i am making an anti roll bar/sway bar, whatever you want to call it, for the rear of my 33 humpback panel truck [the "eternal project"] and i have a question about the pivot bearing mount.
member Gregsdart made one from 1 3/4" dom tubing, and i'm going to imitate his bar.
the question is, can the bushing and mount be on the inside of the tubing instead of the outside ? or will that not allow the bar to work as intended ?
i'm thinking of a slug of nylon, poly, or bronze, the i.d. of the tube and maybe 1 1/2" long or so, bolted to end flanges, which in turn will be welded to the plates shown in the pics with the two 3/8" bolts ahead of the shock mock up bar. the bar arms will be attached to the top of the ladderbar brackets in the usual tubing/heim method.
any thoughts on my idea ? yes, no, maybe ?

anyone ?

Never heard of it, but doesn't mean it can't be done.
However: although the final effect of the bar varies with other dims (center width, arm length) 1-3/4" OD is huge, never heard of one that big in the rear. If you use that size put lots of range in the arms' leverage (longer arm and/or point of attachment reduces bar strength).

Almost looks ready for a pillow block bearing.

I made my anti roll to be basically a solid, no give anti roll. It is made of . 134 x 1.75 diameter mild steel tube for that reason. If you want one that will flex some like an anti sway bar as used on the street, spring steel is needed.
My first attempt was 1 375 diameter x . 125 wall for the tube. Twisted it on the first pass. The bigger one has held up.
For an internal bearing maybe a large caged needle bearing of the proper diameter or a simple bronze bushing could be used. Picture is of the one I built. There are roller bearings inside the ends .

When I built mine the first bar it broke after about 10 passes so I ended up buying the one thats
been in there for years.. with a four link car you sure dont want to break that bar.. I broke mine
when I was down in Norwalk... the car made a hard right turn but I didnt hit anything.. scared
the HELL out of me plus the loud BOOM inside the car.. packed up and went home

mr. P, how big was the bar that broke, and what did you replace it with ?

Maxx, the plates can represent pillow blocks [what i had first thought of] if i decide to go that route, and can find some that would be strong enough in the size bar i eventually decide to go with.

Poly, the C/C of the plates to the upper ladder bar mount bolt is 6", and the plate mounts are 25" apart. as of now, i have a piece of 4130 solid, and the heims needed to attach the arms to the rear. i have access to other diameters of 4130 solid, so i can go up as needed.
the arms are not built, and i have been thinking of possibly obtaining a sprint car torsion bar [??? diameter] to cut to length. when done, [eventually, if i live long enough ] the truck should weigh somewhere around 28-2900lbs or less with me in it. i am building it on the overkill side to prevent breakage, putting maybe 550-575 rwhp through it.
your design ideas are greatly appreciated !

Greg, Thank You for allowing me to copy your idea, or at least the concept !

and to ALL you guys, a BIG two thumbs up steering me in the right direction !

Thanks for the vote of confidence, but I have nothing worth sharing to contribute here, the car is so completely different from anything I've worked on.
VW Type I ("beetle") T-bars are about 22", available in different stiffness, IIRC the ends are splined to allow easy linkage adjustment.
A rear bar where none existed may give massive oversteer when applied, be conservative!

Why an anti-roll bar when using ladder bars? A ladder bar set-up is one big anti-roll bar. With a 4 link set-up it makes sense..
Doug

This crooked twisted launch was produced by ladderbars. All it takes is being real close to the neutral line

The problem was... I screwed up and welded on the inner tube which is what broke.. I forgot
the shop that I bought the new one from but they offered 2 lengths but the same dia(I believe)
but a lot of the chassis shops offer a kit

Mine w/o an anti roll bar. If its twists something is flexing.
Doug

my chassis is all . 134 wall x 1 3/4 dom, on 2x3 x . 125 wall, so the vast majority of flex is in the bars themselves. At one point years ago I had another driver tell me it actually had one rear tire off the track on the hit. Few ladderbar chassis have the ability to get set below the neutral line. Mine is one of them. When I had the front of the bars in the bottom hole in front, they are just at or under the neutral line.
On the hit the driver's side would rise, and passenger side would want to squat, producing a violent twist at launch. My first anti roll bar was 1 3/ 8 x .125 wall me tube, and it was permanently twisted out of shape on the first pass. Upgraded to the big tube, no more twist. One way to prove or disprove my assumption is to suspend your car under the center of the differential . Then support the rear of the chassis with jackstands to immobilize it. Measure exactly how hi both rear tires are off the ground. Suspend 100 lbs of weight on the outside of the right rear . You will see the flex in how much the right rear is pulled down. If you want to check for chassis flex, suspend the front of the chassis so tires are off the ground suspend the back with a jack at the center of the rear housing. A long beam of some sort attached
crossways firmly to the back of chassis that extends out far enough to apply a lot of leverage. Add weight to the outer end of the beam and measure all four corners of chassis height to gauge flex. It may be very little, but if you calculate the torque values going through the drive line it will make sense. Suspending 100 lbs five feet from the center of the rear is only 500 ft lbs of twisting force.
If you have 750 ft pds engine torque, X 2(converter) X 2.45 (low gear) that works out to about 3700 lbs of rotational torque being applied at the hit, trying to twist the rear axle like a propeller. If your ladder bar mounts are 2.5 feet apart, 3700 divided by 2.5 is 2800 ft lbs divided to each side of the chassis. That means at the hit the driver's side is being pushed apart by 1400 pds of force, and the pass side is being pulled together by 1400 ft lbs. Those short term forces try and force the driver's side ladder bar to rise, and the pass side to go down. When way above the neutral line, this is overcome by higher forces of the housing trying to produce rear rise.

