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1970's Mondia repair

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Old 02-26-19, 11:20 PM
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Manny66 
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1970's Mondia repair

So I have a Mondia from the 70's, Ive had it since 1981 and was my main bike when I was a teenager. A few years later I slammed int the rear of a pickup truck while riding and totaled the forks and creased the Head tube. Fast forward to 2018 and Ive finally decided to repair it for sentimental reasons.
I just had the original chrome stripped to be able to repair and braze in a new head tube.

Question 1, after the chrome was removed I noticed the rear dropouts look like the brazeing material is a little thin. Theres a clean gap between the dropout and the chainstays as if the joint is not totally filled completely with brazing rod., would rebrazing this area to fill the fine gap be a typical move, or is it fine and be should it be left alone?

Question 2. I already have replacement tubing and will be cutting the head tube in the center, heating up the lugs and removing the leftover tubing ,and installing the new tubing ,I will be heating the lugs up to reform the lugs to close as possible to original and installing the head tube and silver brazing it. I have Never made a repair like this but think I am in the right direction. Am I correct on this procedure or am I leaving something out??
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Old 02-26-19, 11:21 PM
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Another view of the Droputs
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Old 02-26-19, 11:23 PM
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The Damaged Head Tube.
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Old 02-26-19, 11:25 PM
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And another shot.
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Old 02-27-19, 12:05 AM
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I'd be tempted to grind out the HT from inside the lugs. This frame is seeing enough insult to give it one more, the high heat level to pull a brassed tube out.

Since the drop outs have survived 40+ years I suggest leaving good enough alone. Andy
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Old 02-27-19, 05:05 AM
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It's really hard for me to tell if there is a problem with the dropout. I would have it media blasted.

I agree with Andy. The likelihood of removing that head tube without injuring the lugs is slight. I'm sure the filler is brass. Doesn't take long to remove a head tube with a dremel. A sanding drum is my choice.
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Old 03-01-19, 10:58 AM
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dropout likely , has to be removed, metal surfaces cleaned up, then re brazed..
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Old 03-03-19, 09:23 PM
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So I got some progress done on the frame.

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Old 03-03-19, 09:24 PM
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To This.Took a cut off wheel to it
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Old 03-03-19, 09:27 PM
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grinded the inner tubing ,heated up the thin leftover and they slipped out.
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Old 03-03-19, 09:30 PM
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Now all I have left to do is file everything down tighten the gaps ,make sure its clean ,and get it ready to braze. I practiced on a old univega frame before i tried it on this as I just played it by ear. So far so good.
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Old 03-04-19, 07:18 AM
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Be sure to check alignment of your new head tube to the rest of the frame before brazing it in place. I'm going through a down tube replacement right now and the head tube was out of alignment after removing the damaged tube. I aligned the frame to put the head tube straight and now I'm working on installing the new tube.

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Old 03-04-19, 08:37 AM
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nice
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Old 03-04-19, 08:47 AM
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This is the moment to clean up the lug points too. Andy
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Old 03-04-19, 09:52 AM
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Did the lug pull away from the down tube thus creating a gap where the arrows point? Might just be the photo of course; it seems the focus was on the tool box instead of the frame. Anyway, if the lug did move I think that should be fixed before fitting the new head tube.



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Old 03-04-19, 10:47 AM
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I would put money on the gap being a preexisting condition. And I don't gamble
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Old 03-04-19, 12:17 PM
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Originally Posted by Nessism View Post
Did the lug pull away from the down tube thus creating a gap where the arrows point? Might just be the photo of course; it seems the focus was on the tool box instead of the frame. Anyway, if the lug did move I think that should be fixed before fitting the new head tube.



No, the camera angle only gives that impression. The down tube didnt move at all.I was surprised how easy the head tube came off. I did as suggested, I grinded the tubing from the inside and thinned it down as much as I could without damaging the Lugs. As soon as I put the torch on it the pieces slid out to the ground,only one spot I had to use pliers as I didnt want to over heat the lugs. Everything came off clean. The new head tube slid right into place without any force or pressure. I need to find my thin barrel fine sanding attachment to give it a good cleaning.
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Old 03-15-19, 06:43 PM
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Any updates on your Mondia? Not much time to have it ready for Eroica, will you be coming and will you have a backup bike if the Mondia isn't ready? (paint and such)
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