Truck frame bracing

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Ok heres the run down. I have a 89 silverado with a rotten back 2ft of the frame. I havent tackled mine yet. As it turn out a friend of mine has the exact same issue with his 94 silverado so i jumped on helping him for the experiance. Its was all very easy and it only took us a day and a half. The splice was right between the spring hangers of the rear axle. My question is instead of using a normal fishplate can i use a piece of c channel as the plate. I think this will make it stonger. It will also give me some piece of mind. The area on the truck will alow this because im installing a flatbed and the extra upper lip wont affect anything. Thank you for any help. Attached Images
Reply:Looks professional! I use "RedNeck CAD" too!Aeromax Service Truck w/ 6,000lb Crane to carry my toys.Miller Trailblazer 302'69 Lincoln SA-200A couple of Victor Jr's to make big pieces smaller..........
Reply:here is it installed Attached Images
Reply:What ever works a picture beats words
Reply:A fish-plate is strong and a C channel like you have pictured would be stronger. My suggestion coming from a guy who restores/modifies cars, a step cut on your original frame to the new section will give it strength before you plate it like you have pictured. Here is my picture to illustrate:AHP 200xMiller Trailblazer 251 NTMiller Legend AEAD-200-LEEastwood MIG-175Eastwood 40A Plasma CutterDillon Mk 5 OA setup
Reply:IMO a normal fish plate is all you need along with good welds. Most people over weld things in this situation, Just stand back and take a look at it its only a small frame with nothing much going on.I always tried to work with the oldest hand on the job to gain knowlege but now I can't find any.
Reply:If it were just a normal 1/2 ton frame I would say yes, but he eluded to putting a flatbed on it, which in my mind he is going after a welding rig of some sort? Either way though it is directly over the centerline of the axle and some extra strength there is a smart idea.AHP 200xMiller Trailblazer 251 NTMiller Legend AEAD-200-LEEastwood MIG-175Eastwood 40A Plasma CutterDillon Mk 5 OA setup
Reply:the best patch would be cut from another truck frame of the same typei wouldnt use c-channel as it wont fit the curve of the frame very well and you may end up with an overly stiff condition which could result in the frame breaking at the ends of the patch.
Reply:I work in a truck shop and we do projects like this (shortening frame and lengthening them) and since I'm the "fab guy" I usually do them.  So far you did it just the way we do.  I usually temporarily weld on a piece of channel on the outside of the truck frame to help keep everything straight.  Then clamp, measure, tack, measure, make my plates, measure, tack them in, measure.  You get the drift.  Remember this is suppose to support whatever payload you have in that truck, so it should be made to last.  Don’t get impatient it’s a nightmare to have to redo this if you’re off a little in the measurements.  From here on out though you have two options.1) You can do a fish plate on the outside of the rail.  Do not put it on the inside of the member.  Weld it the full way around and that for most of the time that does it.  I use fish plates when I extend frames behind the axle and sometimes when I do them like yours if space and accessibility is a concern.2) Your other option is to do the C-channel.  I’ll bend a piece of channel it our brake, but if you don’t have one I guess finding a really snug fitting piece of premade channel is an option.  If you do it this way, put the channel over the existing frame.  Weld the tops and bottoms.  Do not weld the side of the frame.  And then drill and add 2 Grade 8 ¾” bolts through the side on each side of the cut (total of 4 bolts).  Do not drill and bolt through the tops or bottoms of the rails.  Personally I think the fish plate is strong enough, but if you’re in doubt then use the channel method.  It escapes me who now, but someone on here said “if you’re not flying or racing it, overbuild it”.  This isn’t a welding cart you’re making though; make sure your 100% confident you can do this.  And like most projects it’s 99% preparation and 1% welding.  Be patient do it right, do it once.
Reply:Ok so your saying stich weld the new channel to the frame only on the top and bottom rail?
Reply:Originally Posted by slowlt1Ok so your saying stich weld the new channel to the frame only on the top and bottom rail?
Reply:that would be great thanks