Fixing Nikon 24-85 AFS VR autofocus hunting problem … by David HK November 2019

Fixing Nikon 24-85 AFS VR autofocus hunting problem … by David HK November 2019

I’ve dropped this lens twice in the past few months, the 1^st drop was at waist height, luckily the lens (attached to a D800 body) hit my wife’s toes first, the lens UV filter was broken.  2^nd drop was from my thighs while I was sitting on a park wood bench.  Since then, the autofocus will need to “hunt” around to get a focus when it is zoomed, and sometimes may not focus at all.

This lens is out of warranty, and the cost of repair will be expensive, likely to be at 2/3 the cost of the lens.  I’ve been ‘guessing’ the issue is mechanical, not electronic, as the drops likely have affected some moving parts rather than electronic parts. 

I researched and watched lots of Nikon lens repair videos, one video drew my attention, the lens is Nikon 18-105 DX, also autofocus problem, it shown the repair is to take out the autofocus module (with the SWM motor and gears intact), pressed all gears to make sure each gear is aligned and can be moved freely, then assembled back to the lens.

I suspected my lens problem is also to do with the autofocus module.  Before I start repair my lens, I need to learn how to take it apart down to the autofocus module.  Finally, a few days later YouTube recommended a complete teardown of 24-85 AFS VR, the video was from a lens repairer in Vietnam goes about cleaning the mold from each glass in the lens.  URL below.

Cleaning Nikon Lens 24-85 mm f/3.5-5.6G ED VR

I started from the mount of the lens, take out the mental mount, the back barrel, then the manual focus ring.  I need to loosen up a small electronic circuit board next to the autofocus motor before I can take out the autofocus module.  After taken out the module, I played around with the gears while the module is intact, then decided to disassemble the module in order to oil each gear.  I rub each gear with a drop of lubricate oil with my fingers, making sure each gear has been rubbed then used a cloth to remove any excess oil, as I don’t want any oil get spit into any glass element surface when the gears are spinning.

Put it all back together in reverse order. 

Now the lens autofocus is super instant, even at the zoomed end.  There you have it, I saved an expensive repair bill, put the lens back to working order, while enjoying the whole DIY fixing experience! 😊