Cracked Dropout fixable?
01-23-23, 02:44 AM
#1
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Thread Starter
Cracked Dropout fixable?
Hi,
Is the cracked dropout pictured below fixable? I have read that it can be welded for so long as it is not too close to the area of brazing. Given these are forged, am I correct in assuming there is no brazing in this area of the crack? Also how far away does the heat have to be to be safe? If I do go the welding route, are there any specifics that need to be said to the welder (i.e. weld on a supporting plate etc)? Also read that replacing the entire dropout would be more expensive than welding. Should I decide to go the proper replacement route, how much does it usually cost to have this replaced with a regular dropout. Is it even possible to still get the same dropout to have re-brazed on?
On another note, what causes these types of dropout failures? Is it all factory defect from overheating during brazing or is there also something that affects it during daily use like maybe overtightened clamping?
Thanks,
Fish
Is the cracked dropout pictured below fixable? I have read that it can be welded for so long as it is not too close to the area of brazing. Given these are forged, am I correct in assuming there is no brazing in this area of the crack? Also how far away does the heat have to be to be safe? If I do go the welding route, are there any specifics that need to be said to the welder (i.e. weld on a supporting plate etc)? Also read that replacing the entire dropout would be more expensive than welding. Should I decide to go the proper replacement route, how much does it usually cost to have this replaced with a regular dropout. Is it even possible to still get the same dropout to have re-brazed on?
On another note, what causes these types of dropout failures? Is it all factory defect from overheating during brazing or is there also something that affects it during daily use like maybe overtightened clamping?
Thanks,
Fish
01-23-23, 08:05 AM
#3
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Failure at the adjuster bolt hole is fairly common. I see it most often on the drive side, after a misaligned derailleur has landed in the spokes. Are you certain this isn't just a crack in the chrome? If it is a true crack, the easiest fix is to remove the adjuster bolt and fill the hole with brass, of course that means no more adjuster on that side. If having the adjuster is important to you, then replacing the dropout is the best way.
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01-23-23, 08:13 AM
#4
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Failure at the adjuster bolt hole is fairly common. I see it most often on the drive side, after a misaligned derailleur has landed in the spokes. Are you certain this isn't just a crack in the chrome? If it is a true crack, the easiest fix is to remove the adjuster bolt and fill the hole with brass, of course that means no more adjuster on that side. If having the adjuster is important to you, then replacing the dropout is the best way.
Yes the crack goes beyond the chrome unfortunately. By filling with brass do you mean brazing the hole solid? I am not particular about the adjuster bolt although it would be nice to try to save it. Any ideas on how much replacing the dropout would cost?
01-23-23, 09:24 AM
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01-23-23, 09:56 AM
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If TIG welded with stainless rod the repair will be practically invisible in the chrome dropout.
Brent
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01-23-23, 10:24 AM
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Yes it can be fixed!
I broke mine as described by J D Thompson. The break and fix are in the thread below, note the careful and experienced welding barely touched the paint let alone affected the brazing. We agreed the adjuster through-hole would be filled in for max strength.
https://www.bikeforums.net/classic-v...-promised.html
I broke mine as described by J D Thompson. The break and fix are in the thread below, note the careful and experienced welding barely touched the paint let alone affected the brazing. We agreed the adjuster through-hole would be filled in for max strength.
https://www.bikeforums.net/classic-v...-promised.html
Last edited by BTinNYC; 01-23-23 at 10:27 AM.
01-23-23, 10:31 AM
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Failure at the adjuster bolt hole is fairly common. I see it most often on the drive side, after a misaligned derailleur has landed in the spokes. Are you certain this isn't just a crack in the chrome? If it is a true crack, the easiest fix is to remove the adjuster bolt and fill the hole with brass, of course that means no more adjuster on that side. If having the adjuster is important to you, then replacing the dropout is the best way.
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01-23-23, 11:04 AM
#9
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Given that there is a socket for the seat stay, is it safe to assume that it is a forged part and not investment-cast? If cast, there may be a better chance of success with brazing than welding.
01-23-23, 01:58 PM
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There were a LOT of cracked Campagnolo short DOs (1010-B) in the 1980s-90s, never seen one of these "Rossin" branded versions before but no doubt they had them made by one of the main suppliers to Campy/GPM/Columbus...etc.
01-23-23, 02:33 PM
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Since you only need one side adjuster to fine-tune wheel alignment, I would consider having the rear part of the dropout slot partially filled with brass.
With this left dropout now establishing the fore/aft position of the axle and wheel, the right side adjuster will handle the wheel alignment task.
The downside is going to be all the chrome that will get torched. So a weld might actually be best here and maybe the hole can be re-drilled?
Since it's the left side, stresses should be a lot lower than on a right dropout fwiw.
With this left dropout now establishing the fore/aft position of the axle and wheel, the right side adjuster will handle the wheel alignment task.
The downside is going to be all the chrome that will get torched. So a weld might actually be best here and maybe the hole can be re-drilled?
Since it's the left side, stresses should be a lot lower than on a right dropout fwiw.
01-23-23, 02:35 PM
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Yes, filling the hole completely. The hole is a stress riser, that's why it's a common failure mode.
01-24-23, 02:23 AM
#13
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Seems like its a good idea to have the hole filled given its a stress riser and could probably also have material irregularity issues. Going to a well regarded machine shop on the weekend to see if they can do it. So to summarize I will be asking them to braze the hole shut with brass and tig weld the crack shut is this correct?
Thanks for this! I shall be looking to see if their guy will do it with a similar method of short 2-3 sec welds at a time to manage the heat.
Yes it can be fixed!
I broke mine as described by J D Thompson. The break and fix are in the thread below, note the careful and experienced welding barely touched the paint let alone affected the brazing. We agreed the adjuster through-hole would be filled in for max strength.
https://www.bikeforums.net/classic-v...-promised.html
I broke mine as described by J D Thompson. The break and fix are in the thread below, note the careful and experienced welding barely touched the paint let alone affected the brazing. We agreed the adjuster through-hole would be filled in for max strength.
https://www.bikeforums.net/classic-v...-promised.html
01-24-23, 06:33 AM
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Seems like its a good idea to have the hole filled given its a stress riser and could probably also have material irregularity issues. Going to a well regarded machine shop on the weekend to see if they can do it. So to summarize I will be asking them to braze the hole shut with brass and tig weld the crack shut is this correct?
Thanks for this! I shall be looking to see if their guy will do it with a similar method of short 2-3 sec welds at a time to manage the heat.
Thanks for this! I shall be looking to see if their guy will do it with a similar method of short 2-3 sec welds at a time to manage the heat.
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