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Post by fuzzyruttin on Feb 4, 2019 19:32:08 GMT -5
You can usually buy bearings in any quantity, size, or configuration, from industrial supply warehouses in any large metro area. Even auto supply stores may have a few common sizes. Call around. I was more concerned about quality, whatever that might entail. Type of metal? Construction? I came across a couple reviews complaining that there was next to no lubrication, or it basically looked like vaseline. I don't intend to start tearing apart new bearings for quality inspections before installing them. And I wasn't sure if there were other basic factors to ensure a smooth ride or longevity, or just plain don't worry about it and go.
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Post by fuzzyruttin on Feb 4, 2019 19:54:51 GMT -5
If the outer races fit into the hub, and should be 'stopped' by a machined edge from being pressed into the hub past a specific point, then I would measure the distance between the ridge the outers will run into, and use that as the length of the spacer, plus some number of thousandths of an inch. IOW, the spacer would be a fraction longer than the distance between the two outer races. How much is a machinists decision. The extra few thou would keep from side loading the inner races, and would allow a slight clearance between the outer race and the ridge they would run into if pressed totally in place. YMMV. I did not measure either length when I did the replacement, figuring it should have been correct from the factory. I don't know how accurate a measurement you can get from one outer race 'stop' to the other, but having something close would be a lot better(for the bearings) than having nothing. The length measured should track with the assembled combination, on the original axle bolt, of bearing-spacer-bearing, measuring between the inner surface of the outer bearing races. tom I wasn't sure how I was going to go about it at first, but what I ended up doing is removing just one of the bearings so that the wheel was open on one side for taking measurements. Then cut off the threaded end of a 6" black pipe with 1/2" ID - bearing bore is 12mm, so that's just about right. Did as close of a measurement as I could without going too short on the spacer, cut it off, then dropped it into the wheel against the other bearing. It's pretty easy to tell if the spacer is flush at that point. With a couple more iterations, I got it to something just a hair longer than flush. (I read your suggestion after I did the work... we're on the same brainwave .) It turned out pretty good. If the axle nuts are really tightened down, there's a little resistant in wheel rotation. Back off less than 1/2 turn and it's good. By the way, since I don't have a lathe to make perfect 90 degree cuts, I used masking tape to mark as straight of a line as I could around the pipe where it was to be cut, and hand-dremeled as carefully as I could, then a little bit of flat filing across the entire end.
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Post by FrankenMech on Feb 5, 2019 4:41:48 GMT -5
The industrial supply outfits will have good quality bearings and good advice about lube etc.
It is late and my brain is dead but I think your bearing spacer is too short. Heat from operation will cause premature wear and possible seizure. The industrial supply outfits will have machinery shims.
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Post by 90GTVert on Feb 5, 2019 11:19:34 GMT -5
I have used everything from no-name Chinese bearings to SKF, NTN, FAG, etc... for front wheel bearings. Real world use; I can't really tell a difference. To be fair, I don't track mileage on them though. I just replace as-needed or if it seems like it's been a long time since I remember doing them occasionally, so if I were experiencing differences that aren't way off I'd likely never notice. That said, these days I tend to buy one of the big brands because it's really not something that I have to replace all of the time and the price difference isn't terrible that way. In something like the TMAX that is heavy and goes 100MPH, I'm not taking any chances and it will only get top brands. The 35MPH TaoTao, I'd still consider cheapo stuff, but prob end up with SKF or whatever. Wish I had more real data for you, but all I've got is .
