DTSFab.com (Desert, Trail and Sand)
Automotive Powered Off Road (AKA: Buggys, Jeeps, Trucks, Etc,Etc. ) => Motor and Drivetrain => Topic started by: fabr on February 08, 2009, 07:30:32 PM
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OK so here's a sketch of the upper and lower rear H arms for the buggy.What is best triangulation positioning? Would a combination of plate gussets and tubes be any advantage? What is sketched will be tube with heims inserted.
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Why do I get the feeling you're :t again?
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Not in the least. Front of car is to the right of screen. I may be fishing in a sense since I think I know what I'll do but it's a legit question and I would appreciate any opinions and why. Remember there's no such thing as a stupid question UNLESS it's asked AFTER you weld something up. ;D ;D
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where are your shocks going to attach?
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Lower H arm front tube approx mid point. Not written stone yet.
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like this approximately.
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how are you going to attach the shocks? Tabs, bung, through hole with welded insert?
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just concentrate on the triangulation of the arms in regard to fore/aft forces.
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Don't get snippy. ;) This is what my instincts tell me to handle for/aft stresses. if you need squiggly pieces, I could prolly find some in my scrap pile. ;D I haven't figured out how to draw straight lines....
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Same here but is there any needed in the area of the outer ends where the tubes willl be only 5.125 center to center? Beautiful squiggles BTW! ;) ;D ;D
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I've seen a lot of that type on the long travel SXS stuff... all manor of bracing, too. I'm thinking you should find something that looks good to the eye and it will be plenty strong. I'd look for some of those squiglies myself. :)
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Same here but is there any needed in the area of the outer ends where the tubes willl be only 5.125 center to center? Beautiful squiggles BTW! ;) ;D ;D
If you use bushings, I would say no, cuz the bearing carrier or hub assembly or whatever you want to call it will stabilize the ends, but if you use heims, I would add another short piece of tube to create a triangle-ish shape.
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same with the inside.
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????plate added?
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?????
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sure, I don't think you really need the inner plates if the cut on the brace tubes is real long. I was going to suggest a hole in the outer plate and then I scrolled down and saw it. remember that any little lips are going to accumulate shit, so if you put a plate on the outside, put it on top so it doesn't collect stuff.
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combination of tube and plate. Box the ends in with a nice trough hole W/tube welded through. Plate can be light like .090 on the bottom and.060 on the top......
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex-1.jpg&hash=a2630bdfbb4170c3e274abf84e4977a632746b7e)
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex2-1.jpg&hash=744f92d8c4692dcbb04ce85b4d6b2d5ea5841f5f)
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combination of tube and plate. Box the ends in with a nice trough hole W/tube welded through. Plate can be light like .090 on the bottom and.060 on the top......
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex-1.jpg&hash=a2630bdfbb4170c3e274abf84e4977a632746b7e)
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex2-1.jpg&hash=744f92d8c4692dcbb04ce85b4d6b2d5ea5841f5f)
I was thinking of plate at the midpoint between top and bottom of tubes, So just one plate/gusset of .125?
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Bad/good idea? I know the tube would strengthen 2 plates but I wonder if 2 are needed?
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I know you don't want to do the plate like bdk's top pic. that puts the weak point right at the shock mount. Either you need equal distribution of force so it all fails at the same time or you need to build it like a tank so your weakest link is still plenty strong. I prefer all tubes so it can flex a little and not shear anything off. Flex causes fatigue, but shearing stuff off will scare the shit out of you!
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Eh, if the triangulation tubes are the same DIA and wall as the outside tubes and the plate is thinner, there won't be any problems. That's why there is a cross tube there to distribute the load. In the direction that the shock is putting force into the arm, the plates will do very little. They are there more for front to rear triangulation as it would be difficult to get tubes in that small of space and have them be effective.
The tube through the center is more for looks than anything else.......
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Bad/good idea? I know the tube would strengthen 2 plates but I wonder if 2 are needed?
That would work also......
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By weak I meant relative to the rest of the arm. I think Fabr's pic with the plate with the hole is about the best. His pic has equal amounts of tube on both sides of the shock mount. that will distribute the load.
With your pic where the shock is at the edge of the plate, from the plate out is going to be rock solid and the tube is going to take the brunt of the force because it is not as strong as the plated structure. for the for/aft support, a bigger plate is better. But we don't have just for/aft loads, so you have to think in 3-d and consider all loads, and the shock is a major one.
