Oversteer

[Grant 302]

What are options to improve this?

Maybe try running more squat in the rear and allow the weight transfer to get you more forward bite. Move the arms up in the bracket up at least one position, and maybe even try the stock position. Soften the front struts a little to help the rearward transfer.

Which LCA do you have? BMR makes several.

Imagine that....

LOL.

 

[Eritas]

There is no debate that the Panhard bar is lighter and simpler than a Watts Link, which are likely primary reasons why its preferred by professional race teams. However, what I like about a Watts Link is the roll center moves in a perfectly vertical line relative to the chassis allowing handling characteristics to be identical in left or right corners. I would first address the tire width issue. I agree with running a 305 or 315 square setup and a smaller rear sway bar before trying a Watts Link.

The roll center doesn't move laterally with a PHB. For a WL, the RC stays stationary relative to the ground which means the moment arm acting on the RC varies with suspension travel. On a softly sprung car this can lead to big changes and larger handling inconsistencies.

WL's should be mounted horizontally, 90* from how they are installed on S197s, which really isn't possible on a street car but is used on tube-frame racecars.

 

[03dakrt]

Thanks all for the feedback. I will try the wheel and tire route thinking 285 square will make a difference.

I see why boss came with 285 rear now.

 

[Mad Hatter]

Don't forget the smaller rear bar with a square setup!

 

[Grant 302]

The roll center doesn't move laterally with a PHB. For a WL, the RC stays stationary relative to the ground which means the moment arm acting on the RC varies with suspension travel. On a softly sprung car this can lead to big changes and larger handling inconsistencies.

WL's should be mounted horizontally, 90* from how they are installed on S197s, which really isn't possible on a street car but is used on tube-frame racecars.

No, that's not entirely true. If the 'propeller' arm is mounted on the chassis side (like on the Fays 2) then the moment arm does NOT stay stationary relative to the ground. Stiffer as the chassis rises. The issue you state is true for diff or axle side propellers.

Don't forget the smaller rear bar with a square setup!

I'm not convinced that's 'needed' on his setup with a GT 24mm bar. It's quite a bit softer than either Boss bars.

REAR S197 bars:
Strano Performance Parts 8419 1" tubular: 162, 185, 225 lbs/in
Ford 20mm Solid (2005-2010 GT): 96 lbs/in
Ford 22mm Solid (2011+ V-6 standard): 147 lbs/in
Ford 24mm Solid (2011+ 5.0, GT500): 193 lbs/in
Ford 25mm Solid (Boss 302): 250 lbs/in
Ford 26mm Solid (Boss 302 Laguna Seca): 275 lbs/in
BMR-SB023 Rear Sway-Bar is: 146lbs/in

 

[Eritas]

No, that's not entirely true. If the 'propeller' arm is mounted on the chassis side (like on the Fays 2) then the moment arm does NOT stay stationary relative to the ground. Stiffer as the chassis rises. The issue you state is true for diff or axle side propellers.

Very true and good example. However it is still vertically mounted and not (properly) horizontally mounted.

 

[Grant 302]

Very true and good example. However it is still vertically mounted and not (properly) horizontally mounted.

Honestly, I'm not sure how or *if* that would work if rotated 90º.

 

[Eritas]

That's the proper orientation for a watts link with less compromises. It won't work with short arms and or a lot of suspension travel.

 

[Mad Hatter]

No, that's not entirely true. If the 'propeller' arm is mounted on the chassis side (like on the Fays 2) then the moment arm does NOT stay stationary relative to the ground. Stiffer as the chassis rises. The issue you state is true for diff or axle side propellers.



I'm not convinced that's 'needed' on his setup with a GT 24mm bar. It's quite a bit softer than either Boss bars.

REAR S197 bars:
Strano Performance Parts 8419 1" tubular: 162, 185, 225 lbs/in
Ford 20mm Solid (2005-2010 GT): 96 lbs/in
Ford 22mm Solid (2011+ V-6 standard): 147 lbs/in
Ford 24mm Solid (2011+ 5.0, GT500): 193 lbs/in
Ford 25mm Solid (Boss 302): 250 lbs/in
Ford 26mm Solid (Boss 302 Laguna Seca): 275 lbs/in
BMR-SB023 Rear Sway-Bar is: 146lbs/in

Your probably right, I only noticed the need for the smaller rear bar when I went to the stiffer $600/#350 cortex setup

 

[Gray Ghost GT]

No, that's not entirely true. If the 'propeller' arm is mounted on the chassis side (like on the Fays 2) then the moment arm does NOT stay stationary relative to the ground. Stiffer as the chassis rises. The issue you state is true for diff or axle side propellers.

+1 I wonder how many points would be assessed for the use of a watts link by a race car since the use of a PHB would be zero; using their allotment of points for their class elsewhere.

What tire pressures are you running cold and hot? http://fays2.net/fays2_watts_link_4_.html and http://fays2.net/fays2_watts_link_22_.html

 

[blacksheep-1]

We run a ton of movement with a PHB, again, I think the Watts is more comfortable to drive, the fast guys will gravitate to the PHB.
In any case, your immediate issue is to get the tire situation sorted.

 

[DipstickMotorsports]

Hey, not to side step too much... but I'm curious if people are running on Rod or Poly ended PHBs? @blacksheep-1 - I assume most are running with rod ends on the PHB? Is it a big difference between the two?

Would love to see comparisons back to back between a poly or rod ended PHB VS Watts Link.... Not the Stock soft rubber PHB vs Wattslink

 

[DipstickMotorsports]

Also to the OP, I have a similar set up... Bilstein HD /w BMR handling springs. Please downsize the rear swaybar asap. I've got the 22mm rear from 11+ v6 and its still even a bit too much, I've also tried the 24mm oem & the 25mm boss. I'd also recommend the front 3 way FRPP "blue bar" I love the way my car is currently balanced for my driving style.... Its just too soft overall now so I'm looking into coilovers but nothing fits my budget so I'm sticking with this set up for now.

Also yes, 285 minimum. Don't know about going 305+ with a stickier rubber like nt01 on this kinda softer overall suspension tho.. I had people tell me from behind it looks like my car is coming OFF of the chassis because its rolling over so much and that was on 285/35/18 RS3 tires.

 

[smallblock]

As mentioned above, wider tires are a must. 265mm is a relatively small footprint for 420hp. If investing in new wheels, save yourself time and money and go straight to an 11" wide wheel like the Apex EC7. You can run anything from a 285 to a 315 tire so as your talent progresses, so can your tire size/grip. I run 305 Pirelli DH slicks on 18"x11" Apex wheels with the mods in my sig and it works extremely well on track.