Alan Cesar Associate Editor
June 4, 2012 9:49 a.m.

We added a rear anti-roll bar to the Fiesta. Interesting how they do it with a twist beam.

Even Per reads the instructions when he installs new things.

http://grassrootsmotorsports.com/project-cars/2012-ford-fiesta/first-blood/

iceracer UltraDork
June 4, 2012 9:52 a.m.

There are several out there.
Which one did he use. ? they simply stiffen the twist part.

Alan Cesar Associate Editor
June 4, 2012 9:55 a.m.

Ours came from Steeda.

mazdeuce Reader
June 4, 2012 10:22 a.m.

I do wonder if it's worth drilling the extra holes to install the steeda part. There are four different options that I'm aware of for the car. The Steeda drill and bolt. The Corksport bolt into existing holes. The Racing Beat bolt on with big U bolts. And an option from Europe that completely ignores just stiffening the beam and uses a conventional style bar. Usually you're just worried with how stiff a bar is. These cars are slightly weird.

Alan Cesar Associate Editor
June 4, 2012 10:57 a.m.

We should try something like this next time:

e_pie Reader
June 4, 2012 11:01 a.m.

Wonder if I could make that fit my Insight, it could use some stiffness.

PHeller SuperDork
June 4, 2012 11:08 a.m.

On the Beam/Channel that the Turbo Dodges used, I found that even bolting a long piece of angle iron into the channel definitely increased lift-throttle oversteer.

Some guys welded them shut.

mazdeuce HalfDork
June 4, 2012 11:12 a.m.
Alan Cesar wrote: We should try something like this next time:

I've been wondering how that would work. It seems like you would need to lock the ends into place to get it to work effectively. What I really want is something sort of like that but one that uses a hex bar. Then I could just adjust how far the collars are from each other, thereby adjusting the effective length of the bar, and thus, stiffness. I need to actually work on things instead of just sitting around thinking about them.

belteshazzar UltraDork
June 4, 2012 11:28 a.m.
mazdeuce wrote: I need to actually work on things instead of just sitting around thinking about them.

that's always the struggle isn't it

Vigo SuperDork
June 4, 2012 10:12 p.m.
On the Beam/Channel that the Turbo Dodges used, I found that even bolting a long piece of angle iron into the channel definitely increased lift-throttle oversteer. Some guys welded them shut.

I weld a plate on mine. Also have two aftermarket bolt-on sway bars. One car has both.

Streetwiseguy SuperDork
June 4, 2012 10:19 p.m.
mazdeuce wrote:
Alan Cesar wrote: We should try something like this next time:

I've been wondering how that would work. It seems like you would need to lock the ends into place to get it to work effectively. What I really want is something sort of like that but one that uses a hex bar. Then I could just adjust how far the collars are from each other, thereby adjusting the effective length of the bar, and thus, stiffness. I need to actually work on things instead of just sitting around thinking about them.

I don't think those hose clamps have quite enough strength, but the rear sway bar on my Camaro is mounted to the axle tubes with 3" muffler clamps. Works perfectly- I've broken lots of end links, but never had a moments trouble with the center mounts.

HiTempguy SuperDork
June 4, 2012 11:25 p.m.
Streetwiseguy wrote: but never had a moments trouble with the center mounts.

BUDUM TSH!

That's for all you enginerds in the crowd.

Alan Cesar Associate Editor
June 4, 2012 11:54 p.m.
HiTempguy wrote:
Streetwiseguy wrote: but never had a moments trouble with the center mounts.

BUDUM TSH!

That's for all you enginerds in the crowd.

Ha! Moments.

Jokes, I get them. Who else is awake too late tonight?

unevolved Dork
June 5, 2012 1:08 a.m.

Me. Just got back from the engine lab, putting the finishing touches on our Formula SAE car before Lincoln in a few weeks.

Derick Freese SuperDork
June 5, 2012 1:49 a.m.

I thought everyone was awake at night...

I need to do something like this to increase roll stiffness in my twist-beam Astra. I'd like to reduce understeer and make the chassis a bit more neutral. As it is, it plows like a pig most of the time.

Ian F UberDork
June 5, 2012 4:20 a.m.

This design is basically the same as the Shine bar used on the twist beam in VW's. I just hope the Fiesta doesn't experience the cracking problem that I've read about sometimes.

Derick Freese SuperDork
June 5, 2012 7:17 a.m.

