[T3] Auto shift issue

[Jim Adney]

You checked the ATF level with the engine running, right? If you 
check it with the engine off, you'll get a wrong reading. (You'll 
think it's fine when it's actually quite low.)

On 15 Sep 2015 at 9:32, Tim Keohane wrote:

> I'm fairly sure the parts are still stock. We have had the engine
> rebuilt twice in the last 23 years. It's possible the IAD is from a
> 72, but I think not. It was originally a California car and still has
> the EGR tube (blocked off) in place. I will start to double check as I
> have several parts boxes and am going to move on the non 73 parts. 

So they must be "stock" but not necessarily '73 stock. As I said 
before, there's something different about the VM ports (plural) on 
the '73 IAD.

> The transmission is one we replaced last fall. It had been rebuilt
> several years prior and was (reportedly) stored with oil in it. We
> purchased it converter and all, then discarded (:( ) the old one. Thus
> the adjustments without a gauge. The mechanic is good, experienced,
> and honest so I have no reason to doubt him. It did come with the "A"
> VM. 

So it may be an earlier ('69-71) version of the AT, for which the A 
version of the VM would be correct. The important parts here are the 
VM, the valve body, and the governor. Those 3 parts need to be a 
matched set.

But, I guess the one important question here is, "Did the combination 
of parts that you have work correctly at some point?" If it did, I'd 
stick with the A VM.

> My Bently (brown cover) says from 1968 on the automatic transmission
> is an A E. If there is a difference it must be internal. The different
> VM's speak to some modifications, but is sounds like the basics are
> the same. So far I am unable to locate a designation on the
> transmission. 

The AE is the prefix to the AT serial number, just like your engine 
number should have a prefix of U or X. Sorry, but I'm not sure where 
to look for it. It's not clear to me whether all Type 3 ATs have the 
AE prefix or if they changed and the changes just didn't make it into 
the Bentley. The Bentley is the absolute best manual out there, but 
it's not perfect.  

>  The Bently photo shows 6 ports with set screws, mine has 4 with cap
> screws, and one with a cast recess but no sat/cap screw or visible
> threads. I left the car up so I can slide under and check again today.
> Will spray cleaner and bring a tooth brush as some spots have a little
> dirt on them. 

Yes, VW used different styles of screws. I think the hex heads are 
always better than hex sockets because they are MUCH less likely to 
strip out the hex. This is simply because the hex is so much larger. 
I was thinking there were just 4 ports, but you're only interested in 
one of them. Figure out where that one is and check the pressure 
there.

> Is there another way the diaphragm can fail? It looks like it was
> tightened with a large set of pliers. The case has some marking and
> the slightest deformation. One must look closely to see it. Thats all
> I can see externally. 

If they get bent, the diaphram won't be able to push the rod that 
controls the valve body. (The rod gets jammed.) This is always a 
problem if the AT has been on the ground. The VM sticks down below 
the pan, so it's quite vulnerable. If it looks bent, try 
straightening it. It's possible that this is all it needs. If that 
seems to fix it, and shifting becomes better, forget about the 
pressure, since there's uncertainty about which pressure you should 
set it at. (Since you're not sure which version you have.)

FYI: There were actually 3 different versions of the Type 3 AT sold 
in the US.

#1 was used in '69 and has 5-bolt side covers where the drive shafts 
come out. It used the A VM and the governor and valve body that went 
with it.

#2 was used in '70-1 and eliminated the side covers and also uses the 
A VM and matching governor and valve body.

#3 was used in '72-3 and also lacks the side covers, but switched to 
the C VM and the matching governor and valve body. This valve body is 
actually different from the early one.

The B version of the VM was used on ATs sold with dual carb engines. 
I don't know what governor and valve body it used.

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