Technical Bench Seat Spring Repair

I’m after a bit of advice on how to repair the bench seat from my Merc. It’s always had a bit of a lean to the side so I plucked up the courage to get it out and get the cover off.


I’ve found that the steel rod that joins the springs together on the edge of the driver’s side has broken where they go into the frame.


What can I do about this? Can I weld the broken pieces back on maybe with a steel plate for added support? Anyone successfully done this?

 

In any event, the fix will be hidden from view. You could even braze something in place.

 

If the steel rod is made of spring steel, any welding will ruin the temper and make a weak spot. But, maybe you’ll be lucky and it won’t crack in your lifetime. If you are going to attempt it, I’d recommend TIG welding as a MIG weld is a hard and brittle weld. Not conducive to bending.

 

Quick cooling from high temperature (cherry red or hotter) hardens spring steel to a very hard and very fragile state. This means that a weld generally will become very brittle and break easily.
Reheating to a lower temp softens it and removes the brittleness. Slow(!) cooling from high temp prevents it from getting hard in the first place.

I'd use a O/A welder, if any.

 

If you weld it, can you swap it end for end so the repair is on the passenger side? That way it would get less use than on the drivers side, and maybe last longer.

 

They’re not symmetrical and there’s an awful lot of seat to take apart to swap them. Plus that’s the Ms’s side

 

Point taken about welding so thinking of getting some spring steel rod and making a u shaped piece that I can clamp to what’s left of the old spring with some rope ferrules.

 

I've welded them before with a Mig welder and not had an issue. If there's any concern about losing temper keep a wet rag closeby and just quench it after welding. I have a friend whose wife does upholstery work and they bring broken springs to me often. Occasionally I use some small pieces of steel under the spring to weld to the broken areas to overlap and make it stronger than just butt welding. I'd suggest doing that for your broken pieces and make it less apt to snap again.

 

I couldn’t work out a way of putting a new bit of spring steel in that I was happy with so went with welding. It looks like it had broken because the wire going into the seat channel was so long it was sitting at a 45 degree angle instead of flat so I shortened it.