[T3] Auto shift issue

[Tim Keohane]

I slipped under the car last night an checked the VM. It's a 003-325-391A. That tells me it's for the 68-71 model T3's. I read where, VM's, for 72-73 T3's and 72-73-74 T4's are the same. I located and purchased one that is supposedly OE and never installed. Ouch $$$. I will presume that is correct and install, however I will still make the gauges to be sure on the pressure settings.
Tim 
73 T3 auto
On Sep 10, 2015, at 5:55 AM, Jim Adney wrote:

> On 9 Sep 2015 at 9:28, Tim Keohane wrote:
> 
>> My T3 is shifting (automatic) from 2nd to 3rd at 55 mph. It seems like it was at 45 mph in april. It has been sitting for 3 months and upon re-introduction to the road it just started this. The shift from 1st to 2nd is at 20-22 mph. The shift is very positive (solid engagement) and that we must run it up to 55 to get it to shift into 3rd. It will stay/cruse in 3rd unless/until the speed drops to 45 mph, then it down shifts to 2nd. It seem like it's about 10 mph to high. 
>> Bently suggestions are the next step: checking pressure 
>> 							        verifying that the vacuum modulator/canister is the proper one. 
>> Does anyone know the thread size for the test ports. ( I will make 2 pressure testers)
> 
> The shift points vary depending on how much throttle it's given. 
> That's what the vacuum modulator does (varies the shift point 
> depending on intake manifold vacuum.) So if you're doing this test 
> with full throttle, shifting at 55 is probably correct.
> 
> If this actually changed recently, the first thing to do would be to 
> pull the vacuum hose off the VM and see if the hose is full of ATF 
> (red.) If it is, you need a new VM. A little bit of black oil is just 
> condensation from the intake, so that can be ignored. The correct 
> '72-3 VM is different from the early one, and is very hard to find.  
> 
> The AT pressure test points are M10 x 1 threads, but a brass 1/8" NPT 
> fitting will work there for temporary testing. The pressure specs 
> given in the Bentley are correct for the '68-71 ATs, but not for the 
> '72-3 ATs. Unless the diaphram in your VM has broken (ATF in vac 
> hose) it's very unlikely that you will find that the VM is to blame 
> for this change, so I would not expect it to need re-adjustment. The 
> VM adjustment is a set once and forget thing.
> 
> It's possible that something in the valve body has just gotten sticky 
> and needs to be "exercised" to free up. It may just need to be driven 
> and warmed up a few times.
> 
>> I have changed the fluids and cleaned the screen.
> 
> Always a good move.
> 
> -- 
> *******************************
> Jim Adney, jadney at vwtype3.org
> Madison, Wisconsin, USA
> *******************************
> 
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