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-   -   Chrome vs. Ammonia (https://www.bikeforums.net/bicycle-mechanics/782874-chrome-vs-ammonia.html)

kuje 11-21-11 01:52 PM

Chrome vs. Ammonia
 
Hello all. I have an old chrome Schwinn Voyageur 11.8 that has the stem stuck in it. I've wasted an entire can of PB Blaster trying to get it out, and have had no luck pounding the unscrewed stem bolt down with a rubber mallet. A friend recommended using some household ammonia, but I'm wondering if it will effect the chrome of the frame. Any suggestions?

JohnDThompson 11-21-11 01:59 PM

No worries.

fietsbob 11-21-11 02:06 PM

chrome plating will not dissolve in the cleaning.

kuje 11-21-11 03:27 PM

Thanks! Also, should I dissolve the ammonia, or just pour a capful straight in?

davidad 11-21-11 03:39 PM

http://www.sheldonbrown.com/brandt/stuck-stem.html

Booger1 11-21-11 04:04 PM

Just for the record,ammonia WILL eat chrome.....not instantly,but it will remove the chrome,the nickle and the copper.It actually attacks the nickle and copper and makes the chrome flake off.If you heat it up,it will take it off fast.

Coca-cola will eat chrome if you leave it long enough.

AEO 11-21-11 04:41 PM


Originally Posted by kuje (Post 13518371)
Thanks! Also, should I dissolve the ammonia, or just pour a capful straight in?

household ammonia should already be mixed with water.


Originally Posted by Booger1 (Post 13518536)
Just for the record,ammonia WILL eat chrome.....not instantly,but it will remove the chrome,the nickle and the copper.It actually attacks the nickle and copper and makes the chrome flake off.If you heat it up,it will take it off fast.

Coca-cola will eat chrome if you leave it long enough.

it should be fine for the purpose of removing an aluminum part, because aluminum is higher up on the reactivity series in comparison to nickel.

dsbrantjr 11-21-11 04:43 PM

kuje: A rubber mallet may not transmit enough energy to the bolt to break the wedge loose. Try giving it a good, solid blow with a steel hammer or, even better, a 2 pound hand sledge and make sure that the fork is firmly supported so that the power of the blow is directed into the stem bolt and wedge, not in moving the fork around. Repeated pounding will do no good if you don't hit it hard enough to break the wedge loose.

kuje 11-23-11 11:23 AM

Update: The ammonia was useless and ended up stripping off the clear coat. I am considering sawing off the stem, as much as I don't want to.

Bill in Houston 11-23-11 03:39 PM


Originally Posted by dsbrantjr (Post 13518715)
kuje: A rubber mallet may not transmit enough energy to the bolt to break the wedge loose. Try giving it a good, solid blow with a steel hammer or, even better, a 2 pound hand sledge and make sure that the fork is firmly supported so that the power of the blow is directed into the stem bolt and wedge, not in moving the fork around. Repeated pounding will do no good if you don't hit it hard enough to break the wedge loose.

This. A rubbet mallet will just make you tired.

AEO 11-23-11 05:13 PM


Originally Posted by kuje (Post 13525895)
Update: The ammonia was useless and ended up stripping off the clear coat. I am considering sawing off the stem, as much as I don't want to.

it's possible the stem has a steel expander.

DannoXYZ 11-24-11 01:32 AM

I like a 10-lb mini hand-sledge for a task like this.


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