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Cleaning Threads on Rear Derailer Hanger

846 views 10 replies 7 participants last post by  helexia23 
#1 ·
I've got a bike that has been powdercoated and the threads in the rear hanger are pretty clogged up. I tried to install the rear der. last night but could not get it started smoothly so I backed off.

I've been thinking that I need a set of taps and this is the perfect excuse to buy some.

I understand the appropriate tap for the hanger is a 10x1mm metric.

Anybody have any advice on the job. I am planning on just starting from the back of the hanger and working my way forward making sure the threads are clean.

Also, anybody have any advice on what tap set to buy. I'll likely just buy craftsman brand from Sears after work. Looking at these:

http://www.sears.com/shc/s/p_10153_12605_00952383000P?keyword=metric+tap

Thanks in advance,

LP
 
#4 ·
McMaster-Carr will have what you need (might even get your head spinning trying to decide which one you want). Could be a bit pricey for a single tap, though...

If you decide the cost is too steep for the real thing, you might be able to fabricate a tap that is good enough to chase the threads if all that is in there is paint...take a bolt of the proper size, file a small groove across the threads (perpendicular to the threads, along the shaft of the bolt). Use the smallest triangular file you can find, and make sure it is sharp. If you file two grooves on opposite sides, you can try to chase the threads and clear out the paint by using the modified bolt like you would a tap..turn it 1/4 turn, back it out, blow it clean, turn it in 1/4 turn further, back it out, clean it, repeat until you are all the way through. I would not try to chase damaged threads this way but you might be able to clean up paint overspray.

I've cut threads in wooden parts this way (works great) but I don't know how hard the powdercoating is and whether the cutting edge of the bolt (where you filed the notch) is hard enough to scrape it away. Would not hurt to try, as long as you were careful to not leave any burrs on the bolt that could damage the threads.
 
#6 ·
lanpope said:
DMW - Thanks for the tip, that trick seems like it would work.

Found a specialty shop in town that stocks the taps. Going to pick up a few bike specific sizes after work. Will update with progress...

LP
10x1 is the only "bike specific" size you'll need, most other fastenings on a bike are standard metric-fine (with the exception of BB and pedal threads)

Park make a 10x1 tap, biketoolsetc.com will stock it or any decent engineering supplies shop will be able to get a non-Park one. As long as you use a decent amount of cutting fluid and use the tap correctly (ie: 1/4 turn forward, 1/2 turn back) it should last forever, especially if you're just cleaning threads not cutting them.

10x1 is also used on Shimano (and a lot of other brands) rear hub axle.
 
#7 ·
Yep - I was able to source them locally.

Got a 10x1mm, a 6x1mm, and a 5x0.8mm for the water bottle and rack bosses, along with a nice little tap wrench and some cutting fluid.

The job on the rear der went smoothly with no problems and I was able to thread the der right in.

Cleaned out all the rack mounts and the bottle mounts too. The bolts go in amazingly smoothly when all that extra pc is gone.

Fun project. Thanks for the tips guys.

LP
 
#10 ·
helexia23 said:
Harbor Freight has sets for cheap. Yes, you get what you pay for but how many times will you actually use it. You can get a 40 piece set for $12 and even if you use it 4 times you'll have gotten your money's worth.
I'm sure those taps are fine for what he'd need them for, but the size he needed isn't included in those sets. 10x1 is not a typical size found in most kits.
 
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