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Old 11-11-2013, 05:25 PM   #76
thegraydog
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Quote:
Originally Posted by Gordy View Post
This is the first I have ever heard of "centering" wheel bearings to true up a wheel. The bearings should bottom into some kind of recess in the wheel, que no?

It maight have been done on some POS english bike back in the day, be we are talking about a modern bike.
Gordy, this is kinda what Mike Carlton said. It's not truing, so much as centering the hub in the forks so that the disc is aligned in the caliper.

I discovered this when I had the wheel off for a new tire, probably two years into the life of the bike. The bearings weren't exactly the same in the cups, so I put them so. Upon reassembly, the disc dragged in the caliper. By trial and error, I returned the bearings to the offset position, probably 1mm in on one side, out on the other, and have kept it that way.

This summer the bearings went wobbly and I replaced them. Possibly this is from rough treatment, but heck, five Ute Cups for twenty bucks in bearings...
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Old 11-12-2013, 07:34 AM   #77
motobene OP
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Quote:
Originally Posted by Gordy View Post
This is the first I have ever heard of "centering" wheel bearings to true up a wheel. The bearings should bottom into some kind of recess in the wheel, que no?

It maight have been done on some POS english bike back in the day, be we are talking about a modern bike.
Que si! The hubs are designed to have the internal spacer the same length as the space between the inner races when bearing outer races bottom against the counter bores in which they are pressed. That is why they have no snap rings. If a hub has no stops for the outer races, that is definitely NOT right and not a general characteristic of GasGas (AJP). If true on a bike it is a rare exception, not the rule.

Bearings are typically pounded out by their inner races. You have to cock the spacer to get at the inner race, then go around radially to knock out the bearing evenly. If done with many smaller taps (no brutally) and evenly to prevent the race from cocking and sticking, the races and balls typically won't Brinnell (dent).

But there's no reason to remove bearings if they are not really trashed. Just pop the seals off, spray them with brake cleaner to break up the grease, and use a air hose to blow out the crap. Re pack them solid and they'll last the life of the bike.

If you do have to replace them with new ones, you all should still pack them solid or they'll get water in them and eventually get rusty mud and degrade.
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Old 11-12-2013, 07:37 AM   #78
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Quote:
Originally Posted by thegraydog View Post
Gordy, this is kinda what Mike Carlton said. It's not truing, so much as centering the hub in the forks so that the disc is aligned in the caliper.

I discovered this when I had the wheel off for a new tire, probably two years into the life of the bike. The bearings weren't exactly the same in the cups, so I put them so. Upon reassembly, the disc dragged in the caliper. By trial and error, I returned the bearings to the offset position, probably 1mm in on one side, out on the other, and have kept it that way.

This summer the bearings went wobbly and I replaced them. Possibly this is from rough treatment, but heck, five Ute Cups for twenty bucks in bearings...
"Bearings not the same in the cups." Interesting! That could only be from a machining error on that particular hub where the bores were machined too deep on both sides! Possible, but rare.
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Old 11-13-2013, 09:15 AM   #79
StuInFH
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Quote:
Originally Posted by motobene View Post
Bearings are typically pounded out by their inner races. You have to cock the spacer to get at the inner race, then go around radially to knock out the bearing evenly. If done with many smaller taps (no brutally) and evenly to prevent the race from cocking and sticking, the races and balls typically won't Brinnell (dent).

But there's no reason to remove bearings if they are not really trashed. Just pop the seals off, spray them with brake cleaner to break up the grease, and use a air hose to blow out the crap. Re pack them solid and they'll last the life of the bike.

If you do have to replace them with new ones, you all should still pack them solid or they'll get water in them and eventually get rusty mud and degrade.
Repack them solid? Guess there is less chance of heat issues on a TB, but I've read several discussions re this on trials boards and heard from more than one gear/bearing specialist engineer that solid is too much. And certainly to not open up new bearings and fill them up. That the manufacturer does not pack them solid because they are trying to save costs, but rather they put in a lesser amount because it is the right amount, all things considered. What I heard, YMMV I am sure to hear.

And here's a tip for bearing removal (for the shade-tree mechanics among us) when you can't dislodge the delicate alloy spacer and there is no notch in it to get a proper purchase on the inner race; get the HF Blind Hole Bearing Removal Tool! It is only $50 and will pay for itself after only ten years of using chi-com bearings instead of real ones. :-)
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Old 11-13-2013, 10:25 AM   #80
lineaway
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Quote:
Originally Posted by StuInFH View Post
.

And here's a tip for bearing removal (for the shade-tree mechanics among us) when you can't dislodge the delicate alloy spacer and there is no notch in it to get a proper purchase on the inner race; get the HF Blind Hole Bearing Removal Tool! It is only $50 and will pay for itself after only ten years of using chi-com bearings instead of real ones. :-)
What, use the right tool for the job? Bought mine twenty years ago. Good money well spent.
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Old 11-13-2013, 10:59 AM   #81
laser17
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You mean im not supposed to use screwdrivers?
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Old 11-13-2013, 04:28 PM   #82
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Originally Posted by motobene View Post
But there's no reason to remove bearings if they are not really trashed.
I generally don't get around to it until the slop is driving me nuts, or the bearing feels crunchy and hard to turn. I suppose that the clean and repack would extend the life.

