Shimmy, Shimmy Shake – Servicing Your Neck Bearings

Published In The June 2015 Issue Of Cycle Source

Article By: Daniel Donley At Pandemonium Custom Choppers www.pandemoniumc2.com

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A service point that is commonly overlooked, is servicing your neck bearings. The reason it is often overlooked is they gradually fail over time and by human nature you just adapt to how they are and don’t realize how bad until they are replaced. It’s very common for people to blame the front tire being worn, or they have a shake or shimmy that is in the front end of the bike when about 95 percent of the time is it actually the neck bearings. Bikes with springer front ends will wear out neck bearings a lot faster. Springer front ends are known to be hard on neck bearings. On acceleration or deceleration between 30mph and 40 mph you will notice a shake or a shimmy more than likely it is your neck bearings. So for this month’s tech I am going to show you a few things to look for and a few tricks to installing and adjusting these neck bearings. So let’s tear into it….. Once you have your front end disassembled and you have your bearings and races removed you will want to inspect them.

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What you are looking for in the bearing races are marks, galling etc. If there is ANY they are bad and need replaced.

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On the bearings you will want to look at the bearing rollers to look for any galling or any types of marks, if there are any in either one then they need to be replaced. As you can see in the photos the race is totally shot and the bearing is iffy so we are replacing them.

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If the bearing and races are good go to the parts washer and clean them both up and repack them and reassemble them. Always clean and repack with new grease.

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When replacing neck bearings a good source is All Balls Racing bearings. The quality is great and the price is right.

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This is a Stock Neck all cleaned up and ready to install the fresh bearings and races. But… Let’s wait a minute I have a little trick to show you here.

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Ok, I am going to show you a little trick here with a stock neck. To make it easier to get the race out next time. With a die grinder and a burr bit grind a little pocket under the bearing race seat. The reason I do this is for the next time I go to change out neck bearings they won’t be so hard to get out. What this does is it gives you room to be able to get a punch up in there and pop it out. This is a cool little trick. Since we all love to build and work on our bikes this is something that helps with making them service friendly.

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When installing neck bearing races I only use either a brass hammer or a brass punch to install them. So I don’t mar up the bearing races. This works just great.

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Just to show you real quick how nice it will work with the little pocket you cut in for next time.

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Get everything cleaned up and ready to reassemble.

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Be sure to use a good quality water resistant grease when packing bearings. Lucas and Dow Corning make good quality products that last.

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OK, when packing bearings something that a lot of people misunderstand is that you need to really PACK the bearings with grease you don’t just put grease on them. So, you ask how do you do that? Take a good dollop of grease like you see in the palm of my hand, then you take the bearing in between your fingers and thumb while doing this you want to pull the inner part of the bearing so it moves, then with a motion of pushing the bearing into the grease and pulling toward you pack the bearing until you see grease coming out of the other side of it. Just like you see in the picture. You keep moving and rotating the bearing until you have grease coming out all the way around.

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Now you just packed the inner bearing, so take the bearing and lather up the outside of it with grease also.

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The race also needs grease and be generous here.

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So you have both bearings packed and greased and everything ready to reassemble. Install the greased bearing into lower triple tree first, then insert the lower triple tree into the neck and then the upper bearing.

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Next you install the dust cap and the bearing tension nut. You LIGHTLY snug this. Then what you will do is work the triple tree back and forth and side to side to feel the amount of the tension on the bearings. You want to tighten the tension nut until you feel resistance on the triple tree when moving it side to side. What you need to remember here is yes it may feel like too much tension but when you put it all back together with the front end it isn’t going to be as much as you think. With this tension this is a good place to start for proper neck bearing adjustment. So….Here is a little story for ya. Back when I first started wrenchin’ I was setting neck bearing tension by doing the fall away test per the manual. When an “Ol’ Timer” stopped by and asked me what the hell I was doing and I said I was adjusting neck bearings. He said “You can’t follow that book”! You get that thing put back together and I will show you how to do it. He said get on the bike, take it down the road and get into 3rd gear, take it up to 40mph, when you get to 40mph let off the throttle completely and take your hands off the handle bars. Let the bike decelerate to 30mph with your hands off the handle bars. Come back and tell me what happens. So I did this and I came back and told the “Ol’ Timer” that the front end started shakin’ like hell at about 35mph. He said ok so now take that bearing tension nut and tighten it up one notch and go do the 40mph de-cell again, So I did and came back again… He said well…. I said it shook again but not nearly as bad but still right at about 35. He said tighten it up one more notch. So I did and when I came back and told him it fixed it. It didn’t shimmy or shake at all. The Ol’Timer said now…. “You have proper real world bearing tension”. He then told me “Son, sometimes you gotta listen to the motorcycle, they tell you what they want. You can’t always rely on books they don’t always work”…. So if you have any questions about this month’s tech feel free to give me a call at the shop. 419-576-6812 info@ pandemoniumc2.com

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