richardm

So I have a Brembo pack suspension setup on my V6 plus Koni orange at the rear. Did the transplant about four months ago.

I got kinda fed up with the rear axle going full retard over broken pavement (it's like living in the 3rd world around here) so I removed the rear sway bar completely. Soooo plush but it's a little too soft back there. A little more low-speed damping from the Konis would help but I think the best compromise might be to return to a V6 rear swaybar. The V6 swaybar that I gave away. Like the idiot that I am.

Before I locate one on eBay or CL, any thoughts on this setup? The only alternative I see might be Laguna Seca springs (191 lb/ft vs 167) but I don't think the Konis nor the OEM track pack shocks would have enough low speed damping to run these springs with no sway bar.

I realize that it's never going to ride like a BMW 335 but the pure track pack setup just isn't tolerable.

Kobie

Don't want to stir up too much here, but I'd recommend putting the Brembo sway bar back on and switching to a Watts link. I know this made a HUGE difference in the way my car behaved.

UPRSharad

There's no right or wrong answer here. Different bars for different setups and driving styles. One driver would like more rear bar than a different driver. And so on.

I can't really help on where to source an inexpensive softer rear bar... but I know I've seen some of the continental tire race mustangs with PUNY little rear bars. I heard they only run a rear "bar" because they have to in the rules, so they put these tiny little things on. Interestingly enough, that's probably why those cars power wheelie out of the corners and pic the inside front tire up off the ground. No rear roll control.

Norm Peterson

The early-S197 GT Mustangs came with a 20mm rear bar. If anybody knows for sure that it would fit, that would at least widen your search.

Another possibility would be if anybody is letting go of one of Sam Strano's early 3-way adjustable rear bars, which were 22mm tubular. The full-soft setting is probably close to the OE 20mm solid.

It should be possible to weld (or maybe even bolt if you can drill holes to a close enough fit for the bolt shanks) extensions to the ends of the bar arms and drill the extensions to make the arms effectively longer, which in turn makes the bar softer. You'd have to keep an eye on clearances around the drop links and the transverse portion of the bar as those things move forward/backward as the suspension moves vertically.


Norm

richardm

I take it Strano's current adjustable rear bar, on the softest setting, is not as soft as the V6 bar?

Norm Peterson

Doubtful.

The soft setting on the 25mm Strano bar is listed at 162 lb/in, vs 96 lb/in that I have in my notes for a 20mm solid bar or about 147 lb/in for a 22mm solid bar.


Norm

richardm

Norm, can you share your sway bar notes? They could be useful in my search for mamma bear's porridge.

Norm Peterson

The 96 lb/in for the 20mm bar is based on Fred Puhn's sta-bar stiffness equation (in "How To Make Your Car Handle"), and the 147 is something I probably scaled up from there using 7/8" rather than precisely 22mm. The scale factor for identically bent sta-bars is the ratio of diameters raised to the 4th power. You'd use ( [OD}^4 - [ID}^4 ) for tubular bars.


To be picky (some might say too picky), those numbers are probably just a little high. There's a little uncertainty in the actual material stiffness property where his formula assumes a specific value, and if you expand Mr. Puhn's approach to include a few more structural deflection terms than just torsion in the center section and arm bending, you get a little more total deflection for a given load, which means softer. But they're small terms, unlikely to amount to much more than 5%, and realistically, worrying about a possible 5% error in 200 lb/in or less is a waste of time for any car that's still fully street-drivable.


I did track down a thread where a commercially-available rear bar was owner-modified to be adjustable over on FRRAX.com - and the individual involved is not a fabricator by profession. Link, with about 3 pages of follow-up text. You'd probably have to register in order to see the entire thread, but I do have a copy of the fabrication process saved to a Word document. Lots of pictures, so it still runs about 40 pages and about 5.5MB. PM me with an email address if you want a copy.


Norm




.

Jande063

A lot of NASA AIX cars do that also, as well as Vorshlag's TT3 car, and of the two ESP mustangs that I have seen, mine waves that inside front tire at the course workers like a DSP BMW in drag (I do not remember if Jadrice's also does this, and his is the only other ESP mustang I have seen in person, but that was over a year ago). Another likely component is the enormous front bar that all of these cars run being so stiff that the coil spring has a difficult time overcoming both the bar and the rebound delay caused by the shocks. Chassis twist is another component, but much more difficult to solve.

Robertatl123

Richardm,

I plan on changing out both of my sway bars towards the end of this month. I have a '14 GT. I'm not sure on this, but I'm guessing the rear bar might be a little stiffer than the six. Let me know if you are interested.

Regards,

Robert