Filling Gaps in Roll Cage

[Leeboy]

Hi guys , im new to the forum and my names Leeboy... I ordered a pre-bent roll cage for my Nova from across the country. Its 1 3/4 x .095 erw . A couple pieces didnt fit that well, and i complained and they basically told me to screw myself , that it was my fault....So, i didnt want to throw out $600 . I modified and put it together , but i had 2 maybe 3 pieces in the whole cage that had some gaps. I plan on gussetting and adding extra braces to those areas in a triangular form for extra strength. So, my question is can this cage still be safe? Heres one of the gaps....

[Tryagn5]

Weld will fill it...

That is not hard to fill with weld. Do you plan on mig welding it, would be very easy to fill that gap, It would be fine and look fine to. Many cages I have done have had gaps like that. No two cars are the same, many times gaps accure, only way to have a perfect one is to make it yourself, and notch yourself.
Kevin

[marveman74]

I would grind or file the tubing to get a real nice fit and then weld it together. Yes you can fill it with weld but I think strength wise and ease of welding you will be better off getting the fit up well and then weld. You might try using some nylon ratchet straps around the bars in the car to act as a clamp while fitting up and welding to make things easier.

[Leeboy]

Thanks gang....I will be mig welding. I was planning on filling, and then running a few more passes. Since its my car, i dont care if anyone makes fun of a bubble-gum looking weld, the car was free, just had to buy the cage for a entry level class. That is a good idea with the ratchet straps. I was going to add a few of these gussets where the gaps were. ( see pic)

[H80N]

Forget filling gaps!!!!!!!!!!!!!!!!!!!

Work on your fitup.... prenotched kits rarely have great fitup... bit of grinding and filing will get you there....take your time and do it right.... forget about FILLING any gaps.... that is a fools errand..
hope this helps
Heiti

[Leeboy]

So basically, a "Weld Fill" isnt strong? I mean, the weld between the gaps is weak?

[Eric Carroll]

I wouldnt do any more than one pass on that thin of tube. Look up some welds on race-dezert.com, you will probably want to try "trigger welding" or "bump welding" . Basically you weld on-off-on-off-on-off. this is not how I would weld thicker sections, but for thin wall tubing it works fine. That gap isnt the best tube fit up ever but its not the worst.

[Aerometalworker]

Airframe handbooks typically list 1x ( sometimes more )metal thickness for gapping the tubes prior to welding. This was in effect to encourage 100% penetration at the root of the fillet and to avoid having un-fused edges of the tube. Both of those conditions can drasticly reduce the fatigue life of the joint. So unless you are over say 2x in your gaps, I wouldn't worry about it.

[H80N]

"good enough"

Leeboy
maybe I spoke too strongly.... but I sure hate to see people do things just "good enough".... when a little bit more effort would make it right... especially in safety related issues..
Thanks
Heiti

[Leeboy]

Hey, no problem Heiti..All advice is good. So, im thinkin of cutting out a portion of the A-pillar, sleeving it with 1 1/2 ( since my bars are 1 3/4) and re-doing that portion for a better fit. What do you think boys?

[Aerometalworker]

Just curious, what are the gaps if you measure them?

[Leeboy]

Well, the one in the picture is probably less than 1/4 inch. There was another, that was larger that i filled before i found help on this forum. That is the one i want to cut out and sleeve and redo. But, now im worried about the "other" piece that it joins to that has gotten hot already from all the filling. Im wondering if i should just leave it or redo it.

[pro70z28]

I didn't see in your posts what type of cage you are building. Drag racing, circle track, road racing?

[Leeboy]

Its the lowest level of dirt racing. It is completely stock class. They dont even want a roll cage. They only want door channel, and a brace from roof to floor and a brace from door to door. I just figured i would throw a complete cage in it for safety. They got sour at me for spending money on a cage..weird club....I am going to take some picture of the piece i want to cut out.

[LarryO]

I wouldnt do any more than one pass on that thin of tube. Look up some welds on race-dezert.com, you will probably want to try "trigger welding" or "bump welding" . Basically you weld on-off-on-off-on-off. this is not how I would weld thicker sections, but for thin wall tubing it works fine. That gap isnt the best tube fit up ever but its not the worst.

Those are not trigger welds ( basically multi spot welding ) as you describe but just a good lookin weld made with a little technique

Not good advice to give to weld up a roll cage that may save your life.