Trussing a rear axle, with a twist

[Stumpalama]

So, I am converting the rear axle in my FJ40 from semifloat to fullfloat (thread here) and I discovered the axle housing is warped, likely from welding the anti-wrap bar mount or spring perches. After I straighten it, I think trussing it is a logical step to prevent any future bending.
Anyway, I'm thinking a rear truss would be ideal, considering the wrap bar would be in the way of a top truss. Here's the rub, I feel like I want to retain the ability to pull the rear diff cover, yet I don't want to build an over complicated truss with a removable center section like I've seen in some Google image searches.
I have a ruff stuff 3/8" thick diff cover, if that means anything...
Should I even worry about it? Do you see any drawbacks to welding the cover on, since most (all?) other FF axles have welder covers.
Cheers,
Stump

 

[Josie'sLandCruiser]

Hi all,

I dunno Stump, I really like having the removal cover on the rear diff, wish there was one on the front diff as well. I find it handy to be able to access the rear diff gears/locker without having to pull the axle shafts and unbolt the third member. Not that I do it that often!

Regards,

Alan

 

[Stumpalama]

Hi all,

I dunno Stump, I really like having the removal cover on the rear diff, wish there was one on the front diff as well. I find it handy to be able to access the rear diff gears/locker without having to pull the axle shafts and unbolt the third member. Not that I do it that often!

Regards,

Alan

Thanks Alan. It seems we think alike on a lot of this stuff.
Part of me says that if i bought a RS or other custom FF housing, I wouldn't have a removable rear cover, so why do I need one. But then part of me thinks exactly what you said, Alan.

 

[LAMBCRUSHER]

anyway to fab a bolt on gurtle? ie, truss both tubes and fab a gurtle to bolt to the trusses straddling the cover? or what about a 2 or 3 piece cover that allowed for a solid truss but had access to the top or bottom half of the pumpkin for poking broken shafts thru? if push came to shove for me, I'd burn that 3/8 cover on and build the bridge across the tubes...

 

[J Mack]

When looking at some of the ultra 4 cars and how they truss the housings and incorporate the link mounts into the trussing I wouldn’t think a truss on top with the wrap bar mount incorporated into it wouldn’t be a big deal. The anti-wrap bar bushings at the rear-end are almost static so minimum clearance is needed, add some internal plates between your two existing anti-wrap bar mounts then build off them for your truss. I looked at this possibility when I built my rear end as I also wanted to keep the option of a removable cover but ultimately decided a truss was overkill for my application.



FYI, the Ruff Stuff Toyota rear cover ¼” thick steel plate for the cap and 3/8” thick for the ring not 3/8” like all their other covers, not that this should deter you if you decide to make a rear truss but it was worth mentioning.

 

[Stumpalama]

When looking at some of the ultra 4 cars and how they truss the housings and incorporate the link mounts into the trussing I wouldn’t think a truss on top with the wrap bar mount incorporated into it wouldn’t be a big deal. The anti-wrap bar bushings at the rear-end are almost static so minimum clearance is needed, add some internal plates between your two existing anti-wrap bar mounts then build off them for your truss. I looked at this possibility when I built my rear end as I also wanted to keep the option of a removable cover but ultimately decided a truss was overkill for my application.



FYI, the Ruff Stuff Toyota rear cover ¼” thick steel plate for the cap and 3/8” thick for the ring not 3/8” like all their other covers, not that this should deter you if you decide to make a rear truss but it was worth mentioning.

I was debating if the wrap bar mount would be strong enough to provide continuity to a truss. I will look into it. A truss is probably overkill for my application as well, I am just unsure about the propensity for the axle to bend again once it has been corrected.

I have one of the original RS covers that was 3/8" all around. I just shaved the lower portion to fit the ring gear.

 

[J Mack]

This was my thought process, when looking at the whole picture a truss on my rear end may create an issue as opposed to solving a perceived issue. First when looking at a car that may actually need or benefit from an axle truss they are doing things not possible with my car and they have supporting components along with the truss that enable them to perform these tasks. My car has leaf springs and 35” tires that will be the limiting factor not housing strength. Second when you look at the housings used on performance cars the tubing is usually 3/8” and all the full floater end cups are welded directly to the 3/8” tube, when I added the full float adaptors to my Toyota tubes that section of tubing was closer to 1/8” thick and I felt that if I added a truss that removed all the natural flex from the housing I would transfer all of the load to this area.

I don’t know anything about your car or the type of driving you do so obviously I can’t speak to what’s best for you but I do believe that your current housing warped more from welding than a single act off road, you should look at building a single unit with sufficient strength for your performance needs and if a trussed stock Toyota housing is needed than you might want to take a second look at aftermarket housing as a better starting point.

 

[Stumpalama]

I think I'll worry about getting the axle straight. Then, if necessary, I'll look at adding a truss.

 

[jstncse]

I trussed the longside of the housing and then built my anti-wrap bar off of that. Just a simple truss that starts at the top of the pumpkin and tapers to nothing just before the leaf spring. If I was jumping it, I would build a more intricate truss. Actually I would start with a bigger axle...

I will look for a pic of mine.

http://i921.photobucket.com/albums/ad52/jstncse/om617/IMG_0799_zps03bf9691.jpg

 

[Stumpalama]

Thanks! You are full of good ideas.