[Patch]

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I am in the process of changing my rear tire and thought it would be a good idea to change my final drive oil while I have the rear end apart. I thought that I read on here some where about filling your final drive a little fuller thatwhatis recommended in the book. I have done a search but could not seem to find anything about this. Did I read this or am I mistaken? If I did read this, how much extra do I put in? How do you fill higher than the fill cap will allow?

 

[AZWinger]

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The book says to put the bike on the center stand and fill until the oil is level with the bottom of the fill hole. You can get a little extra in by putting the bike on the side stand and letting it lean over. That's how I do mine and I have seen it posted where other forum members do it the same way.

Bob :11grey:

 

[markgaeth]

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Greetings,

Use the center stand on a level surface!!!!. The oil should be at the opening threads for the proper level. Using the side stand will put in too much and may blow out the breather cap and make a mess.

That's my story and I'm sticking to it.

Mark Gaeth

 

[GWNorman]

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Chris, you can get a bit more oil in by leaving the bike on the side stand when filling. The extra bit wont spil out of th event later on either.

 

[markgaeth]

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Greetings,

I guess the question would be why would you need to put in more oil than is specified?

Mark

 

[BRowan]

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markgaeth wrote:

Greetings,

I guess the question would be why would you need to put in more oil than is specified?

Mark

Haveyou ever drained your diff oil Mark? Not an awful lot in there at all and many of us believe that putting an extra bit of oil in can only do good.

 

[johnmac]

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Mark,
At the recomended oil level, some components don't always get as much lube as they need.
Filling the final drive with the bike on it's side stand will let you get a bit more in it.
I did this on a " leap of faith" and have not had any problems on my '85 1200.

 

[GLester]

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GWNorman wrote:

Chris, you can get a bit more oil in by leaving the bike on the side stand when filling. The extra bit wont spil out of th event later on either.

The only problem I have with overfilling differenials is that the gear oil has a tendency to foam when the level is too high. Once the fluid starts foaming, air bubbles form, and the air gets where the oil is suppose to be. After a long time, excessive wear begins. The reason the oil fill hole is down so low, is that the engineers have determined the proper level of oil to where it will not start foaming and breaking down prematurely, thus causing excessive wear. Even with the oil hole so low, there is suffient oil to lube the gears. Also, too much oil causes higher pressure in the rear end, and thus can cause premature oil seal failure.

Gene:waving::11red::11red::11red::cooler:

 

[markgaeth]

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Greetings,

A little extra oil will not hurt it but have yet to see a failure of a rear end due to the oil level at the recommened level. Now if someone has the bike on the centerstand on an unlevel sloped surface then I could see a possiblity of not getting in the correct amount. I did that once on the engine oil and ended up putting a 1/4 quart too much, so I could see it going the opposite way.

I would respectfully submit that any failure of the rear end was due to a failure of another cause or the oil leaked forward of the pinion seal and into the shaft tunnel reducing the amount of oil in the final drive enough to cause a bearing/gear failure. I have seen a plugged breather vent with caked on crude that caused the pressure to build in the final drive and blow out the pinion seal and was damaged before the owner saw any signs of oil leakage. He did say that he smelt something baking back there but just kept ridding instead of checking and adding gear lube to get him home.

Just my for what its worth. My opinions are always FREE and are freely given.

Mark

 

[johnmac]

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Gene, Mark,
You both have a good point. I ran across a web site where the guy running it claimed final drives failed as a result of low oil level. This guy didn't say to fill while on the side stand.
In fact, he didn't give any real answers, only clues. I think he was selling his repair services, and making you think he knew all the "trickes".
He also mentioned the oil pump in the final drive. Looking in my parts book, I don't find anything called a "pump" or any part number for anything close to a pump, not even a slinger.
As for the foaming, good point. I my do a re-check of my oil level and my drain a bit out.
My '85 has over 96,000 miles on it. If anything is wearing out, it's probably due to age and mileage.

 

[markgaeth]

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Greetings,

Your right there is no pump in the final drive. The only slinging is from the gears splashing. The oil level at proper level covers the side thrust bearings and the pinion is splash lubed. I would not drain a little out unless you just changed it. For the small cost I would replenish with new oil after draining a warm rear end.

Good luck have a good evening.

Mark

 

[exavid]

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johnmac wrote:

Gene, Mark,
You both have a good point. I ran across a web site where the guy running it claimed final drives failed as a result of low oil level. This guy didn't say to fill while on the side stand.
In fact, he didn't give any real answers, only clues. I think he was selling his repair services, and making you think he knew all the "trickes".

I heard the same thing from a guy selling his services on this forum a while back. I don't believe the claim that Honda did a bad design on the rear drive on these bikes. There are too many of them running up mileages that would be impressive in trucks, much less bikes. My 1993 has 99500miles on it and the rear drive looked fine when I pulled it for checking while replacing the rear tire. I also fill the final with oil on the side stand. It really doesn't make much difference, I just like to get a wee bit more in. Overfilling isn't going to do anything other than make a bit of a mess when the excess is thrown out the vent. Sidestand filling doesn't add enough to do that. Pump in the new oil until it slobbers out the filler hole and screw the lid back on. That's it! and that's all there is unless you are planning on flushing. To do that I just fill it and run it a couple hundred miles and drain and refill again. Unless the stuff has been sitting in a defunct bike for years and has the consistancy of slightly thin tar that's all you reall need to do.

 

[Patch]

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Well, I drained my final today as I was putting everything back together. The oil was the consistancy of Karo corn syrup and black as tar. I put in some new oil and some MMO and will do another change in a few days. Thanks for all the good replies.