New or old asked again

We do this often always weld frame ground flat then 3' frame bolted inside of frame with 8 1/2 bolts followed with a cross member 6 1/2 bolts centered on weld it the only way we will do it

 

if you search long enough on the internet you can actually find the o/e's guide lines. it takes some digging but iv found them before. all of them want a insert in the frame rail that extends a min of twice the height of the frame. they do generally want the ends of the re-enforcement to be tapered and bolted in rather than welded. your see one oe's recommendations vary a bit from the next. the steel for the insert should match the frame rails in tensile and thickness as closely as possible and the weaker of the two is what is used for any strength calculations.

your want to make your cut on your frame as far back as you can because you don't really want your splice to end up in the center of the span between the steers and the drives that is where your frame is under the most stress. when i did my frame i really was a bit further ahead than i wanted to be but that was as far back as i had good frame rail to work with.

iv seen frame jobs done many different ways, different cuts, different ways of re-enforcement, or even no re-enforcement what so ever. only ones iv ever seen that have failed anyone with eyeballs would have looked at and said it was a hack job. bubble gum welds gaps bridged by scrap metal ect

if you are going to tig weld it i would say your going to need to take lots of brakes to let things cool even though you can weld with less heat its a slower process so over the length of the weld you may end up dumping more heat into the surrounding metal. the good thing about tig welding is it tends to produce a very ductile flexable weld thats not prone to cracking witch is a good thing on a truck frame. im not sure if i have ever seen a tig welding procedure outlined from a oe but its been a while now sense iv looked and i forget a lot of things. id have no issue with a tig welded truck frame, but like any other welding process prep prep prep for a good solid weld build the weld material up above the frame rail and if you want it smooth grind it back down but don't grind into the base metal to make it smooth biuld it up above the base metal then grind it down. leaving the weld bead unground and above the rail would be the strongest.

but anyway im no expert i know we have talked about some of this before

if my frame job were to fail anywhere i bet it would fail on the original frame rail at the end of my reinforcement at the back of the cab but not in the least bit worried about it. i could have made it better by extending my reinforcment under the cab and tapering it, but i don't think it was necessary when im loaded heavy my lift axle will be down moving the center high stress point much further forward and shortening the span. and i wanted to be able to remove my insert to descale down the road if that were to become a issue without taking the entire truck apart. but iv seen much worse jobs rolling down the road with never a issue.

 

Z Split it at a crossmember then fish plate. As good as new for 80k truck.

 

here is a couple good links
https://www.trailer-bodybuilders.co...rs/article/21740757/truck-frame-modifications

some good info on frame welding starting on page 46
https://www.macktrucks.com/-/media/files/body-builder/manuals/7-frame.pdf

 

I will second @Superhauler process too. Normally we took that ahead of the most forward crossmember or bunk rear crossmember. Seen a few done between tandems. Never ended well.

 

having a splice at a suspension mounting point would certainly not end well moment loads can crack frame rails without any welding having been done.

 

I saw one once near Milwaukee. A friend of mine was contemplating having his done. The frame was spliced centered on the rear axle spring hanger. Turning the rear axle hanger into the front axle hanger. It looked perfect, couldn’t tell at all.