Sway bar tabs bending?

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Beerj

Sonzabitches!
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3,529
Just trying to figure out what I'm missing here. Recently purchased and installed a TK1 sway bar for my buggy. They have a real nice write-up on their site laying out all of the optimal positions for the whole thing. Such as end links at least as long as the shock travel, end link to axle attachment locations 1-2" wider at the bottom and arms level at 50/50 travel. I did all of that and cycled everything and was satisfied. Took it out for the first time and at some point early on I noticed the tabs where the end links mount to the axle were bent over pretty hard. Now, the kit came with just 2, ⅛" thick tabs. I thought they seemed pretty insufficient but figured that's what they sent so maybe they'll work. Also, the heims provided have studs pressed into them that only stick out on 1 side so they can only be mounted single shear, on ⅛" tabs, with the pivoting part being 1¼" away from the tab.

I sent some pics to Tony at TK1 and he immediately said something must be binding. So I disconnected 1 side and fully flexed the rear. Absolutely nothing is anywhere near binding. Did the same for the other side and got the same results. So I took a bunch of pics and measurements and sent them over. After radio silence for 2 days I asked him again, what's the deal and made it clear that I'm blaming the single shear tabs. He said that's extremely unlikely and 100's of others aren't having issues. He then blamed it on me having the lower heims turned 90° from the uppers. They're not binding at all and I'm really having a hard time understanding how that would make any difference whatsoever.

I could cut off the tabs, turn them and try it but that just seems asinine to me since in my mind, it won't make a difference and I'll just be cutting them off again. I'm leaning towards just mounting them double shear with ¼" tabs and hopefully being done with it.

Also, my reasoning for mounting the lower heims with the studs perpendicular to the axle housing is that since there's not much change in the angle of the lower heim, when viewed from the side, that the most angle change would be when viewed from the back, as the end link stays relatively vertical but the axle angles quite a bit from left to right.

What am I missing here?
 

Beerj

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3,529
Also, seems to me that if something was binding, that the tabs would be bent the same direction. However, they were opposite, like it occurred during flex.
 

squeak12

Well-Known Member
Messages
116
There are many ways to design a swaybar system and each will be somewhat unique to the application. While this design is viable, it isn't really ideal. Single shear at all points with additional leverage by having the studs, relatively low quality looking heims, thin mounting hardware, etc. Also consider that most offroad vehicles in this genre are sprung extremely light and ask a lot out of the sway bar in an attempt to maintain flex while avoiding body roll. That is a viable strategy if the situation dictates, but be prepared to beef up everything related to the swaybar. The loads have to go somewhere and the weights and forces offroad are quite different than other motorsport categories that have smoother load transfer on smaller tires, axles, less travel, etc.

All that being said, I'd boil it down to poor design/execution if you indeed aren't binding. Most just build to whatever they think is big enough with no regard to the weakest link, ultimate loads, or how the mounting points move throughout travel. Here it appears the mounting tabs either being too weak or loaded above their rated capacity... Be prepared if you increase the strength of the tabs (assuming binding is not occurring), the load will go elsewhere not disappear. Could end up breaking heims, bending links, or snapping a swaybar sooner which is actually to be expected on any swaybar, they are just torsion devices that fatigue over time.

I'd also add that it is possible that your pinion angle change may be binding the heims. I don't know what those are rated at versus the misalignment of the heims. Also consider that flexing out the suspension is not the same as if the entire suspension is under a dynamic load. Things bend and have inertia/momentum when actually loaded versus slowly moving through the travel. If you aren't near the limits it will be closer to the real thing, but quite a dangerous assumption to make if you fall in the other category.
 
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whiskeymakin

Well-Known Member
Messages
1,632
Pull that rod end and use a heim with small misalignment spacers and double shear mount it. Thats about the only option i see
 

FlatlandFSJ

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Messages
1,029
I fought a similar issue with the antirock on the rear of Ray's buggy. The arms are shorter then Currie would like, and the end links mount halfway up the trailing arm.

At first we would twist the actual sway bar arm, single shear endlink with the stud hanging off the side. Beefed up the arms with some plate, turning them into l beams essentially. That fixed the issue of twisting the arms, but showed the next weak link. Started pulling the rodends off the built in studs or breaking the studs into 2 or 3 pieces.

Normally we kept a few spare rodends in the trailer, this last time we didnt have a left hand thread spare. I ground the end of the stud off, punched it through the heim and replaced it with a 1/2" grade 8 bolt and small spacer.

It hasn't broke or bent the bolt yet so i plan to just replace the studs with bolts as they break.

The tk1 on the front is single shear at the bar and double shear at the frame(axle mounted bar), it hasnt given us any issues yet.

If you can double shear everything, its the strongest option in my opinion. The studs in those lil rodends are made of some bs potmetal most the time.
 

