What is this part number? Not in any parts lists

[chickenstrips]

There's a leak in my Cb750 DOHC front sprocket area. I try googling this specific issue, but no matter how I use quotes etc, I end up finding SOfreakingHC threads!

It seems that the shaft is leaking around the bushing. I just replaced the seal and I'm tracing the leak to that specific mating surface.

So where can I find the part number for the rubber that goes inside of this metal bushing?

Stole this image from this site:

[Lucky 1]

First you need a workshop manual.
then you can determine if that seal can be removed from the outside.
If that seal leaks the oil can go anywhere there is space.

If the crankcase breather is clogged up it will leak oil out of this seal check that breather.
If you feel like air pressure coming out around that seal it means the crankcase breather is clogged up.

[shinyribs]

First off, are you positive it's leaking? That area gets really,really funky. It could just be residue from chain lube. But if you're sure it's leaking, or just want to replace it for good measure, looks like that seal is ~$20 or less.



Found this: http://www.cmsnl.com/honda-cb750f-750-super-sport-1980-usa_model7241/partslist/E++16.html

Looks like component #25 which is: http://www.cmsnl.com/honda-cb750f-750-super-sport-1980-usa_model7241/oil-seal-40x62x13_91205425003/#.Uu2EG7Q2DNo

OEM Part # 91205-425-003

Oil seal-Dimensions: 40x62x13 (mm's)

So I hit up ebay...

First, I typed in the OEM Part # http://www.ebay.com/sch/i.html?_trksid=p2050601.m570.l1313.TR0.TRC0&_nkw=91205-425-003&_sacat=0&_from=R40

Then I typed in "oil seal 40x62x13" : http://www.ebay.com/sch/i.html?_odkw=91205-425-003&_osacat=0&_from=R40&_trksid=p2045573.m570.l1313.TR0.TRC0.X&_nkw=oil+seal+40x62x13&_sacat=0

^^^ NO direct matches, but some more digging mat turn up one of those $4 beauties for your application.


Hope this helps. :)

[chickenstrips]

The red arrow is pointing at the metal bushing. Inside that metal bushing is a piece of rubber. it seals between the SHAFT itself and the bushing. I need the piece of rubber inside the bushing.

I already replaced the shaft oil seal and the oil leaks without even starting the engine. All I do is rotate the shaft by hand and oil fills the sprocket splines.

I can clearly see that the oil is coming between the shaft and bushing. No trace anywhere else.

In THIS groove

[icerigger]

It's just a o-ring, 9.8 x 2.4 - OEM # 91305-422-000. Less than $2 from Honda Parts Nation.

[chickenstrips]

No no no. It's NOT in a parts list anywhere I look. You're referring to the o-ring that goes beneath the bolt to close off the hole in the shaft.

There is a bushing. The bushing surrounds the countershaft. Between that bushing and countershaft is a piece of rubber that is supposed to seal the mating surface between the bushing and countershaft.

[shinyribs]

If I understand you correctly you are talking about this bushing right here:


Once installed on to the countershaft that gear/bushing is inboard of the outer countershaft bearing:


There are no orifices or continuation of splines from where that bushing sits that run to the other side of the countershaft bearing. If you are leaking oil through the splines, and not around the case seal, then I'm really curious as to how it's finding it's way out.

Cracked countershaft?

And this leads me to another question: are you positive that is the correct countershaft for that transmission/engine case? It seems awfully short. Like it barely protrudes out of the case.





The only seal the FSM mentions for the countershaft is where it exits the case:


And also the o-ring Icerigger mentioned that seals the inner bore of the countershaft,like you said.

Do you have a picture of this seal you are seeing? Unless it's just some sort of o-ring, it should carry some sort of marking,part number or size on the seal itself.

[chickenstrips]

Boom! That's the bushing I'm talking about!

The image posted is not mine. I mentioned I stole it from this site.

Think about it folks, if there is a bushing around the shaft, what seals the space between the bushing and the shaft?? There is a piece of rubber that sits in the bushing. The rubber seal, however, has no markings...

This bushing



The groove in which the culprit seal fits

[shinyribs]

Ok, now we're getting somewhere!

There's no bushing where you have your red arrows at. That is the surface that the outer-most seal rides against. That bushing slides inside that gear that goes on the opposite of the bearing that the seal is on. It's what protects the countershaft and that gear from each other.

[chickenstrips]

It slides right off. Maybe the picture is a different bushing, but the one on I keep indicating has that same groove.

Look in the first picture at how the splines go in deeper than the outer-most surface of the bushing. You can tell that the bushing and shaft with splines are not one piece.

I'm buggered.

[shinyribs]

Man, this kinda has me stumped. Can you access this bushing just by removing the front sprocket? I might have to go take a look at mine and see what's up. This has me curious.

I can understand exactly what you mean, I just didn't think there was a bushing right there. It does look like it has a groove on the I.D. of the bushing in that picture, but I just assumed it was recess used to retain oil in that area, which is pretty common for a bushing to have. I just can't imagine what a bushing between the countershaft and the case seal would be for. And I don't see it on any parts list either. Maybe it's not supposed to be there?

Have you had your transmission apart?

[chickenstrips]

It's never been apart.

I think it's odd that there is a bushing in this location as well. I can't recall seeing this on any other bike.

You access it by removing the sprocket, but t won't come out without removing the seal or prying/damaging the bushing itself.

[shinyribs]

Hmm...alright. This is officially my pet project now. This has me curious.