Bare metal epoxy primer for truck frame

[Hay Dude]

Asphalt or old ziebart type undercoating?

Both, but this truck was used to haul asphalt as well as plow roads.

 

[crashz]

Looks good! Glad you got the rust jacking out. As far as the gap, I'd leave it alone and treat with FF after you paint. You want that to wick into the gaps that you can't reach/see. Clean and re-apply once a year if you can. This will last a long time. Probably longer than any of us!

My F450 was in a similar state when I had the new dump body installed. The shop that installed the body blasted and painted the frame. I added a tow hitch and have been spraying down with FF and NH Oil Undercoating ever since. No rust except for the brakes

 

[Hay Dude]

Looks good! Glad you got the rust jacking out. As far as the gap, I'd leave it alone and treat with FF after you paint. You want that to wick into the gaps that you can't reach/see. Clean and re-apply once a year if you can. This will last a long time. Probably longer than any of us!

My F450 was in a similar state when I had the new dump body installed. The shop that installed the body blasted and painted the frame. I added a tow hitch and have been spraying down with FF and NH Oil Undercoating ever since. No rust except for the brakes

Yes, that’s the plan.

I had a passing thought: What if I added a piece of inverted L frame from cab back, on the outside of the existing frame? Only thing to need to be moved would be rear axle U-bolts, which look like they’ve seen better days and install slightly longer frame bolts?

This would add strength to the frame and give the frame a new looking piece of steel!
Wondered if there’s a locating pin atop the axle that would prevent me from doing this?

We are almost done getting the rust jacking out of the lower frame flanges
Then indoors to get the rust converter applied, then prime & paint.
Going slow, but it’s making progress each day.
Can’t wait! Next will be brakes & repairs for state inspection.
Seems like forever.

 

[crashz]

I'm not sure if the juice is worth the squeeze. Your frame looks to be in pretty good shape, the rust jacking didn't really stretch it too bad and wouldn't reduce the frame strength. I think you'd be adding weight for very little benefit.

 

[Hay Dude]

I'm not sure if the juice is worth the squeeze. Your frame looks to be in pretty good shape, the rust jacking didn't really stretch it too bad and wouldn't reduce the frame strength. I think you'd be adding weight for very little benefit.

Wonder what 2) 12’ pieces of inverted L frame would weigh? Ot what they’d cost?Remember this truck has a 41,780 GVWR, so weight isn’t much an issue.
The outside of the frame is pitted pretty good and the steel where the leaf spring mounts are isn’t cracked, but it’s deeply pitted.

Would look great to see smooth, black painted steel there again….

on edit: And get a stronger frame.

 

[crashz]

Oh - I didn't see that at first. Still doesn't seem too bad, but you could plate it like you said. You're right about the spring width, that will change. I have no idea if it has center pins in the spring packs but you could crack 'em open and see. With a square housing, maybe they don't.

9" x 4" x 1/2" angle is 27lbs /foot. So * 24ft and you get 648lbs. I guess its not much of a concern

 

[groundcover]

Not for strength but it could look like a show truck with a skim coat of bondo on the frame.

 

[mrmikey]

I'm on the same wavelength as crashz.
If, and that's an 'if' I was to put another piece of frame anywhere it'd be under the hoist cylinder mount under the cab as far fwd as I could and back behind the mount a good foot or so. But it would be dependent on the appearance of the original frame.

Wonder what 2) 12’ pieces of inverted L frame would weigh?

Roughly 11.8lbs per ft for an 11" x 3" x 1/4" bent angle so it'd be another 280lbs or so....ballpark. I'd be a bit nervous also of the chunks of rust getting between the existing frame rails once you remove the bolts. Isn't there also bolts thru the spring perches into the bottom flange of the frame...I think but I could be full of it too LOL. If there was, you'd have to modify the perches as they'll be out another 1/4" so the holes won't line up

 

[dodge man]

I’m curious I keep seeing the term “Jack rust”. I’ve had a bridge inspection class and there was a term called “pack rust”. It’s where rust gets between layers of steel and can give it a wrinkled appearance. Is the same thing as Jack rust?

 

[Hay Dude]

I'm on the same wavelength as crashz.
If, and that's an 'if' I was to put another piece of frame anywhere it'd be under the hoist cylinder mount under the cab as far fwd as I could and back behind the mount a good foot or so. But it would be dependent on the appearance of the original frame.


Roughly 11.8lbs per ft for an 11" x 3" x 1/4" bent angle so it'd be another 280lbs or so....ballpark. I'd be a bit nervous also of the chunks of rust getting between the existing frame rails once you remove the bolts. Isn't there also bolts thru the spring perches into the bottom flange of the frame...I think but I could be full of it too LOL. If there was, you'd have to modify the perches as they'll be out another 1/4" so the holes won't line up

The areas I found the frame outer channel to be roughest is
1. Where the old hoist mount was, which is behind the battery box and where the wing plow frame was on the other side. I think it could be from frame flex being covered with wing plow frame and dump hoist frame.
2. Inside the “cups” formed by the spring perches. Asphalt packed in there for years and stayed damp.

Dropping an inverted L from under the cab to the tail would probably be more like 13’ (to reach under the cab a bit).
But it would improve looks and make up for any lost strength in the steel from scaling.

Probably add a decent amount of cost, but not too bad.

Now is certainly the time to do it.