Frame advice

[john87442]

Ok gang so I have the frame out from my 87 442 and talk about UGLY. I new the rear rails were bad so I purchased a set. And today bought the washer set for the frame to weld in where the Ohio weather and years have done their damage. I also bought the FX kit to box the frame for support since I’m adding more horsepower and it’s a t-top. Question I would like to ask everyone is does anyone have any experience with cutting and repelling the rear rails, should I put a plate and weld in the support over the seams? It just doesn’t look like it would be strong enough with a butt joint weld. Also any tips on alignment of the rails is welcome. I have my ideas on how to do this but I often overthink it and I know there’s a lot of good advice here. Ok I’ll try to attach some pictures.

 

[Ribbedroof]

Butt joint with a sleeve is how the OEs specify it on frame rail end replacements

 

[john87442]

I have tried to look up info about this but couldn’t find anything so thanks. So sleeve the four interior sides and then use a butt joint. I think I’m missing something here because it would be pretty difficult to weld the inside of the rails with a sleeve.

 

[Ribbedroof]

So, the sleeve gets welded to the rail end.. either tacked or plug welded through the sides. The rail end is positioned in place leaving a gap of 1.5x the thickness of the rail, then you weld the seam through to the sleeve, ensuring the weld joins both sides to the joint. This ties it all together, and is stronger than an open butt weld

It's for an F150, but pg 26 of this shows the general idea

https://fordcrashparts.com/wp-content/uploads/2020/12/F-150_Frame_Instructions.pdf

The OE service kits come with the sleeve already welded to the stub, but you can make the sleeve from old sections of the rail being replaced on your car.

 

[ck80]

I have tried to look up info about this but couldn’t find anything so thanks. So sleeve the four interior sides and then use a butt joint. I think I’m missing something here because it would be pretty difficult to weld the inside of the rails with a sleeve.

To be perfectly honest, in this application and location I don't feel it matters all that much. You've got your frame on the floor right now, once you pull the rear end out of it walk over to one side of the back, grab the rail, and pull upwards. The amount of flex in these things is ridiculous. They're also welded out of a ton of smaller sections if you look at the rail as you walk. It's not that strong.

The section you're looking at replacing is less about collision strength to the body than supporting the weight you put in the trunk and preventing flex in the quarter from having a load back there. And these days with bumper heights and the 'suv/pickup craze' your frame (and likely car) is probably done if you get rear ended anyways.

That doesn't mean half-a** it, but, it's not as critical as, say, dealing with the front where the crossmember is. Alignment matters so the body mount lines up properly. Aside from that, treat it like you would a notch job and I think you'll do OK. Good welds with good penetration.

 

[Ribbedroof]

Or, you could do what they did to a buddy's 62 Impala SS LF rail end back in 1980.... they overlapped the joint about 8" and booger welded the top and used a couple 1/2" bolts through the overlap on the side.

Collision repair has changed a tiny bit since then

 

[ck80]

Or, you could do what they did to a buddy's 62 Impala SS LF rail end back in 1980.... they overlapped the joint about 8" and booger welded the top and used a couple 1/2" bolts through the overlap on the side.

Collision repair has changed a tiny bit since then

The Official GM repair for the original S10 front frame horn repair with the front bumper mounts is similar to that.

You cut off the front 3 inches on each side. They made a slightly wider extension, figure 3" x 6", and the repair was to slip the new extension over the cut off tip, then drill a couple holes in the frame rail and pass 3 long bolts through all of it left to right... not even weld at all.

The bolts and frame extension were packaged as a kit with its own gm part number. I bought a nos one to fix a wrecked s10 blazer back around 2016.

 

[Supercharged111]

Fish (?) plates for reinforcement are pretty standard as is putting in an L (the aforementioned overlap?) where the cut is. My frame is about the same condition as yours. Given my location, I'm more inclined to just start over with a clean frame. Have you tried hunting one down and struck out?