Question for all the 250es fans out there

[motordude]

Went on my first ride this past Saturday. Absolutly head over heels about the Big Red. Although, about 30 miles into my trip, started to smell Gear Oil. Looks like it has been leaking from where the drive shaft goes into the rearend casing. I have yet to look at it as I am tied up with work at the moment. Cleaned it real well, drove it around the yard for 10 mins and It did not leak at all, and yes I checked the rear end fluid, it was slightly low so I filled it again prior to my yard thrashing. Any ideas or has anyone noted this as a common place for a gasket to let go? I will be checking out the manual tonight to see how it is set up back there.
Thanks

[Big Sal]

There is no ATF in a Big Red...rear gear oil & motor oil only...sounds like a rear pinion seal.

[motordude]

Yes, you are correct, I meant Hypoid gear oil, I was just thinking of what I needed to rebuild my shocks. thanks for catching that. Rear Pinion Seal eh?

[atc007]

Whole things a recipe for disaster. Pull out the diff,and rebuild it. It will save you expensive headaches in the VERY near future!! Seals now,, or,,bearings and pretty ,fancy, pinion bearing removal tools later : )

[dougspcs]

I agree with 'atc007', don't wait for disaster..

But, check the vent tube on the diff to make sure it isn't plugged 1st..as the diff warms up the expansion needs to breath. If the tube is plugged it will push fluid out a seal out!!

Start with the simple stuff..this could be your leak...

If not then what 'atc007' said for sure..

[Big Sal]

Listen to these guys...that assembly is expensive to repair. I didn't even think about the vent. That's the one part on the shaft drive that lots of people don't maintain properly...that gearset with normal use and proper care will last a long time...gear oil is cheap...I change mine every 3-4 rides or anytime I "submarine" my SX...cheap insurance.

[tri again]

yupp, at only 3 Point 3 ounces of gear oil, it seems like it needs every drop.

[motordude]

Sorry guys, been away in Milwaukee for the past 3 days. On my way home now and will check the vent tube first, but either way I think I will rebuild it regardless. I do not want to run into issues in the future and part with excessive greenbacks.
Thanks and I will let you know what I find out.

[dougspcs]

Rebuilding the differential isn't a really fun job..I'm in the middle of it on my SX.

Put the rear on jack stands and slowly turn the wheels when the engine isn't running and it's it neutral..if there is any growl. Then tear it down!!

If it passes the noise test, I suggest you check the tube, change the oil and watch/listen. I will tell you is a problem is developing..

[motordude]

Sounds great Doug, will do.
Thanks

[motordude]

Well, I finally got around to checking out the rear end on the BR. The guy I bought it from is the original owner and says he never tore into or replaced anything other than tires and fluid. (he has been a long time friend) My question is......could this have happened at the factory? (the lip of the seal looked to have been molded/flipped from day one during assembly) I am glad I found the issue and everything else has checked out perfect. All bearings and seals are in tip top shape, other than the one in the pictures. I was rather happy to find how clean it actually was inside the swingarm and such. I was worried that the entire rearend would need a rebuilding from a few of the comments I got in regards to "gear wine" but turns out the noise I was hearing was from the spring in the lip seal rubbing......whewwwww:naughty:

Sorry for the bad pics, my crackberry sucks!

Thanks to everyone on here for thier help, I really appreciate it:beer

[atc007]

Pop the seal out,,I don't think you'll be as chipper when you get in there : ). Hopefully,I am wrong! Take it apart and let us know! And,,No,,that didn't come from the factory like that! : (

[motordude]

I have removed the seal, everything looks great unless you have any ideas for what I should be looking for. Rotation was as smooth as silk!

[dougspcs]

Luck be with you..bad seals almost always mean water/dirt intrusion.

[atc007]

The pinion bearing would usually be shot. As with the rest of the bearings in there! If the pinion bearing is Tight and all seems well,,,run her! just look it over real well! The oil in it was green? Not milky at all? We just want you to know all is well before buttoning her back up!

[motordude]

The oil in it was clean"ish" had a tint of black/green. No signs of any water at all. Spinning the pinion gear by hand was silky smooth with no gritty feeling. I think I caught this in time. Bearings seem to be tight and all the other seals and bearings look/ feel good............ The axle came out clean as well as eveything else.

[tri again]

I love the sound of 'smooth as silk'.
It's a wonderful feeling we can all relate to.
I think we're supposed to also check, like up and down play and axial, like back and forth
for play.
I forget how we checked backlash.
There wants to be some, like the gears mesh with a little bit of slop, like when you wiggle correctly adjusted valves.

But also sure there are numbers and specs that relate.
I think we used some blue dye or white grease to see the mating surface and contact of the ring
and pinion.

Yeah, wiggle everything and really TRY to find some sloppy direction.
as in loose bearing tolerances, but ALL directions in addition to that wonderful rotation you have going.

New seals ( we used to glue them in with a little contact cement) so they wouldn't sneak back out.

The correct hypoid gear oil and run it?
If you're the only operator, you'll most certainly be in tune for funny noises.

oh wait.
now WHY exactly did that seal lip do a flip?
I wouldn't be able to sleep until I figured THAT out, but that's just one of my personal issues
I need to address.
If something works, I need to know why.
Maybe I'll outgrow it.

[motordude]

I spent a good two hours last night going over everything/cleaning. The only "play" that I found was when I spun the pinion by hand back and forth abruptly which was very minimal. Everything seems perfect..............but I am going to see which tolerances I can check without taking it apart.

Now as far as why the seal lip was inverted on one side? Looks to have been like that for a long time as it basically molded itself that way. The friend I bought it from (55 years old) is a very honest guy, no reason to BS me, said he has never done anything to it since new, other than fluids. He said it sat for 17 years and he has been driving it for the past 6 only to head out on his lake for ice fishing and up and down his 1/4 mile driveway to get the mail.

When I told him I did two 40+ mile days on it, he almost dropped! He said that is the most distance it has gone in its lifetime in one day. Another thing was when I picked it up last month, he filled the tank for me and had to make sure he told me he had not put any fuel stabil in it as he was all out. I told him not to worry, this tank will be gone in a couple of weeks anyway, again he was shocked!

[dougspcs]

Well that lip was turned by installing the shaft..no question of that.

So it comes to this..your mate is an honest guy and says he's owned it since new and never opened the differential.

Therefore, it's been there since factory days..1+1=2. Simplest answer the correct one!!

Luck that he didn't ride it much or go into the water..would have been the death of the differential for sure.

Anyway the answer is in your hands..clean, lube the driveshaft nub, install a new seal and put her back together. BTW that little bit of backlash you feel is totally normal..Case closed!

One more thing..credit to you for taking the time to explore the cause of the leak. You unquestionably saved yourself a major repair by not ignoring the problem. Paying the machine respect and good maintenance will ensure you got a machine that will last you til your an old man!!

I'd drain that tank and start fresh!!

[motordude]

One last question and thank you to everyone for your help.

Any ideas as to where I should purchase this seal? I know I can get it through bike bandit, ebay, local dealer and such but I just wanted to try to keep the money circle throughout this forum and not give my hard earned $10-$15 to some stranger.

OIL SEAL (38X64X11)
91251-HC5-005
:wondering