaybar itself. You can also see the way they adjust the swaybar by using a quick-change mount and just replacing the whole swaybar according to their needs. This setup (and swaybar size) was on every 302R that I looked at.

 

[cp85gt]

DD GTS RD, How do you like you're AST's so far? I noticed you have the stiffer spring rate package. How is this package on the street? At this point I'm trying to decide on spring rates. I don't use my Boss as a daily driver but still would like to drive it outside of autocross and track events.

 

[DD GT3 RD]

I think I would prefer a square set up and then could soften my rear sway, I just keep spending dough ;( although I would only have to buy 2 new front rims.


To the above post. I really like them. I notice a big difference. Around town I have them set on softest and I'm fine with the ride. And it still feel better around turns on softest than the other shocks on any setting.

 

[Zquez]

I think I would prefer a square set up and then could soften my rear sway, I just keep spending dough ;( although I would only have to buy 2 new front rims.


To the above post. I really like them. I notice a big difference. Around town I have them set on softest and I'm fine with the ride. And it still feel better around turns on softest than the other shocks on any setting.

+1

I was riding around today on mine on full soft and it was perfectly streetable. Indistinguishable from my D-specs with BMR springs with OE rates, but taking corners the car still outperforms my old setup. The car is just so much flatter and responsive. And I'm running -1 degree of camber, but there's grip everywhere as far as street handling is concerned.

 

[VoodooBoss]

Hey if any of you Boss owners are looking to sell 1 or both or your rear shocks please send me a PM. My friend with a Boss had on of his blow and spew oil everywhere.

 

[Grant 302]

The answer to decreasing front "push" that many drivers don't like to hear is... be patient. 99% of the understeer is due to the driver pushing the car beyond its limits.

The point is - decreasing rear end grip - larger/stiffer rear swaybar - doesn't solve this problem. It only means that when it comes time to stomp on the go pedal, you have less traction available than you would otherwise on corner exit.

List of things I'd verify:

1. Front ride height. Did you lower your ride height in the front? If so, you probably decreased available front end grip. Stock the Boss is IMO already on the "wrong side" of having good front end geometry. There are solutions to this - like the extended LCA ball joints.

2. Alignment - camber. You have a good deal, but what you don't really know is if it's ideal for your setup. Only tire pyrometer readings and a meaningful interpretation of those readings will help. Consider the possibility that you may have too much neg. camber.

3. Rake. How does your current rake compare to stock? More or less? I've worked on many setups where 2/10ths of an inch difference in rake meant the difference between "neutal" balance and terminal understeer.

4. Tires/pressures/etc. Are you still running a staggered setup? If so, why? The only reason to run a staggered setup is if you're cramming the absolute largest tires you can under the fenders - because we know that you can stuff wider tire in the rear. Anything less than that and you should run a square setup.

5. Spring rates. Do you have enough spring up front, or not enough? I trust Terry in terms of getting this right, so I would assume you're "close enough". That said, given the weight of the 'stang and it's weight bias, the rate seems low to me.

6. Front swaybar. With your increased spring rates do you now have too much front bar? Either way, an adjustable front bar would be an ideal place to start. Put it on full soft and see where you end up.

This post is absolutely on the money. Totally missed it while eating dinner and typing my shitty short response.

All of it applies to Sam's setup. The only things I'd add are:
1. Both points 2 and 4 above can be checked/adjusted based on the pyrometer readings
2. Consideration for connections that deflect...did you already replace the majority of rubber bushings that will affect your handling? I'm sure you did most with the Hotchkiss setup, but did you also get the front LCAs?

 

[DD GT3 RD]

I don't have front LCA's but if anything next will be front 285 tires and rims.

 

[isrboss]

I don't have ASTs, but if it helps to have another reference point I am running KWs w/ 515 front, 230 rear. Originally it had 400lb rear but was too difficult to get power down on exit, I switched to the 230 rears and played with the bars a bit and now I have the car set up like I want it +/- some minor rebound adjustments at various tracks.

When you were running the 400lbs/in rears, did you have a smaller rear sway? Given when the bar is loaded with the factory rear springs at 186lbs and bar at approx 250lbs/in = 436lbs/in. If you used a stiffer rear bar with the 400lbs springs you would have been near or more than 650lbs/in when loading the bar and rear spring in a turn. Yeah that might be causing some traction issue if you were still loading the rear when getting on the go pedal.

I am sold that I will not be able to get rid of the sway bars completely, but I am going to add to the springs and take away from sways until the ride gets to harsh fro me on the street.

 

[zzyzx]

That's the reason why I started the Watts Link vs. Kenny Brown roll center relocation kit thread. Steve if you have any thoughts on the other thread please post in it.

I'm not a good resource for real data on Watts linkages. That said, I think you're going the right route and getting a Watts link as opposed to the RC relo kit. I just got caught up on the controversy over the legality of diff cover replacements in SCCA autox - I was not aware this was an issue. So, that could be a limiting factor. The Fays2 looks like a quality unit that I assume bypasses the legality issue. Anyways, I'll do some more homework and weigh in on the other thread.

 

[zzyzx]

My "spaghetti-sized rear swaybar" hyperbole isn't very useful, so here's a pic:

Awesome pic! Makes you wonder why even bother? I refer to this thickness as "paper clip" size.

 

[ArizonaBOSS]

When you were running the 400lbs/in rears, did you have a smaller rear sway? Given when the bar is loaded with the factory rear springs at 186lbs and bar at approx 250lbs/in = 436lbs/in. If you used a stiffer rear bar with the 400lbs springs you would have been near or more than 650lbs/in when loading the bar and rear spring in a turn. Yeah that might be causing some traction issue if you were still loading the rear when getting on the go pedal.

I am sold that I will not be able to get rid of the sway bars completely, but I am going to add to the springs and take away from sways until the ride gets to harsh fro me on the street.

Was running a smaller (22mm) adjustable bar. I just couldn't get the exit traction I was used to with the (much) softer stock springs, and that traction was a big advantage in getting off the corners and putting distance on other cars.

 

[isrboss]

Was running a smaller (22mm) adjustable bar. I just couldn't get the exit traction I was used to with the (much) softer stock springs, and that traction was a big advantage in getting off the corners and putting distance on other cars.

Great help ArizonaGT! So it would appear going above 350lbs/in on the rear might be a fight for traction. I am trying to keep the factory Boss rear spring and bar total near the 436lbs/in. Since Pobst raved about the rear grip. It looks like 300lbs/in in the rear with 22mm rear bar might be what I'm looking at trying. Then tune the balance with a front 32mm adj. bar. Thanks for all the input guys.

 

[ArizonaBOSS]

Let us know how it turns out!