Step-Thru Frame and Paint Concerns

Bike from the Dead · Sep 20, 2024

I really want to enter this prewar Monark into the STBO, but I don't know if I'll be able to paint it the way I want.

For starters, the frame is pretty rusty. It's not bad enough that I can't ride it, but if I want to strip it down and repaint it, I'll either need to use a good filler primer or Bondo. I haven't seriously painted a bike before, especially one this rough, so I'm a little intimidated by the process.

Second, if I'm going to paint this bike, I need to get the old chain tensioners out. I might be able to get one out just fine, but the other chain tensioner is bent, and I'm not sure how to get it out. Does anyone know how I can remove the chain tensioners without damaging the frame?

Finally, the last concern I have about painting this frame is that when I disassembled this bike, I cracked the seat post clamp when I used a screwdriver to pry it open so I could get the post out. I didn't know the clamp was welded to the seat post. Is there an easy way to repair this?

idiotboy · Sep 20, 2024

for your bent bolt, I would get a Dremel with a cut off wheel, cut the end with the head as close to the frame as you can, cut a slot in the bolt so you can use a flat head screw driver to turn it out towards the dropout so youre not trying to get the bent part through the frame. also PB blaster

Bike from the Dead · Sep 20, 2024

idiotboy said:
for your bent bolt, I would get a Dremel with a cut off wheel, cut the end with the head as close to the frame as you can, cut a slot in the bolt so you can use a flat head screw driver to turn it out towards the dropout so youre not trying to get the bent part through the frame. also PB blaster

Good idea. That may be the best way to take care of that part.

Pondo · Sep 20, 2024

For the tensioner bolts I would soak them for a couple of days, if you have the time, with penetrating oil. Bend the one straighter with a screwdriver or something and work them back and forth until they loosen up. Might need to heat them with the propane torch to help also. This might allow you to reuse the bolts. If you're not concerned about using the tensioners you could just trim them off or leave them in place for the paint job. I've read that the dropouts are stronger with bolts in them so I would try to have something in there at the end.

Do you have access to a sand blaster or bead blaster? That's going to get all of the old paint and rust off of there so you can see the actual condition of the metal. From there it will just be a matter of using etch primer then high build primer or maybe a little filler to even up the rough spots. There's lots of paint tutorials on youtube, which I've been watching lately.

The cracked weld on the seat post clamp should be fairly straightforward. I would put a bolt in to bring the clamp back to the tube and then put a series of weld tacks on the crack. File it flat, clean out the inside of the tube and you should be good. I've read that spray cooking oil makes a good anti-splatter so the weld splatter is easier to clean off, might be good to spray some of that down the seat tube before welding. Good luck and have fun!

Captain Awesome · Sep 20, 2024

Pondo said:
The cracked weld on the seat post clamp should be fairly straightforward. I would put a bolt in to bring the clamp back to the tube and then put a series of weld tacks on the crack. File it flat, clean out the inside of the tube and you should be good. I've read that spray cooking oil makes a good anti-splatter so the weld splatter is easier to clean off, might be good to spray some of that down the seat tube before welding. Good luck and have fun!

If you have a Dremel, I would put a v notch in that crack to give yourself something for the weld to root to, and also to get the contamination out of there. Not like it’s a super high strength area but if you’re gonna do it, do it right. Also, if you have an oxyacetylene torch, a very dirty sooty flame down the seat tube will make for good anti spatter as the soot has very good properties for that and then it wipes right off

Pondo · Sep 20, 2024

Captain Awesome said:
a very dirty sooty flame down the seat tube will make for good anti spatter as the soot has very good properties for that and then it wipes right off

I didn't know that, I'll give it a try next time. Thanks!

Bike from the Dead · Sep 20, 2024

Pondo said:
For the tensioner bolts I would soak them for a couple of days, if you have the time, with penetrating oil. Bend the one straighter with a screwdriver or something and work them back and forth until they loosen up. Might need to heat them with the propane torch to help also. This might allow you to reuse the bolts. If you're not concerned about using the tensioners you could just trim them off or leave them in place for the paint job. I've read that the dropouts are stronger with bolts in them so I would try to have something in there at the end.

