|
Post by fuzzyruttin on May 4, 2019 17:16:20 GMT -5
Yesterday I posted in the conspiracy thread about my misadventures on Friday. While WOT and about 50 mph, the rear wheel locked up and it literally came to a screeching halt. Very very thankful there were no cars around me at that moment, and I kept the bike up. Man, serendipitously enough, I walked right across the street to the bar and had a beer! After taking the tranny apart just now, the first thing I noticed is the drain plug was missing. I just checked the tranny fluid level last weekend, and it was fine... did not re-torque the drain bolt. Anyway I figured there would be a broken tooth that bound the gears, but it turned out to be blown bearing to the transmission input shaft / clutch shaft / whatever you call it shaft. Questions to fellow forum comrades: Would you recommend replacing just the blown bearing, or do you suppose the others have been jeopardized as well? They feel snug. Personally I think I would leave them as-is, but wanted to get ya'll's feedback. There is no noticeable wear on the gears. What about the bearing seal(s), can they be re-used or are they demolished as a matter of bearing removal procedure? Obviously clean out all the metal flakes and other crud before reassembling everything. I've been liking partsforscooters... shipping prices don't screw you over on the inherently cheap stuff, and you get discount codes from affiliated forum member(s). A GY6 clutch shaft bearing seal looks readily available. But there's also a complete transmission bearing kit. Not sure which way to go, see previous question. Thanks
|
|
|
Post by fuzzyruttin on May 4, 2019 20:25:13 GMT -5
Also, though I am capable of tapping out bearing cases and finding my way as I go, is there a good diy on this? It's convenient to have a reference procedure rather than "reinventing the wheel."
|
|
|
Post by oldgeek on May 4, 2019 22:28:48 GMT -5
I dont think you will ever get all the metal out of the other bearings. Also since you ran without gear oil for a while, I would expect definite gear damage, whether you can see it or not. I ran my gearbox without gear oil once myself, it sucks! It damaged my cases because some gearboxes do not have a ball bearing for every location. They sometimes use a machined pocket that is actually cast in the cases. You should need a blind hole bearing slide hammer kit to get the bearings out. Using the hot/cold method should get them installed, or possibly a large C-clamp and some properly sized sockets to press them back in.
|
|
|
Post by fuzzyruttin on May 5, 2019 19:27:45 GMT -5
I dont think you will ever get all the metal out of the other bearings. Also since you ran without gear oil for a while, I would expect definite gear damage, whether you can see it or not. I ran my gearbox without gear oil once myself, it sucks! It damaged my cases because some gearboxes do not have a ball bearing for every location. They sometimes use a machined pocket that is actually cast in the cases. You should need a blind hole bearing slide hammer kit to get the bearings out. Using the hot/cold method should get them installed, or possibly a large C-clamp and some properly sized sockets to press them back in. Hammering got me absolutely nowhere in the fight to get the damaged bearing off the shaft. Decided to dremel a cross-cut on the outer bearing casing, then it came off in a cinch. I dremeled the inner casing as close as I could without scoring the shaft, then with one hit of a chisel, it snapped all the way through. It slid off the shaft with a few gentle taps after that. There was some pitting on the shaft, so apparently the inner bearing casing and the shaft slipped at the mating surface. That may have been the saving grace. I used the dremel grinding wheel to smooth out the rough parts, and sanded it smooth. Everything cleaned up really well with copious amounts of WD40 and break cleaner. There's no binding in any of the other bearings and they easily free-wheel. I think I'm just gonna replace the clutch shaft bearing and see how it turns out. I spent like an hour looking for a replacement gear box drain bolt. The local hardware store would certainly have something that fits, but sheesh. There's every part for a GY6 to be found but the gear box plug? This is the only one I could find ( jonway) from France. Can't imagine the shipping on that. Cover. Note shaft pitting. This was before I dremeled/sanded it smooth. You could eat out of the gearbox now:
|
|
|
Post by jackrides on May 5, 2019 19:39:31 GMT -5
Safety wire the drain plugs. Look at each every morning.
|
|
|
Post by oldgeek on May 5, 2019 20:12:50 GMT -5
From the pictures there looks to be contact damage on the primary shaft gear teeth. There appears to be blueing which would indicate the gears heated up and the heat traveled down into the primary bearing inner race. But pictures can be misleading.
I would stick a shaft in the other bearings and give them a spin by hand to check them. On my recent primary shaft bearing failure, the bearing on the stub of the primary shaft felt fine, but as soon as I put the primary shaft in it and gave it a spin, it was apparent that it was also damaged.
Either way you go, good luck!
|
|
|
Post by FrankenMech on May 19, 2019 1:12:12 GMT -5
Match up the thread diameter and pitch then look for a flange bolt. I would replace all the bearings. That input shaft and gear looks suspect.
|
|
|
Post by fuzzyruttin on May 21, 2019 17:37:30 GMT -5
Match up the thread diameter and pitch then look for a flange bolt. I would replace all the bearings. That input shaft and gear looks suspect.
partsforscooters hooked me up with a proper drain bolt. For what it's worth, my buttometer says I've run about 200 miles on the gearbox since having replaced only the shaft bearing. Everything seems fine as far as I can tell. Unfortunately my wrist torque is not calibrated for cast aluminum, and a couple of bolts spun. Damn. What's the best remedy - tap to same size, tap next size up, or thread lock repair inserts?
|
|
|
Post by FrankenMech on May 23, 2019 19:47:15 GMT -5
Inserts.
|
|
|
Post by GrumpyUnk on Jun 24, 2019 12:01:21 GMT -5
I have gone through this once. The input shaft bearing actually was in multiple pieces, with the separator for the balls in chunks within the CVT case and the gear case. I had to weld some 'nubs' onto the outer race as there was nothing I could whang on. All those little bits of broken metal were circulated by splash into every lubricated part of the gear case. Into the ball bearing races, in between the gear teeth, and place I cannot even think of to mention. I would have checked how smooth the bearings turned, with the expectation that any roughness would soon lead to further, more definite roughness. There's not much clearance between the two race surfaces and the balls that roll on them. When you feed in some bits of grit/steel/ground gears, there's not enough room, so something has to give. You either get a damaged sphere(ball) or a damaged race. Scarred races tend to bind more, and lead to more scarring. Not to say yours will fail, but inspection of each bearing for smooth operation would be a good idea. What did you do to the bearings that are installed into the cases? How did you check behind the bearings for grit/sludge/etc? Did you flush with brake cleaner or other solvent to (hopefully) wash out any contaminating metal or other bits? I could not be sure, even though the bearings seemed smooth, so I replaced them all. FOr the blind bearings, I melted candle wax into the blind area, and thumped on it with a shaft that fit snugly to generate pressure on the 'in' side that would drive the bearing out. It was a mess, but successful. New gasket and a couple new seals, and it actually worked better than several others with a lot less miles on them. One last thing is the other end of the input shaft. It looks as if it has not seen lubrication in a long time. It is rusty. You won't get rust if there is lube being splashed on as the gears rotate. Something amiss, and I have no idea. A second last thing would be to rotate the input shaft manually, using the clutch bell(belt removed) so you can feel how smooth the gears and bearings are moving inside the case. You can use the rear wheel if you want to see the input shaft spin at a good clip. You want to feel for any difficulty in rotating, as the effort should be smooth without change for about 11-12 turns of the input shaft. You have to turn that many times to get all the gears to go through one revolution. Any rough spots, and you can expect to have another failure in the future. tom
You asked for a 'howto', and I would note that there is a post onsite, and a video on youtube done by 90GTvert... he had a similar failure and had to replace just about everything. I do not have a link. tom
|
|