Finally pulled my finger out and got to working on the front HP30 diff for Black Betty. I had previously cleaned the old mounts off, welded in the inner sleeve and tack the majority of the mounts on so it was time to burn everything in. Some test were also done to see how well the pumpkin would weld, test was done first without pre-heating the weld stood up to stress test and weld inspection so it seems there is really no need to preheat the pumpkin on a Dana30 diff at all.
I took a bunch of measurements to track any warpage, I knew the risk was way down due to having already welded in the axle sleeve but there is no need to become complacent. It took 8 hours of welding over 12 hours and I have no warpage at all from side to side and a total of less than 1mm over the whole length (warped down not up). There is some real fear mongering around welding on a Truss which simply is not legitimate, I think most of that comes from people with crappy welders and a lack of skill……
First thing was burning in all the mounts (lower arm, spring & shock), this was easy enough just took a lot more effort than anticipated due to all the weird angles and flipping the diff around and over constantly. Next up were the C-gussets, some trimming needed to clear some welds and make room for the spring perches, they were then burnt into the cast ends and allowed to cool (to prevent shrinkage issues). After they cooled down I then burnt the gussets to the axle tube and then to the spring perch ensuring everything thing was tied together from gusset to arm mount to spring perch.
In between the cooling of the ends I moved on to the Truss itself, tacked it all together and made sure it fit well, a little trimming in length was required due to the big spring perches (Artec doesn’t do front spring perches for HP30) and some trimming for the weld from axle tube to pumpkin. I then welded a bit of 15mm plate to the top of the Truss to prevent it becoming a banana while I welded it inside and out. Due to the Truss being a box design, it has thinner sides so I had to take my time and weld the cross bracing in to prevent it distorting the ‘box’ then allow things to cool in between welds so it did not warp down the length. I decided to weld the Truss inside and out, not that it needed it, but seeing as I was already there and taking so much care……..why not
Once the Truss was welded together I cleaned up the pumpkin and welded the Truss to the axle tube but did not weld it to the spring perch (so any contractions during cooling would not cause a warp). I then let the whole thing cool off while I got the Panhard mount sorted out. I did not go with standard TJ spring perches (they suck and are too thin) which meant no Panhard mount, not that you can get a RHD one. I decided to use a shock mount, designed to mount the shock sideways, unfortunately it was a bit short of fitting and the wrong profile on the back of the mount, that and I couldn’t get the welder tip in under the spring perch to secure it. The mount was off by about 15mm in depth so I chopped off the back of the mount square, then grabbed a couple of bits of 15mm plate and welded the mount to one bit of plate and then welded a “tongue” perpendicular to the back so I had enough metal coming through under the spring perch to weld it from the back side. I made sure it was tied into the spring perch and arm mounts. Last thing to do before welding the pumpkin was to add the swaybar mounts (only synergy branded item worth buying). I decide to add these to the outside of the spring perch so they would tie into the cast ends, c-gussets, spring perch and panhard mount ensuring everything is tied to 2 other things. Sure it is massive overkill on the thickness of mounts and the amount of welding overlap but I don’t plan on ever having to sort out the front diff again.
After letting that cool of I decided to heat the pumpkin up to weld to it anyways (had the stuff there to do it), only heated the sections being welded then reheated each section and wrapped it with a couple of fire blankets and then a giant welding blanket around that. Originally I was just going to chuck it into a bunch of sand to slowly cool but the sand got wet during the week so had to find an alternative to slow the cooling. I can’t tell any difference welding the cast vs the plate steel, I spent some time checking the welds and there has been no cracks or concerns anywhere so all should be good. Even if a crack did occur somewhere there simply is so much weld there that it wouldn’t really matter anyways. Just have the final weld between Truss and spring perches to do plus the upper JJ arm mount & ram mount to weld in, then get it stripped and powder coated so it looks pretty.
