Cotter Question
02-13-23, 08:42 PM
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Le Crocodile
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Cotter Question
This pin is mated flat to flat on a mockup. I have it pushed to one side of the flat on the BB spindle.
First time working with cottered cranks here. As you can see, the flat portion of the spindle allows for a relatively massive inboard/outboard movement of the crankset/chainline before the pin is driven in. I "know" that if properly installed, it shouldn't shift in use, but yikes C+V crew, I am scratching my head on this one!
Were they all this "sloppy" (relatively speaking)?
02-13-23, 08:56 PM
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While I am no expert, I *can* confirm that the cottered axles and pins that I have all look like that, however once the pin is inserted through a crank arm and pressed in tight there is no lateral movement I have ever experienced.
02-13-23, 09:55 PM
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u r fine
wedgebolt should be 9.0mm with "medium" cut
remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
u r dune just fine
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u r fine
wedgebolt should be 9.0mm with "medium" cut
remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
u r dune just fine
-----
02-14-23, 07:44 AM
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remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
-----
remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
-----
I've always put a thin layer of grease on the cotter, though I've always wondered whether that's a good idea. Opinions?
02-14-23, 07:58 AM
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the standard advice given from experts far more knowledgeable than meself is to not lubricate so i do not
another common home tool which can be used for cotter pin removal and seating is a bench vise
with that tool one really needs a confederate to help hold everything in place whilst the bench vise's crank is being turned...
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02-14-23, 10:17 AM
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Just to add my $0.02 (CAD)..... I found that there is inevitably a need to file the flat of a new cotter to ensure a tight and even fit (mostly measured by ensuring approximately the same amount of the pin extends out of the hole on each side). Using a sharpie to colour in the flat before filing allows one to see high spots while filing to ensure you keep the flat, um, flat.....like engineer's blue except almost everyone has a Sharpie to hand.
For removing the pins I have tried the bench vise (awkward as juvela points out but effective), a large C clamp (worked on most but was hard to maintain centering pressure so occasional mishaps occurred) and finally a proper cotter press (not the be all end all but the most consistent of the bunch and easy to use). For re-seating the pins any of the above tools works great.
For removing the pins I have tried the bench vise (awkward as juvela points out but effective), a large C clamp (worked on most but was hard to maintain centering pressure so occasional mishaps occurred) and finally a proper cotter press (not the be all end all but the most consistent of the bunch and easy to use). For re-seating the pins any of the above tools works great.
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02-14-23, 02:58 PM
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u r fine
wedgebolt should be 9.0mm with "medium" cut
remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
u r dune just fine
-----
u r fine
wedgebolt should be 9.0mm with "medium" cut
remember when assembling things to mount pins symmetrically - either head leads in rotation or tail leads but the same on both sides
if one fails to do this arms end up out of registration by fifteen degrees or so
pins need to be pressed in, no pounding
do not rely upon nut to seat pin
a C-clamp can be employed for seating
u r dune just fine
-----
Appreciate the picture and advice. It's provides some needed guidance.
02-14-23, 04:37 PM
#9
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Why, what's the downside of pounding? I almost always hammered them in, and I don't recall ever seeing problems from that.
I also greased all surfaces during assembly. I don't know if that's necessary, but I can tell ya for sure it doesn't cause loosening.
In the early and mid-'70s I worked at a big shop that sold a lot of cottered bikes, and offered a half-price "winter special" overhaul to keep the lights on in the off-season, so I would often work on multiple cottered bikes per day. Certainly hundreds over the years. Not saying my way is the only way, but I think if there were severe downsides to the way I do it, I should have seen them back then.
Nowadays I go years between bouts with cottered cranks. Sometimes I use my Var #07 press just because it's awesome. But even owning the Var, I'm still more likely to reach for my hammer'n'punch because that's how I roll.
Hammering is definitely more dangerous, both to the bike and the operator, if you should swing and miss. But I don't see anything wrong with a solidly-landed blow that doesn't glance off and hit something it's not supposed to. Since I have a lot of hammering experience, that's easy and reliable enough for me, but as the adage goes, "good aim comes from experience; experience comes from bad aim".
Jesus Christ was a carpenter, and to this day we call out His name when we hit our thumb with a hammer.
Mark B
I also greased all surfaces during assembly. I don't know if that's necessary, but I can tell ya for sure it doesn't cause loosening.
In the early and mid-'70s I worked at a big shop that sold a lot of cottered bikes, and offered a half-price "winter special" overhaul to keep the lights on in the off-season, so I would often work on multiple cottered bikes per day. Certainly hundreds over the years. Not saying my way is the only way, but I think if there were severe downsides to the way I do it, I should have seen them back then.
Nowadays I go years between bouts with cottered cranks. Sometimes I use my Var #07 press just because it's awesome. But even owning the Var, I'm still more likely to reach for my hammer'n'punch because that's how I roll.