I think for the bent tensioner, I'll just try @idiotboy's suggestion. I'll definitely soak them in PB Blaster for a while, though. Hitting them with the sandblaster might help as well. I'll probably add some new bolts or tensioners if all goes well.

Pondo said:
Do you have access to a sand blaster or bead blaster? That's going to get all of the old paint and rust off of there so you can see the actual condition of the metal. From there it will just be a matter of using etch primer then high build primer or maybe a little filler to even up the rough spots. There's lots of paint tutorials on youtube, which I've been watching lately.

Yeah, my dad has a sandblaster at his shop I can use. Etch primer? High-build primer? Never heard of those, nor can I say I've seen them in the spray paint section of any hardware store. Then again, I may have missed them because I wasn't looking for them.

I can check out some tutorials on YouTube, but it's a lot harder to tell the good ones apart from the bad ones ever since they removed the dislike counter. Guess I'll just have to experiment.

Pondo said:
The cracked weld on the seat post clamp should be fairly straightforward. I would put a bolt in to bring the clamp back to the tube and then put a series of weld tacks on the crack. File it flat, clean out the inside of the tube and you should be good. I've read that spray cooking oil makes a good anti-splatter so the weld splatter is easier to clean off, might be good to spray some of that down the seat tube before welding. Good luck and have fun!

Captain Awesome said:
If you have a Dremel, I would put a v notch in that crack to give yourself something for the weld to root to, and also to get the contamination out of there. Not like it’s a super high strength area but if you’re gonna do it, do it right. Also, if you have an oxyacetylene torch, a very dirty sooty flame down the seat tube will make for good anti spatter as the soot has very good properties for that and then it wipes right off

Would I need to protect the seat tube from splatters if I have it TIG-welded? If so, I can try the sooty flame technique, if my welder friend has the equipment. I know we had a Dremel, but I have no idea where the tool went. I know where the attachments are, but not the tool itself. I might know someone who'll let me borrow theirs though.

Captain Awesome · Sep 20, 2024

Bike from the Dead said:
Would I need to protect the seat tube from splatters if I have it TIG-welded?

No

Bike from the Dead · Sep 20, 2024

Captain Awesome said:
No

Alright, thanks.

Pondo · Sep 20, 2024

Bike from the Dead said:
nor can I say I've seen them in the spray paint section of any hardware store.

Try the local auto parts store, they should have everything you need.

As for paint tutorials, just watch some that look like fun and are along the lines of what you have in mind. You can't go too far wrong with the bodywork. Just keep sanding and reapplying until you're happy with what you see. You can get decent results with spray paints. I haven't tried using a paint gun yet but I'll get into that project eventually.

Bike from the Dead · Sep 20, 2024

Pondo said:
Try the local auto parts store, they should have everything you need.

As for paint tutorials, just watch some that look like fun and are along the lines of what you have in mind. You can't go too far wrong with the bodywork. Just keep sanding and reapplying until you're happy with what you see. You can get decent results with spray paints. I haven't tried using a paint gun yet but I'll get into that project eventually.

I'll swing by a few places after I check out the BMX Vintage National Show & Swap tomorrow. I wanted to look at some glitter paint and some anodizing paint anyway, so this would be a good time to look at Bondo and primer too.

I'll browse around on YouTube and see what's out there. I was just planning on using rattle-can paint anyway. I don't have a paint gun.

Pondo · Sep 20, 2024

Bike from the Dead said:
Bondo

I doubt you'll need any 2 part filler. You'll probably be fine with glazing putty, or spot putty, and filler primer.

The Renaissance Man · Sep 20, 2024

I believe that once all of the paint is removed, the metal will not be as bad as you think. That's one good thing about brushed on house paint, it does actually make a pretty good protective barrier.

Bike from the Dead · Sep 21, 2024

The Renaissance Man said:
I believe that once all of the paint is removed, the metal will not be as bad as you think. That's one good thing about brushed on house paint, it does actually make a pretty good protective barrier.

It's the areas where the paint has rusted away that I'm concerned about.

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