Short Frame Extension

[thebearded1]

This winter I'm looking to extend the rear of my frame by about 1 foot to allow for a push bar/bumper and maybe the rear legs of a bolt in roll bar (not for street use). The frame is 1.5"x3" 1/8" thick tubing and I was going to use a smaller sized tube inside as a slug to plug weld on the original frame and frame extension. The problem is I can't find any steel tubing that will fit close inside. Current inside diameter of the tube is roughly 1.25"x2.75". I can find 1"x2.5" tubing should I do that and add in some 1/8" flat stock to take up the gap? I could drill the original frame and the flat stock so that both could be plug welded to the slug inside.

Any other ideas for this?

 

[RodStRace]

That sounds reasonable, BUT if this Not For Street Use rollbar might just have a sanctioning body with rules and stuff, I'd consult with those who inspect.

 

[thebearded1]

It's a vintage racing group that I run with now without the rollbar. I just want to add it in for a little extra protection, place to mount shoulder belts.

I'm taking it off for street use because a roll bar while not wearing a helmet can be bad news

 

[Spanky]

The frame is 1.5"x3" 1/8" thick tubing and I was going to use a smaller sized tube inside as a slug to plug weld on the original frame and frame extension.

As I recall the 1/8" wall tubing has a fairly sharp 90 degree corner, so would it be possible to use short lengths of angle iron for the "plug" pieces?

 

[thebearded1]

Yea that's the only other thing I've come up with. It will just be a lot of drilling and welding to secure each corner of angle iron vs one tube. The other option I guess is to redo the rear frame rails from the kickup back and just add on longer ones

 

[Mike L]

Easiest way to support the joint is to use six inches of 2" x 1/8" flat and plug weld them to the two 3" sides of the existing chassis rails. Weld the extension on, then plug weld the support pieces to the extension.