Axle truss

Well, I broke my rear dana 44 housing nearly in half yesterday. I have all winter to fix it I guess. Since my Detroit locker and gears are pobably fine, and since I have another housing, I believe that I will be sticking another 44 back in. There are two changes that I believe I will structurally make:
1) A truss that goes over the pumpkin, so I don't affect ground clearance.
2) Since it is soa, I use a traction bar. I will probably go to two traction bars.
Anyone have any advice on making the truss? I am basically thinking about using square tubing over the pumpkin like this _____/---\_____ connecting the left and right traction bar mounts which will be welded to the tubes.

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Where did it break - where the tube goes into the housing? Break the plug welds and spin or break the housing? What were you doing?

 

Didn't spin the tubes. Cracked it in the lower left section, below the left tube. It is sagging right there. Probably cracked it in a previous trail ride where I let it bounce on a hill climb. I replaced the axle shaft then, but I didn't notice anything else wrong with it. I even checked the fluid before this last ride. But over the course of some difficult rocky trails, what I probably just barely cracked before, turned into a major issue. The twin stick transfer case was nice as I just disengaged the rear axle and drove out mostly in front wheel drive. Often I engaged the front locker, and a couple times I had to engage the broken rear axle. But made it back to the trailer unassisted. The top of both my rear tires were (are) leaning in.

Modify it, break it, modify it some more.

 

Trussing on the top is very inefficient and does no where near what trussing on the bottom does. I understand your trying to keep ground clearance at a max but trussing underneath is the way to go.

 

The Baja racers would truss the front, but not the rear. It might be enough just to weld the tube more solidly to the housing - that distributes the strain more evenly to the housing. A heavier tube also helps, since it reduces the bending at the junction of the tube and housing. The last I saw, Brian C. no longer trussed the 30s on the front of the Jeepster race cars, but only welded around the joint. He claimed that the later, heavier tubes eliminated the need for a truss. Don't know how it worked out, but that was the claim.

 

CJ-X,

Got any pictures of the break?

 

No pics yet.

McRuff, Curious as to why you think that trussing on the top is inefficient. The only difference I see, is that on the bottom, the truss would be pulled on, and on the top, the truss would be pushed on. Can't I make a top truss strong enough to handle being "pushed" on? If I use strong square tubing?

 

On the top it will crumple. On the bottom it will tear. It's much easier to crumple than tear metal, is what I've heard.

 

For trail use, truss the top, one tube to the other and over the pumpkin. To help strength, add some way to capture the top two or three bolts on the cover. Make sure it's removable so you can take the cover off easily.

Blue Torch Fab and a couple other places have full rings available that fit between the housing and the cover and give three bolt holes to attach a truss or link suspension. It's ain't cheap, but it would be very strong.

Trussing under the axle is the best for high speed, but most trail work needs clearance over ultimate strength.

 

I concur w/ NorCoJeeper but stay with single traction bar and locate near center of axle with proper configuration plenty of info on traction bars on the net, two would limit articulation IMO.

 

Yes, the truss HAS to go on the top for the trails I like to do. I've had a truss on the bottom before. (Never again). I might consider the idea of hooking into a few bolts on the top of the cover. Good idea. I really do not like to weld too much on the casting.

The reason for the two traction bar idea is to reduce the possibility of spinning tubes. I thought I was preventing it with my first single bar design. I made the mount that attaches to the axle attach to both the tube and the housing. It worked, I did not spin a tube, but instead probably helped tear the housing. With two traction bars, I believe that I can more evenly distribute the pressure attaching only to the tubes. I may also weld the housing to the tubes a little extra. I can make the traction bars so they do not limit articulation at all.

I'm sure I will change my mind a few times before I start fabricating.

 

If you use the right material and weld it solidly, the truss should take care of any issues with spinning a tube. 3/16 or 1/4" plate for the truss, especially if you tie it into the housing, will definitely keep the tubes solid. Dual traction bars would be stout, but overkill with the truss.

Of course, if you build them right, they would do a great job of protecting the driveshaft

 

Don't forget that welding on axle housings causes them to warp, so check the end to end alignment when you're done.

 

I believe that you have given me my idea. I never thought about using flat plate for the truss. That would be strong. I can attach it easily to the pumpkin, the tubes, and both (yes, I think I will do two), both of the traction bar mounts that I will make. My pinion is pointing up, so my truss would cross over foward of the diff cover on top. I think I could just take some nickle rod, pre-heat and weld the truss to the pumpkin across the top.
What do you think?