Bent stancion tubes?

[skids]

I was doing a fork oil change yesterday and noticed something strange. The damper rod was not centered in the top of the right fork's stancion tube. I then rotated the tube in the slider and noticed that the top of the tube did not rotate in place. I checked out the the exposed length of the tube with a staright edge from the dust seal to the top, and it seemed to be about 3/16 inch from straight. (that is a lot)

I checked out the other tube and it was about 1/8 inch from straight. I am thinking that the bike was wrecked before I bought it. The previous owner said "it was never down as far as I know." I have put 18000 miles on it and hadn't noticed any steering or suspension issues. I think the only real way to check for servicable limit is to disassemble the darned forks and check runout on the bench. Am I wrong?

I turned the tubes in the tree so that they are aligned with the bike rather than left or right. At least that way the wheel wont lean as the forks compress.

Does this sound potentially disasterous? Anyone know where to get some good used forks? (2003 ABS)

 

[dwalby]

I have put 18000 miles on it and hadn't noticed any steering or suspension issues. Does this sound potentially disasterous?

I think you may have answered your own question, if it were potentially disasterous you probably would have noticed it by now. I rode a bike home from Idaho to SoCal with one fork leg bent so bad that the bars were probably at a 20 degree angle from where they normally are to compensate for the bend. Rode it a few more weeks like that then finally replaced the top tube to straighten it back out. The top tube isn't terribly expensive, if you take the forks apart and verify your suspicions about the tube being slightly tweaked are true you can probably just swap the top tube and be done with it. You may also want to replace the bushings as well while you're in there though.

Edit: I guess the top tubes are a bit more expensive than I thought, they're in the range of $250 each for the ST1100 forks, not sure what the 1300 would cost but it certainly wouldn't be any cheaper.

 

[woodybelle]

Tubes can be straightened. My neighbor straightened one for me with his hydraulic press. It sprung back some so he had to over bend some.

 

[skids]

Must be nice to have friendly neigbors like that!

 

[Art Franz]

I've straightened them out before, too. Get 3 pieces of hardwood, preferably about 4in square. Cut a notch along the length of the grain on each one. Lay the tube across 2 of the blocks ones using the notches as a saddle, positioned so that the high point of the bend is centred between the 2 blocks. The 3rd block is what you push down with in your hydraulic press. Use a straight-edge to gauge when you're straight. As one of the other posts mentioned, you will have to 'go past' straight as the metal has a memory in it. Whatever you do, do not use a hammer on this at anytime, as the shock waves from the impact will alter the memory of the metal, and you will never get it straight.

BTW I've got a straight one (has not been bent and then straightened) that you can have for $100 plus freight.

Edit: Caveat to all this - you can only straighten them if they're not bent too much. When they bend too far, they start to kink/the tube starts to flatten out, and you can't get them round anymore. That's also why you use wood as your saddles, not steel. Mic-measure them after you're done to make sure this has not happened, or else they won't work properly in the bushings, seals, etc.

 

[bdalameda]

I have straightened many fork tubes over the years. It is very important that a bent tube does not have a kink in it particularly right where the T-stem clamps to the tube. If there are any kinks or dents in the tube the tube should not be straightened and used.

Dan