Seal Bore Size

[jchek779]

Hello All,

I am working on a home project involving a 2 stroke engine. When replacing a crank seal, the seal bore was beat up and since I have tig welded a few 'beads' to the spots that were chewed up. I know have to rebore the engine case and want to make sure I am going to bore at the right size. I plan on using a cylinder bore snap gauge on the untouched portions of the bore for my inteded inside diameter, but I want to touch base with you guys on interference fits and sizes.

Inside the bore goes a rubber seal with a 37 mm outside diameter. I dont have a new seal to measure to be more accurate, but this is the information i am getting about the seals from a website. What type a interference should I be looking for here? .001? .005? Thanks for the help.

Jason

 

[jchek779]

I forgot to mention that the case is aluminum.

Thanks,
Jason

 

[jet1749]

Bore out to dead size, the rubber covered oil seal should have enough "oversize" built in

 

[dichtung]

I'd recommend a radial shaft seal (rss) with elastomeric coating since they can follow the expansion of the housing better. Use bore tolerance d2 H8 or if your housing/recieving bore thin-walled is, then F8. The manufacturer are obligated, according DIN 3760, to produce a rss within tolerances +0,15 +0,30 till oter diametere d2<50mm! If you are constructing 2-stroke motore beware of choosing right material (high rpm=high resistance=high temperature) and constructive form: &quot;normal&quot; rss can catch only 0,5bar and typical for your machine are pulsating presures 3-5 bar!!