Beerj

Sonzabitches!
Messages
3,529
There are many ways to design a swaybar system and each will be somewhat unique to the application. While this design is viable, it isn't really ideal. Single shear at all points with additional leverage by having the studs, relatively low quality looking heims, thin mounting hardware, etc. Also consider that most offroad vehicles in this genre are sprung extremely light and ask a lot out of the sway bar in an attempt to maintain flex while avoiding body roll. That is a viable strategy if the situation dictates, but be prepared to beef up everything related to the swaybar. The loads have to go somewhere and the weights and forces offroad are quite different than other motorsport categories that have smoother load transfer on smaller tires, axles, etc.

All that being said, I'd boil it down to poor design/execution if you indeed aren't binding. Most just build to whatever they think is big enough with no regard to the weakest link, ultimate loads, or how the mounting points move throughout travel. Here it appears the mounting tabs either being too weak or loaded above their rated capacity... Be prepared if you increase the strength of the tabs (assuming binding is not occurring), the load will go elsewhere not disappear. Could end up breaking heims, bending links, or snapping a swaybar sooner which is actually to be expected on any swaybar, they are just torsion devices that fatigue over time.

I'd also add that it is possible that your pinion angle change may be binding the heims. I don't know what those are rated at versus the misalignment of the heims. Also consider that flexing out the suspension is not the same as the if the entire suspension is under a dynamic load. Things bend and have inertia/momentum when actually loaded versus slowly moving through the travel. If you aren't near the limits it will be closer to the real thing, but quite a dangerous assumption to make if you fall in the other category.
All great points. At this point, after cycling the suspension every which way and having plenty of travel left in all of the heims and no crazy angles, I'm thinking it is indeed a matter of there just being that much pressure on the components. The bars active diameter is 1" stepping up to 1¼" at the splines and is 33" long. The end links are 15¾" long eye to eye with 14" shocks. If I have the rear flexed out and only the extended side connected, the arm on the compressed side is only 4½" eye to eye between the tab and arm. So I'd say it's seeing some considerable torsional force. Also, the rear springs are 100/150, fronts are 150/200 so the bar is definitely getting a workout. I'm sure it took some hits to 1 rear tire going 40-50 mph so I don't think that was doing it any favors either.

I understand that by strengthening the tabs, the forces have to be transmitted elsewhere. However, isn't that how it's supposed to be? Like, with no binding, then the forces are what they are and I just need to build everything strong enough to accommodate those forces, such as making the mount double shear. The only way that I could see to reduce the force, would be to run a thinner or longer bar or run longer arms. Really no way to fit a longer bar or arms and my understanding is that if I can currently obtain full articulation, then the bar itself isn't too stiff and any reduction in diameter would just equate to less body roll control.
 

Beerj

Sonzabitches!
Messages
3,529
Pull that rod end and use a heim with small misalignment spacers and double shear mount it. Thats about the only option i see
That's what I've been leaning towards. If the force can't change, then components need to beef up. If I was breaking axle shafts, I wouldn't run a smaller engine, I'd just upgrade to bigger shafts. The difference here is there's angular forces involved but as long as they're within reason, then it should be a non-factor.
 

squeak12

Well-Known Member
Messages
116
A properly designed and executed swaybar system isn't typically designed to take a ton of force. They are just systems that transfer existing forces. They aren't creating anything merely a link in the chain that is subject to whatever force is applied. I think the issue is probably more with the general geometry of the situation which unless your are willing to spend a lot of time really examining and measuring and calculating and potentially reworking, then you are pretty much stuck making the best of what you have. Not to sound negative at all just the way it is. Typically the offroad mindset is to beef it up so the weak links are stronger and instead of breaking they will just bend less and handle the stress better. Going with double shear and heavy grade stuff is 100% a viable answer to address small amounts of binding or misalignment, but the better answer is to design it from the beginning to not be put into a situation where the hardware is going to be loaded inefficiently.
 

Beerj

Sonzabitches!
Messages
3,529
I fought a similar issue with the antirock on the rear of Ray's buggy. The arms are shorter then Currie would like, and the end links mount halfway up the trailing arm.

At first we would twist the actual sway bar arm, single shear endlink with the stud hanging off the side. Beefed up the arms with some plate, turning them into l beams essentially. That fixed the issue of twisting the arms, but showed the next weak link. Started pulling the rodends off the built in studs or breaking the studs into 2 or 3 pieces.

Normally we kept a few spare rodends in the trailer, this last time we didnt have a left hand thread spare. I ground the end of the stud off, punched it through the heim and replaced it with a 1/2" grade 8 bolt and small spacer.

It hasn't broke or bent the bolt yet so i plan to just replace the studs with bolts as they break.

The tk1 on the front is single shear at the bar and double shear at the frame(axle mounted bar), it hasnt given us any issues yet.

