Kia Rio front swaybar and radius rods

[Advancedynamix]

Just had a thought: the festy sway bar is solid... So what's stopping us from lopping it in half, milling a groove into each end and coupling them back together to maintain position but allow the articulation we're looking for?

Thoughts Charlie?

I'm not really sure I know what you mean.
As it is, the festiva bar is sort of a strange part. If it's allowed to move from side to side at all, the car does some really peculiar things. I realised this after Dragonhealer did the DIY poly sway bar bushings that were a popular mod awhile back. The car would pull to one side under throttle and pull the opposite way under braking. He changed out all sorts of other stuff (brake calipers, control arms, ect) to try and fix the issue, but it turned out to be those sway bar to frame bushings were allowing the bar to walk a little from side to side. This is more proof of the importance of maintaining the geometry of the front of these cars, and backs up the importance of the reinforced lower rad support on high hp cars.
Anyway, I'm now very cautious to do anything that would allow that bar to move side to side. As it is, it's kind of held in place by luck, since there is no thrust surface to limit the travel. It relies on the bends of the bar being squished by the bushing.

[sketchman]

But if you just use the longitudinal sections and put rod ends on the front ends they still can't move side to side. And you are using the same springy parts that do the magic to keep traction.

[robotrob]

That's what I'm thinking.. Seems easy enough, even if we weld the rod ends onto the ends of the cut swaybar arms they seem to do most of their magic in the middle section so we'd only be messing with the metallurgy at the very end of the rod, as long as somebody knows how to weld appropriately for the conditions/materials then I don't see it being a problem

Although if I could run a die straight over it that matched straight up to a cheap threaded rod end that would be easier for me to, and I think adequate, I can think of a number of cars that have threaded radius rods

[robotrob]

Hmmm.. 22mm swaybar, m22x1.5mm die is only $30, 22mm threaded rod ends cheapest I could find $37 a pair shipped.. A couple of m22x1.5 threaded rod couplers and I think I can do this.. Or at least try

[blake4591]

Hmmm.. 22mm swaybar, m22x1.5mm die is only $30, 22mm threaded rod ends cheapest I could find $37 a pair shipped.. A couple of m22x1.5 threaded rod couplers and I think I can do this.. Or at least try

I wouldn't use rod ends. I would take a rio bar cut it approximately 1.5" from the chassis bushing end. Then go to the next straight section (after the tight ~30° bend but before the largest radius bend) cut that to the correct length to stay under the front frame rail. Od thread both of these parts put a coupler over the two pieces and put in a couple rosettes to keep everything in place without putting in a lot of heat. I think this would be the safest, easiest and most reliable method but it would require a custom lower chassis brace as the mounting points would be directly under the frame rails instead of a couple inches inside.

The problem with rod ends is that they are extremely rigid and tend to fatigue and break sheet metal. Just ask the fox chassis guys about worn out and broken torque boxes.

[robotrob]

I tend to agree with you about rod ends being too rigid.. But the later rio rods are bolted to the LCA and have the bushing on the other end that looks a lot stiffer than my sway bushes at the moment.. Surely a rod end at the sway bar to chassis bush end and standard swaybar to LCA bushes would be comparable in rigidity and probably allow more flex than the 02-05 rio set up?

[sketchman]

Yep. Look at the one that's totally solid at the control arm. I'll bet it'll be fine.

[robotrob]

Im beginning to wonder if the 02-05 rods being bolted to the arms might have been in an effort to eliminate the pivot point at the swaybar to LCA bushing and prevent the LCA from rotating on its axis.. As much as the LCA bushes would allow anyway.. The vertical as opposed to horizontal mounted bushing on the rod could only be designed to limit travel more.. One would imagine.

My idea with the rod end would not restrict movement at all

[Advancedynamix]

But if you just use the longitudinal sections and put rod ends on the front ends they still can't move side to side. And you are using the same springy parts that do the magic to keep traction.

Exactly. I'm not sure where Arty is talking about cutting them and I'm having trouble imagining his design. Chances are that it's a good idea (Arty has a good track record for good parts ideas.)

That's what I'm thinking.. Seems easy enough, even if we weld the rod ends onto the ends of the cut swaybar arms they seem to do most of their magic in the middle section so we'd only be messing with the metallurgy at the very end of the rod, as long as somebody knows how to weld appropriately for the conditions/materials then I don't see it being a problem

Although if I could run a die straight over it that matched straight up to a cheap threaded rod end that would be easier for me to, and I think adequate, I can think of a number of cars that have threaded radius rods

I am a 10+ year certified aerospace welder who has established 2 automotive parts companies that design suspension components for the aftermarket auto industry. Trust me, I've seen the results of ignoring metallurgy guidelines. It's not pretty. Lol.
Keep in mind that nearly 100 percent of the Festivas driving torque is transmitted through these links, as well as 80 percent of the braking forces (far greater than acceleration forces in most cars.) These bars are serious buisiness on this chassis.

