Help!!!! Fork inner surface not straight.

[bkaushansky]

History. Stripped a set of forks for shaving and powder. One went back together no problem. The other.... Well, the chrome shaft is binding about 4" short of bottom. No other parts installed. Tried a brake hone and got 1/2" more travel. Darn thing cuts so slowly.

Anyone have any ideas. I don't want to redo one fork.

Thanks.

 

[Airwolfie]

Try rolling it on a glass sheet or flat surface to see if its bent.

 

[bkaushansky]

What am I rolling? the lowers don't roll since the they aren't round at the bottom. The chrome upper is straight.

 

[Airwolfie]

I'd say the chrome upper. It may LOOK straight, it just needs a small bend and it will bind...

Try it, what have you got to lose? If anything, it will eliminate them being bent.

 

[TwoManyXS1Bs]

Coupla more ideas:

http://www.xs650.com/forum/showthread.php?t=1741
http://www.xs650.com/forum/showthread.php?t=27950

 

[wherearewe]

I'd say chrome stanchion is bent or bowed. Roll it on a sheet of glass like suggested.

I bet it's difficult to put back into the triples. You might also want to assess them for trueness.

 

[bkaushansky]

The chrome stanchion is straight!! Verified on flat surface and checked using the lowers on the other side. The brake honing tool got me within 2" of the bottom. Going to try a flap wheel. I used a marker to color the stanchion then looked for marks inside the tube. Seriously, its like there's a paper thickness in some spots thats causing the binding. Could it have been distortion during powder baking or the exterior polishing????

 

[Royboy]

Powder coating cures at about 400 degrees. Not all that hot but possibly enough to relieve internal stresses and lead to a minor out of round condition.

roy

 

[Xsbob]

I had almost exactly the same thing a couple of weeks ago, with the exception that the tube would go in 2" short of bottom.
Legs were powder coated but one was rubbish so had it redone. Am guessing they had to "burn" it off in the oven and it warped the leg slightly.
I got over it by carefully measuring where it started to bind, then wrapped some cloth and then some wet&dry paper around that on a length or threaded rod. Pushed rod in until got to right length and then spun it in my drill (with WD40 on paper)
It worked after a while and they are both ok now.
FYI both fork tubes are new.

Hope this helps.

 

[bkaushansky]

Thanks. Picked up some parts from the "depot". Drill extension and sanding drums.

 

[jd750ace]

Those temperatures are right in, or just beyond typical artificial age hardening temperatures for the majority of castable alloys. The artificial age hardening process is known for causing minor distortion (through internal stress relief) particularly in cast alloys, which are prone to irregularities that are usually caused by uneven mold temperatures, so yes, the powder coating process can, and does, induce dimensional change. You just happen to be dealing with a part with moderately snug tolerances. When a wheel gets done, nobody notices if it warps .004" but it regularly does.

 

[bkaushansky]

All fixed!!! Sanding drum on 18" bit extension. I marked the stanchions with machining dye and inserted until if was snug. Looked down the tube for touch point and slowly sanded material away. Followed up w/ cutting fluid and brake hone to get the surface completely smooth.

Now onto assembly....Why are race tech springs so short??? Now I need to make spacers.

-B.