Question on welding my swingout tire carrier

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I'm building a tire carrier for my Land Cruiser.  I plan on welding a heavy duty spindle onto a support arm as pictured below.  I wanted to ask the community about how to weld it onto the frame of the truck to achieve maximum strength.  I'm mindful of the forces that these welds will be under - the tire carrier swingout will have to carry my 285x75x16 inch tire - about 100lbs on a long swingout that will magnify the torque and twisting force on these welds when going over bumps...I don't know if I should weld the piece to the frame all around - on all 4 sides or just on the vertical sides or just on the two horizontal sides...This image here is showing the projected forces on this piece with the tire carrier in place - the twisting forces pivot point will be at the intersection of the two lines (horiz and vert) and the forces will attempt to twist the metal piece as shown.  And click here to see a view from another angle.  If you need to visualize what the carrier looks like after it's finished - here is one:http://www.wildyoats.com/images/RTCweb8.jpgAnd for reference, here is his full build article - article link.Last edited by Carbide; 12-20-2013 at 08:34 PM.
Reply:Personally, I'd opt for a bolted connection. If you screw something up, bend it etc, it's easy to pop out a few bolts and solve the issue. A stiffener plate with bolts will be a stronger mount to the frame than just welding. You spread the loaded are out over a larger area and if need be can add gussets etc if needed..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Cut the tacks loose cut a half inch off the tube and bolt a half inch plate to the 3or 4 holes that are right there. It looks like you could put a backer plate behind as well , 1-4 inch would woek for that.Weld the tube 4 sides to the plate and you are much stronger than welded to the frame.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:I agree with the others on bolting it.  On the other side I'd make it so when the carrier is latched in place it's supported on the other side as well.
Reply:I can't figure why you want to weld a heavy duty spindle and hub on to bolt the spare to. You're just adding unneeded weight.                                                                MikeOl' Stonebreaker  "Experience is the name everyone gives to their mistakes"Hobart G-213 portableMiller 175 migMiller thunderbolt ac/dc stick Victor O/A setupMakita chop saw
Reply:Originally Posted by AntiblingI agree with the others on bolting it.  On the other side I'd make it so when the carrier is latched in place it's supported on the other side as well.
Reply:Originally Posted by mla2ofusI can't figure why you want to weld a heavy duty spindle and hub on to bolt the spare to. You're just adding unneeded weight.                                                                Mike
Reply:So I would weld a plate to the heavy tube and then bolt that plate to the frame?!  I've seen that done by one of the guys.
Reply:Originally Posted by AntiblingI agree with the others on bolting it.  On the other side I'd make it so when the carrier is latched in place it's supported on the other side as well.
Reply:Have you checked out some of the Australian forums? Every man and his dog has a landcruiser and there are lots of people building those kinds of carriers. A good one to check out is 4wdaction.com.au/forum
Reply:Originally Posted by D1ckoHave you checked out some of the Australian forums? Every man and his dog has a landcruiser and there are lots of people building those kinds of carriers. A good one to check out is 4wdaction.com.au/forum
Reply:Use grade 8 bolts.
Reply:Originally Posted by CarbideSo I would weld a plate to the heavy tube and then bolt that plate to the frame?!  I've seen that done by one of the guys.
Reply:Well, I've spent many frustrating hours today trying to get that 1/2 inch plate lined up with a backing plate inside the large frame tube and getting new holes drilled so they line up with the old holes.  My main struggle is that I don't know a good way to line up the new holes in the plate in such a way that they would match up with the existing holes.   I thought about not using the existing holes and just drill new ones besides it, but there isn't much room left on there so I probably need to use 3 existing holes.   Just having a heck of a time lining everything up - any tips/tricks on how to do that 'blindly' once the plate is over top of and I can no longer see them?!Last edited by Carbide; 12-21-2013 at 10:04 PM.
