Cases

[ford832]

This is probably a dumb question but here goes anyway.I was reading the thread were the guy had rebuilt the Stihl with some of the Aussie parts and it was mentioned that you can't mix cases and they come as a set from Stihl.My question would be,why not?Assuming neither was badly distorted and they were lapped true I can't see an issue.Are they assembled as a set at the factory then bored for crank bearings etc?I guess otherwise I couldn't see too much difference from something that was cast from an identical mold.then again,as my wife says,what do I know anyway? Thanks,
AF

 

[PES+]

I don't know where Lakeside got his info

To my knowledge no manufacturer assembles then line bores cases it is not practical for an assembly line to do so. Also as soon as you take the two halves apart you lose any precision advantage that may be afforded by line boring the two pieces together. If there really was 1 thousandth of an inch tolerance for the crank centers you would never be able to pull them apart and reassemble the halves without major heating/cooling pressing ......ad nauseum.......

A much more critical place for precision from a performance and service life aspect is the cylinder being centered over the crank accurately but even there run of the mill production saws are sloppy as can be.

 

[Lakeside53]

My info came from Stihl engineering in Germany. Believe it or not, it's up to you. It would sure make it easier to stock the cases as separate parts, and they'd sell a lot more... Some cases are available separately (like TS400, older series saws, some weedeaters), just not the 024-088 series.

Check the cylinder mounting surface as well - that is machined while both cases are held in position by location pins - you can see the continuity of marks on some. This you could lap to remove minor variations if you really want to go this route.

I know of some being used mismatched, and I have two very nice clutch sides for an MS440 if anyone wants to try, but...

 

[ford832]

Hmmmm,interesting.I think I'd try it.Maybe when the 026 goes down for a rebuild I'll swap a case with somebody so I can check it out:hmm3grin2orange:
Now that I've said that,I'll probably end up needing one