[T3] Early vs Late Automatic

[Jim Adney]

On 12 Dec 2013 at 6:37, Adam Douglass wrote:

> I keep hearing of "early" vs "late" units. How do I identify one vs
> the other? What part numbers am I looking for? Where are the part
> numbers located? 

There are actually 3 generations:

'68-9 had 5-bolt flanges around the output shafts. These were 
eliminated in '70, making the construction slightly simpler, less 
leaky, and more reliable. Very early ones came with torque converters 
that had fewer, larger cooling fins. Those are less desirable, but 
the later TCs are an exact replacement.

'70-1 lacks the 5-bolt output flanges and has a vacuum modulator with 
a diaphram section (the large diameter part) that's less than 1/2" 
thick. These are the best units in my opinion, but that's based on 
very little data. If your car is a '69-71, this is the style you'd 
hope to find.

'72-3 looks just like the '70-1 except that the vacuum modulator has 
a diaphram section that's more than 1/2" thick. If your car is a  
'72-3, I hope you find one of these.


On ALL of these ATs, it's important to know that the vacuum modulator 
is located in a place that's very vulnerable if the AT is sitting on 
the ground. If the VM gets bent, you may be able to straighten it, 
but it's likely that it will have to be replaced. And if you have to 
replace it, it MUST be adjusted, which is a fair bit of work.

> I also hear that the automatic unit out of a Squareback is unique.
> What is the difference? Again, what am I looking for? 

Fastback and Squareback ATs are the same, but they are different from 
all other VW ATs. Don't try to make do with a different version.

> Any words of caution anyone has? I am pretty much stuck with this
> unit, but I want to know what I am getting. It can help on the price
> negotiation if I have more knowledge. 

If it's been dragged around on the ground the VM is toast. The late 
VM is expensive, and you can't replace it with the early one. Try to 
get it with the TC, but pull the TC off to check the snout on the 
tranny for wear where the seal seals. Polish that snout before you 
reinstall.

There is a dome cover on the upper left side that is sealed with an 
O-ring. Replace that O-ring before you install the AT. It's just easy 
to get to then, and that O-ring always needs to be replaced. I have 
the O-rings or you may still be able to get them at a VW dealer. 

In general, our ATs have been very reliable. The most common problem 
is that leaky o-ring and leaks around the output shafts that leave 
the final drive dry and ruin the differential gears. Note that this 
unit takes both ATF and GL-5, so make sure to drain and fill both.

If you take off the AT pan to check it out and drain the fluid. Don't 
overtighten the pan bolts. Tighten to the spec torque, wait 5 
minutes, tighten again, wait 5 minutes, tighten again. I STRONGLY 
recommend a set of Belleville washers here to replace the split ring 
lockwashers that VW used. The Belleville washers will prevent 
deformation of the pan, as long as you don't overtighten the bolts.

It's a bit of extra work, but you might be wise to remove the output 
flanges and replace the output seals before you install an old unit. 
If it's been sitting a long time, there could be rust there that 
would quickly destroy the seals and lead to oil loss and failure of 
the final drive.

When you go to install it, pull the TC off and check the inner shaft. 
It will pull out and you'll want to spin it in your fingers as you 
install it to make SURE it's all the way in. Then install the TC. The 
TC isn't in correctly until the stump in its middle is flush with the 
mating face of the tranny. Check it with a straightedge. Make SURE 
this is correct BEFORE you mate it to the engine.

These ATs have been so reliable that I have to ask, what went wrong 
with yours?

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