Protege 5 Stock Sway Bar Rates

[benjpi]

See what I get for working when tired? I did all my calc's based on solid bars. If the AWR bar is hollow, its stiffness won't improve, but the measured rates should look more reasonable. I just (incorrectly) assumed that since the bar has closed ends that it was solid. I guess its capped.

Is the RB bar solid or hollow?

 

[Jeff@Tri-Point]

See what I get for working when tired? I did all my calc's based on solid bars. If the AWR bar is hollow, its stiffness won't improve, but the measured rates should look more reasonable. I just (incorrectly) assumed that since the bar has closed ends that it was solid. I guess its capped.

Is the RB bar solid or hollow?

Tim from Mazdaspeed told me that the racing beat bar is solid. Interesting, it's possible the Racing Beat bar with the clunk fix might be stiffer then the AWR larger bar on full stiff, maybe even straight up without the clunk fix?

Also the Racing beat bar measures at 20mm O.D.

 

[njaremka]

you guys should make sure you have the angle on the endlink correct, too. the ES / Pro5 endlinks are NOT perpendicular to the end of the bar when installed at standard ride height. however, the RB / MP3 / MSP rears are.

 

[Jeff@Tri-Point]

you guys should make sure you have the angle on the endlink correct, too. the ES / Pro5 endlinks are NOT perpendicular to the end of the bar when installed at standard ride height. however, the RB / MP3 / MSP rears are.

I didn't think the angle of the end links are going to have any effect on the bar rate except preload right? Mounting points on the strut are still going to be similar so motion ratios will be similar still.

 

[njaremka]

well, the angle of the endlink will have an affect on HOW the bar gets loaded, and how much of the load gets transfered to the bar.

 

[Jeff@Tri-Point]

well, the angle of the endlink will have an affect on HOW the bar gets loaded, and how much of the load gets transfered to the bar.

I guess I misunderstood, are you talking about the Protege ES and Protege 5 stock rear bar? I guess how does the endlink affect how stiff the bar is? The end links are both straight and the movement from the arm to the mounting point are still the same. Isn't that why we get adjustable endlinks, to take out the preload?

 

[njaremka]

because the "Arms" on the stock rear bar are very long, the endlink are at an angle when it sitting static. so, a 1-inch movement at the strut end might only translate into a 1/2 inch movement at the bar end. whereas, on the mazdaspeed, a 1-inch movement at the strut might result in a 1-inch movement at the bar end.

 

[Jeff@Tri-Point]

because the "Arms" on the stock rear bar are very long, the endlink are at an angle when it sitting static. so, a 1-inch movement at the strut end might only translate into a 1/2 inch movement at the bar end. whereas, on the mazdaspeed, a 1-inch movement at the strut might result in a 1-inch movement at the bar end.

the motion ratio is still the same though, so the bar movement would remain constant regardless of the static ride height endlink angle. The Bar is moving in conjunction with the strut.

 

[njaremka]

gsh-yeah, you're right, i must be on a sugar low or something

 

[benjpi]

Had some time to waste tonight, and I didn't feel like working. I re-ran the sway bar models, I wasn't happy with the constraint settings I used the first time, I think they were too restrictive (the program I use is feature limited, so I have a more limited selection. Hey, it was cheaper than the full-on version). I also updated the AWR bars to be hollow, with a 0.20" wall thickness. My model also assumes the RB bar is NOT hollow.

This is what I got for the rear bars:

Stock RB - 238 lb/in
AWR with "long" settings - 161 lb/in (SOFTER than stock RB)
AWR with "short" settings (about same distance as RB) - 384 lb/in
RB "klunked" - 660 lb/in

I was surprised by the last one, the bending of the bar to get to the stock mounting point takes alot out of the bar. The RB klunked number isn't really true, since the it will deflect the bushings more and I didn't (couldn't) account for that.

Also, I can't account for bushing deflection at all, but it will have an affect. I think it would be worse on stock mounting points versus klunk-fixed, since the effect of the deflection is "magnified" by the lever arm length. In general, though, "actual" rates measured at the wheels will definitely be lower.

The two pics I've attached are from the RB simulation, both the stock and the Klunked setups.

From what I see, the RB bar with the klunk fix is the better setup. I've got an RB bar & the klunk fix in the garage, I'll be changing back soon. I just can't take the noise of the AWR setup, and it appears there's no other benefits..

 

[Jeff@Tri-Point]

Anyone that wants to look at our swaybar tester, there is a picture of it in the Sports Car April 2008 Magazine on page 32.

 

[khaosman]

I noticed that! I was like "hey... I wonder if that's the thing Jeff was using to give us all this info!"

Cool man

 

[Azi]

has anybody felt the need to goto a larger bar than a 22mm?