Protege 5 Stock Sway Bar Rates

[Jeff@Tri-Point]

Protege 5 FSB & MSP RSB Rates

Co Worker helped me measure the sway bar rates on the Protege 5 FSB and MSP RSB

Protege 5 Front Sway Bar -120lbs/inch


MSP Front Sway bar maybe 142lbs/inch ~ figure 18.5% Increase

MSP Rear Sway Bar - 144lbs/inch

A little weak? (boom07)

 

[aMaff]

how'd you measure them?

 

[Jeff@Tri-Point]

how'd you measure them?

I'll have to take a picture of it, it's really accurate.

Partial of a press with a rod end, some aluminum blocks with holes drilled in for the sway bar brackets, a flat square that has some square tubing with a rod end that sits on a scale.

 

[ForceFed]

And this would compare to say..an AWR how?
I am just curious..Its nice to throw out these numbers..but what does it really mean?

 

[Jeff@Tri-Point]

And this would compare to say..an AWR how?
I am just curious..Its nice to throw out these numbers..but what does it really mean?

I don't plan on buying an AWR rear bar, so if anyone wanted to send one, I could possibly test it.

From my understanding, swaybars are used to add additional roll resistance without adding spring rate. You will need X amount of spring rate to be able to allow the car to run in it's natural frequency and let the tire be able to asborb the bumps in the roads and you would use swaybars to balance the car in a perfect world.

 

[aMaff]

It means that the P5 front sway, for example, basically gives you the equivalent of a 120 lbs/in spring under compression. I think this is invaluable information for any of the serious 3rd Gen protege autocrossers on here. To a lot of us, these numbers mean a great deal.

 

[benjpi]

Jeff,

Did you measure the rate holding the bars at their actual pivot points? The actual "rate" on the rear bar is lowered by the distance to the pivots. The "klunk fix" bracket raises the rate by eliminating the bending.

I ran FEA on the RB rear bar and the AWR. Depending on the location of the adjustable clamps, the AWR bar can be SOFTER than the RB bar.

Maybe when I get home tonight I'll post the pics from the FEA output.

Ben

 

[Tom03es]

subadubado!

 

[njaremka]

subbin', only because i'm running a stock ES / Pro5 front bar and a MS rear with the klunk-fix brackets...

looks like my set-up might actually give equal front-rear wheel rates? (combined with the springs and all?)

 

[Tom03es]

I have the same set-up and really like the feel. I've driven other FWD cars set up for extreme understeer and extreme oversteer and the Protege seems to sit well right in the middle.

 

[njaremka]

yeah, it feels very balanced. i can get on it running up to speed on the highway on ramps, and it just plants and goes.

 

[Jeff@Tri-Point]

Jeff,

Did you measure the rate holding the bars at their actual pivot points? The actual "rate" on the rear bar is lowered by the distance to the pivots. The "klunk fix" bracket raises the rate by eliminating the bending.

I ran FEA on the RB rear bar and the AWR. Depending on the location of the adjustable clamps, the AWR bar can be SOFTER than the RB bar.

Maybe when I get home tonight I'll post the pics from the FEA output.

Ben

All tests were done at the stock pivot points. I'm sure moving them out would increase bar rates. Does anyone know how far it's moved out compared to the stock location?

 

[benjpi]

RB bar, field measurements on pivot points & overall lengths. NOT exact data, I was using this to test some theories. The load I applied was 100 lbs at the bar load point (end link connection). So, the NET deflection for the RB (double what's in the picture limited as max) equals 100 lb/0.27" or 370 lb/in.

Note this WONT represent the rate measured at the wheel, the connection point of the swaybar is at the strut but is inboard of the wheel centerline. Not sure of the exact ratio.

 

[benjpi]

Here's the AWR bar, with the adjustable clamps located towards the end of the adjusment range, so that its more towards the rear of the car.

rate = 100 lb/0.29" or 344 lb/in. Again, measured at the BAR, not the wheel. In any case, the AWR bar with the clamps out at the ends is LESS stiff than the RB bar. I had estimated/measured the bar length at 9". I don't show the bend cause its not really important.

 

[benjpi]

AWR bar, 5" length, meaning adjusters between rear lateral links. 100 lb/0.14 in. or 714 lb/in. Much stiffer than stock.

 

[benjpi]

RB bar, 5" length, klunk-fixed. Estimated, don't have mounts on. 100 lb/0.07" or 1428 lb/in. Note that a klunk-fixed bar MAY be stiffer than an AWR even when the AWR bar is set to the short length. This is due to the bending of the bar in addition to the twisting.

 

[benjpi]

NOTE: the above was done after a days work, and I'm tired. I didn't make CERTAIN all my boundary conditions were set exactly the same, but really I was just using FEA to make pretty pictures. The basic facts are: (1) the increase in bar diameter from 3/4" to 7/8" doesn't overcome the doubling of the bar length if the AWR bar is set BEHIND the rear lateral link (2) setting the AWR link in front of the rear lateral link makes it stiffer than an RB bar by shortening the arm, allowing the increased diameter to have an affect (3) the inboard location of the rear sway bar pivots compromises the effectiveness of the bar in torsion, which is its intended job and (4) the klunk-fix bracket offers a significant stiffening of the rear bar.

Based on this, I'll likely be taking my own AWR bar off & putting my RB & klunk fix brackets on. I've run the RB bar before, but never the klunk fix. Curious to see if the reality is close to the pretty FEA pictures.

 

[Jeff@Tri-Point]

The basic facts are: (1) the increase in bar diameter from 3/4" to 7/8" doesn't overcome the doubling of the bar length if the AWR bar is set BEHIND the rear lateral link (2) setting the AWR link in front of the rear lateral link makes it stiffer than an RB bar by shortening the arm, allowing the increased diameter to have an affect (3) the inboard location of the rear sway bar pivots compromises the effectiveness of the bar in torsion, which is its intended job and (4) the klunk-fix bracket offers a significant stiffening of the rear bar.

Based on this, I'll likely be taking my own AWR bar off & putting my RB & klunk fix brackets on. I've run the RB bar before, but never the klunk fix. Curious to see if the reality is close to the pretty FEA pictures.

I've never used the AWR bar, just seen pics.

The racing beat bar has a bend in it, is there any way to change your drawings and recalculate? To me it seems like you're comparing apples to oranges because the AWR bar is straight and the Racing Beat bar is not. That doesn't suprise me that if the AWR set to the softest setting, it would be close to the racing beat.

Also do we know if the inside wall thickness on the racing beat bar the same as the AWR bar?

Do we know how far the clunk bracket moves the bushings outwards? I can always retest at the anti-clunk bracket settings.

 

[benjpi]

Jeff,

I don't think that the bend in the middle would have a big effect, but maybe I can try it tonight to see. Also, I don't think that either bar is hollow, I think they're both solid.

Ben

 

[Jeff@Tri-Point]

Jeff,

I don't think that the bend in the middle would have a big effect, but maybe I can try it tonight to see. Also, I don't think that either bar is hollow, I think they're both solid.

Ben

There is also a 7/8" (21.5mm) fully adjustable bar available with a wall thickness of .20"

AWR fabricates a 3/4" (19mm) 2 way adjustable rear sway bar the 1995-2003 Protg. It has a wall thickness of .20"