I have always cleaned and repacked my bicycle bearings. The older ones are loose bearings in adjustable cones and races. You pack those pretty full of grease. But, there are plenty of gaps for the grease to disperse if you overdo it.
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Old 11-14-2013, 08:10 AM   #83
mung
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MB- " and use air to blow out the crap".The problem I see with that is that you are not blowing out the crap,you are blowing IN the crap.You are blowing all the old grease and solvent into the inside of the hub [unless you have a way of getting inside the hub and blowing out]. If you have old grease and solvent washing around in there it will contaminate the new grease you put in the bearings.Unless you are blowing it through the bearing and out the other side of the hub? That would be tough to do with another bearing in the way. It seems then that there would be considerable contamination left in the bearings.So then you have not gained much.Any slop,noise or any other aberration is reason enough to change them-do you want to save 20 bucks on bearings and then ruin your hub?

mung screwed with this post 11-14-2013 at 08:20 AM
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Old 11-14-2013, 01:14 PM   #84
StuInFH
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Originally Posted by mung View Post
MB- " and use air to blow out the crap".The problem I see with that is that you are not blowing out the crap,you are blowing IN the crap.You are blowing all the old grease and solvent into the inside of the hub [unless you have a way of getting inside the hub and blowing out]. If you have old grease and solvent washing around in there it will contaminate the new grease you put in the bearings.Unless you are blowing it through the bearing and out the other side of the hub? That would be tough to do with another bearing in the way. It seems then that there would be considerable contamination left in the bearings.So then you have not gained much.Any slop,noise or any other aberration is reason enough to change them-do you want to save 20 bucks on bearings and then ruin your hub?

For me, the easy answer is to simply pop in a new chi-com bearing, at $1.67 each. With my new bearing puller making the job so easy, I will replace at first sign of water intrusion. I'll let you know if they trash my hub, but I am going to watch them closely for awhile.
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Old 11-18-2013, 09:41 AM   #85
motobene OP
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Regarding blowing crappy grease out of bearings, I assume you all are competent enough to figure out how to do that well.

I too used to assume RPM was a limiting factor to solid packing motor bearings and idler bearings on serpentine belts and other applications, nothing ever blew up, and I stopped replacing bearings on very high miles and hours machines. Problems with solid packing roller bearings in our real-world applications at modest rpms? Problems for me? Zero. Benefits, many.

It's been my experience that there is an endless supply of 'specialists' who will tell you can't do something or that you should do some very specific, narrow thing because, well, they are the experts. It has profited me greatly in life to question them and find out for myself.

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Old 11-18-2013, 01:28 PM   #86
mung
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Not real sure if it is about competency? Just asked what you did about the old grease and solvent that you blow into the hub and that is waiting to contaminate the new grease.You would need to pull a bearing to get in there and clean the old stuff out.Then you would need a new bearing anyway.That is and was my point.
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Old 11-19-2013, 05:35 AM   #87
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Originally Posted by mung View Post
Not real sure if it is about competency? Just asked what you did about the old grease and solvent that you blow into the hub and that is waiting to contaminate the new grease.You would need to pull a bearing to get in there and clean the old stuff out.Then you would need a new bearing anyway.That is and was my point.
I got your point. In making it you refuted what I said. Now I realize you were objecting based on your assumption that there is no inside seal on the wheel bearings. On the moderns there are... on all the bearings. Thus no blowing crap 'into the hub'... if the suggested trick is done competently.
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Old 11-19-2013, 04:00 PM   #88
StuInFH
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Quote:
Originally Posted by motobene View Post
Regarding blowing crappy grease out of bearings, I assume you all are competent enough to figure out how to do that well.

I too used to assume RPM was a limiting factor to solid packing motor bearings and idler bearings on serpentine belts and other applications, nothing ever blew up, and I stopped replacing bearings on very high miles and hours machines. Problems with solid packing roller bearings in our real-world applications at modest rpms? Problems for me? Zero. Benefits, many.

It's been my experience that there is an endless supply of 'specialists' who will tell you can't do something or that you should do some very specific, narrow thing because, well, they are the experts. It has profited me greatly in life to question them and find out for myself.
Good point. I was taught to fill them up 40 years ago, but if a current crop of specialists is telling me to save the time, effort, expense, and possible damage, I will stop doing that and see for myself if that will cause problems. :-)

It sure seems easier to change them out vs the cleaning mess for $1.67, even at my level of competency. ;-)
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Old 11-20-2013, 05:34 AM   #89
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Originally Posted by StuInFH View Post
Good point. I was taught to fill them up 40 years ago, but if a current crop of specialists is telling me to save the time, effort, expense, and possible damage, I will stop doing that and see for myself if that will cause problems. :-)

It sure seems easier to change them out vs the cleaning mess for $1.67, even at my level of competency. ;-)
Go for it.
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