Sprocket output shaft seal machining fault?

[speights_bud]

So earlier in the week I ordered an "All Balls" front sprocket seal kit for my '04 KTM 250exc.

When I opened the kit I found the new sleeve has a coarsely turned/machined finished on the outside diameter that the seal is supposed to run on. When I pulled out the leaking one from the engine (Not OEM) I found the same coarse machined finish. I think the coarse finish is tearing the seal lips.

From my experience as a machinist the OD of the collar should be finely finished and ideally polished? I would be surprised if the old kit ever sealed at all with the current finishing.

The collar I took out looked barely worn on the surface, and like the seal had never seated correctly, just gotten torn up.

I polished the old one in the lathe as it needed bugger all and am happy. Some photos of the new one next to the old before & after

I've written to the supplier but I would appreciate some KB wisdom as I've been wrong before!

Cheers

[swarfie]

I polished the old one in the lathe as it needed bugger all and am happy. Some photos of the new one next to the old before & after

I've written to the supplier but I would appreciate some KB wisdom as I've been wrong before!


100% correct in your thinking. The surface any seal runs on should be at least a ground finish if not better. No wonder the seal didn't last long. Be interesting to see if the supplier/manufacturer ever replies however my thoughts are that they make these kits cheaper than OEM for a reason, more profit...simple really.
I've put grease nipples in the A-arm joints, shock eyes and swing arm linkage pivots in the last three sports quads I've had so the bearings last longer (indefinitely) . If the manufacturer did that they'd not sell any spares I guess. It's a throw away society we live in.

[speights_bud]

Yea I have been too lazy to do the suspension pivot grease nipples on mine, perhaps I will over winter if the mud isn't too attractive 😁

[speights_bud]

Be interesting to see if the supplier/manufacturer ever replies...

Had a reply from the supplier this afternoon, nice and quick, he's also from a machining background and agrees it should be polished.
He is going to contact the manufacturer and see how that goes.

He came to the conclusion that I did with the guys at work today, the sleeve probably hasn't been finish machined/ground after heat treatment.