Sway bars

[bootlegger]

The stock links tend to bend with track use, so maybe a good idea while you're at it.

Or with some aggressive weekend commuting in my case.

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[Norm Peterson]

I put together a chart that shows the bar rates (published and tested), and the effective wheel rate of the bars. You can add those wheel rates to the spring wheel rates published on Page 8 of the Spring rates sticky thread. This will allow you to see total roll stiffness and bar stiffness contribution to the total. I do not have Steeda front bar rates yet. View attachment 351548

Link to the spring rates:
https://www.mustang6g.com/forums/th...s-all-in-one-thread.44925/page-8#post-1637308

Question - are these rates basically bar end to bar end, i.e. similar to Fred Puhn's sta-bar model?


Norm

 

[BmacIL]

Question - are these rates basically bar end to bar end, i.e. similar to Fred Puhn's sta-bar model?


Norm

That is what I understand, yes, and that most of them have been bench tested for these rates with the mounting hardware.

 

[Norm Peterson]

This particular topic is a classic discussion of a single change having both a primary effect and a secondary effect, where the two effects work at cross-purposes. Maybe even tougher to visualize when the secondary effect is comparable to or exceeds the primary effect.

Typical track surfaces permitting, I'd be tempted to "overdo" the front bar enough to permit using the rear bar for final fine-tuning. Assuming that the rear bar adjusts in smaller lb/in steps, anyway.


Norm

 

[BmacIL]

Typical track surfaces permitting, I'd be tempted to "overdo" the front bar enough to permit using the rear bar for final fine-tuning.

Couldn't agree more.

 

[Norm Peterson]

That is what I understand, yes, and that most of them have been bench tested for these rates with the mounting hardware.

Do you know if anybody has correlated those translational stiffnesses to rotational stiffnesses as applied to the chassis?

I'm finding that inputting sta-bar stiffnesses as torsional stiffnesses at the chassis rather than as couple-force stiffnesses at the wheels does a better job of predicting deg/g roll amounts. I suspect it's related to the inboard spring working against the bar rather than with it.


Norm

 

[Norm Peterson]

Another question occurred to me overnight - has anybody run the full TLLTD evaluation for these combinations, and compared those results to the S550's weight distribution? Sprung mass through roll centers, sprung mass through elastic suspension components, and unsprung mass.


Norm

 

[Roadway 5.0]

Do you know if anybody has correlated those translational stiffnesses to rotational stiffnesses as applied to the chassis?

I'm finding that inputting sta-bar stiffnesses as torsional stiffnesses at the chassis rather than as couple-force stiffnesses at the wheels does a better job of predicting deg/g roll amounts. I suspect it's related to the inboard spring working against the bar rather than with it.

Norm, can you elaborate on the statement in bold?

 

[Norm Peterson]

When the suspension on the outboard side of the car compresses under the load transferred to it in a corner, it pushes that side's end of the bar up against its stiffness. But bar stiffness is developed against the other side's suspension, not the chassis directly, so the bar's inside end also wants to go up - trying to compress the inboard suspension as well. Which is in the opposite direction of what the inboard spring is doing (extending as load is transferred off of it).

Think in terms of spring + bar on the outboard side, spring - bar on the inboard side. Part of why you don't feel very much impact when you run the inside wheels over a track curbing.


Norm

 

[Roadway 5.0]

Great detail, thanks for the clarity @Norm Peterson

 

[Roadway 5.0]

@Bluemustang @BmacIL

My Steeda bar at full soft is about 280lbs/in -- medium setting is about 350lbs/in and full stiff sees over 425lbs/in.

Considering I have 225lbs/in front springs in respect to my comparatively softer rear springs at 880lbs/in (compared to say the GT350R or BMR handling) and will have a very fat staggered wheel/tire setup, I don't see dramatic oversteer coming in to play when slamming in or out of a turn. Of course, I'm open ears for counterpoints and, frankly, keeping the bar at the medium setting means less wrench time.

Anyway, do you all have any rates for GT350/R or PP2 OEM bars? I'd love to see some caparisons.

Looks like I had my data points on the Steeda rear bar WAY off. Per their latest YouTube video, the rates are:

Full Soft: 190lbs/in
Middle: ??
Full Stiff: 293lbs/in



@BmacIL if you could update the sway bar chart I would appreciate it

 

[BmacIL]

Looks like I had my data points on the Steeda rear bar WAY off. Per their latest YouTube video, the rates are:

Full Soft: 190lbs/in
Middle: ??
Full Stiff: 293lbs/in



@BmacIL if you could update the sway bar chart I would appreciate it

When I get back from vacation I will.

 

[GTP]

@BmacIL what would you suggest for my new 2019 PP1 car? Assume square set of 275/40 MPS4S, PP1 springs, MR dampers.

I just swapped out the stock bars for GT350R front and rear. I really don't want to ever have to put the stock PP1 bar back in because of the captured brackets (or else I would at least crack them open first). Rear bar swaps are so much easier.

From the chart the 350R bars appear to be softer than any of the after market bars.

 

[BmacIL]

@BmacIL what would you suggest for my new 2019 PP1 car? Assume square set of 275/40 MPS4S, PP1 springs, MR dampers.

I just swapped out the stock bars for GT350R front and rear. I really don't want to ever have to put the stock PP1 bar back in because of the captured brackets (or else I would at least crack them open first). Rear bar swaps are so much easier.

From the chart the 350R bars appear to be softer than any of the after market bars.

Probably just stick with the R bars.

 

[KingBowser]

Figured I'd ask here rather than start a new thread although its a necro, Have been reading up more on sway bars and I think I'm slightly confusing myself more than learning, 2019 PP1 on FP Track suspension with BMR SP083 springs, Was thinking a BMR bar in the front and leaving the original PP rear, also will have Steeda front end links. Any advice would be appreciated!

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