air head guys !

[Alfetta]

im wanting to replace the outer most lip seal on my r75/5 final drive. It looks like i have to extract the shaft that the axle slides through then remove the needle roller bearing for the crown wheel to gain access to this seal. However i am not finding a source for a replacement.

I don't know if this seal is a normal "off the self" size or if it is special.

Can anyone give me input on this ???

[Dirk_S]

Have you tried MAX BMW or BOB’S BMW for part sourcing?

Also, just so we really know what part you’re referencing, any chance you can point out the part from the parts fiche? Link to Max’s parts landing page for the R75/5:

https://shop.maxbmw.com/fiche/DiagramsMain.aspx?vid=51885&rnd=10232024

[Alfetta]

It is item 2 in this image.



I have looked at several BMW sources, Max, Capitol, Bob's, etc...  Found an England site but they say contact us on this part.

[Dirk_S]

Is this it? Found on Euro Moto Electric (EME definitely should be in your top 5 biz for airhead parts)

https://www.euromotoelectrics.com/searchresults.asp?Search=33+12+2+301+019&Submit=

[Antietam Classic Cycle]

Fairly common size seal - 30 x 42 x 7 - so should be available from bearing retailers.
https://www.mcmaster.com/1199N317/

[Alfetta]

Thanks Dirk and ACC...  Once i saw dimensions were given on Bob's web page, i placed an order at local bearing supply house.

This looks like a challenge to extract the needle bearing without damage.  I don't see much space between the end on the bearing and the lip seal for a extraction tool.
and i may be pulling on the thin wall on the bearing end.  Not a friendly seal to service, that's for sure.

[Antietam Classic Cycle]

Thanks Dirk and ACC...  Once i saw dimensions were given on Bob's web page, i placed an order at local bearing supply house.

This looks like a challenge to extract the needle bearing without damage.  I don't see much space between the end on the bearing and the lip seal for a extraction tool.
and i may be pulling on the thin wall on the bearing end.  Not a friendly seal to service, that's for sure.

I've never done the job on a BMW, but on big-block Guzzi rear drives I heat the housing in an oven (or on the woodstove in Winter) and the outer race of the needle bearing either falls out by itself or after a few bonks onto a piece of soft wood. When installing, chill the bearing and warm the housing. 

[guzzisteve]

I used to work on them everyday, haven't since 90's. You need to pull out needle bearings, similar to Guzzis. BMW has a special puller for it as I believe.
When finished you need to check contact area w/ink or blueing. Good Luck. Another source is Nathen at BoxerWorks in Watkinsville, GA. Good Luck, I don't miss it at all.

[n3303j]

Get out the torch and heat the aluminum housing a bunch (or throw it on the barbecue).
The steel parts expand a lot less than the aluminum.
The steel parts will almost fall out.

[Alfetta]

I cant get it much hotter that 150F as i don't plan on extracting the pinion gear. and i am not touching the seals on that shaft.
The intent is to get this old girl operational at a minimum cost. but the crown wheel was leaking badly so it must be corrected.
ring and pinion are in very good shape. so if i don't pull the pinion and return the original crow wheel shims, it should be good enough.

[n3303j]

I assume you don't have all the tools to service this final drive.
If you did then pinion removal is easy (and non invasive).
Pull the ball spline on the input shaft and threaded ring in the housing.
Then the assembly pulls out of the housing.
If you replace all the shims as you found them AND use the original cover gasket then all gear tooth relationships  will remain as found.

[Moparnut72]

A heat gun was one of the most used tools in the aircraft engine shop where I worked for a bit after retirement. We had to replace them on a regular basis. Makitas lasted the longest.
kk