If you can double shear everything, its the strongest option in my opinion. The studs in those lil rodends are made of some bs potmetal most the time.
That makes me feel a little better. And for what it's worth, the tabs weren't constantly bending all day and they saw maximum articulation countless times after being initially bent. So I would assume that the rest of the components had seen the maximum articulation force and held up thus far. Though hard hits with 1 rear tire at speed is anyone's guess as to if it'll see anything harder but I definitely wasn't taking it easy on it. At that point (after bending the tabs) I wanted to push it as hard as I could to see if anything else would fail.
 

squeak12

Well-Known Member
Messages
116
Also, to flex it out correctly to check for binding you really need to leave the links attached so the system is "in situ" and remove the springs so it will move more easily. Then force the axle corners up and down. It isn't going to be a simple task, though, and you can possibly get away with not doing it unless you keep breaking things after trying some other stuff. Another not huge thing is that the shocks will compress further under an actual load that compresses the rubber bump stops.
 
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Beerj

Sonzabitches!
Messages
3,529
A properly designed and executed swaybar system isn't typically designed to take a ton of force. They are just systems that transfer existing forces. They aren't creating anything merely a link in the chain that is subject to whatever force is applied. I think the issue is probably more with the general geometry of the situation which unless your are willing to spend a lot of time really examining and measuring and calculating and potentially reworking, then you are pretty much stuck making the best of what you have. Not to sound negative at all just the way it is. Typically the offroad mindset is to beef it up so the weak links are stronger and instead of breaking they will just bend less and handle the stress better. Going with double shear and heavy grade stuff is 100% a viable answer to address small amounts of binding or misalignment, but the better answer is to design it from the beginning to not be put into a situation where the hardware is going to be loaded inefficiently.
The geometry aspect is something I tried to get right from the start. I'll admit that I don't know much about the technical side of these things such as arm length vs rod diameter vs length etc, so that's why I left it up to TK1 to advise me on what bar to run. The best I could do was to make sure everthing followed the suggestions and made sure (multiple times) that nothing was binding. I thought that would've been fine but I guess there's other factors that are determined on a vehicle by vehicle basis.
 

squeak12

Well-Known Member
Messages
116
You are also stuck with whatever your 4 link gives you as far as how the mounting points and axle move around during travel. You can try to make the best by optimizing sway bar placement and sway bar geometry, but usually the sway bars go on last wherever they will fit. Nothing is one size fits all unless it is a known OEM vehicle or a system with extensive math and/or testing. I think you will be fine with better hardware and double shear mounting, just don't be so sure that it is anything more than the "best" for what you are working with at the moment.
 

Beerj

Sonzabitches!
Messages
3,529
Also, to flex it out correctly to check for binding you really need to leave the links attached so the system is "in situ" and remove the springs so it will move more easily. Then force the axle corners up and down. It isn't going to be a simple task, though, and you can possibly get away with not doing in unless you keep breaking things after trying some other stuff. Another not huge thing is that the shocks will compress further under an actual load that compresses the rubber bump stops.
I ran it up the rti ramp at the end of the day and didn't see anything close to binding then either. However, like you said, it wasn't really possible to compress the rubber at the end of the shocks in that scenario. At least not as hard as you might actually see on the trail. I was originally thinking that the live load was more than I was seeing by flexing and checking, and it probably is. However, I measured the heims to have 60° of travel and the most I measured on any while flexed was 44° max to max. Again, it could be my ignorance showing but I just couldn't envision another 16° of change no matter how much force was applied. I know it probably sounds like I have an excuse for everything but it's just that I've really put some effort into looking, measuring and thinking about every possible issue that I could come up with. Again, I understand what the sway bar does and how it does it, but you most definitely have more knowledge as to what sort of force is being applied and how best to deal with those forces.
 

squeak12

Well-Known Member
Messages
116
Also, I am not criticizing anything you are doing, just helping think through the process. I'll say also, that measurements are only as good as the tool and the user. And then back to the measurements trying to simulate situations versus actually measuring during said situations. I'd be more concerned with binding in the middle of the travel just as much as at the ends. With that many links all working together in a system, while it seems pretty simple, a lot of angles move around all through out travel and having stable, non-binding paths can be more important than what the max limits are.

We assume everything is rigid for math, but that is never the case. It may be negligible, but things are always bending. The more things you have in a system, the more they can add up and cause issues. Say for example something goofy is happening somewhere and something starts to bind. You better believe it isn't going to halt the vehicle and stop the swaybar from moving With the kind of force I would expect, it is going to bind then push straight through. If you are "lucky" you are below the force which your materials permanently deform, and the links or tabs or bolts or whatever bend back leaving you none the wiser. Making everything stronger can be a fix, but isn't necessarily the right fix. Also being most right isn't always affordable or even required in every situation.
 

Smalls

Active Member
Messages
28
I threw those 1/8 tabs on the shelf and made my own out of 1/4. I figured if those were welded on one side like you have that would be too weak, imo. It would probably be fine in double shear with 1/8. Im not saying my setup is correct but it works. TK1 swaydar with 16" travel airshocks. I used all their provided hardware.
20200710_114222.jpg20200710_114205.jpg20200710_114255.jpg
 
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Zjman

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Messages
1,866
I’m a dummy but looks like to me when the axle articulates the heim could be running outta rotation and binding and bending the tab over cause it ran outta movement. That one is actually touching the truss, I could see mounting it parallel and it not binding that way. Just my view of it
 

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