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"Mercedes" method

Started by marku, 09 March 2017, 09:48 AM

marku

Saw a crankshaft, for an early Porsche, that was described as made using the Mercedes method. That is with solid connecting rods that don't split for the bearings and assembled throw by throw. This so and when did the practise stop?
450SE silver green/bamboo velour/green vinyl roof

UTn_boy

I've not ever seen this on any Mercedes engine I've ever been inside of.  The engines I've been inside of range from the late 1930's up until the early 1990's.  In addition, I've never seen a Porsche engine made this way either. 
1966 250se coupe`,black/dark green leather
1970 600 midnight blue/parchment leather
1971 300sel 6.3,papyrus white/dark red leather
1975 450se, pine green metallic/green leather
1973 300sel 4.5,silver blue metallic/blue leather
1979 450sel 516 red/bamboo

marku

OK I had never heard of it either and it seemed a really unnecessary way of making one - even changing the rings would mean the crank coming out. Wouldn't take much common sense to see that it was a non starter.
450SE silver green/bamboo velour/green vinyl roof

1960mog

Could be a early 356 Carrera . They used this type of roller bearing crank.
78 6.9 #4084
79 6.9 #6669

marku

That seems right but what would you gain by it? Does seem a lot of work to manufacture and are roller bearings really better than shells? And why was it called the "Mercedes" method as there doesn't seem to any Mercedes engines with it.
450SE silver green/bamboo velour/green vinyl roof

1960mog

In the old days most high performance engines had roller bearing cranks.  Plain bearing technology wasn't that good back then.
They could take higher RPMs since the rod is not split and they don't need oil pressure.
Splash oil is enough, in a two strokes some oil in the fuel is enough.
Roller bearing cranks are still used today in some motorcycles.
78 6.9 #4084
79 6.9 #6669