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Welding to unibody

B

bluebeast

NAXJA Forum User
Location
Nor Cal
Im planning on getting tubing with the same I D cutting it in half and sleaving my unibody frame rails. Ive never welded 1/4 inch steel to sheet metal before. Is it stronger to just weld beads along the top near the floor board, or drill holes in the tubing and weld them in attatching it to the sheet metal in many spots. Ive got a 60 front and 70 rear that I cant wait to put in but I've never worked without a frame to weld to before. Any input would be appreciated. also I was wondering if I should run the reinforcment all the way to the bumper? Will the unibody bend or crack under heavy winch loads or side pulls? I would like to avoid it if possible to keep the weight down.
Or has anyone cut the factory frame rails completly off and started from scratch? It is one of my options but it's a lot more work.
 
Last edited:
bluebeast said:
Im planning on getting tubing with the same I D cutting it in half and sleaving my unibody frame rails. Ive never welded 1/4 inch steel to sheet metal before. Is it stronger to just weld beads along the top near the floor board, or drill holes in the tubing and weld them in attatching it to the sheet metal in many spots.
Click to expand...
Both.
Attaching the sleeving to the rails in as many places as possible is the way to go.
bluebeast said:
I was wondering if I should run the reinforcment all the way to the bumper? Will the unibody bend or crack under heavy winch loads or side pulls? I would like to avoid it if possible to keep the weight down.
Click to expand...
Shouldn't be necessary. I ran mine from where it spreads out in front to just above the rear axle(to tie the rear of my cage to the frame)
bluebeast said:
Or has anyone cut the factory frame rails completly off and started from scratch? It is one of my options but it's a lot more work.
Click to expand...
Sounds like way more work than I would want to tackle. Plus, the sleeving will probably be stronger since you're still using the OEM rails.
 
bluebeast said:
thanks, no comments from anyone else? come on
Click to expand...
Excuse me?
Did I leave something out?
 
bluebeast said:
thanks, no comments from anyone else? come on
Click to expand...


it'll never work...

in order to prevent cracking and bending from axle forces you have to projection/stitch weld in 1/2" increments using high tungsten content wire and with pre and post op heating...

the honeycomb pattern works best...

or...

just listen to Kid's advice
 
I would use 3/16, but maybe that's just me. Also, I cage tied into the subframe will do tremendous amounts to increase rigidity. I would stitch weld the lengths along with as many rossette welds as you have the patience to drill for.
 
small hi-jack: what size is the tubing or U channel used to sleeve the "frame" rails, i know 3/16 to 1/4 thickness, i was wondering about the ID of the material.( too lazy to measure for my self LOL...LOL)
 
Starboard M said:
What is the best setting for welding to the unibody? I know each welder is slightly different, but a starting place would be helpful. Thanks.
Click to expand...
Each welder is completely different. Even more so the wire diameter you use.
Just start pretty low. If you don't get penetration into the 3/16" go higher. If you start blowing through the rail go lower.
 
Starboard M said:
What is the best setting for welding to the unibody? I know each welder is slightly different, but a starting place would be helpful. Thanks.
Click to expand...

I thought this was adv fab. not welding 101?
 
The bottom line is that trying to get a good bead when welding the frame is tough. The galvanized coating causes outgassing and little volcanoes in your weld. For best luck, sand blast well where you are going to weld before starting. You need to get all the old galv off. Also, the gas given off is toxic. Historically, I have had better luck on a MIG when I use flux core wire and gas instead of standard wire. It seems to do a better job without all the hassles.
 
Flux core with argon? The honey comb pattern is a sweet idea but I think a lot overkill plus all that drilling and welding is going to take me the rest of my life not to mention ruining the reinforcing idea unless I fill each hole all the way to the top. I know spot welds in many places always work good with sheet metal to sheet metal but this peice is going to recieve a lot of torsional force when the frame wants to flex like it normally does. I just dont want a bunch of little tack welds to break and dont want to waste time or ruin my unibody.
 
Old man , thanks for the advice, I never knew about the galvanized coating. It was bad enough getting that crappy undercoat off. I haven't bought the steel yet so I might go with 3/16 to cut wieght down. Cant wait to try my hand at 3 and 4 link engineering after sleaves are done.
 
bluebeast said:
Cant wait to try my hand at 3 and 4 link engineering
Click to expand...
Oh yea, That chit's da bomb.
Can't remember when I've had this much fun.

It's right up there with shattering (4 pieces) my clavicle mountain biking.
 
dunno if this helps, but when i did my frame sleeving I used 3x3x3/16 angle, turned my 175amp mig welder to the middle setting, aimed at the angle and worked the weld puddle "into" the jeep's thin frame. I think i burned through maybe once or twice, but that was my mistake aiming at the framerail for too long.

the hardest part of this project is cleaning the frame prior to welding.
take your time and make sure all the factory undercoating is gone, cause it will contaminate your welds(it will cause little bubbles)

I used plug welds about every 5" and stitch welds whenever possible.
 
sixditch said:
dunno if this helps, but when i did my frame sleeving I used 3x3x3/16 angle, turned my 175amp mig welder to the middle setting, aimed at the angle and worked the weld puddle "into" the jeep's thin frame. I think i burned through maybe once or twice, but that was my mistake aiming at the framerail for too long.

the hardest part of this project is cleaning the frame prior to welding.
take your time and make sure all the factory undercoating is gone, cause it will contaminate your welds(it will cause little bubbles)

I used plug welds about every 5" and stitch welds whenever possible.
Click to expand...

Thanks, how is it holding up? I wheel so much I go through springs about every 15 months so I need stuff that's really going to last. I got the undercoat off but what about the galvanized coating?
 
bluebeast said:
Thanks, how is it holding up? I wheel so much I go through springs about every 15 months so I need stuff that's really going to last. I got the undercoat off but what about the galvanized coating?
Click to expand...

It has held up really well, ive hit plenty of rocks and the angle iron hasnt moved at all. I have since put herculiner over the frame rails to try and seal it all up a little better.

About the galvanized undercoating, all I can say is grind every welding area very well so all you see is the raw steel of the unibody framerail. I think that if you do this then you will get welds that are plenty strong for hard wheeling.

Some of my welds dont look all that great cause of my poor grinding skills, but they are still going strong, no cracks or signs of fatigue.
 
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