thanks for the test procedure Greg.
i will have to do that and see just what "may" happen. if i need a bar, at least i have a place already to mount it.
my chassis is like yours. 2x3x1/8 with a cage of 1 3/4x.134 wall. i know this is heavier than necessary, but i decided the weight penalty would be offset by added stiffness.
there are still more bars to add, gaining reinforcement and triangulation.
the body is basically just a skin, attached to the chassis at the cowl/firewall, front and rear of the front door opening[s], the wheel tubs, and at the rear of the body.
even i can lift the front and rear of the body to put it on something higher than jack stands to work on it. if i can do that, the body can't weigh much.

Not to argue. But to discuss and learn. Not sure I agree with this statement. Both sides will either separate, squat, or do nothing. Neutral line location has nothing to do with which side is loaded. Engine torque will try to twist the housing. But with ladder bars the only way this can happen is if the large anti roll bar (ladder bars and housing) flex. Or if the chassis flexes. Agreed the anti roll bar will add another member to act in the same manner as the ladder bar/housing. I guess my question is why would a chassis car with similar power and gearing twist more than a stock frame rail car? For what it's worth mine is on the neutral line or very close to it.
Doug

I agree with dvw my car has been 1.18 60' with ladder bars and no anti roll. Straight and level every time. I would be more concerned with those welds on the 180 degree brackets. If it hooks hard and the welds let go the rear is coming out of there. The pic isn't great but the welds don't look like they have very good penetration.

The body on mine is just a shell also I use to pick up the whole body by myself when I was
building it..a bath room scale is your friend

One thing to think about when using less expensive bushed anti-roll bars. The end bearings need to be perfectly square to the ARB or it will bind. The better ones use a spherical bearing that can tolerate some miss-alignment.

Good info. I figure that to prevent bind it may need to have a bit of extra clearance in a bushed app. A bit of Pre load would keep it from rattling.
Also a book on Chassis by Herb Adams is a great read. It covers much more than drag apps.

For $236 I would never try and build my own...

https://quartermax.com/quarter-max-anti-roll-bar-kit/

i don't like those welds either. they will be cut and re-done, and have been marked for such. thanks for pointing that out !
i also have a fixture to straighten the housing when the proper weld heat is applied to it.

If your rolling to a great extent then you are twisting the housing or bending the bars. Both need to be addressed correctly. The axle housing in a ladder bar set up is the Anti Roll bar. Anti Roll bar on a ladder bar car is nothing more than a ...

put the back of your ladder bar car on jackstands. Pull one front bolt. See how easy it is to pry the front of the ladderbar up or down. That, my friend, is flex. A ladder bar may try to act as an anti roll, but the leverage is too great. All metal objects compress, expand, or twist under load. If you want to see this, measure a connecting rod bolt with a stretch gauge when it is loose . Now tighten only with your figure tips. You should see a very minor stretch, maybe . 0001 or. 0002! Now, translate that into what a 900 hp, 750 ft lbs of torque multiplied by converter and low gear can do. It can bend stuff, like ladder bars , brackets, bolts, housings. Hence the need for an anti roll when simple pre load or other adjustments can't compensate enough. On my car the bottom hole in the front brackets is the one that an anti roll is needed.
Higher holes I could compensate with preload and shock settings.

Every ladder bar car I know that installed a Anti Roll bar, picked up ET, and made the car more consistent. I'd never run any dedicated race car without one again.

i really appreciate the teaching moment this has been for me from you folks !
the knowledge shared is being noted and compiled, and although this project is/has been a lengthy one, i hope to be able to [one day] report how it goes down the track.
when this thing was acquired almost a half century ago, i had a vision of what i wanted this to turn out to be, and i'm staying pretty close to it all these years later.
if i was smart, [ ] i would have had a shop of sorts do work for me, possibly having it done years ago. however, the skills i have acquired during this build, plus the knowledge learned that can be also applied to other builds, is priceless.
meaning, a LARGE amount of this is credited to YOU FOLKS here !
if possible, please continue to assist me along this journey with your criticism and wisdom, and try not to beat me too hard when this old guy asks stupid questions.
Thank You All again !

FWIW we run a large splined anti roll on the vette. It seems to be a big help for us keeping the car level at the hit. 60' times in a small tire SB NA car says it must be working ok

says UP TOO 800HP.
My cost to build my own was leftover tubing from a chassis I built, some 1/4 inch cold rolled plate, 8 5/16 bolts, and whatever it cost for the rod ends and tube for the links. Plus two large roller bearings. I doubt I have over $90 in it.

i always like to use up the leftovers to use in other projects like you Greg !
as a retired machinist, it keeps my skills up, and keeps me out of trouble.
besides, i have to budget my bucks so the doctors and hospitals get THEIR fair share !

I wished I had been in a trade like yours Mx. My machining capabilities consist of a chopsaw, angle grinder, drill press, welders and plasma cutter. But determination can take a guy quite a ways.
Looking forward to your anti roll creation👍