4th hole?

I finally got all the broken fasteners done, the cab back off its back and the one big dent on the back is now about 15 little dents. I just need to sand, clean and paint the darn thing.

But, I started looking at the firewall before I got to sanding yesterday and can't figure out the 4th hole. The hole at 12 oclock is the wiring. The hole at 10 oclock is steering column. The 3 oclock hole is the heater ducting. What is the hole at 6 oclock?

The next picture down shows the drivers side hood hinge mount on the cowling. It is cracked and not smiling at you. Weld, grind and put together with the stock backing plate? Or weld, grind, make a huge plate that goes all the way to the firewall so the next crack will rip the cowling off the truck?

Thanks.

No idea on the holes since that's not my area of expertise but as far as the crack, I'd weld it, grind it and then put it back together with a decently large plate behind it. Something that spreads the load out about 2" in every direction and then I'd tack weld the plate to the cowl so it will be more rigid and reduce the flex.

Lanty, You mean weld upside down? That hurts!

About what I was thinking. But, since this is a new to me model truck, I was wondering if maybe this crack is common and a fix that works has already been figured out.

Don't want to get in a race with Tom on that "wheel" invention thingy.

Good point, lol. And yeah, I mean weld upside down and yeah, it does get uncomfortable. Especially the nice sizzling balls of molten metal that bounce into your ear and make a bunch of noise for a few seconds. I have always wondered why that doesn't hurt like hell but I guess I should be glad it doesn't, lol. I'd say the crack probably has a lot to do with a stubborn hinge more than a weakness of the metal. It's probably pretty common, but also pretty preventable if the hinge is kept in good working order. All the same, I'd plate the area just to be on the safe side and to get rid of any issues of the welding heat making the metal flex more or anything similar. Typical overbuilding, lol..

When welding at odd angles, I've found that TIG works better than MIG (should not be any splatter if you're doing it right). Another option is brazing with a gas torch.

One trick that I've done is to drill out the ends of cracks before you weld it up. That will make double-sure that the fractures have been filled with weld and stopped from spreading. (Ive seen cracks continue even after they were welded in high-stress areas). I usually go 1/8-1/4" hole depending on the thickness of the metal. I read that trick in a book somewhere about welding. Probably not a big deal in this case if you sister on a backing plate to hold the load better.

I think I've read that the fourth hole is for the steering shaft when the cab is mounted on a 5 ton. why both would be knocked out? My deuce has no heater,
so I don't have the three o'clock or six o'clock holes knocked out.

littlebob

I believe Littlebob is right on the money. As far as the cracks, my replacement cab for the wrecker is just like that. The metal backing plate that goes behind the hinge needs to be a little bigger. It doesn't go all the way to the firewall as it should.

I have the same crack too. Wonder why it only happens on the drivers side? I was just gonna make a backing plate for it, install it and let it be.

Somewhat common problem and a common fix. Thank you gentlemen.

I painted a bunch of small parts and a few more rims tonight. While waiting for the first coat to flash, I got to looking at the running truck cab and realized the smaller hole outside and above the heater inlet was also something my other cabs don't have. Any idea what this 5th hole is?

Now I need to figure out if I want to weld a cover over the "5th" hole and the "5 ton" hole or make a square plate to bolt over them in case I need to use them in the future. By the way, Pistolnut's M35 has the same "5 ton" column hole.

Something else I noticed tonight was a hole on the defroster ducts. The drivers side has it and the passenger side still has the cutout in place. Can anybody think of an advantage to this hole?

Tim, rotate the cab so that you are welding right-side up.

OK, I figured out that the small hole at the far outside 2 o'clock position is for the wiring harness to the flame heater. I couldn't find any pictures for it, but the cab has other evidence that one was installed at one time and the plug from the controller to the heater fits the hole just right.

I plugged the hole in the defroster duct with a welded up washer and made the patch below for the 5-ton steering column hole. All in all, a productive day. The cab is almost all the way sanded, all the little parts for the cab have at least one side painted the proper color now too. I just hope the weather stays work capable like it has been the last few days around here.

On your crack, don't use brass on it. That is not a place for brass - it will fatigue in no time, and re-crack. It needs to be welded, with a backing plate inside, as large as is practical, so that it distributes the stress over a broad area.

Merry Christmas

Lee in Alaska

I agree that it needs to be welded not brazed. I think I would make a bigger backing plate, grind out the crack and then weld the crack shut affixing the backing plate with the weld, no burning chest or earlobes. Then grind the weld flat and you are done. I do not mind welding extra reinforcements to my vehicles and the backing plate being attached to the body would not hurt anything as long as it is bolted tight.

It does appear to be a smiling silver smurf or something like that.

Tim,
Merry Christmas and I want to thank you and the crew that brought the door for me if I haven't already. I went to work on mine afew minutes ago and wondered if yours had the reinforcing plates under the hinge mounting bolts on the hood and cab. I should have two sets if I haven't lost any.
let me if you need them.
littlebob

Barrman said:

...I plugged the hole in the defroster duct with a welded up washer and made the patch below for the 5-ton steering column hole. All in all, a productive day.

Click to expand...

Guess you will have to "unplug" that small hole again...
It's there to make room and have access to nut #7.

G.

I had given up on getting one in on mine. now that I know it goes through the duct for the defrost, its like Merry Christmas to me. Thanks for the Christmas present.
littlebob

Uh-oh. Guess I will scratch some paint then. I attempted to paint the cab last night.

By the way, if you are set up to paint at 1600 hours and the temperature is 60. But, you don't start because a fellow green iron addict is coming over on his way from Alabama to Montana and you don't want the paint to go bad while you talk. Don't go ahead and start painting "because everything is all set" 3 hours later when he leaves and the temperature is now 40 degrees. Even with one of those turbine style Kerosene heaters running full blast. I had runs everywhere, everything in my shop has a fine 24052 overspray mist, my head hurt and even after 90 minutes, the paint still hadn't flashed. I started with a coat on a bunch of small parts like all the tunnel parts, the dash and all the nuts and bolts that go with them along with the inside of the firewall. Planning to hit them with a second coat and move onto the inside cab rear and outside firewall and then work my way to the outside parts once the inside had two coats. When I realized that didn't work, I just hit everything with a thin coat figuring it will be an ok base coat to sand all the runs off with. That was last night. I haven't had the nerve to walk outside and see how bad it looks yet this morning. Look like today is going to be another day of sanding instead of cab removal as planned.