Hammering is definitely more dangerous, both to the bike and the operator, if you should swing and miss. But I don't see anything wrong with a solidly-landed blow that doesn't glance off and hit something it's not supposed to. Since I have a lot of hammering experience, that's easy and reliable enough for me, but as the adage goes, "good aim comes from experience; experience comes from bad aim".
Jesus Christ was a carpenter, and to this day we call out His name when we hit our thumb with a hammer.
Mark B
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02-14-23, 05:24 PM
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Why, what's the downside of pounding? I almost always hammered them in, and I don't recall ever seeing problems from that.
I also greased all surfaces during assembly. I don't know if that's necessary, but I can tell ya for sure it doesn't cause loosening.
In the early and mid-'70s I worked at a big shop that sold a lot of cottered bikes, and offered a half-price "winter special" overhaul to keep the lights on in the off-season, so I would often work on multiple cottered bikes per day. Certainly hundreds over the years. Not saying my way is the only way, but I think if there were severe downsides to the way I do it, I should have seen them back then.
Nowadays I go years between bouts with cottered cranks. Sometimes I use my Var #07 press just because it's awesome. But even owning the Var, I'm still more likely to reach for my hammer'n'punch because that's how I roll.
Hammering is definitely more dangerous, both to the bike and the operator, if you should swing and miss. But I don't see anything wrong with a solidly-landed blow that doesn't glance off and hit something it's not supposed to. Since I have a lot of hammering experience, that's easy and reliable enough for me, but as the adage goes, "good aim comes from experience; experience comes from bad aim".
Jesus Christ was a carpenter, and to this day we call out His name when we hit our thumb with a hammer.
Mark B
I also greased all surfaces during assembly. I don't know if that's necessary, but I can tell ya for sure it doesn't cause loosening.
In the early and mid-'70s I worked at a big shop that sold a lot of cottered bikes, and offered a half-price "winter special" overhaul to keep the lights on in the off-season, so I would often work on multiple cottered bikes per day. Certainly hundreds over the years. Not saying my way is the only way, but I think if there were severe downsides to the way I do it, I should have seen them back then.
Nowadays I go years between bouts with cottered cranks. Sometimes I use my Var #07 press just because it's awesome. But even owning the Var, I'm still more likely to reach for my hammer'n'punch because that's how I roll.
Hammering is definitely more dangerous, both to the bike and the operator, if you should swing and miss. But I don't see anything wrong with a solidly-landed blow that doesn't glance off and hit something it's not supposed to. Since I have a lot of hammering experience, that's easy and reliable enough for me, but as the adage goes, "good aim comes from experience; experience comes from bad aim".
Jesus Christ was a carpenter, and to this day we call out His name when we hit our thumb with a hammer.
Mark B
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02-14-23, 05:48 PM
#11
Industry guy
For my little bit:
There are a lot of variations of cotters-
diameters from 8mm to 9.5mm
Tapers can be long(total length of the cotter), medium(something over half length), and short (half or a little shorter)
potentially different angles to the taper
Make sure to use matching cotters and if possible when replacing them, match the original in all aspects.
Cotters should be inserted from opposing sides( that is when looking at a static crank the heads should be from oppositie sides)
If not, the arms will be at angles other than 180degrees;
The crank arm should be aligned so the spindle is flush with the crank arms;(saves ankle scraping!)
I never lubricate a cotter pin taper (or the spindle - this qoes for sqaure taper/cotterless styles as well)
To inset a cotter, a proper press is the best but.....
Even after I use a press, I like to put the nut on and with a wrench to turn it, I "tap" (not whack) the head multiple times while tightening the nut.
This tends to seat the pin.
We would always check cotters and the nut when bikes came in, even for just air.
rusty
There are a lot of variations of cotters-
diameters from 8mm to 9.5mm
Tapers can be long(total length of the cotter), medium(something over half length), and short (half or a little shorter)
potentially different angles to the taper
Make sure to use matching cotters and if possible when replacing them, match the original in all aspects.
Cotters should be inserted from opposing sides( that is when looking at a static crank the heads should be from oppositie sides)
If not, the arms will be at angles other than 180degrees;
The crank arm should be aligned so the spindle is flush with the crank arms;(saves ankle scraping!)
I never lubricate a cotter pin taper (or the spindle - this qoes for sqaure taper/cotterless styles as well)
To inset a cotter, a proper press is the best but.....
Even after I use a press, I like to put the nut on and with a wrench to turn it, I "tap" (not whack) the head multiple times while tightening the nut.
This tends to seat the pin.
We would always check cotters and the nut when bikes came in, even for just air.
rusty
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02-15-23, 01:22 PM
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"Jesus Christ was a carpenter, and to this day we call out His name when we hit our thumb with a hammer"
Jackson Brown would add "And in all our bold endeavors".
Jackson Brown would add "And in all our bold endeavors".