Reply:
Reply:Originally Posted by Antibling
Reply:It looks like there is room to measure the centers on the holes in the frame. Facing the two top holes measure the outside left side edge to the outside left edge of the second hole. Outside to outside is the same as center to center on the holes. Then do the top to bottom the same way. Once drilled and checked, set the drilled plate on top of the inner plate. Best way to mark holes in inner plate is with a transfer punch. Mark, and drill. Are you having problems measuring ?   Transfer punch   http://www.harborfreight.com/28-piec...-set-3577.html   If you don't like the measuring part, slide plate inside the frame, hold where you want it, and then lightly spray paint through the holes from outside onto the inside plate. Center punch hole locations.Then drill holes, set drilled plate over the outside plate and use transfer punch for marking. I'm not being a smart a$$ but trying to explain. Hope this helps. It would be easier to show you then typing.
Reply:slide your backing plate into the frame and mark the holes with a silver pencil. then pull it out and drill the holes you have marked through both the backing plate and the plate that you are going to weld the carrier on.  Mac
Reply:Originally Posted by dcoffmanjrI think i just peed my pants a little laughing at this.
Reply:In all seriousness you should be able to measure the centers of the holes in relation to one another and mark that out on your plate.  Drill the holes a size bigger and it should get you close enough.  I mounted a flatbed on my old man's super duty and the mounting brackets I made I only drilled 6 new holes in the frame out of 16 used to secure the bed, those were in spots that were easier to drill new holes instead of working around the fuel lines and crap mounted by the factory holes.
Reply:Originally Posted by GumpYep, that was a good one!Carbide, is there room to use transfer punches to mark your holes?
Reply:Transfer screws will do what you want. Just insert them in the threaded hole and put your plate over them and give it a good thump with the hammer to mark the locations. Samm has posted up using these in the past. In a pinch I've made my own with a grinder and chucking the bolt in the drill press when I didn't have access to the lathe.A "trick" to locating holes with a taps it to use the edge of the hole vs the center. If you measure for say left edge to left edge, you get the same measurement as center to center. This will give you the dimensions between holes, then to locate center from an edge, add 1/2 the bolt size..No government ever voluntarily reduces itself in size. Government programs, once launched, never disappear. Actually, a government bureau is the nearest thing to eternal life we'll ever see on this earth! Ronald Reagan
Reply:Cut a piece of paper same size as plate, tack it on with tape then just rub it by the holes. The outline of the holes will show right up. Tack your backer plate to the outer plate and drill them together.Miller xmt304,  Miller S22 p12, Miier Maxstar SD, Miller 252 w 30A, Miller super32p12, Lincoln Ranger 9, Thermal Arc 181I with spoolgun, Hypertherm 10000 ,Smith torches. Esab 161lts miniarc.
Reply:I posted a link for the '' transfer punch set ''  # 17. Another option is to put a bolt through the hole from the inside of the frame and and snug a nut in it for measuring. Use a telescoping magnet with bolt on it to stick in hole. If you don't have a magnet, wrap some fine wire on the threaded end of the bolt and fish wire through the hole. Pull wire through hole with bolt attached . I do this for trailer hitch installation
Reply:Originally Posted by DSWA "trick" to locating holes with a taps it to use the edge of the hole vs the center. If you measure for say left edge to left edge, you get the same measurement as center to center. This will give you the dimensions between holes, then to locate center from an edge, add 1/2 the bolt size.Make the backing plate first.  Use transfer punch to mark the backing plate.  Drill backer, then use transfer punch to mark the front plate.  Drill front plate and the thing is done.
Reply:Well - I finally got the support arm built, bolted to the Frame with the backing plate, grade 8 bolts - per recommendations.Today I've got everything trimmed and fitted together nicely ready for assembly and welding together...  kind of scared of messing it up - I'm a weak intermediate at MIG welding.   Just got 2 small projects under my belt and I'm intimidated by this one because the joints here are going to experience some pretty good forces so my welds have to penetrate deeply and be really good else my big tire will pass me going down the road at 55mph.I'm especially concerned about the spot where the spindle meets the tube...   that's the most crucial place and a fulcrum for all the forces.Need some advice on how to make my passes so the end result is strong - I wonder if I need to make several passes: root pass and then another pass over it for maximum strength?I've got a Hobart Handler 180; a 220V machine with 50/50 gas mix (CO2 and Argon).Need some wisdom, advice, luck and pixie dust to make this happen.Here is what I've got right now:Last edited by Carbide; 12-27-2013 at 08:44 PM.