Twist beam mods

Anyone have experiences with modding twist beam rear suspension for more roll stiffness on the cheap? Maybe weld it so that the c shape beam is a D shape beam?

What kind of car? Is this the recently acquired Prius?

add a sway bar to the Hyundai/Kia platforms.

I used to mount GM front sway bars under the twist beam axles of my A2 VW GTIs. I could get several different bar thicknesses for $10 each at the local U-pull-it yard. It required drilling 4 holes in the bottom side of the beam to mount a couple of flat plates and a couple of the usual style of end links.The GM sway bars came in 1/8 increments from about 3/4" to some ungodly diameter.

The Mazda2/Fiesta use an additional bar between two other points. Now in order to twist the bar you need to pull all of the other stuff along. Word is that it works well.

EASY! just bolt on U-bolts the more you put (equally spaced apart) the more stiff it gets. that what I did and it works great!

I've seen , or read that some old school VW autocrossers would weld flat bar and create the D-section ,too.. OR, make yourself a straight sway bar that mounts inside the C-section (like the Shine Racing bars did on VWs).

Whatever happened to Shine Racing?

ProDarwin wrote: What kind of car? Is this the recently acquired Prius?

I did exactly what you describe to my 1991 VW GTI about 15 years ago. I boxed the rear beam with a piece of 3/16" flat bar. It really stiffened up the car and made it a bit tail happy.

The Fiesta/Mazda 2 bar works really well.

Bolts to two existing holes. QED

The aforementioned hybrid supercar for which the thread was created has a c shaped twist beam with an oem bar inside it bolted through the bar at either end, could I find another oem bar and bolt it to the outside of the c whilst retaining the oem bar or something?

Doesn't it look like you could bolt on another one on the bottom? Idk, maybe I'll just cough up the $140 for the trd. I'd love to achieve the same goal for near free though. The car pushes like crazy and has rediculous body roll. Needs something.

In reply to sesto elemento:

I can't see the ends of the trailing arms to tell if I could mount another bar below the beam. What I can see suggests that I could, but can't be sure.
You might be able to weld up a thicker version of the bar that's there.

Don't wanna hijack the thread, but why couldn't someone take a "sawzall" to the beam and separate it? Making for IRS.

echoechoecho wrote: EASY! just bolt on U-bolts the more you put (equally spaced apart) the more stiff it gets. that what I did and it works great!

To further the U-bolt trick:

Use a piece of steel flat stock the length of the C-shaped beam and wide enough to fit the U-bolts.

You can add or remove U-bolts to alter stiffness and/or play with material thickness/multiple plates, etc.

Should cost you a couple of bucks and eliminates some of the issues with adding a separate sway bar. Mostly the add-on bar and the trailing arm can move in different planes and you can get binding, which causes inconsistent handling.

Add some rubber fuel hose to the U-bolts to reduce the tendency of it to rattle or squeak.

I think you could find a swaybar about as wide as the rear beam with fairly straight ends and clamp it onto the trailing arm section with 4 muffler clamps, no mounts needed. A lot of RWD GM stuff did it that way, just bolted the bar to the lower links, front end of an old VW bug is similar.

Trackmouse wrote: Don't wanna hijack the thread, but why couldn't someone take a "sawzall" to the beam and separate it? Making for IRS.

"Trailing arms" aren't very well located laterally and are designed to flex, remove the link between the two and the two arms will now likely move side to side quite a lot and make for a very scary ride.

Add a bracing lateral link to near the center close to the same plane as the pivot for the trailing arm and you can have a independant trailing arm solution and you'll still lift the inside rear wheel due to the weight and spring rate at the front suspension. Or add multiple links running from the center of the car to the ends of the trailing arms to provide the needed lateral stability.

In reply to BrokenYugo:

and the bar will move in different planes as the axle twists and moves and you'll not be able to keep it from binding or worse breaking mounts.

Most twist beams don't use bars like that, only the aftermarket companies tend to do that. The factory typically adds a bar to the middle of the "C" shaped portion and weld it in place at both ends.

Here is the DDMWorks rear twist-beam stiffener/brace for the Chevrolet Sonic. It is certainly one possible way to stiffen a rear beam, although a conventional sway bar is also available from other vendors.

sesto elemento wrote: Doesn't it look like you could bolt on another one on the bottom? Idk, maybe I'll just cough up the $140 for the trd. I'd love to achieve the same goal for near free though. The car pushes like crazy and has rediculous body roll. Needs something.

So to be clear, it has a bar in the c from the factory already like in this pic, the trd one is just stiffer.

On my challenge Saab I just bolted a piece of angle iron across the car between the wheels. The twist beam looks like a c when looking down on the car from above, and each wheel is located at the end of the c. My angle iron connects the two loose ends.

In reply to Robbie:

Got pics?

sesto elemento wrote: Doesn't it look like you could bolt on another one on the bottom? Idk, maybe I'll just cough up the $140 for the trd. I'd love to achieve the same goal for near free though. The car pushes like crazy and has rediculous body roll. Needs something.

Remove stock bar, weld extra material to it, reinstall? Angle iron would be easy button.

In reply to sesto elemento:

Not with me (traveling for work), but I think I have some on the PC at home.