[CR]Help with loose botton fork cup

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From: "Howard Darr" <hdarr@embarqmail.com>
To: "'Howard Darr'" <hdarr@embarqmail.com>, "'CR List (E-mail)'" <classicrendezvous@bikelist.org>
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Date: Mon, 6 Oct 2008 20:02:39 -0400
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Subject: [CR]Help with loose botton fork cup

Kinsman OH USA I want to thank everyone who sent me info on how to fix a loose bottom cup on a zeus.

I thought you might like to have for the archives the collective wisdom of the group on how to fix it.

1. I think there is a Loctite for this situation. We also used to use thin brass shim material. (I've had the same envelope of brass shim stock for like, 30 years, I think) In a pinch, aluminum cans. 2. Had this problem while working in a bike shop a couple of time. We just would use a sharp punch and work around the outer side of the cup setting a couple of punch holes on the cup- This will lead to material coming up next to the punch hole (imagine rifles) and at most times the cup can be installed without falling out again. Works also on the steerer tube where the lower ring goes if that would be loose. Obviously you don't want to harm the paint by messing with the head tube. 3. Loctite has various products that might work including the common 271(Red) Thread locker, but the Loctite 660 Quick Metal Retaining Compound is probably the correct stuff to use. Google for info. It should be available at any decent size auto parts store that carries their products. 4. It might be easier to punch the inside of the bottom part of the head tube where the cup inserts - it's softer steel. 5. a. Clamp your frameset by the SEAT POST -- NOT seat tube into the bike stand. b. Remove the fork and lower cup. c. Rotate the frame in the stand 180 degrees so that you can work with the area where the lower cup is to be fitted. d. Get a sharp, pointy drift punch and ball-peen hammer. e. Place the drift inside the lower head tube where the lower cup contacts the surface. Strike the drift and then move it to another location nearby and do it again. Continue doing this until you have gone all the way around the area (a circle) where the lower cup will fit. What you are doing is reshaping the metal in the head tube so that it is now protruding into the area where the lower cup goes. When I perform the aforementioned procedure I use the lower cup itself to gauge the grip. When it gets to the point where I absolutely cannot push it in by hand, I know I am ready to press it in. I will sometimes add a couple of drops of red loctite to the inner part of the frame as an added security measure. 6. Brass shimstock and Loctite BlueCut shimstock so it does NOT overlap, a tiny gap is OK. Use thickness that fills the gap as a hand press fit. 7. Was probably ridden with a loose headset. Suggested fixes which have all worked for me. After facing the head tube I have...

* used a shim made out of a diet Coke can (1/2x1'') place this on the cup and slide cup in, use your HS tool to finish installation * use Locktite Green bearing mount (I would use the stick version not the liquid)twisting until it sets * Epoxy ,clean surfaces put epoxy around cup and then press in, twist until it sets * use a chisel and raise cup material around edge (if you have a lathe and knurler that would even be better) 8. Take baby steps... 9. hopefully the frame is not stretched, I would locate a guy with a lathe and a knurling tool. chuck up the cup, and knurl the extension that presses into the frame. shims might work, but more of a chance of misalignment.

Howard Darr
Kinsman OH USA