I just noticed it, but is that Tucker's $2011 Miata in the background there?

alfadriver UberDork
June 5, 2012 7:44 a.m.

Am I the only one who things that if you use the right shaped beam that can rotate- you can use that to adjust the roll stiffness of the twist beam?

Say length - most of the main twist beam, width- say 2", thickness- 1/4"- if you try to bend that one direction, it's not that hard- the other, virtually impossible. Change the angle, change the stiffness. So an easy, adjustable swaybar.

the other easy way is to have mounting points that start close, and move out- farther out = stiffer. Again, pretty easy to put in.

Streetwiseguy SuperDork
June 5, 2012 7:47 a.m.
alfadriver wrote: Am I the only one who things that if you use the right shaped beam that can rotate- you can use that to adjust the roll stiffness of the twist beam? Say length - most of the main twist beam, width- say 2", thickness- 1/4"- if you try to bend that one direction, it's not that hard- the other, virtually impossible. Change the angle, change the stiffness. So an easy, adjustable swaybar. the other easy way is to have mounting points that start close, and move out- farther out = stiffer. Again, pretty easy to put in.

I've seen the rear frame bar on race karts be rotated to change chassis stiffness. Similar sort of thing could be workesd out for a sway bar, you would think.

Ian F UberDork
June 5, 2012 7:55 a.m.
alfadriver wrote: Am I the only one who things that if you use the right shaped beam that can rotate- you can use that to adjust the roll stiffness of the twist beam? Say length - most of the main twist beam, width- say 2", thickness- 1/4"- if you try to bend that one direction, it's not that hard- the other, virtually impossible. Change the angle, change the stiffness. So an easy, adjustable swaybar. the other easy way is to have mounting points that start close, and move out- farther out = stiffer. Again, pretty easy to put in.

The problem I can see with the idea is the attachment points at the ends of the bar. On a Shine VW bar, there are 2 thru bolts on each end to transfer the twisting forces. And these forces are severe (given the VW beam sometimes cracks where the thru holes are drilled). I'm not sure how a moveable mounting point could be done that would hold fast without shifting. Maybe a sliding clamp, but I'm not sure...

On VW's, when an adjustable RSB is desired, a more traditional style of bar is used and clamped to the beam with sliding end links attached to chassis points.

alfadriver UberDork
June 5, 2012 8:01 a.m.

In reply to Ian F:

My thought was more of a spline end- where you could take the end out, rotate it, and bolt it back in. Splines can take tremedous loads. For this- one could even use a blade design that was cut from a torsion spring. Should work great.

Ian F UberDork
June 5, 2012 8:06 a.m.

Yes, but the torque forces are still concentrated on the specific mounting points of the beam at each end of the bar. Unless you can vary the diameter of the bar, and thus its stiffness, I'm not sure how rotating the beam will change anything other than maybe tweaking the bar towards one side or the other.

alfadriver UberDork
June 5, 2012 8:15 a.m.
Ian F wrote: Yes, but the torque forces are still concentrated on the specific mounting points of the beam at each end of the bar. Unless you can vary the diameter of the bar, and thus its stiffness, I'm not sure how rotating the beam will change anything other than maybe tweaking the bar towards one side or the other.

If you put the beam far enough out, more of the force will be in bending instead of twisting. And the bending stiffness is easy to manipulate via the cross section that will be tried to be bent.

Yes, all of that force does have to move through the mounting ends and into the twist beam, but that seems like a farily basic design.

One of the cool things about using the stiffness of a twist beam to act as a sway bar is that you can put the additional stiffness anywhere, not just below the car.

mazdeuce HalfDork
June 5, 2012 8:15 a.m.

I think that's the difference. In a kart the bar is actually bending, so rotating something non symmetrical works. With a twist beam, it's just twisting, mostly anyway, so that same idea won't work.
The Racing Beat bar clamps on with what looks like fancy exhaust clamps, which is pretty nifty from a stress reduction standpoint. The bar is welded to end plates though. If you had a bar that was splined along its length, or square or something, and you could slide the clamps in and out you could adjust the effective length of the bar and it's stiffness.

dyintorace UltraDork
June 5, 2012 8:19 a.m.
Derick Freese wrote: I just noticed it, but is that Tucker's $2011 Miata in the background there?

As a matter of fact, it is! I sold the car to the rally school as an addition to their school fleet. Rumor has it that it raced in the recent Daytona chump car race too. I wonder if they kept the turbo on for that. If so, it would have been pretty illegal by CC standards!

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