[T3] Automatic Shifting

Jim Adney jadney at vwtype3.org
Fri May 2 08:00:43 PDT 2014


On 2 May 2014 at 7:33, Craigs List wrote:

> I have a question for those with automatic transmissions. Do all of us have
> to shift with fluctuation of the gas pedal? My automatic likes to shift
> into second far to early and never wants to shift into 3rd. I have to let
> of the gas completely to coax it into shifting.

It seems odd that one shift happens early and the other happens late, 
but the fact that blipping the throttle helps the 2-3 shift tells us 
that this is related to the vacuum modulator in some way. No, this is 
not normal.

First, what year is your Type 3? The '72-3 ATs were different from 
the earlier ones, and they take a different VM. So the place to start 
is to make SURE you have the right VM and that it is adjusted 
correctly. The AT chapter of the Bentley manual covers the adjustment 
of the VM. The pressure they give there is correct for the early 
years; if you have a late AT, I'll have to dig for the number.

You don't need the fancy pressure setup from the AT shop, but you 
will need a 50 psi pressure gauge that will screw into the 10 mm port 
on the side of the AT. I find that a 1/8" NPT gauge will screw in 
there nicely.

Genuine VW VMs will have the part number stamped on the face of the 
VM. Early FI VMs end in A with a yellow paint stripe, while the late 
ones end in C and have a brown paint stripe. Genuine VMs adjust with 
an Allen wrench. If yours takes a small screwdriver, it's a generic 
aftermarket replacement and it will probably help if you install a 
correct one in there, especially if this is a late AT. 

If your car has been  converted to aftermarket carbs, this may be 
part of the problem, as the vacuum signal will be different from that 
which the VM was designed for.   

You should also pull the vacuum hose off the VM and see how much, and 
what color, oil drains out of there. A small amount of dirty black 
oil is normal and is just condensation from the intake manifold. If 
you get a lot of red oil, that's ATF and that means the VM is leaking 
and should be replaced (and adjusted.) Check the condition of the 
hose to make sure it is sealing well at both ends. Hose clamps should 
not be necessary, but the hose should be snug on its connection at 
each end.

Finally, the VM sticks down slightly below the AT pan, so it's 
possible that it's been hit and bent. If it's bent, you could try to 
straighten it, but you may have to replace it. A bent VM can be 
sticky, and this might also explain your problem.

If you have to replace your VM, keep in mind that ATF will pour out 
of that hole when you remove the old one. Have the new one ready and 
don't forget the alum sealing washer.

Depending on what year you have, I may have a new VM if you need one.

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