Author Topic: Drive shaft leak b.s 90 sport  (Read 3711 times)

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Offline Dan44

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Drive shaft leak b.s 90 sport
« on: August 12, 2015, 10:23:54 AM »
A couple of weeks ago I drained and refilled the oil in the transmission.  I left it up on it's stands and everything looked good. I took it out yesterday and noticed that when the bike leans on the kick stand transmission oil runs down the kick stand and pools under the bike, but it doesn't leak when it's on the main stands. Does anyone have any insight for this?  I also seem to only be getting 40 mph.  Thank you
« Last Edit: August 16, 2015, 12:09:55 PM by Dan44 »

Offline mqtsteve

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Re: Transmission leak b.s 90 sport
« Reply #1 on: August 12, 2015, 04:04:09 PM »
Hey Dan44,  there are two oil seals on the left side of the engine that hold back transmission oil.  One on the gear shift shaft and one on the drive sprocket shaft. Either or both may have failed or dry rotted over the last 40-50 years.  It could be a bad gasket or there could be a hole in the crankcase near the sprocket.  You should clean and dry the engine and figure out where the leak starts.  Hope this helps, Steve
Steve S.
4/1966 BS90 Sport(o.i.), 5/1966 BS90 Sport(o.i.),
1965 BS90 Trail, 1965 BS90 Mountain

Offline Dan44

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Re: Transmission leak b.s 90 sport
« Reply #2 on: August 12, 2015, 07:56:26 PM »
Ok I'll take a closer look,  Thank you for taking the time to answer my question

Offline Dan44

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Re: Transmission leak b.s 90 sport
« Reply #3 on: August 15, 2015, 10:55:17 AM »
So I cleaned her off and followed the leak to the drive sprocket  shaft  :(   I'm not seeing anything in the manuals for replacing this seal without disassembling the entire engine.  Is there a little easier way to get to this?  I have attached a photo, the screw driver points the the seal that is leaking.

Also looking in the parts manual I think 09090-107 is this oil seal, is that the only part I'll need to replace?

Thank you
« Last Edit: August 16, 2015, 10:46:30 PM by Dan44 »

Offline mqtsteve

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Re: Drive shaft leak b.s 90 sport
« Reply #4 on: August 17, 2015, 07:29:04 AM »
I have never tried and don't know if it's possible.  You may be able to remove the oil seal collar p/n 2483-5000 then the oil seal p/n 09090-107 and replace it without disassembling the engine.(?)  Any other members have any thoughts on this procedure?  Remember, I haven't tried this.  Steve
Steve S.
4/1966 BS90 Sport(o.i.), 5/1966 BS90 Sport(o.i.),
1965 BS90 Trail, 1965 BS90 Mountain

Offline BRT-GTR

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Re: Drive shaft leak b.s 90 sport
« Reply #5 on: August 17, 2015, 08:41:33 AM »
Dan,
       I'm not familiar with this particular engine but based on looking at the parts manual, you have nothing to lose by giving it a shot, Seal 21x35x7 could be available from any good supplier. Also have a look at the collar, if it's deeply grooved replace that as well and maybe the seal 12x22x7 on the gear shaft, just to be sure.     
      Just a thought, was the sprocket nut tight, the collar seems to rely on being clamped against the inside bearing and the sprocket to stop oil creeping between it and the shaft.
     Good luck and let us know how you go on for future reference.
   Brian. 
Growing old is compulsory, Growing up is optional.

Offline Dan44

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Re: Drive shaft leak b.s 90 sport
« Reply #6 on: August 17, 2015, 08:53:41 AM »
Actually when I took the cover off I found that the nut that is supposed to hold the sprocket on was missing.  Maybe I should try getting a nut on there and see if it still leaks?

Thanks guys!

Offline OldSwartout

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Re: Drive shaft leak b.s 90 sport
« Reply #7 on: August 17, 2015, 09:09:18 AM »
For future info, most seals like that can be removed using sheet metal screw(s).  Use a very sharp punch (hardened nail, ice pick, etc.) to punch a hole through the face of the seal (this will be metal), screw in a sheet metal screw, then use a pry bar or slide hammer puller on the screw to pull the seal.   Don't drill the hole for the screw as you don't want drill chips in the bearing behind it. Don't screw the screw in very deep either as you don't want to damage the bearing. This doesn't always work cleanly, but in general seals can be pried out one way or the other without disassembling the engine. Heat around the seal also helps.
Karl Swartout
Mooresville, IN
BS175 Roadracer
BS350 GTR

Offline Dan44

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Re: Drive shaft leak b.s 90 sport
« Reply #8 on: August 17, 2015, 09:41:44 AM »
Ok that's what my buddy here at work was telling me this morning too.  Then after the old one is out I should be able to oil up the new one and tap it in with a slightly smaller diameter socket and mallet right?

Offline slawsonb

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Re: Drive shaft leak b.s 90 sport
« Reply #9 on: August 17, 2015, 11:24:49 AM »
Yep, just tap her in, taking care to keep the seal aligned with the bore, so it goes in straight. Be sure to lube the OD of the seal ( I use wheel bearing grease, but oil should work as well).
...bert

Offline Dan44

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Re: Drive shaft leak b.s 90 sport
« Reply #10 on: August 20, 2015, 02:21:30 PM »
I found a nut that fits the drive shaft (M16-1.50)  refilled the transmission and drove it around for a while then let it sit idling, the leak seems to have stopped.  Thanks for your help guys.

Offline slawsonb

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Re: Drive shaft leak b.s 90 sport
« Reply #11 on: August 20, 2015, 04:38:54 PM »
Cool! Enjoy the ride!
...bert

Offline mqtsteve

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Re: Drive shaft leak b.s 90 sport
« Reply #12 on: August 20, 2015, 06:47:33 PM »
Hey Dan44, there's a 17mm splined lock washer p/n 09047-103 under the nut.  That may be why it fell off in the first place.  Did you check out the parts manual?  Have fun, Steve
Steve S.
4/1966 BS90 Sport(o.i.), 5/1966 BS90 Sport(o.i.),
1965 BS90 Trail, 1965 BS90 Mountain

Offline Dan44

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Re: Drive shaft leak b.s 90 sport
« Reply #13 on: August 22, 2015, 06:42:23 PM »
Yes sir, the lock washer was still there oddly enough

 


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