Removing Montesa 315 Rear Wheel Bearings

[donmurray]

How to remove rear, or front, wheel bearings? The spacer between the bearings has a slightly smaller ID than the bearing. Can heating the hub and driving this ridge with a brass drift get the bearing out?

[bob abell]

I use a short length of 20mm ground shaft, this fits the bearing and will press on the end of the spacer. Tap the lower bearing out, remove spacer, flip the wheel over and tap out the other bearing. Pop the inner seal out of your new 6004-2RS bearing, fill with grease and replace the seal. Use a large socket (size of the OD of the bearing) and tap in one bearing, flip the wheel, replace spacer and carefully tap in the other bearing. I also have a short length of pipe, about 60mm diameter that I put on the bench below the hub when tapping out the bearing.

I wouldn't drive the edge of the spacer with a punch as you are sure to damage it.

I did a front wheel bearing change mid-trial last year, 15 minutes including a sandwich....and yes I should have checked it before the trial.

[essex boy]

I have used a deep socket that fits into the centre of the bearing to tap out

the spacer and bearing

[brian r]

Hey Bob, next time I'll hold that sandwich for ya.

[donmurray]

I use a short length of 20mm ground shaft, this fits the bearing and will press on the end of the spacer.  Tap the lower bearing out, remove spacer,  flip the wheel over and tap out the other bearing.  Pop the inner seal out of your new 6004-2RS bearing, fill with grease and replace the seal.

Why do I need to remove the seal and pack a new bearing? Don't new bearings with seals both sides already have grease?

[alan bechard]

Because the bearings used are "off the shelf" or "Catalog Items" geared for general use, and these bearings in particular are rated for high speed use in the electric motor industry. Therefore, if you pull the side cover off of one, you will find that the bearing is roughly half full of grease and there is a considerable amount of air space in there. This allows for the grease to flow and fully lubricate the balls at the high speeds these bearings were designed to operate at. Also, by having the correct amount of grease in there, at the high speeds, the balls will roll around in the track and not slide through the track.

Now, on your bike, the bearings never turn any where near high speed (3600 rpm ) I have never done the math, but they just do not spin that fast. And as you take out your old ones, I would bet that it will be obvious that what did the old bearings in was a combination of dirt and water that intruded into the sealed area of the bearing. Sometimes folks even used the sealed one sided bearings and put the open faces towards each other.

Anyway, by pulling the seals, clean out the old grease (eliminating any possibility of grease problems from dissemelar thickening agents) and then fully greasing the bearings and popping the seals back in, you have made it so that the water has no where to go inside the bearings. If you speak with the bearing industry folks, or the grease folks, they will tell you that this is not proper procedure because the balls will probably slide in the grooves rather than roll, but again, look at what is the primary cause of failure in our application, and that is water and dirt intrusion. Anything that can be done to prevent that surely puts us a step ahead.

Several very well respected folks reccomend using a combination of Antisieze and grease as the lubricant. I personally do not do this as I believe the likely hood of incompatible thickeners is too great and you could potentially degrade the product that you are trying to improve.

Hope that makes sense.

I just had the opportunity to visit the testing and verification section of FAG / INA bearings in Germany and speak with the lead engineer there at length about this question, as well as a couple of other motorcycle specific questions. It was facsinating too me to see the testing and development stuff that they do there.

As a side note, RYP has an excellent set of drivers available for this task.

[charliechitlins]

Al!

I'd love to talk to a serious bearing engineer about the dreaded, mythical bearing skid.

I have been told by an engineer from a well-known American motor company that you can't use super-slippery additives on bikes with needle bearings because they skid.

I wonder if the same would be true for our newest synthetic lubes.

My gut feeling is, skid or no skid, less friction is best.

I could be wrong...again.

[alan bechard]

He was a lot less concerned with the lubricant than I ever imagined. They spec grades etc. but not type or brand. They review some folks choices, and run tests to verify, but where not nearly as concerned with it as I would have thought.

He did agree wholeheartedly though, that water and dirt intrusion where far greater concerns than any of the other maladies and that in our application overpacking would be the best way to go.