Check Out This Rear End... - Page 2

motoyoyo · 05-05-2003, 11:20 AM

Definitely would want to service that one myself. A little adjustment to the air gap at the fuzzbox should do it.

shannonnunley · 05-05-2003, 12:03 PM

waiting....

Rapid Dog · 05-05-2003, 12:16 PM

'been wondering about this myself...

Moose-"My rear boot leaked, although not that badly. My dealer replaced the zip ties with stainless hose clamps designed for the job at no cost, saying those plastic clamps were a problem. They should replace the crummy clamps even if you are out of warranty."

Has anybody got a part# for that bigga clamp?
THe zip tie is about 18". They put mine on half-arsed and left a gap.
I've been searching for a nice narrow satinless ose clamp just that size.

__________________

pmc847 · 05-05-2003, 12:16 PM

This is a rearend!

shannonnunley · 05-05-2003, 12:26 PM

mmmmmmm.

Rapid Dog · 05-05-2003, 12:31 PM

butt, butt, butt,,,what abutt those part numbers I need...

05-05-2003, 01:24 PM

I think the answer to your number query is found in the "21st digit"

Dave Hopkins · 05-05-2003, 01:44 PM

Do I dare ask, does this rear ends seals leak?

shovelstrokeed · 05-05-2003, 04:58 PM

Still not that attractive if it is leaking.

pmc847 · 05-05-2003, 06:38 PM

The drive shaft and seals fit very tight, needs to be gently broken in.

Markermc · 05-07-2003, 07:59 PM

Brad Black said...
"the cyclic noise/vibration - i have it on very good authority - is rear drive backlash related. from people who have fixed the problem more than once. we've never had to do one. adjust the shim under the small, outer rh (as fitted to the bike) bearing"

Hey Brad,

what exactly does that mean in laymans terms? Which bearing are you referring to?

I took mine to a dealer back in March to remove rear wheel play, and when I got it back (after the repairs they did from letting it fall off the workstand onto its right side) they said they had shimmed the rear wheel bearing and replaced the paralever bearing.

It suddenly then had a cyclic vibration that varied its frequency by gear selection, and not by rpm, one that it had not felt before. It also still had play at the rear wheel. I took it back, and they adjusted the paralever bearing, and it still had play, upon which they told me that my swingarm bearings were shot and had to be replaced...

I vehemently disagreed (after doing some "feel" and "sound" tests of my own at home, while isolating the swingarm bearings from motion) when I brought it in for the scheduled surgery, and they re-looked at their bearing job again, and told me that I was right... they had to re-shim the rear wheel bearing instead.

I havent ridden it enough since getting it back to say if it still has the cyclic vibration though.

My concern of the vibration though, is that another local dealer told me that a cyclic vibration as I described was common to a failing output shaft bearing, which would require a transmission teardown...

Is this correct?

Thanks

Mark

roger albert · 05-07-2003, 10:30 PM

Hmmm,

tough call. Sound's like the dealer isn't quite that rear end expert that pmc847 is.

There are a couple places to shim in the rear drive. One is the main carrier bearing /housing interface. It is a very large (both I.D. and O.D. shim) Done properly, it should not affect lash. In fact, it would have to be horribly botched to have much effect, other than rear wheel play. I recently had this one fixed as the cause or rear wheel play (as opposed to the pivot bearing problem some others have experienced) There are also two other shims. One is on the tapered roller bearing on the inside of the case. It determines backlash by moving the crown gear left or right. Bunch of noise if it's not right, though normally more of a whine than a cyclic drone. Lastly, there's the shim that moves the pinion fore/aft, which is the one that determines the tooth contact pattern. Frankly, until I was recently forced to do an airhead rear drive, I had those latter two options (backlash and mesh) a bit muddled/mixed in my head. Nothing like doing stuff for real to knock incorrect/fuzzy theories out of your head

Anyway, the cyclic thing is more often the trans output bearing (in my limited oil and fairly large air-head experience) Much less commonly, the input bearing to the rear drive (pinion bearing) I honestly don't have a good feel for failure modes on the rear pivot joint between those. Don't have enough experience except to say that they usually just fail with a lot of slop.

