Monark frame repair?

[h.i.]

Hi

Been lurking for a few years, finally have something to post. I picked up the frame last weekend and while trying to remove the adjuster from the rear dropout, one of the repairs failed. The dropout had been welded in this area. There are other repairs to the lower rear stays closer to the BB. The other repairs seem fairly solid. My buddy can tig this back together, but I worry about it failing again. I'm wondering if I should (1) try to reweld/repair the dopout, or (2) cut them off and make them from steel, or (3) hang it on the wall and move on. Love to hear any opinions.

Thanks for any help!

Top tube repair

dropout

dropout 2

lower stay

lower stay 2

lower stay 3

Junk!

BB

Head

 

[user 135]

Tough to say. Aluminum repair can be difficult. If you buddy is good, go for it.

 

[bicycleguy]

I've seen a few of those frames that are cracked or broken. If it were me I'd get it welded then just keep an eye on it to make sure there aren't any hairline cracks or small stress fractures.

 

[outskirtscustoms]

It would be a difficult repair but not impossible. If you know a good welder go for it. Just take it easy on it and keep looking for small cracks and such.

 

[h.i.]

Thanks CeeBee, I was wondering about the "duralium" also. My buddy is a good welder. He welded the skid plate for my rally car, and it held up, haha. Thanks, I will keep you guys posted on the progress.

 

[c.p.odom]

The welding is not big deal if you are good but there is more to it. When the welding is done you will have a completely annealed area (O condition). This area will have little of the original strength. I doubt anyone is taking the appropriate steps to have the frame solution heat treated after repair. Fix it, polish it, hang it on the wall.

 

[h.i.]

If my brief research is correct, "Duralumin" is junk anyway. 2024 at best? I didn't buy it to hang it on the wall. If we can't come up with a good weldable repair solution, I will try to fab new dropouts from steel or aluminum. Then when the other repairs fail, I can replace them too, haha. Makes it more of a hot rod anyway, right?

 

[h.i.]

Thanks for the extra help CB! I really like that idea. The more I think about it the more I am leaning that direction also. Nicely designed fish plates welded over the repairs to spread the load. Still working on the dropout idea. Garage night tonight so the welder is coming over and he can take a look at it and see what he thinks. Thanks again.

 

[c.p.odom]

2000 series aluminum is alloyed for forming processes, casting, forging, bending, etc. It is not considered a weldable aluminum. Adding plates of 6 series may sound like the solution but the repair will only be as strong as the welds. Any fix to the dropouts does not address the rather dodgy repairs to the chain stays.
Really you bought a wall hanger or a very large paper weight and you are on your way to turning it into scrap.
If you need to continue down this path then do it the best way possible. Cut the existing dropouts off and weld some nicely crafted new ones on.

 

[h.i.]

Thanks CP, you make a great point. The best solution by far for the dropouts is to make new ones. As for the stays, that is where I was thinking about fish plates over the repairs. I understand the metallurgical issues. I don't think any new or additional repair in that area will make it worse than it is now, if anything it should make it stronger if done right. Any ideas for that area?

 

[c.p.odom]

I don't disagree with everything that CB is saying. However, as a Fabricator, Mechanical Engineer, and Engineering Manager by profession and a restorer as a hobbyist I will state that the physics of mechanical properties will not be denied. For any margin of safety the dropouts will need to be cut off the frame and new ones fabricated. The chain adjuster and bottom bolt preclude any clean installation of repair plates. Cut the new dropouts with "U" shaped slots to fit on both sides of the chain and seat stays. It is important to remove all existing weld repairs and start with fresh metal. With this dropout design you can get 2+ inches of weld bead on each ear of the dropouts.

 

[h.i.]

Thanks guys! Design by committee rarely provides the best solution for a problem, but in this case i think we all agree, whether it seems like it or not, haha. I plan to whittle out some new dropouts on my friend's mill on sunday, time permitting. I found some 6061 .25 plate and some other unknown 5/16 or 3/8 plate in the scrap pile. Maybe I could start a real build thread for that. As far as the stays, I will let breakage dictate replacement. Thanks again for all your replies and thoughts on this issue, I do appreciate it.

 

[c.p.odom]

Glad the dropout issue is settled. CB and I ran out of pee. I am still claiming best distance while he scored best in accuracy.
Now there is still the open issue of the chainstay repairs. Anybody have some ideas?

 

[deorman]

My opinion on this may not be welcomed, but I'm inclined to offer it up anyway. Given the extent of the damage, and the crystalline nature of older aluminum, I wouldn't trust that frame as far as I could throw a Typhoon with full newspaper baskets. Even if every repair was perfect, It probably has other defects which are not visible on the outer surface. :|

 

[h.i.]

Fixed the links for anyone who's interested

 

[h.i.]

I started another thread on this bike, it can be found here:

viewtopic.php?f=21&t=65157

 

[h.i.]

Update! This thing rides great. I only put about 30 miles on it, but it did the job it was built to do which was haul me around the pits at bonneville.

 

[h.i.]

Cool! Got a link? I searched around in your old posts but didn't see anything. Curious if you had any issues welding the old stuff? no weird problems, etc...