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Sway bars necessary

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I lowered my 2013 BOSS with the BOSS specific lowering springs. I replaced the Panhard bar with an adjustable unit. I have Whiteline UCA and LCA's with the lower relocation brackets.
I was thinking about replacing the stock sway bars with Whiteline units.
Any thoughts on this?
Thank you Steve
 
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IMO, I'd re-think the rear swaybar since the car has been lowered.
Because the rear end of the Mustang is a solid axle, the roll center remains in the same location even if the car is lowered. The interesting thing with this is that when you lower a car, the CG drops (duh!), so then the roll couple is shortened (the distance between rc and cg). The shorter roll couple makes the car more resistant to roll in the back. On the surface, this is fine. But what this really means is that:

1) The rear is more resistant to roll due to geometric changes over stock
2) The rear is even more resistant to roll due to spring rate changes over stock
3) The rear is resistant to roll due to lower cg

The combination of all of the above simply means you have increased roll stiffness out back greatly in relation to any changes made up front. This affects mid corner rear grip (a reduction in rear grip, actually) and will make the car more touchy to throttle inputs mid corner. The roll steer you're getting with the LCA relo's also isn't helping with the perception of reduced mid corner bite with all the changes noted.

Now, if it were me, I'd first try the setup completely without a sway bar and see what the improvements are like. If it's too floppy out back, then buy an adjustable rear to tune the mod corner bite.

Yes, some may argue you can get an adjustable front and stiffen it up front to "bake in more understeer". But reducing front grip to compensate for reduced rear grip is not a good solution IMO. Plus, stiffening the front does other things in other cornering phases which you may not have sought after.

Just my 2c. I've been thinking long and hard about what to do about the rear end if I were to change ride height...and it's for that reason I havent touched ride height yet at this time. More reading on roll center if it intrigues you: http://dreamingin302ci.blogspot.com/2013/06/flckle-roll-center.html
 
Maximum Motorsports recommended to me that I consider removing the rear bar if I lower the car without changing the front bar. Call em... Nice folks.

Sent from my Nexus 7 using Tapatalk
 
Thanks boro92! I know many of you guys are running a smaller rear bar (or no bar) but I've never read a good explanation as to exactly why.
 
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wherermykeys said:
Thanks boro92! I know many of you guys are running a smaller rear bar (or no bar) but I've never read a good explanation as to exactly why.

No sweat! I pondered on and on about this a while ago. It's funny how a car with a simpler rear suspension can actually get more complicated when making decisions on setup. Lots of stuff goes on back there once you lower it!
 
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boro92 said:
IMO, I'd re-think the rear swaybar since the car has been lowered.
Because the rear end of the Mustang is a solid axle, the roll center remains in the same location even if the car is lowered. The interesting thing with this is that when you lower a car, the CG drops (duh!), so then the roll couple is shortened (the distance between rc and cg). The shorter roll couple makes the car more resistant to roll in the back. On the surface, this is fine. But what this really means is that:

1) The rear is more resistant to roll due to geometric changes over stock
2) The rear is even more resistant to roll due to spring rate changes over stock
3) The rear is resistant to roll due to lower cg

The combination of all of the above simply means you have increased roll stiffness out back greatly in relation to any changes made up front. This affects mid corner rear grip (a reduction in rear grip, actually) and will make the car more touchy to throttle inputs mid corner. The roll steer you're getting with the LCA relo's also isn't helping with the perception of reduced mid corner bite with all the changes noted.

Now, if it were me, I'd first try the setup completely without a sway bar and see what the improvements are like. If it's too floppy out back, then buy an adjustable rear to tune the mod corner bite.

Yes, some may argue you can get an adjustable front and stiffen it up front to "bake in more understeer". But reducing front grip to compensate for reduced rear grip is not a good solution IMO. Plus, stiffening the front does other things in other cornering phases which you may not have sought after.

Just my 2c. I've been thinking long and hard about what to do about the rear end if I were to change ride height...and it's for that reason I havent touched ride height yet at this time. More reading on roll center if it intrigues you: http://dreamingin302ci.blogspot.com/2013/06/flckle-roll-center.html

Mind blown. Thanks for the link. I did lower my car, front turn in is still nice, but the car is really loose at the back and steps out in an instant. But all this will change with the coilovers when I really start tuning.
 
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sadil said:
Mind blown. Thanks for the link. I did lower my car, front turn in is still nice, but the car is really loose at the back and steps out in an instant. But all this will change with the coilovers when I really start tuning.

Yup - it's for this same reason that you'll notice the grandam cars running tiny or no rear bars. The roll couple is really short when the car is lowered.
The other approach you can take is get a watts link with adjustable roll center. Something to play with and fine tune. I like the KB roll center relocation panhard, but there are only 2 settings on it--and the 2 settings are inches apart. IMO the Cortex watts link is much better.

FWIW maximum motorsports road&track grip box that lowers the car 2 inches recommends running no rear bar. They also provide a beefier front bar, if that gives you an indication of how far out of whack the rear end becomes when lowered (especially to that degree). They do not have anything to play with rear roll center, thus the "compromise" in the lack of rear bar.
 
Thank you for all the input!
I have decided not to change out the sway bars, just leave the stock ones in.
I like the Watts link idea.
Am going to the the UCA and LCA'a today.
Thank you Steve
 

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