sort of solved - Sloppy Rear Wheel By trailheadmike (Read 1,856 times)

[trailheadmike]

This is a follow up to this thread: thescooterprofessor.proboards.com/thread/2213?page=1

A few months ago the board helped me diagnose a bad bearing as the reason why I had lost my rear axel nut and along with it the short spacer. I replaced the bearing, the short spacer and the nut and all was fine. The twisting-upon-acceleration-and-deceleration symptom that caused me to discover the problem in the first place was gone and the nut was and has been fine since.

Then I began to feel the same twisting-upon-acceleration-and-deceleration again, and upon further inspection I saw that although all pieces were in place my rear wheel was wobbly again.

The sequence of parts here is the wheel, the long spacer shaft, and then the swing arm, and on the inside of the swing arm (on the side of the swingarm facing the wheel) is a 25x40x8 seal. On the outside of the swingarm is the short spacer and then the nut.

I took the wheel off and inspected the parts and concluded that the wheel was probably snug last time because the long spacer shaft had probably been sitting on top of the seal on the inside of the swingarm. The spacer shaft now went into the center of the seal and rested on the bearing probably like it was supposed to, resulting in 8mm too much extra space. I had an extra seal, so I put it between the wheel and the spacer shaft to take up the space (which, again, I'm thinking was essentially the width of the seal). This kept it snug until it didn’t, and I see that the seal I was using as a spacer got mashed and isn’t spacing properly anymore.

My thought now is to get a 20x45x8 steel washer and epoxy it onto the end of the spacer shaft that presses on the wheel to take up the space. Finding the right washer is a task in itself, but I did locate one (but the wrong thickness) from a farm supply shop! I'm thinking I can get two or three thinner ones and stack them.

Before I start epoxying anything I was hoping you guys could offer any insight into whether you think this is the way to go or whether you think there might be a better course to follow. Thanks in advance, and wishing all a very healthy and happy new year!!

[JR]

Mike the spacer shaft goes right to the bearing itself. The seal surrounds the shaft. The only reason it has this seal to begin with is just to help keep extra dust and water out because the bearing is a sealed to begin with.

The outside seal is the same, fits tightly on the short outside spacer.

As you can see the seal is only a dust cover and should never be in between the spacers and the bearing. The spacer shafts bolt up tightly to each side of the bearing, the center shaft part of the bearing not the seal. The ID of the seal should be a hair smaller than the OD of the shaft and fit on snuggly.

In one picture when I do a tire change I take a thin bladed knife and pop out the seal cover on the bearing being careful not to damage it and then pack the bearing with quality bearing grease and then re-insert the seal.

Put it back together and tighten the outside nut well.

JR

[trailheadmike]

JR - thanks for the reply, but perhaps I'm not using the right terms because I think I've done what you've said.

Here is the drawing for this area. roketa.com/product/parts_detail.jsp?partId=30732&partName=ENGINE The bearing I have (#36 in the drawing) is a sealed bearing. I inserted the 20x45x8 seal in the recess that exists on the wheel side of the swing arm even though that seal is not in the picture. I reinstalled the larger dust seal (#35) on the nut side of the the bearing and put back in the short spacer (#37) and the nut (#38).

The long spacer that goes on the axle (#33) goes snugly into the 20x45x8 seal and comes to rest on the inside of the bearing like it should, so I don't think that seal is not interfering with anything. Even so, the wheel is sloppy after i tighten everything up BUT was snug when I stuck another 20x45x8 seal on the other end of the axle between long spacer (#33) and the wheel itself. The only purpose of this second seal was to take up space and it seemed to work for a while.

So I think I've already done what you said but the wheel still became loose. Perhaps I'm just not tightening the nut enough. I suppose the bigger question is where did the extra 8mm of space come from that I'm trying to fill?

[richardthescooter3]

Hi trailheadmike,
When the wheel and tire pushed back and tighten, can you move the tire in and out or do you notice it as your ride

[trailheadmike]

Hi Richard. The wheel is "wobbly" from side to side. there is no front to back play. The splines on the wheel and the axle both look to be in good shape. It's definitively a result too much space on the axel - I guess why that would be is the root of the problem.

I have read threads saying to look for a loose motor mount but that is definitely not what this is here. thanks.

[tvnacman]

Mike could the spacer that was lost be different then the one you replaced it with , or notched to go under the seal . Maybe you installed the corrects pacer backwards . The notched side to the wheel . Maybe the bearing in the swing arm needs to pushed in some more towards the wheel ?

Make sense ?

John

[trailheadmike]

Hi John. That might make sense if it was someone other than you who helped me replace the bearing!! The bearing went in fine and the ring clip opening was right where it needed to be so I think it's in right. The replacement short spacer and nut were ordered straight from Roketa per the drawing and fit perfectly so I don't think that's it either. All the pieces from the drawings are there so I'm stumped.

It seems awfully coincidental that the gap is the thickness of the seal, so the only thing I can think of is that something else was covering the recess where I now have that seal the made the long spacer sit on top of that and not on the bearing. I wish I took pics of the dis-assembly then but I didn't and tossed the old pieces at the time of the repair.

This all started when I ruined my rear rim on a huge pothole so I suppose I can also check the width along the axle on the replacement rim I have now compared to the original which is still in my garage. It was a rim from another parted out Vog so it did not occur to me that it would be any different from the original.

[tvnacman]

will the drive shaft move in and out (inner bearing play) .

when I did my drum to disk conversion the spacer between the wheel and swingarm bearing was short I just put a few stainless steel washers in between the wheel and the spacer to push it out some .

John

[JR]

The only purpose of this second seal was to take up space and it seemed to work for a while.

Wrong, the only purpose of the outside seal is to keep dust and moisture out. This seal is not a load bearing type seal.

The outside spacer should stick out just enough that when the nut is fully tightened the nut will NOT ride upon the seal. If it does then Roketa sent you a spacer that was too thin. I would consider making one myself, have one custom made at a machine shop or put a thin washer on the outside to take up the slack.

JR

[trailheadmike]

And I guess we're back to where I started - I need something to take up the extra space. The small spacer from Roketa rides on the bearing and just a tiny bit of the axle protrudes when the nut is tightened so it appears they sent the right size. Nothing is touching the outside seal that should be there or the inside seal that I put in. The seal that i put in as a spacer failed just like JR predicted it would. I'm going to go with my original idea I guess (and suggested by John as well) to put in some stainless washers by the wheel to take up the phantom 8mm. Thanks for the suggestions one and all.

[richardthescooter3]

Keep us updated (Good Luck).

[trailheadmike]

I ordered a washer the same dimensions as the inner ring on the axle bearing and that did the trick. no more wobble. When inspecting the rear wheel when I took it off, however, it looks like the wobble took a toll on the splines. The axle splines are fine, but the splines inside the wheel are noticeably worn down. I assume that the wobble allowed movement to wear them down, but who knows - maybe the wobble was ultimately caused by worn splines. It rides fine now with the wobble gone, so I guess I'll just put another replacement wheel (it'll be the second replacement) on the list. Thanks again all for your suggestions.

[tvnacman]

Mike I hope you cote the shaft with grease .

John

[trailheadmike]

REally? I thought they used to say no grease on Scootdawg. I did not not grease it and it does not look like it was ever greased. I am going to start crying if I have to pull that rear wheel one more time. Will do, thanks.

[JR]

Mike, "always" put grease on the rear axle spline.

JR