1-2 shift too soft

[Ron]

I lost my old pressure gauge, so I tried turning it maybe 10 teeth (15psi), and it gave me a very bad slipping 3rd gear shift and really only marginal improvements with 1>2.

I'd put it back where it was and investigate further...
(Of course , the D's "Vacuum Capsule" is different than a modulator valve...)

[David T]

If the problem is the timing of the shifts the most likely cause is a problem with the shift computer. There are plenty of tech articles on how to troubleshoot and repair it.

[81dmc]

It?s not a timing issue. I have a DMCH computer.

Issue is the shift from 1 to 2 takes a bit of time, then it goes into gear, or it shudders into gear.

I guess I?ll have to go get a gauge. Is it 1/8npt?

[81dmc]

FWIW, there's bubbles on the dipstick, and it's at the perfect level too. Running Valvoline Maxlife synthetic ATF.

[Ron]

FWIW, there's bubbles on the dipstick...

There's a red flag!...since the level seems OK, maybe: filter, vent stopped up, etc.

[81dmc]

There's a red flag!...since the level seems OK, maybe: filter, vent stopped up, etc.

Where's the vent?

I put a DMCH filter because I had some things packed, but now I can install one of the filters Michael offered. I have a box of them. Also, maybe I'll put some Allison Transynd ATF.

Anything else I should inspect in there? Should I pull the VB?

[David T]

Where's the vent?

I put a DMCH filter because I had some things packed, but now I can install one of the filters Michael offered. I have a box of them. Also, maybe I'll put some Allison Transynd ATF.

Anything else I should inspect in there? Should I pull the VB?

The transmission was designed to use Dexron III. I have no idea how it would react to anything exotic or synthetic. The gauge port is a metric thread. I can't think of any good reason to remove the VB. If it is shuddering into gear you should get a light box and see what the shift computer is doing. Maybe it is commanding 2 gears at once or it is fluctuating between 1st and 2nd. You should also go over all of the external adjustments, throttle cable and gear shift linkage.

[Ron]

I put a DMCH filter because I had some things packed, but now I can install one of the filters Michael offered. I have a box of them. Also, maybe I'll put some Allison Transynd ATF.

Anything else I should inspect in there? Should I pull the VB?

Valvoline Maxlife synthetic ATF is supposed to be usable where Dextron VI is called out. Dextron VI is downward compatible with all previous Dextron ATF. The manual calls out Dextron II...
So, your fluid should be fine.
You should be able to see anything that's wrong with the filter: loose/torn/clogged up...
The VB is the last thing you want to mess with, imho.

I can't remember exactly where the vent is...you can blow smoke into the dipstick tube and look for it near the top of the case.

[81dmc]

I decided to take a whiff of the atf from the dipstick, and I don't know if it's my nose playing tricks, but I smell gear oil.

Is it even possible for that to happen? I thought pressure alone would push atf into the final drive not the other way around...

In any case, I?m going to change the ATF and collect a sample to be sent to blackstone. They can tell me if something is mixing.

[81dmc]

Here's a video, it's mainly noticeable by looking at speedo during 1-2 shift. It's like a hesitation before it shifts, and it's getting worse.