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Re: [T3] Crankshaft Specs...???


On 21 Apr 2002, at 21:52, John Jaranson wrote:

> Bearing #        MJD        Measured
>                  (mm)        (mm)
> Main #1        54.83        54.88
> Main #2        54.83        54.86
> Main #3        54.83        54.88
> Main #4        39.82        39.87
> 
> Rod #1         55.84        54.87
> Rod #2         55.84        54.87
> Rod #3         55.84        54.88
> Rod #4         55.84        54.88
> 
> Cam #1         24.86        24.90
> Cam #2         24.86        24.90
> Cam #3         24.86        24.90

>From Service Without Guesswork, range of acceptable sizes:

Crankshaft 1,2,3: 54.97 - 54.99mm
			4: 39.98 - 40.00mm
			rod: 54.98 - 55.00

Camshaft: 24.99 - 25.00mm

Your numbers seem low with enough consistency that I wonder about the 
calibration of your instrument. It's tough to measure to this accuracy.

I would think that this amount of undersize might be little problem. A more 
important question is often how smooth is the journal? Also how round? If it 
is still both smooth and round, then it is probably fine. You lose significant 
strength and hardness when grinding undersize, and I think this is often done 
when it really isn't needed.

I don't ever recall worrying about the camshaft journal wear. The limiting 
factor is always the wear at the crest of the lobe. I frequently reuse cams 
which show a bit more wear than VW (see the Bentley) recommended. I only 
did this because I was cheap, but nowdays I'd worry that a new cam would 
not be of good quality.

Did you know that Berg can weld counterweights without grinding the crank? 
You can send it to them and ask if it is good enough, then get the CWs 
added if it is, or exchange it for a .010/.010 if it isn't. This is a very good 
option if you're inclined to go that way.

-
*******************************
Jim Adney, jadney@vwtype3.org
Madison, Wisconsin, USA
*******************************

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