Abnormal damping rod piston ring wear.

Joined
Mar 2, 2016
Messages
114
Location
Silicon Valley
I tore my front forks down to replace a leaking right fork seal. After removing the Springs, I measured the fork oil level height in each Fork, and the right side was 2 or 3 cm lower than the left, nothing drastic. When I examined the damper Rod piston ring for the right side, I noticed that the piston ring was worn down nearly to the wear grooves, and the wear was visibly non- concentric. The piston ring for the left Fork looked Nearly New, and the thickness all the way around was 2.05 mm. In contrast, the wear on the right piston ring measured 1.9 mm at the ends where it splits, and down to 1.3 mm at its thinnest just to one side of the wear indicator grooves. I purchased the bike with 5000 miles, the bike has only 10,000 miles on it now, and I was not expecting to need to replace bushings and rings at this mileage. I really dont think a slightly lower oil level in The Right Fork wouldn't contribute to this drastic wear, and and when I had the front apart to install Ricor's (since removed), I made sure that the forks were aligned by pushing the entire wheel and Fork assembly all the way up with the Fasteners loose, and then following the proper tightening sequence, and then checking for binding in fork travel. Does anybody have any suggestions on what could be causing one side to wear drastically compared to the other? All the other bushings with the Teflon Coatings look evenly worn between sides.
 

DirtFlier

Site Supporter
Joined
Dec 13, 2010
Messages
3,332
Location
Troy, OH
Bike
2010 Silver NT700V/ABS
It sounds as if the damper rod might have been mismanufactured? If you could spin it in a holding fixture, such as a lathe, you could check runout at the piston end. I recall buying a set of damper rods for the NT and was pleasantly shocked at the very low price.

ps. I just looked up the price for the damper rod (no ring) at <cheapcycleparts> and it was only $19.85. :smile:
 
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OP
OP
Turbo DV8
Joined
Mar 2, 2016
Messages
114
Location
Silicon Valley
I just tried measuring the run out of both damping rods, but my setup does not allow results consistent enough to come to a reliable conclusion. I'm just going to swap the damper rods right to left, button it up with new rings and bushings, make a note of it and check it again in about ten thousand miles. If the wear problem has switched sides, then I will just go ahead and get a new damper Rod. The reason I'm not doing it now, is multifaceted... The bike has been up precariously on stilts with no front end for a week, and a new damper Rod would mean another week. I live in earthquake country, and I have never gambled a dollar in my life! The other reason is, all those damping holes I need to drill out and chamfer by hand for the Race Tech gold valve emulators.
 
Last edited:
OP
OP
Turbo DV8
Joined
Mar 2, 2016
Messages
114
Location
Silicon Valley
I decided not to switch the suspect damper Rod to the other side. I noticed ridges on the outside of the fork tube which I could faintly feel with a fingernail. This may have been what caused the fork seal to leak in the first place, or maybe not. In the end, if I don't sell the bike first, it looks like I'll end up having to drop 3 G's for a new Right Fork. And all for a manufacturing defect in one of the components, because no fork with 10,000 miles should show this kind of wear. Made in Thailand strikes again!.
 
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