Seatpostclamp enlarge to M5?
08-27-22, 03:34 PM
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Seatpostclamp enlarge to M5?
Hi,
I have a faiing seatpostclamp, probably tightend to hard en the thread is gone.
It was M4 , I would like to fix this instead of buying a new one... Can I use a tapset to enlarge the M4 hole to M5? What is the process to do this, drill with 4 and then use a M5 tap? I'm new in tapping :-)
Thx
I have a faiing seatpostclamp, probably tightend to hard en the thread is gone.
It was M4 , I would like to fix this instead of buying a new one... Can I use a tapset to enlarge the M4 hole to M5? What is the process to do this, drill with 4 and then use a M5 tap? I'm new in tapping :-)
Thx
08-27-22, 04:12 PM
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The answers are maybes. First thing i would want to understand is why the OEM clamp became an issue. You say aero. As in a non round seat post? The clamp having a tapered rear profile? Both?
If the issue turns out to be the clamp's binder slot closing up and if the replacement clamp has the same potential than no bigger binder bolt will cure that. It's more common for aero clamps to have binder slot closing up problems and it's harder to open up the slot with a file.
When considering sixing up a clamp's bolt a few aspects are to be minded. First is the amount of surrounding material about the OEM (and "smaller") bolt. Will opening up the hole compromise the clamp's strength or interfere with something else. If the clamp has the threads for the bolt to engage (a threaded hole) will there be enough threads with the coarser pitch that a larger bolt usually has? About 4 or 5 threads of overlap are where max "strength" begins). If the clamp has counterbores for the bolt heads to nestle into they will likely need enlarging too. Counter bores are not cheap.
The common 5x.8 (M5) thread wants a 4.2mm pilot hole (not a 4mm), I use a #19 drill (.1660"). Andy
If the issue turns out to be the clamp's binder slot closing up and if the replacement clamp has the same potential than no bigger binder bolt will cure that. It's more common for aero clamps to have binder slot closing up problems and it's harder to open up the slot with a file.
When considering sixing up a clamp's bolt a few aspects are to be minded. First is the amount of surrounding material about the OEM (and "smaller") bolt. Will opening up the hole compromise the clamp's strength or interfere with something else. If the clamp has the threads for the bolt to engage (a threaded hole) will there be enough threads with the coarser pitch that a larger bolt usually has? About 4 or 5 threads of overlap are where max "strength" begins). If the clamp has counterbores for the bolt heads to nestle into they will likely need enlarging too. Counter bores are not cheap.
The common 5x.8 (M5) thread wants a 4.2mm pilot hole (not a 4mm), I use a #19 drill (.1660"). Andy
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08-27-22, 04:20 PM
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Hi,
I have a faiing seatpostclamp, probably tightend to hard en the thread is gone.
It was M4 , I would like to fix this instead of buying a new one... Can I use a tapset to enlarge the M4 hole to M5? What is the process to do this, drill with 4 and then use a M5 tap? I'm new in tapping :-)
Thx
I have a faiing seatpostclamp, probably tightend to hard en the thread is gone.
It was M4 , I would like to fix this instead of buying a new one... Can I use a tapset to enlarge the M4 hole to M5? What is the process to do this, drill with 4 and then use a M5 tap? I'm new in tapping :-)
Thx
Don't practice on something you can't afford to screw up.
08-27-22, 05:50 PM
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Is your seatpost clamp a removable collar type? Is it circular, not oval or aero? If yes to both questions, replacement seatpost collars are readily available from almost any bike shop or on-line bike shop or Amazon to fit a wide range of seat tube diameters.
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08-29-22, 03:02 PM
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hevysrf ah that seems the most safe option :-)
Andrew R Stewart ]hx for the info, that was I was looking for drill 4.2 for a m5, altough I could just buy a new one for 10$ but I like to fix stuff so gonna give it a go !
Thx !
Andrew R Stewart ]hx for the info, that was I was looking for drill 4.2 for a m5, altough I could just buy a new one for 10$ but I like to fix stuff so gonna give it a go !
Thx !
