May seem a silly question but I am asking just to be sure:

Which way goes the crank seals? Open side towards the crank or towards the bearing?

Quick answer appreciated. I am working on it now..

-Jan

May seem a silly question but I am asking just to be sure:

Which way goes the crank seals? Open side towards the crank or towards the bearing?

Quick answer appreciated. I am working on it now..

-Jan

Geez, I'm trying to remember, but in my experience, the "open" side goes towards the side that contains the fluids. Think about the kickstart and shift shaft seals, open side goes towards the trans fluid, and I would think the open side goes towards the bearings, which are lubed by the transmission fluid.

Any help?

Jon

Geez, I'm trying to remember, but in my experience, the "open" side goes towards the side that contains the fluids. Think about the kickstart and shift shaft seals, open side goes towards the trans fluid, and I would think the open side goes towards the bearings, which are lubed by the transmission fluid.

Any help?

Jon

Yes and no.. I was really hoping that you could tell for sure.

What You say makes sense. I have also thought in that direction. On the other hand the seals must seal on both sides because they must also withstand the compression in the crank chamber right? Kickshaft and shiftshaft seals have only one mission to keep oil inside.

And: I am pretty sure, but not 100% that when I first split the cases in february the open side was against the crank and the closed side against the bearings.

Hmm... I have another engine "laying around". Do i have to open it to have a look...

-Jan

Yes and no.. I was really hoping that you could tell for sure.

What You say makes sense. I have also thought in that direction. On the other hand the seals must seal on both sides because they must also withstand the compression in the crank chamber right? Kickshaft and shiftshaft seals have only one mission to keep oil inside.

And: I am pretty sure, but not 100% that when I first split the cases in february the open side was against the crank and the closed side against the bearings.

Hmm... I have another engine "laying around". Do i have to open it to have a look...

-Jan

I think I just found the answer myself.

Went looking for that other engine I have when I found two case halfs that I forgot i had. The two halfs is from two different bikes and both had the seals intact and turned with the open side towards the crank.

I am a bit relieved because I had already put the seals in the case... puh..

Thanks anyway. Actually good to discover that you don`t know everything Jon..

-Jan

I think I just found the answer myself.

Went looking for that other engine I have when I found two case halfs that I forgot i had. The two halfs is from two different bikes and both had the seals intact and turned with the open side towards the crank.

I am a bit relieved because I had already put the seals in the case... puh..

Thanks anyway. Actually good to discover that you don`t know everything Jon..

-Jan

Jan,

Darn, that serves me for guessing! I just looked at the parts manual and it seems to show the seal with the open side to the crank (it's tough to make out by the drawing). Goes to show you, I'm not too old to learn.....

Actually, it makes some sense to me now after looking at the seal lip structure, as the pressure side (open) would tend to seal better with the pressure fluctuations, kinda like how shock absorber seals are designed to seal under pressure.

Cheers.

Jon

Edited May 21, 200917 yr by JSE

Jan,

Darn, that serves me for guessing! I just looked at the parts manual and it seems to show the seal with the open side to the crank (it's tough to make out by the drawing). Goes to show you, I'm not too old to learn.....

Actually, it makes some sense to me now after looking at the seal lip structure, as the pressure side (open) would tend to seal better with the pressure fluctuations, kinda like how shock absorber seals are designed to seal under pressure.

Cheers.

Jon

Hehe.. I also looked at the parts manual and thought I saw the same as you, but then I discovered that they had used the same drawing on both sides. Then that picture was nothing worth...

-Jan