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combination of tube and plate. Box the ends in with a nice trough hole W/tube welded through. Plate can be light like .090 on the bottom and.060 on the top......
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex-1.jpg&hash=a2630bdfbb4170c3e274abf84e4977a632746b7e)
(https://dtsfab.com/proxy.php?request=http%3A%2F%2Fi55.photobucket.com%2Falbums%2Fg122%2Fbdkw1%2Findex2-1.jpg&hash=744f92d8c4692dcbb04ce85b4d6b2d5ea5841f5f)
I don't think you need the tube gussets.... As long as the main tubes can't buckle, they will not fail. The light plates give the greatest strength/lb. And they are in the correct place to keep the main tubes from buckling. The one in compression (front) is the biggest concern IMO.
I do think you will need some additional undergusseting for the shock mount area, and it will in turn tie into the rear tube somehow.
What is your current arm and axle length? and what size tube are you planning......
Surely you are going longer than 12" on the rear shock...... Wont it be a bit closer to the end of the arm?
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The axle will have plenty of clearance at full droop and bump correct correct? My axle on the car i built ran into the plane of the lower arm I had to make sure i had clearance.... ;D
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Nevermind, you have plenty of width to the car not to worry about that... ;D
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How about some input now about mounting/gusseting the shock mount. I have a couple of inches to play with above the tube to play with.Maybe something along these lines?
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Well after looking at the trailing arm thread, Maybey you whould just have them Waterjet from 1" plate:
http://dtsfab.com/index/index.php?topic=988.0 (http://dtsfab.com/index/index.php?topic=988.0)
We need a picture of Enemy's setup hint hint. He is the only one on here running rear A-arms that I know of. His didn't seem to have a ton of gusseting, and wasn't as wide based at the frame, which IMO will add quite a bit of strenght to yours.
Ok I decided to grab some of Enemy's pictures from another thread....... Couple crosstubes to keep anything from buckling. No undergusseting for the shock mount.... You better ask DS what tube he used to get a baseline.
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How about some input now about mounting/gusseting the shock mount. I have a couple of inches to play with above the tube to play with.Maybe something along these lines?
I am glad to see you decided to go with the 1" plate!
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Or this and gussets plated on top? Maybe?
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Well after looking at the trailing arm thread, Maybey you whould just have them Waterjet from 1" plate:
http://dtsfab.com/index/index.php?topic=988.0 (http://dtsfab.com/index/index.php?topic=988.0)
We need a picture of Enemy's setup hint hint. He is the only one on here running rear A-arms that I know of. His didn't seem to have a ton of gusseting, and wasn't as wide based at the frame, which IMO will add quite a bit of strenght to yours.
Ok I decided to grab some of Enemy's pictures from another thread....... Couple crosstubes to keep anything from buckling. No undergusseting for the shock mount.... You better ask DS what tube he used to get a baseline.
1.5 x1/4 wall DOM.
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I am glad to see you decided to go with the 1" plate!
All tube dude! ;D 1.25 x .095 4130
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Waterjet them from 1.25 alum... ;D
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I wonder what the weight would be? I HAVE considered it tho.
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I'm not too sure it would save weight.
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I'm not too sure it would save weight.
Find out what a Tatam car front arm weighs. and a alum spindle. That would give a good idea.
Or some of the engineers on this site could just figer out what crom verse's alum is.
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My concern would still be the shock attachment point.
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I wonder what the weight would be? I HAVE considered it tho.
cant imagine it would be heavier than boxed plates and all them welds... ;D
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My concern would still be the shock attachment point.
Youd have to weld that on, or water jet a hole in the arm for it to set in, then drill thru the arm for the shock bolt...
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Youd still have to mill the bushing holes and stuff anyhow, Make it a bit thicker, like 1.5"
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My concern would still be the shock attachment point.
There would be no concern. The shock attachment point could be machined in the arms. anything in the way of 6061-t6 or 7050t351 would be supper strong. Machining a double shock tab on the lower arm would not be a prob.
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1" is 14lbs per sq ft... so 1.5 21 lbs per sq.... 36 arm 12" wide 63lbs, Less 3/4 material 16 lbs or so sound about right?
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There would be no concern. The shock attachment point could be machined in the arms. anything in the way of 6061-t6 or 7050t351 would be supper strong. Machining a double shock tab on the lower arm would not be a prob.
The problem with that is the expense of all that extra aluminum just to get the mount tabs integral to the arm.Another 1.5" or so of plate to buy and machine most away.
