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-   -   Tips to loosen a seized cog? (https://www.bikeforums.net/singlespeed-fixed-gear/701689-tips-loosen-seized-cog.html)

hpmcardle 12-19-10 11:45 PM


Originally Posted by Scrodzilla (Post 11950583)
So wait...Chuck Norris shooting uzis at a cheap rear wheel will turn it into a Phil Wood cog?

Yes.

I mean, ****, he's Chuck Norris.

Sixty Fiver 12-19-10 11:49 PM

Am not sure what was used to secure that cog but if you are dealing with thread lockers penetrating fluids will do jack squat.

Blue Locktite requires extra mechanical force while red Loctite requires the use of a torch of it has been used properly and even then can make for some difficult removal.

Soil_Sampler 12-20-10 06:58 PM

Stein
 
http://jastein.com/Html/Unfixie.htm


heat
cog/freewheel vise

blickblocks 12-20-10 07:37 PM

Did the OP try rotafix yet?

Unless your threads are seriously messed up, or the metals have fused (tbh unlikely either way), rotafix is the way to go. Has worked great on all the wheels I've built.

blickblocks 12-20-10 07:38 PM


Originally Posted by Soil_Sampler (Post 11961278)
http://jastein.com/Html/Unfixie.htm


heat
cog/freewheel vise

Please don't use heat, you will ruin the hub.

evilcryalotmore 12-20-10 09:01 PM

get some good torque and slow down. Breaker bar.

Try rotofix, But go slow. dont put all the pressure at once.

If you feel the threads bite add some triflow.

work slow. work slow. when its off. toss that shizz

Soil_Sampler 12-21-10 06:31 PM

give me some heat...
 

Originally Posted by blickblocks (Post 11961485)
Please don't use heat, you will ruin the hub.

negative.

heat the cog, not the hub with a heat gun.

Scrodzilla 12-21-10 07:32 PM


Originally Posted by Soil_Sampler (Post 11966159)
heat the cog, not the hub with a heat gun.

Exactly. No one is talking about subjecting the hub to a nuclear warhead.

blickblocks 12-22-10 04:37 PM


Originally Posted by Soil_Sampler (Post 11966159)
negative.

heat the cog, not the hub with a heat gun.

If you heat the cog you will heat the hub too. The threads will be weakened severely. Heat should never be used for this purpose unless you don't want to save the parts.

Scrodzilla 12-22-10 05:03 PM

What do I know, I'm only a bicycle mechanic. :rolleyes:

Amesja 12-22-10 05:26 PM


Originally Posted by Scrodzilla (Post 11970700)
What do I know, I'm only a bicycle mechanic. :rolleyes:

Hit it withthe oxy-acetylene torch and FEED in that oxy!

TejanoTrackie 12-22-10 05:44 PM

Regarding the use of heat to loosen a steel threaded cog on an aluminum hub:

1) The coefficient of thermal expansion of aluminum is approximately twice that of steel.

2) Both the hub and cog will expand radially outward when heated.

3) The good heat transfer properties of aluminum will ensure that the heat applied to the cog will transfer to the hub.

4) Therefore, the hub will expand more than the cog, the cog will become tighter on the hub, and this technique will be ineffective.

5) Brother 65er's recommendation to use heat in post #27 was made in the context of breaking down a red threadlocker compound, and not as a method to loosen a tight cog.

6) IME the most effective method is to use some sort of impact technique such as in post #6.

Amesja 12-22-10 05:49 PM


Originally Posted by TejanoTrackie (Post 11970873)
Regarding the use of heat to loosen a steel threaded cog on an aluminum hub:

1) The coefficient of thermal expansion of aluminum is approximately twice that of steel.

2) Both the hub and cog will expand radially outward when heated.

3) The good heat transfer properties of aluminum will ensure that the heat applied to the cog will transfer to the hub.

4) Therefore, the hub will expand more than the cog, the cog will become tighter on the hub, and this technique will be ineffective.

5) Brother 65er's recommendation to use heat in post #27 was made in the context of breaking down a red threadlocker compound, and not as a method to loosen a tight cog.

6) IME the most effective method is to use some sort of impact technique such as in post #6.

The thing you fail to account for in number 4 is that once the Al hub cools it'll shrink twice as much as the steel one and may be looser after a few heat cycles. This is exactly the reason why lightbulbs sometimes get loose in light fixtures and why Al an Cu wires connected with wire connectors not listed for Al/Cu will get loose as well -causing a fire possibly because of a loose connection.

Heat cycling MIGHT work to help loosen it up -but probably not until after it cools or goes through a few heat cycles. It might also work to break up some threadlock that was put in there too.

Scrodzilla 12-22-10 05:54 PM

I'm lighting my bikes on fire right now.

Soil_Sampler 12-22-10 06:16 PM

smores
 

Originally Posted by Scrodzilla (Post 11970915)
I'm lighting my bikes on fire right now.

break out the marshmallows!:D

Soil_Sampler 12-22-10 06:27 PM


Originally Posted by blickblocks (Post 11970599)
If you heat the cog you will heat the hub too.
The threads will be weakened severely.
Heat should never be used for this purpose unless you don't want to save the parts.

how much heat?
are you an engineer?
I have a 10 year old Phil wood hub still going strong after getting the cog off in this manner.

Scrodzilla 12-22-10 06:31 PM


Originally Posted by Soil_Sampler (Post 11971050)
I have a 10 year old Phil wood hub still going strong after getting the cog off in this manner.

C'mon, dude. You're just saying that.

Soil_Sampler 12-22-10 06:38 PM

Honest.
 

Originally Posted by Scrodzilla (Post 11971069)
C'mon, dude. You're just saying that.

it's fact. no foolin'!

Squirrelli 12-22-10 06:38 PM


Originally Posted by TejanoTrackie (Post 11970873)
6) IME the most effective method is to use some sort of impact technique such as in post #6.

.
.
.

Originally Posted by Vixtor (Post 11946907)
Wrap it with a chain whip, give the handle a few tap with a mallet.

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Thirteen. 12-23-10 03:28 AM

I'm surprised this thread is still going. I do appreciate everyone's advice and tips although I've already gotten the cog off a few days ago and have posted so somewhere on page 1. Basically, I used the rotafix method continuously once every 30 mins until the cog finally loosened.

Scrodzilla 12-23-10 08:30 AM

Right on, Thirteen.

We just like to hang around after the party's over and and bicker over who get's the last beer. :lol:


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