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Post by snaker on Feb 5, 2019 15:45:24 GMT -5
I wasn't sure how I was going to go about it at first, but what I ended up doing is removing just one of the bearings so that the wheel was open on one side for taking measurements. Then cut off the threaded end of a 6" black pipe with 1/2" ID - bearing bore is 12mm, so that's just about right. Did as close of a measurement as I could without going too short on the spacer, cut it off, then dropped it into the wheel against the other bearing. It's pretty easy to tell if the spacer is flush at that point. With a couple more iterations, I got it to something just a hair longer than flush. (I read your suggestion after I did the work... we're on the same brainwave .) It turned out pretty good. If the axle nuts are really tightened down, there's a little resistant in wheel rotation. Back off less than 1/2 turn and it's good. By the way, since I don't have a lathe to make perfect 90 degree cuts, I used masking tape to mark as straight of a line as I could around the pipe where it was to be cut, and hand-dremeled as carefully as I could, then a little bit of flat filing across the entire end. .. Your description of running the nut tight and backing off a tad works for conventional automotive front wheel bearings on a rear wheel drive but is not appropriate on this type wheel. The nuts on these need to be very tight.I don't know if scooter mfg's give axle nut torque specs, on motorcycle's its 1/2" breaker bar tight (don't have any torque # off hand). These designs have several pieces "stacked" and clamped down by the axle nut. That would include the axle bolt head, washers, adapters, forks, bearing INNER races and the tube spacer. All of this is intended to be tight so that the bearings are at a very precise position, If the wheel binds up at the proper tightness, that means the tube spacer is too short and is allowing the bearing inner races to be pulled towards each other. Because the outer races positions are set, the bearings start to be stressed laterally.Loosening the nut relieves the stress on the bearing but it also loosens the "stack" which is supposed to be locking down on the bearing inner races to keep them from spinning. It also gives the nut the potential of spinning off the axle.If you insist on running the machine with the axle nut loose I hope that the nut is a lock nut at the least. You could safety wire the nut to keep it from coming off during riding for added security.
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Post by fuzzyruttin on Feb 5, 2019 17:31:05 GMT -5
Your description of running the nut tight and backing off a tad works for conventional automotive front wheel bearings on a rear wheel drive but is not appropriate on this type wheel. The nuts on these need to be very tight.I don't know if scooter mfg's give axle nut torque specs, on motorcycle's its 1/2" breaker bar tight (don't have any torque # off hand). These designs have several pieces "stacked" and clamped down by the axle nut. That would include the axle bolt head, washers, adapters, forks, bearing INNER races and the tube spacer. All of this is intended to be tight so that the bearings are at a very precise position, If the wheel binds up at the proper tightness, that means the tube spacer is too short and is allowing the bearing inner races to be pulled towards each other. Because the outer races positions are set, the bearings start to be stressed laterally.Loosening the nut relieves the stress on the bearing but it also loosens the "stack" which is supposed to be locking down on the bearing inner races to keep them from spinning. It also gives the nut the potential of spinning off the axle.If you insist on running the machine with the axle nut loose I hope that the nut is a lock nut at the least. You could safety wire the nut to keep it from coming off during riding for added security. Understood - the axle has built-in catch pins on both ends, and I used liberal amounts of red locktite. I went all last riding season like that with no spacer at all. It's good that I am able to tighten it further now, but based on recent feedback, perhaps it should be re-done to make the spacer longer... however, I also have to surmise that the ends are not perfectly 90 degree cuts, and when everything is tightened down, one or both bearings are getting tweaked. It sucks that I have to keep going through guys at work that I know have the necessary tools to get the job done right. In this particular case, it's trial-n-error because I do not know the exact length that will work, which complicates the handoff. I bought the pipe from Home Depot, and had them cut off one of the threaded ends, knowing that I'd have to free-hand the other. Well when they were done, it looked like a goat chewed it off, so I ended up dremeling both ends anyway.
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Post by snaker on Feb 5, 2019 18:24:55 GMT -5
Through the years I gathered up a couple coffee cans of various bearings. I would grab a old bearing as a installing helper. A light sanding/filing of the outer surface or the inner surface will leave the bearing amazingly loose to slide on a shaft or drop into a casing. Hardly any metal has to be removed but it has to be removed all the way around, no high spots. just remove the shine of the bearing surface.
The old bearing can be hammered on or put in a press and it protects the new bearing from impact oop's. Works great when a bearing has to get set deep into a casing. Set it with the old bearing on top and then simply let the old bearing fall out. It also helps square up the new bearing for easier install starting.
This would be a good time to do this for your project. You can repeatedly install and remove the old loose bearings to get the right fit for your tube spacer. Once you get the right fit then install the new bearings and save the old for the next project.
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