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There would be no concern. The shock attachment point could be machined in the arms. anything in the way of 6061-t6 or 7050t351 would be supper strong. Machining a double shock tab on the lower arm would not be a prob.
Waterjetting, not machining tho.... ;D
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It ain't gonna happen on the bottom arm. I MIGHT do the top one from aluminum tho.
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You could even use the thinner material and machine the shock tower out of a smaller piece of alum. Then use bolts and a couple of drift pins to locate the tower on ether upper or lower. That way you could machine the tower at and angle to more align with the shock also.
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I have a target weight to come in under.....
http://dtsfab.com/index/index.php?topic=988.0 (http://dtsfab.com/index/index.php?topic=988.0)
Page two!
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My whole heavy ass midboards only weigh about 35#'s and will still get put on a diet.
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If you mount the shock on the rear upright your arms don't need to be braced for that force/impact and can therefore be lighter?
Arms should need very little (if any) bracing..... in my typically humble opinion
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Good point and has been considered but that makes for a near 1:1 ratio and I'm not happy with that. It also makes for a poor shock angle.
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what's your problem with a 1:1 ratio? it's not like the buggy weighs any where near what the shocks are rated for?
I could look it up but you could explain it ;D
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He cant get the 40" pf travel out of the shocks then... ;D
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More travel in shock = more fluid to transfer and MAY cause a slowing of the suspension beyond the valving when hitting whoops with a long shock. Just an example of one train of thought. For me ,on this buggy,I'd need a 21" travel shock (yes, it will have a true 21" rear travel with 3" frame clearance at full bump)for my application IF it was at a 90 to the wheel.Rather LONG! Therefore it pretty much rules out a 1:1 shock ratio I think. ;D
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I had some custom made Bilstien 20" bypass shocks at one time. They were still running 1.8-1 though........
The other problem with long shocks and 1-1 ratio on your buggy would be the shock towers. They would be quite tall.........
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that's what I was talking about them being long.The fricken towers would be above the top of the car.THAT'D look sweet,huh? LOL!!!
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Function before form.... ;D I like both function and form myself, what good is a wet one if its 600 lbs, still functions, but not to much form there.... ;D
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Making it look cool AND function is the goal .
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You wanna be Yoshi?
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Or this and gussets plated on top? Maybe?
this is a must but I don't know if you really need to go full length but what the hell if you got the room.
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Well after looking at the trailing arm thread, Maybey you whould just have them Waterjet from 1" plate:
http://dtsfab.com/index/index.php?topic=988.0 (http://dtsfab.com/index/index.php?topic=988.0)
We need a picture of Enemy's setup hint hint. He is the only one on here running rear A-arms that I know of. His didn't seem to have a ton of gusseting, and wasn't as wide based at the frame, which IMO will add quite a bit of strenght to yours.
Ok I decided to grab some of Enemy's pictures from another thread....... Couple crosstubes to keep anything from buckling. No undergusseting for the shock mount.... You better ask DS what tube he used to get a baseline.
I would like to add this for everyone's info. yes a wider stance at the frame would be stronger ( enemy's is 1 1/2 that of the wheel side ) and I like fabr's idea on his front end a-arm mounts. if you were to use something similar on the rear but upright that would help a lot also. on the rear lower h-arms on enemy's rail we did use 1020 dom 1 1/2" od 1" id 1/4" wall tube and three straight pieces across them for bracing. there has been no problem with the arm bending front to back but the tube has bent slightly under the shock. so that is why I say in the above post that fabr's idea of full length shock mounts is a must or atleast 12" long or so. enemy does like to spend half his time in the air. for most this would never be a problem but for those that like to play hard this shock mount idea is a must!!!
the lower h-arm tube on enemy's rail is I think 23" long itself ( 26" long heim to heim ) and the shock is mounted 12 1/2" out from the frame side , just over half way on 1 1/2" od 1" id 1020 dom tube and it has still managed to bend "slightly" after one season, so we will have to build some full length shock mounts ( thanks for the idea fabr ) for the new h-arms. I don't believe plating half the arms would help in fact IMO it would actually weaken the arm for an up and down load.
I would also like to add that if you build with c- channel for frame side arm mounts that you need to tube gusset the mounts to spread the load out and brace the tube back to the frame and or to the other side to handle the load of landing when the track width gets wider and your wing span ( so to speak ) is grabbing a lot more ground, the forces applied to the rear of the arms is very high!!!! hope this is of use to someone.
on another note I still think that enemy and his builder did one hell of a job ;D ;D ;D ;D
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Good info DS,thanks!