[T3] Brake Pedal Pushrod?

[Jim Adney]

Questions about the brake pedal pushrod come up here occasionally, 
typically if someone upgrades an early car to a tandem master 
cylinder. I've always assumed that the change was due to some 
difference between single circuit and dual circuit master cylinders, 
but right now I've got a handfull of early Type 3 single circuit 
master cylinders in my basement. So I decided to measure them to find 
out where the difference was.   

It turns out that there is no difference between the geometries of 
those 2 versions of master cylinders! Both versions have the same 
amount of length in the casting and the same depth of the hole in the 
piston.  

So I went to the parts lists to try to figure out what changed and 
when. The first thing I discovered was that while tandem master 
cylinders started at the beginning of the '67 model year, the early 
pushrod continued in use for several months, up to VIN 3x7 123 354. 
That's up to Oct or Nov of 1966.  

So the early pushrod was used with tandem master cylinders for the 
first several months of '67 production.  

So what changed? I've looked at the pans, and there's no change 
listed as of that VIN, and no change for the pedal cluster then, 
either. I can't find anything else that changed at that VIN. I know 
Bob H. has been down this road, and he even has a photo of the 2 
styles of pushrods, side by side. The late pushrod is a lot longer, 
right, Bob? Did you have to replace your pushrod when you upgraded?  

Right now, it sounds to me like you should not have to change your 
pushrod if you update an early car to a tandem master cylinder.  

I know I have a drawing from Dave Hall of the gauge to be used to 
adjust the pushrod, but I can't find it right now. I'm wondering if 
it's only for cars after that VIN.  

If you're updating a single circuit pushrod to a tandem, one thing 
you might want to be aware of is that the shaft of the early pushrod 
is larger in diameter, so it would be best to re-use the rubber boot 
from the early master cylinder, because it has a larger hole for the 
pushrod.  

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