81 R65 Rear Main Seal Removal & Replacement

[Mike V]

Looking for some opinions and favorite procedural help for;

1.) Removal of Rear main Seal. Drywall screw method or pry w/fulcrum method?  I really hate prying on stuff back there.

2.) Depth for new seal installation, is it critical - necessary? Press it home?  If not, what's the best way of determining the correct depth? Oil coat on new seal, yes, no? Or, light oil film on case?

Old main seal is still installed. That thrust ring was a bear. But Bum's instructions are perfect about using a blunt drift to spin the ring just slightly on the crank flange. I didn't pry or use pliars. Here's a nifty little way I figured out last night.  The trusty slide hammer with single hook attachment.  Any opinions on the above is appreciated guys.  Here's a picture link to last night's work. Thanks!

http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Engine/?albumview=grid

Mike V.

[Bob_Roller]

I've used an automotive body dent puller, with a sheet metal screw on the end, just drilled 3 small diameter holes in the seal, threaded the puller in, and a couple of hits with the slide weight, and he seal comes out .

Just make a measurement before pulling the seal out .

Don't know if you are aware of this already, there is an o-ring inside the cap that goes over the end of the crankshaft .

[Mike V]

Bob,

Yes I'm aware of the interior thrust ring o-ring.  All replacement parts are on hand and waiting. The puller method is what I was leaning towards, thanks. I'll take an outboard measurement on the existing o-ring and drive the new one the same amount.  Is there any damage of driving the new seal all the way home into the case seal seat?  

Maybe I can set my seal driver screws based on the existing seal depth.

[Bob_Roller]

I'm not sure if it matters too much, I was told, that if the cap that goes over the end of the cranksgaft, has a wear mark that you can feel, where the main seal was riding on, you could adjust the seal, so it didn't contact that area again .

[Mike V]

Bob,
Main seal work went flawlessly, and, I believe your ststement about depth of the seal not being important is true. I measured the original seal depth with the press tool and re-set the new seal to the original depth just in case. There's plenty of contact area on the guide ring. The new and old seals are obviously different in appearance and manufacturing. I've attached a Photobucket pictorial link with instructional text in case anyone wants a graphic review before executing the work on their own bike. The bike is a 1981 R65. Critique and any corrections to errors is always welcome.

http://s428.photobucket.com/albums/qq8/gruntyman66/81%20R650%20Restoration/Rear%20Main%20Seal/
 
Mike V.

[Crossrodes]

Very nice tutorial Mike.

[Rob Valdez 79 R65]

I added a comment to one of the pictures!

[trolle]

You did remember to block the crankshaft at the front end to hinder the shaft from slipping forward??

greetings from a grey, wet, cold, and dark north - even at mid day

[nhmaf]

It would be a very good addition to our maintenance/repair wiki section - if you contact Justin B or Justin Morrison they can help you with moving pictures over, etc.

[Mike V]

Thanks guys, I've made some amendments to the pictorial to clarify. I "did" include the crank blocking originally but just now embellished a bit in the opening photo.
I'm currently experimenting with using the existing stator bolt instead of a fabricated block or having to purchase a special bolt. Any experience with the use of the stator bolt is welcomed. Seems like a very appropriate "airhead" procedure to me.
I will definately look into the posting of the Wiki. Justin Morrison is local, I'll give him a shout. Appreciate the advice and help!

A big shout out to the Vet's today, Happy Veteran's Day and a heart-felt thank you to all of you that have served in any capacity!

Mike V. / San Diego

[Semper Gumby]

Nathan at Boxerworks insisted that I soak the new seal in motor oil for two hours before installing.  I've been waiting form mine to start leaking.....


...still waiting.

Is the Heavy Flywheel 1979 and 1980 have the same bits as this one?  I don't recall the inner o-ring.

[Mike V]

Semper, I was informed that soaking the seal is not necessary since the seal material of the new seals do not absorb oil. The new seal's material looked nothing like the original that I removed. The original seal was pliable with an internal spring nestled in an interior groove of the wiper, much like I would expect to see. The replacement seal (11 11 1 338 342) was made of an abrasive type of material with a copper color and a very simple wiper. There are spec sheets available on the material. I was informed by the airhead gurus only apply a light film oil to the case at it's seal seat to aid in the installation.
The earlier, heavier flywheels don't have an individual thrust (guide) ring, the ring is part of the flywheel and I don't know that there is an inner o-ring on that application.
I'll let you guys know if it starts spewing oil when it's finally running.  

[Rob Valdez 79 R65]

I'm currently experimenting with using the existing stator bolt instead of a fabricated block or having to purchase a special bolt. Any experience with the use of the stator bolt is welcomed.  

I cut a short length of the appropriate sized allen key.  It protrudes from the rotor bolt and creates an interference.  I will measure it when I get home, if you like.
Some folks weld a thin piece of flat steel to one end to act as a buffer against the front cover.  I don't have a welder.

[Rob Valdez 79 R65]

Is the Heavy Flywheel 1979 and 1980 have the same bits as this one?  I don't recall the inner o-ring.

Yes, there is a groove on the inside of the flywheel for the o-ring.

[Landlubber]

Thanks Mike for all your effort, much appreciated. Nice to see someone take so much care in their work.