I finally got around to working on the M100 again yesterday. I decided (in my mind) to use the frame off of my other M100 chassis because of how much rust was on this one. After checking out the other frame, it wasn’t worth the extra trouble – the other one was only slightly better. The rear crossmember wasn’t rusted away on it.
So…. I dragged the original frame out of the scrap pile and inspected it again. The rear crossmember needed replacing for sure. About a 1/4″ of the edges of the 2 middle crossmembers were rusted away – which I ground down when I was working on it before. So, I decided to go with it – I was going to replace the rear crossmember and leave the middle ones. I started removing the rear one.
If you’ve never looked at how the frames are assembled, they used 3/8″ rivets AND welding. The rear crossmember uses BOTH methods. There is a rivet on the bottom of each side and the edges are welded on the end and the bottom. I used the plasma cutter to cut the welds so that I could remove the crossmember so that I could get in there with my side grinder to grind down the bottom of the rivets and the rest of the welds that weren’t cut off. Once they were ground down, I was able to use my air chisel to drive out the top half of the rivets.
Then I set the frame on the tub for the first fitting:
It fit pretty good! There are a couple of spot welds that need to be ground down a little more for it to fit flush to the tub though. Overall, it fits well. It should fit right back in the original location. I WILL have to do a little more fitting on the front angle, as it is TOO far away from the new metal that I welded in. I don’t know what is going on there yet.
I think today I am going to scuff the bottom of the tub down (after I grind those spot welds and make sure the frame fits flush) and spray some OD on it. I might go ahead and spray the frame with primer (maybe the bottom of the tub too) and paint it too.
There is a metal fab business a few miles away that I am going to go ask if they will bend a channel for me. If so, I’ll get a FEW4′ pieces bent. The rear crossmember measures 37.5″ inside of the outside frame rails. I am guessing that the pieces of channel need to be 42″ long so I will have enough material to cut and bend the tabs on the ends. By the way, the metal is 12ga.
Here are a couple of pics of the rear crossmember after I cut it off. You can see how bad it was rusted.