Seems reasonable, I am no mechanical engineer but seems that with the gusset on the bottom the steel is in tension where it is very strong. With it on top the load on the gusset is in compression, could buckle under a heavy load.

Another reason I suspect desert racers put it on the bottom is to leave more clearance above the axle. With the large amount of travel they have the top of the axle would probably interfere with other components on the truck under full compression.

 

I reall y dont think there would be any strength difference in a top or bottom truss if it is designed properly. As long as the tubes, knuckles, and center section are connected.n I think the reason why most crawler/trail riders do it is for clearance and to support their upper link mounts... As for prerunners and desert racers.. the theory about under the axle for suspension travel is probrbably accurate.


Look at old school truss bridges... some had the structure below the road way.. while others had it above the road way. Same principal as an axle.

 

lots of talking not a whole lot of doing.
put it on top.
reasons:
1. ground clearance. the best reason for larger tires is so that your dif aint dragging
2.welds will hold together better under compression than tension. why do all the damn doors SAG on every cherokee made? they are under tension when you open it.
3. you could go around your existing upper control arm mounts but if your going to be jumping it the stock ones WILL fail. my buddy jumped his then stock cherokee and bottomed the shocks, broke the drag link, and broke his uppers clean off. that meant we couldnt drive it home and isnt that always the end goal?

and start building! thats the only way your going to know exactly what works for you.

 

that axle was orininally build by curt leduc, i bought it from the guy who had it after the guy who had it in that picture. its trussed, plated, gussted, and the tubes are sleeved inside with .250 wall DOM, set up to run coilovers and bypasses. total weight empty with no cover on it was 143 lbs, nice guess

here's a couple more shots of it after i had it powdercoated.





i might have a couple more pics in my pbucket but its blocked at work those are all i had on facebook.

 

I gusseted and trussed my d30..... I used the ballistic fab truss that was about 80 bucks and got the inner c gussets for I wanna say 40 from iron rock..... I kept the stock control arm mounts and just plated everything, but here's how mine came out and I'm happy with her

 

Absolutely correct. I built mine on top, and it not only hit the oil pan on a hard hit. But the truss buckled and the axle bent. Truss is 3/16" thick steel plate cnc cut.

 

Piece of crap app! Keeps crashing when im loading pics! On top of axle is plenty strong if done right and heavy material. I was gonna post pics of mine in progrss and done but app wont let me!

 

Hah the app is now working.....top truss 1/4" rec tube and flat stee...

 

for desert racing, there is no problem putting the truss on the bottom.

but once you get into some rocks.... the bottom truss is an annoying *****.

 

extreme4x4 did an episode about trussing the bottom vs. top
stupid work computer won't let me watch these vids. but I'm pretty sure it's one of these

http://www.powerblocktv.com/player/s..._num=XT2006-21

http://www.powerblocktv.com/player/s..._num=XT2007-09