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Changing the Driveshaft Seal


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Read through the maintenance manual, reviewed the Ural CD's and looked at instructions/pix on Bill Glaser's website and it seems pretty easy to get the rear wheel and final drive/driveshaft off the bike. What I have not been able to find is how does that chrome donut/small driveshaft come off the back of the trans so I can get to the seal? Outside of greasing up all of the splines when I put it all back together, is there anything else I should do maintenance wise to that chrome donut assembly or driveshaft/u-joint while they are off the bike?

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The flex coupler is just a press fit onto the 2-finger yokes, pry it off with a large screw driver or similar tool. Use a little grease or silicone spray when re-assembling and the flex coupler will slide right back on.

 

Nothing more than greasing the splines is needed.

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The flex coupler is just a press fit onto the 2-finger yokes, pry it off with a large screw driver or similar tool. Use a little grease or silicone spray when re-assembling and the flex coupler will slide right back on.

 

Nothing more than greasing the splines is needed.

 

How does the yolk come off the trans? Will need to take it off to get to the seal. Is it reverser threaded as well as the nut in the middle of the yolk? Should I use some RTV sealant on the threads of the yolk and center nut to prevent oil leaking through at those points?

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Once the doughnut is removed, in the center of the 2-finger yoke out of the gear box, you will see a 22 mm castellated nut with cotter pin. The cotter needs to be removed and the nut loosened. Usually, it is difficult to get a wrench or socket on the nut as the well in the yoke is tapered (you'll see). A tommy bar (punch) and hammer used on the flats of the nut will loosen it up. Easier to do with the gear box off the bike.

 

After you get the nut off, the 2-finger yoke slides off the splines. Use a screw driver to pop off the old seal and carefully drive the one on using an appropriate sized mandrel (seal driver). Hopefully you have two seals in case you bugger the first on up. You can get the seal from aftermarket sources as it is in fraction's of mm's. I think the 2007 year bikes now use all standard seals.

 

On my site, I have not filled in the verbage on gear box disassembly, but you can look through the photo's and find the ones showing the removal of the 22 mm nut and 2 finger yoke.

 

There is not a good way to prevent oil weeping from this area. The bearing on the end of the main shaft is open to allow oil to splash onto the speedo drive gear which is to the right side (seen from back of g.b.). The splines on which the 2-finger yoke ride are a direct route out for the oil. The factory uses black RTV at the back of the bearing I.D. in an attempt to block the oil flow along the splines. Usually, they do not do a sufficient job in sealing this area. Some folks gob some sealant under the 22 mm nut to attempt the same type fix with limited results.

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Once the doughnut is removed, in the center of the 2-finger yoke out of the gear box, you will see a 22 mm castellated nut with cotter pin. The cotter needs to be removed and the nut loosened. Usually, it is difficult to get a wrench or socket on the nut as the well in the yoke is tapered (you'll see). A tommy bar (punch) and hammer used on the flats of the nut will loosen it up. Easier to do with the gear box off the bike.

 

After you get the nut off, the 2-finger yoke slides off the splines. Use a screw driver to pop off the old seal and carefully drive the one on using an appropriate sized mandrel (seal driver). Hopefully you have two seals in case you bugger the first on up. You can get the seal from aftermarket sources as it is in fraction's of mm's. I think the 2007 year bikes now use all standard seals.

 

On my site, I have not filled in the verbage on gear box disassembly, but you can look through the photo's and find the ones showing the removal of the 22 mm nut and 2 finger yoke.

 

There is not a good way to prevent oil weeping from this area. The bearing on the end of the main shaft is open to allow oil to splash onto the speedo drive gear which is to the right side (seen from back of g.b.). The splines on which the 2-finger yoke ride are a direct route out for the oil. The factory uses black RTV at the back of the bearing I.D. in an attempt to block the oil flow along the splines. Usually, they do not do a sufficient job in sealing this area. Some folks gob some sealant under the 22 mm nut to attempt the same type fix with limited results.

 

Thanx to Bill for the explanantion and taking some time to discuss and "train" me on the phone. Looks like the seal may not be the culprit, but rather the oil is leaking through the center nut holding the fork to the outpust shaft. I will endeavor on trying to seal up this area with RTV sealant rather than try to replace that main seal which appears to be near impossible to replace while the trans in on the bike. Sounds like all/most of you are having this same oil migration/leak problem, inherant design flaw.

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.

 

Thanx to Bill for the explanantion and taking some time to discuss and "train" me on the phone. Looks like the seal may not be the culprit, but rather the oil is leaking through the center nut holding the fork to the outpust shaft. I will endeavor on trying to seal up this area with RTV sealant rather than try to replace that main seal which appears to be near impossible to replace while the trans in on the bike. Sounds like all/most of you are having this same oil migration/leak problem, inherant design flaw.

 

Flaw? WTF? That's not a "flaw"... That's the Ural patented self lubrication and waterproofing system! :wacko: They even have an upgraded system that keeps your right boot and pantleg properly lubed!

 

Bill is a big help. He has saved my bacon many a times.... :laugh:

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  • 6 years later...

Guys, how much Oil on your Foot is acceptable - I've posted another post about what I now think is a final drive seal oil leak which spits oil off onto my Foot and the Sidecar. Reading up on it here, I have to take the Rear Drive and Wheel off to get to change the seal - and mines a 2WD so probably even more complicated. Seems like I run my Gearbox oil down to near zero every 4 weeks so at the moment so quite a lot is getting lost. Advice?

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You should not be loosing any oil!!

that i believe is the idea! and mine doesnt leak at all

So...would be an idea to remove this output flange and check it is not marked and runs true...

get seal and check fit....if not find one that does...fit seal , as mentioned above,

an impact gun removes nut well! after you have removed pin of course,

Add required and specified amount of oil and ensure breather is breathing!

Then maybe add a bit of sealer to flange /spline joint,

Then Torque nut to specified torque, ( not with impact gun!)

Then ...well try it aint it!!

As long as you degrease everything you should see any leaks as they appear...or not!

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  • 2 weeks later...

You should not be loosing any oil!!

that i believe is the idea! and mine doesnt leak at all

So...would be an idea to remove this output flange and check it is not marked and runs true...

get seal and check fit....if not find one that does...fit seal , as mentioned above,

an impact gun removes nut well! after you have removed pin of course,

Add required and specified amount of oil and ensure breather is breathing!

Then maybe add a bit of sealer to flange /spline joint,

Then Torque nut to specified torque, ( not with impact gun!)

Then ...well try it aint it!!

As long as you degrease everything you should see any leaks as they appear...or not!

Thanks scheduled !

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I haven't been into any Ural transmissions yet, but have been into my Dneprglide a few times now and it doesn't leak! On the Dnepr transmission there is a o-ring that goes on the output shaft right behind the yoke look at the back of the flange and see if its flat or has a small dished area on the end of the yoke that goes in the transmission and look where the nut and washer that holds the yoke on and see if it has a surface for a o-ring there! I noticed on a 10-36 trans it didn't have a surface for one but I put one in anyway and it didn't leak. Just a thought, hope it helps. Lobofuego is right look really well at the surface that the seal rides on, it Must Be Smooth! No rust, dings,grooves, make sure its round too if it has always leaked, put a new seal on the yoke while its out and look how the lip seats all the way around, turn the seal around the yoke it should glide and be snug not tight not floppy loose. I always put grease in the back of the seal,where the spring is and around the lip when installing new seals to help it lube the first time it's used because you can burn the lip off a new dry seal if its run fast before oil gets it wet on the backside! Been there done that, I hate leaks!

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