Hmmm.. 22mm swaybar, m22x1.5mm die is only $30, 22mm threaded rod ends cheapest I could find $37 a pair shipped.. A couple of m22x1.5 threaded rod couplers and I think I can do this.. Or at least try

That would be the route that I'd go. You'll want to be really careful with the die, and buy an adjustable one so you can take several light cuts.

I wouldn't use rod ends. I would take a rio bar cut it approximately 1.5" from the chassis bushing end. Then go to the next straight section (after the tight ~30° bend but before the largest radius bend) cut that to the correct length to stay under the front frame rail. Od thread both of these parts put a coupler over the two pieces and put in a couple rosettes to keep everything in place without putting in a lot of heat. I think this would be the safest, easiest and most reliable method but it would require a custom lower chassis brace as the mounting points would be directly under the frame rails instead of a couple inches inside.

The problem with rod ends is that they are extremely rigid and tend to fatigue and break sheet metal. Just ask the fox chassis guys about worn out and broken torque boxes.

I might be more inclined to use a heavy duty threadlocker or sleeve retaining compound than rosette welds, but this is solid advice.
Heim joints have a ton of great applications, but direct TQ loads is not one of them. I might use them for the inner control arm pivot, as that fulcrum only sees partial lateral forces, but that would only be if I couldn't use a suitable rubber or poly bushing system.

[sketchman]

I think Arty meant to cut the bar up front in half and then put a sleeve over it to join it back together using a radial? groove in the bar to somehow lock the halves laterally but still allow free rotation turning them into (essentially) just links.That design would also keep the front bushings stock.

[Advancedynamix]

Ahh. Yeah. That might get messy because of the shape of the bar. If it were a simple u shape, that could work with a pinned sleeve of some sort. The bar has a dip in the front though, which buggers up the geometry for that type of slip joint. Maybe not though.
It's easier for me to bend up new rods than it is to fuss with the factory sway bar, that's why I'll go that route.

[blake4591]

I tend to agree with you about rod ends being too rigid.. But the later rio rods are bolted to the LCA and have the bushing on the other end that looks a lot stiffer than my sway bushes at the moment.. Surely a rod end at the sway bar to chassis bush end and standard swaybar to LCA bushes would be comparable in rigidity and probably allow more flex than the 02-05 rio set up?

It's a little different. You're talking about removing the isolater that transmits alot of forward forces to the car. The rubber bushing at the swaybar/ control arm is there to allow some relative movement that is needed with the festiva design to handle the spring load coming in on the sway bar. Either of the Rio designs don't really need this bushing as there is a separate sway bar. I would guess that the main reason for removing the bushing was cost reduction. Rubber bushings, washers and a cotter pin cost more to buy and install than two nuts. Both rio designs though retain the bushing on the chassis side. Could it still work with the rod end absolutely yes but I would have a back up plan to use a bushing if needed.

Ahh. Yeah. That might get messy because of the shape of the bar. If it were a simple u shape, that could work with a pinned sleeve of some sort. The bar has a dip in the front though, which buggers up the geometry for that type of slip joint. Maybe not though.
It's easier for me to bend up new rods than it is to fuss with the factory sway bar, that's why I'll go that route.

Aspire sway bar as a long straight part that is on axis with the mount/rational center lines. It would be the best candidate to do this style of a slip joint. You still have to deal with the keeping it from moving side to side though

[Advancedynamix]

I tend to agree with you about rod ends being too rigid.. But the later rio rods are bolted to the LCA and have the bushing on the other end that looks a lot stiffer than my sway bushes at the moment.. Surely a rod end at the sway bar to chassis bush end and standard swaybar to LCA bushes would be comparable in rigidity and probably allow more flex than the 02-05 rio set up?

I didn't see this originally.
It is best to isolate both ends, but even Porsche only isolates one end on thier cars (they don't have the trick flexible link though, but Audi used to use it).
You've also got to have a way of keeping the trailing link clocked properly. If it's allowed to freely rotate on one end and has a circular bushing on the other, it will try to rotate slightly. This could alter your caster from one side to the other and make the alignment hard to keep in check.
This is why I would use a vertical bushing (see Porsche 996,997,986,987,991,981 cars) in my control arm and a bushing lIke the rio has in the front. I would make the caster adjustable from the front with shims on either side of the bushings. This is simple, easy to manufacture and it can utilize OEM rubber bushings which are superior to Poly if not overloaded. It would take a little R&D to get right, but that's what I do.

[FestYboy]

I think Arty meant to cut the bar up front in half and then put a sleeve over it to join it back together using a radial? groove in the bar to somehow lock the halves laterally but still allow free rotation turning them into (essentially) just links.That design would also keep the front bushings stock.

That's what I was seeing. And reading the posts after my brain storm: this coupling should be able to be placed anywhere on that section of the bar as the amount of rotation will be likely under 15* and therefore keep any off Axis loading to a minimum.

[Advancedynamix]

You'd want the sleeve to cover a good portion of the bar for support. Otherwise, it'll want to buckle in the middle with TQ load.