Otoh, I'd be tempted to go with Brad's input. I think that one has to be further off than I've personally seen to cause that noise, but Brad and his source seem confident, so I'd tend to trust that. Add to that, the fact that there have obviously been issues with the rear drive's initial build and remedial service quality. I'd look there before worrying too much about the trans.

brad black · 05-08-2003, 01:17 AM

well, i started typing before reading rogers bit, so i'm repeating him to some extent.

there are 2 bearings supporting the crown wheel. one is a large ball bearing, and mounted inside the black bolt on cover that forms the inner side of the rear drive. the other is a tapered roller, mounted on the crownwheel carrier, with the cone on the rear drive, in the little lump you can see on the rh outer.

this small tapered roller is the bearing used to adjust backlash, by varying the thickness of shims 'under' the bearing. thicker shim moves the bearing 'out' to the right, and the crown wheel to the left. this increases backlash.

as i said, i haven't had to do one, but i have spoken to techs from other dealers who have, and this fixes the common, usually 4th gear cyclic vibration. of course, you don't have to believe me.

my bike had the vibration, but i never used 4th gear on cruise really - only in 80 km/h zones that i rarely rode in. so i never bothered about it.

roger albert · 05-08-2003, 03:33 AM

I'd believe him. If someone has cured it that way then it probably works whether I happen to understand it or have seen it

Any idea Brad. I was wondering if someone changed the inner/small shim, but then not the outer/large, that the resulting change in bearing preload (I'd assume an increase if the wheel didn't become loose) could cause the noise.

Less likely, but possible it seems you'd then need to redo the pinion shimming too. So it would seem anyway? Anyone know for sure?

Markermc · 05-08-2003, 05:39 AM

Thats funny. My cyclic vibration, as I recall was most "feelable" (is that a word?) in 4th gear at about 3k - 3.5k rpm. It was actually present in 3rd thru 6th but changed frequency enough that you wouldnt have realized it was a cyclic vibration so much as in 4th.

It was a very low frequency in 3rd... sort of like whummmmmmmmm whummmmmmmm whummmmmmmm, but in 4th it was clearly more of a whummm whummm whummm, then in 5th it became whm whm whm whm whm very rapidly, and in 6th it went to what felt like a grating vibration almost as though you were holding a metal grinder against your butt on the seat. (how's that for a description?)

You both have me really curious now, so I will have to get the bike out before work this morning and take her for a ride. We have had so much rain here lately that I have been riding the dual-sported XR400 instead (which has its own issues to fix right now). I will let you know if the adjustment they did on the rear end shimming seems to have fixed it.

Thanks a bunch for the great input.

Mark

Dave Hopkins · 05-08-2003, 08:40 AM

Mark
If or as it changes with shifting gears that sounds more like transmission than rear drive! I don't have the shop manuel handy but I am going to guess that 4th gear is the rear most gear in the trans, maybe 3 next, 5th next? 6th at the front? Thus indicating a look see at the transmissions rear bearing.

DavidSoine · 05-08-2003, 10:49 AM

Harmonics/subharmonics of the gear mesh frequencies are lining up - if the pinion gear on the rear drive has 12 teeth...

How many teeth on the output shaft gear for 3rd, 4th, 5th gears?

That explains the beating phenomena being described here.

Trouble could be at either end of the driveshaft - output shaft bearing, or shims/bearings at the rear drive.

best,

Dave

DavidSoine · 05-08-2003, 10:52 AM

BTW looks like gears from back to front are 1st, 5th, 3rd, 4th, 6th, 2nd.

best,

Dave

brad black · 05-08-2003, 07:21 PM

this has worked in warranty situations, dealing with typical wailing owners, so i accept it.

it would have to effect the preload i guess, but it may not be that big a change anyway. dunno, never done it.

Markermc · 05-09-2003, 04:35 PM

I finally got to ride it in anger today... the verdict is that the cyclical vibration has been almost totally eliminated by the re-shimming of the rear bearing.

There is still a VERY faint cyclic vibe there, but it is almost undetectable now. It doesnt surprise me that this was the case, and I was hoping it would be, since the vibe started when I got it back from the dealer who didnt quite get the rear wheel slop tight enough the first time (or second for that matter).

Yeeeah!!

I will be sure to watch for the vibe now more closely, knowing that it could also be a trans problem one day... and thats not a good thing.

Thanks all for your input.

Mark