C Drive Rear Seal Replace

[lv2plyguitar 172]

My engine is inverted and the rear seal on the C drive just in front of the rubber donut is leaking.  Can this seal be pulled out the back and replaced or do I need to remove the gear and bearing with a press and then replace the rear seal.  Just hoping for a shortcut and it looks like it could be pulled from rear.

 

Thanks

Edited 8 Apr 2013 by AVID STOL HH

[1avidflyer 1983]

When I changed mine last fall, I didn't pull the bearing out.  Had the gearbox off the engine though.  Also,  I didn't buy the $72 one from Rotax.  My Leading Edge catalog called it a 32X47X7 oil seal.  Those are millimeters.  I ordered mine for less then $10 from a bearing house.  It's been fine for 57 hrs now.    Jim

[lv2plyguitar 172]

how did you pull the seal?

[1avidflyer 1983]

Because the gearbox was off the engine, I had the shaft that goes through the seal out of the way.  That shaft stays with the front half of the gearbox.  If I remember right, I just used a screwdriver to work it out.  They don't really hold tight in there.  I also think I used some Locktite adheasive on the seal when I put it back in there.  If you don't want to take the gearbox off the engine, you probably can take a L shaped pick and grab the seal and pull it out.  Just be carefull to not scratch the shaft or the next seal will start to leak also.  Take care,  Jim Chuk

[lv2plyguitar 172]

The seal I am referring to is the one the crank shaft slides into as opposed to the shaft the prop is on.  It is item 13 and part # 950-084 on the lockwood diagram.

 

Thanks 

[1avidflyer 1983]

Now I'm starting to question my memory some more.  I'll have to go measure the old seal.  I remember (at least I think I do) right where it's hanging in the garage.  Looking at it again, the # 13 part is probably the one I changed.  You do need to get the gearbox off to change that one.....  Went out to the garage, and the seal was right where I remembered it.  It's the # 13 part  32X47X7 MM.  seal.  I must have been half asleep this morning.  At any rate, I'm sure you will figure it out if you pull the gearbox apart.  I know mine doesn't leak after  7 months, and I didn't remember which one I changed.  Sorry I led you off in the wrong direction.  (Maybe I should be shot after all)   REALLY i'M JOKING, REALLY i AM!  BOOM BOOM ..........

[saskavid 47]

How full is your gearbox?Overfilling has been the issue in the past for some flyers with leaking front gearbox seals.

[lv2plyguitar 172]

My seal (item 13 on the diagram) is the rear one where the gear box slides onto the crankshaft.  The problem is the gear box is 20 years old with sixteen hours on it.  The seal probably dryed out.  I am just trying to figure out how the gear and bearing remove to get to the seal to replace.  If you look at the seal from inside the case it looks like it could be pulled from the rear without touching the gear.

 

What are your thoughts

Edited 8 Apr 2013 by AVID STOL HH

[SuberAvid 617]

Jeff,

 

With the diagram showing the seal on the inner side of the case it is most likely that the seal has to be installed and removed from the inside.  There has to be a shoulder in the case that it seats against, either on the outside or inside.  I had mine apart and replaced the seals in it but it has been so long now that I don't remember exactly how they went in.  The redrive comes apart pretty easy when you split the case; the pain is that you have to remove the rubber donut on the crank connection side.  Not problem to remove it but then it shrinks up a bit and is a pain to get stretched back out to get the bolts through it again when you put it back together.

 

Randy

[1avidflyer 1983]

You don't have to take the donut apart to get the gearbox part off that holds the bad seal.  You do have to remove the allen bolt part # 19 in the diagram posted that holds the small gear to the donut.  When ;you remove the gearbox from the crankcase, the donut and round flywheel part # 1 will still be fastened to the crankshaft.  They can stay where they are.  I don't think you have to pull the bearing # 14 out to get at the seal.  I'm sure you can get it out the back.  I do know for sure there is no shoulder that the seal goes up against.  At least there wasn't on my C box.  That's why I put the locktite glue on it.  I wasn't comfortable with it just sitting in there.  It hasn't given any problems since I changed it. last fall.  My advice (for what it's worth) is this: buy the seal, if your'e carefull you wont hurt the gasket between the two halves of the gearbox, but you might want to have another one handy.  Pull the gearbox off and I think you will find it really isn't that hard.  I just ran out to the garage and looked at the glue I put on the seal.  It was Locktite 574 which is actually called a flange sealant.  I had it from when I put a 912 gearbox togeather, that was what was used on the two halves of the gearbox instead of a gasket.  It doesn't call for anything on the seal, but it didn't look all that secure to me the way it sat in there.  One other thing.  if you push it in from the back, don't push it all the way up against the bearing.  Look at the position of where the old one was before  you pull it out.   One other thing, when you pull the small gear out, make sure the spacer rings # 16 end up exactly where they were before.  They set the clearence of the gear.  Well look at the pics again and see what you think.  Take care,  Jim Chuk 

[lv2plyguitar 172]

That seal came out very easy and went in fairly easy.  No need to remove the gear at all. 

[1avidflyer 1983]

If you mean you didn't have to remove the small gear # 17 in the picture, can you explain how you did it?  Thanks,  Jim

[lv2plyguitar 172]

Seal # 13 slides over the smooth short shaft on item 4.  Item 4 is what the rubber doughnut mounts to.  The c drive is not sealed until it is reinstalled on the engine and item 4 slides into the seal.  The seal pulls out and installs easily from the back side of the case once the case is removed from the engine. 

[1avidflyer 1983]

I see it now, again I couldn't remember.  You did have to pull the #19 allen head bolt out that holds the gear to the # 4 part didn't you?  Once the bolt is out, the gear could stay where it is, but there isn't anything else holding it in as I remember.  Glad you got it fixed.  At least I was right when I said I was sure you could do it........  Jim