Replacing trailer spring hanger

[MillWeld]

A rear spring hanger on my trailer has an extremely oblong bolt hole. To replace it I plan to grind off the old and weld a new one in its place. My concern is drawing the frame when I weld the new one. Any tips here? I have welded before on undersides of beams and have drawn them - I do not want to repeat that. What type of electrode to use? I will be using an AC welder.

Bob

 

[Mark @ Everlast]

You can either restrain the weld by clamping it with a structural reinforcement on the back side OR you can weld a bead on the reverse side of the beam first to draw it in the opposite direction before you weld.(that's how they do mobile home frames to allow for the load without drooping.

Couple of things: You only need to weld across the end of the hanger, not down the sides. With many hangers, welding down the side IS discouraged if not forbidden. A smooth weld laying it in there with medium heat. If you are going to MIG (which you say you are not,but I am including for posterity's sake), no more than 17 volts. If you stick it, a 7014 or dry 7018 3/32 at about 80 amps is all that is needed. Too bad you don't have DC.

 

[rankrank1]

Another option is to simply weld up the oblong portion of the hole on the existing shackle and then use a die grinder to make the hole round again. Install new bolts and will be good as new.

I successly did this when all I had for a welder was a little 115 mig. I did not trust my little welder (or my skillset as welder) to cut off the shackle from the frame and weld on a brand new shackle on a heavy duty 12000 lb GVWR trailer that would be traveling road speeds. Hence, I used the little mig to weld up the oblong portion of the hole and then ground it round again. My non-traditional repair has worked great.

 

[yomax4]

If you want to fix the oblong without replacement, You can also buy a stick of Carbon that is the same size as your bolt. If you have a part of the oblong that is where it is supposed to be, You can hold the carbon in place and weld all around on both sides. When you get it filled in, Knock out the carbon and you are done. I have done it a ton with broken threaded aluminum castings from Motorcycles. ( the weld does'nt stick to the carbon.)

 

[MillWeld]

Interesting solutions.
Yomax4, where can I get carbon? welding supply place? I'm not sure I trust my welding skill to fill in around the carbon adequately but it is a technique I could practice with until I get it.

What about this approach: weld a grade 8 washer on the outsides of the hanger and use a slightly longer bolt? This could be used together with the carbon rod trick.
Bob

 

[MillWeld]

Couple of things: You only need to weld across the end of the hanger, not down the sides. With many hangers, welding down the side IS discouraged if not forbidden.

Mark, why is this? it sounds just the opposite of what I would expect. welding across the frame is what tends to draw the frame. Welding parallel (down the sides) would not.

 

[Mark @ Everlast]

Across won't draw the frame as much as down the seam. You have much less surface area to draw the frame. Also the stress is front to back on the axle hanger, not so much side to side. Properly welded, that is.

 

[rankrank1]

What about this approach: weld a grade 8 washer on the outsides of the hanger and use a slightly longer bolt? This could be used together with the carbon rod trick.
Bob

I think most trailer shackle bolts are either 9/16" or 5/8" diameter. If you can not find the carbon rod in a big enough size, another trick I have used is to use a scrap piece of copper pipe as a guide to weld up to. You can even slit the copper pipe to expand or compress it to an approximate size that you need or use a coupling fitting which is slightly bigger - simply knock it out with a hammer when done. I usually still have to clean the hole slightly with a diegrinder/dremel tool though.

Two possible disadvantages of adding the weld washers:
a) Verify no clearance issue with the tire if the bolt head moves a washer thickness closer to the tire. (I had one trailer where clearance was extremely tight and adding washers would have not been possible).
b) May limit you to using regular type bolts. I actually prefer the designated shackle bolts that have the knurled portion near the bolt head that keeps them from turning in the shackle. Unfortunately, these true shackle bolts are not easily findable in custom lengths from the standard length. Regardless, I still prefer the true shackle bolts for the anti-turning feature, plus I know they are proper grade of steel for application.