87 ninja 750 axle trouble, help - Sportbike Forum: Sportbike Motorcycle Forums
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post #1 of 17 (permalink) Old 07-21-2004, 07:46 PM Thread Starter
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Unhappy 87 ninja 750 axle trouble, help

Ive got an 87 ninja 750R. great bike, i love it, but for some reason the rear wheel is eating bearings on the right side (brake side). Ive swapped wheels, replaced bearings, axle, and spacers, but it just ate its 4th one tonight. the one on the left side runs fine. any suggestions?
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post #2 of 17 (permalink) Old 07-22-2004, 01:29 AM
 
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Is the rear brake dragging and cooking the bearing?

is the hole for the bearing out of round and cocking the bearing and putting uneven loads on it?

Did you ever replace the left one; if not then maybe the instalation process you are using is damaging the right one that you have replaced? You have to be VERY careful to only place force on the outer race when driving the bearing into the hole.

Are you using the correct torque and spacers on the rear axle assembly?

Did you do the replacements or a dealer? You may want to compare ALL the pieces of the axle assembly to the parts list at Kawasaki's web site to see if you have all the right spacers AND washers if there are supposed to be any.

Is it a sealed bearing (I would expect) or open ball type. If it's open ball you need to grease it very well and regularly.

Sorry no more specific help but those are things that popped up in my mind as reasons the bike would do this. I would be 99% sure that you are damaging the bearing during insertion or there is some kind of side load being placed on the bearing which comes from any of the above issues.

Also, what makes you thing the bearing failed?? Rough to turn?

Grant
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post #3 of 17 (permalink) Old 07-22-2004, 03:02 AM
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True about driving the bearing on the outer race only. Sometimes the old bearing can be used as a driver because the seal land is a larger OD than the bearing and therefore the new bearing will bottom before catching the old bearing being used as a driver.

Also, get a manual with a blow up view of all of the spacers and washers or ask your dealer to allow you to look at the parts blow up view and make sure every washer, spacer, etc. is there. A missing spacer between the bearings in the hub or between the cush drive bearing and left wheel bearing will jack some wild side loads on the bearing that it was never meant to see. The rapid failure makes me think that's where you'll find the problem.

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post #4 of 17 (permalink) Old 07-22-2004, 03:57 AM
 
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I copied the diagram from www.kawasaki.com, we'll see if it will transfer to this site.
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post #5 of 17 (permalink) Old 07-22-2004, 04:00 AM
 
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That was too easy. Hope it helps.

If you need part names to go with it go to

www.kawasaki.com

Vehicle info

search for 750cc and 1987 and you get your ninja and a vulcan as options.

The pic, parts #'s, and part names are listed in a separate window below the diagram.
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post #6 of 17 (permalink) Old 07-22-2004, 09:34 AM Thread Starter
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yes, im using a dealer manual and the parts diagrams at buykawasaki.com and have replaced both bearings in the wheel. the race looks to be in exelent shape. But about the brake maybe cooking the bearing? I hadn't thought of that. also because i really don't know beans about bikes or brakes. anyways, so far i have replaced all the spacers and bearings in the rear wheel, a new axle, but havent messed with the brakes at all. guess ill buy all new bearings this week and try again.

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post #7 of 17 (permalink) Old 07-22-2004, 02:33 PM
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Again, nothing specific about your bike but is it possible that somebody replaced the wheel as an assembly from another year that fit, but the parts details are different? Maybe a different length spacer for example? Probably a reach but not impossible. There's something fundamantally wrong to be having this trouble.

Really striking the bearing hard on the inner race could do this, as already mentioned. If it were the rear brake, you would have glowing rotors, strong brake smell, and other really evident brake problems to transfer that much heat to the hub so I wouldn't expect that to be the trouble. If this try doesn't fix it, I'd have a competant mechanic look at it. His trained and accustomed eye may see things we haven't thought of. Good luck.

Edit add:
Are you sure that the spacer identified as #92049A in the parts blow up, located in the sprocket hub picture, is there? That's one that will allow for a bad side load on the brake side wheel bearing and the bearing in the cush drive. The chain side wheel bearing in the wheel will not be badly loaded in this scenario so will probably still be good.

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Last edited by Dad; 07-22-2004 at 02:41 PM.
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post #8 of 17 (permalink) Old 07-22-2004, 06:12 PM Thread Starter
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Quote:
Originally posted by Dad
Edit add:
Are you sure that the spacer identified as #92049A in the parts blow up, located in the sprocket hub picture, is there? That's one that will allow for a bad side load on the brake side wheel bearing and the bearing in the cush drive. The chain side wheel bearing in the wheel will not be badly loaded in this scenario so will probably still be good.
actually, the parts labeled 92049 and 92049A are rubber oil seals that just sort of slip on outside the bearings. so far iv'e replaced all spacers, both bearings, axle, sprocket, and a new wheel. so unless i take it to a mechanic, im fresh out of ideas

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post #9 of 17 (permalink) Old 07-23-2004, 12:04 AM
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Quote:
Originally posted by Mr.E
actually, the parts labeled 92049 and 92049A are rubber oil seals that just sort of slip on outside the bearings. so far iv'e replaced all spacers, both bearings, axle, sprocket, and a new wheel. so unless i take it to a mechanic, im fresh out of ideas
It is hard to tell from the pictures, sorry. The point is though, a typical wheel assembly has a spacer that spaces between the bearing in the cush drive and the bearing in the hub. It also acts as the sleeve that the seal rides on, sealing that part. That's the piece I'm referring to and maybe shows up as #42036. Looking at the picture, that makes more sense as it is usually shouldered to fit inside the bearing, acting as a reducing sleeve to fit the ID of the cush drive bearing to the OD of the axle. If that piece is missing, tightening the axle puts the full force of the axle's tension through the bearing instead of just clamping all of the inner races together. That is the most likely scenario to wipe out bearings as rapidly as you describe.

You might also find some bright fresh rubbing marks in the metal body somewhere on the cush drive fingers, outer hub, or inner hub near the bearing with the equivelent marks inside the pocket where that assembly sits in the wheel. That would be the contact marks where the cush drive is bottoming out against the wheel, which it should not do.

If you take a minute to envision that whole assembly and where the axle tension is exerted on the parts, you will see what I'm talking about. If you are missing either that spacer or the one in the hub that spans the two wheel bearing's inner races, the same problem occurs. The two bearings badly affected are the cush drive one and the brake side wheel bearing. The other wheel bearing usually isn't hurt because it's not being improperly loaded.

Hope that helps. I certainly sympathize with your frustration.

Keeping the "Hap" in "Happy Holidays"!

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Blind patriotism is worse than no patriotism.

Last edited by Dad; 07-23-2004 at 12:29 AM.
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post #10 of 17 (permalink) Old 07-24-2004, 01:20 PM Thread Starter
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hey thanks for everyone's help. got it running breifly again this morning, but this time its the worst yet. this time it wiped out both chain adjusters, the same bearing, threw the chain, and scarred up the swingarm. speaking of swingarm, thats the only thing back there i havent replaced yet. although it doesnt seem warped, im playing with the idea of replacing the whole setup. Or just take it to a mechanic and get raped on labor cost.

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