[T3] camshaft bearings

[Jim Adney]

On 21 Jun 2013 at 7:58, ken2k wrote:

> For a standard 1600 rebuild what is the difference between single
> thrust and double thrust camshaft bearings and which should i get?? 

A set of camshaft bearings consists of 6 half bearing shells. In the 
stock set, only one shell has end faces to take the thrust caused by 
the helical cut cam gear. You can buy sets with 2 such shells, so the 
2 shells that are nearest the cam gear share the thrust. This is 
probably most useful when you're changing something about the valve 
train that requires more effort on the part of the drive gear and 
thus produces more thrust: things like wilder cams, stiffer springs, 
more lift, larger valves, etc.  

A stock engine really doesn't need the extra thrust faces, but I 
sometimes install them anyway. You would have to modify either the 
bearing or the case to accept the tang that keeps the bearing from 
spinning. Sometimes I will reuse the old thrust bearing and add that 
to a new single thrust set if the old bearing shows minimal wear.

If you do a lot of engines, you will also find that different makers 
provide different lengths of shells for the middle bearing. I can't 
tell you much about that, but it's probably of minimal importance 
because there's not much force on that bearing.

-- 
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Jim Adney, jadney at vwtype3.org
Madison, Wisconsin, USA
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