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rear anti roll/sway bar mounting bushing ??? #2989049
11/25/21 02:40 PM
11/25/21 02:40 PM
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north of coder
moparx Offline OP
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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 ?
beer

PB250011.JPGPB250010.JPG
Re: rear anti roll/sway bar mounting bushing ??? [Re: moparx] #2989290
11/26/21 11:46 AM
11/26/21 11:46 AM
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north of coder
moparx Offline OP
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anyone ? shruggy
beer

Re: rear anti roll/sway bar mounting bushing ??? [Re: moparx] #2989362
11/26/21 03:22 PM
11/26/21 03:22 PM
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New York
polyspheric Online content
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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).


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Re: rear anti roll/sway bar mounting bushing ??? [Re: polyspheric] #2989364
11/26/21 03:39 PM
11/26/21 03:39 PM
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Apollo, PA.
B1MAXX Offline
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Almost looks ready for a pillow block bearing.

Re: rear anti roll/sway bar mounting bushing ??? [Re: polyspheric] #2989469
11/26/21 09:59 PM
11/26/21 09:59 PM
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Frostbitefalls MN (Rocky&Bullw...
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Originally Posted by polyspheric
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).

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 .

20201211_111812.jpg

8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: rear anti roll/sway bar mounting bushing ??? [Re: gregsdart] #2989513
11/27/21 08:23 AM
11/27/21 08:23 AM
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Romeo MI
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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
wave

Re: rear anti roll/sway bar mounting bushing ??? [Re: MR_P_BODY] #2989597
11/27/21 01:36 PM
11/27/21 01:36 PM
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moparx Offline OP
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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 biggrin] 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 ! up bow

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

Re: rear anti roll/sway bar mounting bushing ??? [Re: moparx] #2989631
11/27/21 03:42 PM
11/27/21 03:42 PM
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polyspheric Online content
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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!


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Re: rear anti roll/sway bar mounting bushing ??? [Re: polyspheric] #2989659
11/27/21 05:22 PM
11/27/21 05:22 PM
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MI, usa
dvw Offline
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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

Re: rear anti roll/sway bar mounting bushing ??? [Re: dvw] #2989702
11/27/21 08:14 PM
11/27/21 08:14 PM
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Frostbitefalls MN (Rocky&Bullw...
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Originally Posted by dvw
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

Dart pics + others 105.jpg

8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: rear anti roll/sway bar mounting bushing ??? [Re: moparx] #2989729
11/27/21 10:11 PM
11/27/21 10:11 PM
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Romeo MI
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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
wave

Re: rear anti roll/sway bar mounting bushing ??? [Re: MR_P_BODY] #2989775
11/28/21 08:51 AM
11/28/21 08:51 AM
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MI, usa
dvw Offline
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Mine w/o an anti roll bar. If its twists something is flexing.
Doug

Clay city wheelie.jpg
Re: rear anti roll/sway bar mounting bushing ??? [Re: dvw] #2989803
11/28/21 09:55 AM
11/28/21 09:55 AM
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Originally Posted by dvw
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.

IM000058.JPG
Last edited by gregsdart; 11/28/21 10:46 AM.

8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: rear anti roll/sway bar mounting bushing ??? [Re: gregsdart] #2989878
11/28/21 02:59 PM
11/28/21 02:59 PM
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north of coder
moparx Offline OP
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thanks for the test procedure Greg. up bow
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.
beer

P9070001.JPG
Re: rear anti roll/sway bar mounting bushing ??? [Re: gregsdart] #2989927
11/28/21 05:11 PM
11/28/21 05:11 PM
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dvw Offline
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Originally Posted by gregsdart
[quote=dvw]Mine w/o an anti roll bar. If its twists something is flexing.


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.

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

Re: rear anti roll/sway bar mounting bushing ??? [Re: dvw] #2989929
11/28/21 05:27 PM
11/28/21 05:27 PM
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Memphis TN
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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.

Re: rear anti roll/sway bar mounting bushing ??? [Re: moparx] #2990026
11/28/21 11:27 PM
11/28/21 11:27 PM
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Romeo MI
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Originally Posted by moparx
thanks for the test procedure Greg. up bow
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.
beer


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
wave

chassis1.jpg
Re: rear anti roll/sway bar mounting bushing ??? [Re: MR_P_BODY] #2990070
11/29/21 07:27 AM
11/29/21 07:27 AM
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NW Indiana
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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.

Last edited by fbs63; 11/29/21 07:27 AM.
Re: rear anti roll/sway bar mounting bushing ??? [Re: fbs63] #2990100
11/29/21 09:34 AM
11/29/21 09:34 AM
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Frostbitefalls MN (Rocky&Bullw...
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Originally Posted by fbs63
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.


8.77 153 mph best, 3055 lbs 528 indy 440-1 alky
Re: rear anti roll/sway bar mounting bushing ??? [Re: gregsdart] #2990135
11/29/21 11:26 AM
11/29/21 11:26 AM
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SE Washington
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For $236 I would never try and build my own...

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

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