[T3] Dizzy drive gear...

Jim Adney jadney at vwtype3.org
Fri Apr 12 19:20:30 PDT 2013


On 12 Apr 2013 at 16:21, FE Meek wrote:

> It can be done...but be aware of the components involved.  There
> should be at least one, if not more washer/shims under the upper shaft
> flange. 

Our engines should have 2 shim washers.

> If these do not come out with the distributor drive, they are either
> missing originally or missing currently, having fallen into the
> case...not good either way but the latter is more immediately
> concerning. 

The most common outcome is that the 2 washers remain in place on the 
shelf where they belong. While there's always the possibility of 
falling into the engine, I was reassured by Russ that out of all the 
hundreds of engines where he had done this, he had never had one of 
those washers come up with the drive gear or fall down into the 
engine.

I should add, that if this is a carbed engine, with a mechanically 
driven fuel pump, you MUST remove the fuel pump, the pump pushrod, 
and then the pushrod guide, IN THAT ORDER. Do not try to pull them 
all out together.

> There is also the problem of removing the drive initially.  If you have
> the proper tool, things are better, but still this will not prevent the
> shim(s) from going south.  The safest solution is to do this on an
> engine stand, minus most of the oil, (let it drain for a day or more),
> and turn the engine so the case drive hole is upside down...and still
> be ready with a magnet or two when you pull out the shaft.  

Even this doesn't always work, but I can see the appeal.

I just pull the drive gear now and hope for the best. Work slowly and 
carefully, with no quick jerks. Once the drive gear is out, stick a 
long stiff wire down there, all the way thru the washers and the 
bottom drive gear bearing. Then you can move it around to re-center 
the washers.

The real trick is in figuring out how the drive gear must go back in. 
You have to be at TDC, but the angle shown in Bentley isn't exactly 
right. I think there are 12 teeth on that gear, however, so that's 30 
deg per tooth, so there's only one location that's reasonably close 
to the illustration. As was already pointed out here, make sure you 
understand the illustration before you start. The case halves mating 
plane is the key. IIRC, the illustration is drawn as if you were 
standing on the left side of the engine.

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