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Automatic Transmission not shifting into 3rd
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jcboland
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PostPosted: Fri Jan 15, 2021 9:25 am    Post subject: Automatic Transmission not shifting into 3rd Reply with quote

My Bus //
1975 FI 1.8L with Bendix 003 Automatic Transmission

Issue //
I was driving home two days ago and for some reason my bus wasn't shifting into 3rd gear. It had been fine two hours before when I drove to the beach, but all of a sudden it wasn't shifting to 3rd anymore. 1st to 2nd was still fine, but I was driving around 43 mph and surging up to 4,300 rpm and it was staying in 2nd.

Background //
Ever since I've had this bus (about 2 years), it has had issues with hard shifting. It would sometimes make a bit of a jerk when it was shifting gears. I recently changed the ATF (about two weeks ago) with Castrol Transmax DEX/MERC as it said it was Dexron III. At the time, my filter was pretty clean and there wasn't much concerning in the pan I thought. I am just starting to learn about the automatic transmission so I thought I would post my thought here to get some help trouble shooting.

What I've done so far //
I have a copy of the Dasher Bentley manual as it has a more comprehensive coverage of the automatic transmission. It suggested that this issue could be from one of three things:

1. Governor or governor drive defective
2. Valve body assembly dirty
3. Direct and reverse clutch defective

- I've been hoping that because I can still drive in reverse, the D/R clutch can hopefully be eliminated. Is this fair assumption?
- I pulled out the valve assembly and cleaned the exterior without opening it up. I was a bit wary and intimidated and it was a bit more of an exploratory mission to understand what was in there as I was hoping to keep the bus operational during the day as it is my only car. I carefully separated the valve body, separator plate and transfer plate making sure to keep an eye on the balls and springs.
- I cleaned everything out by hand and replaced the balls and springs. I noticed that the ball valve (labelled "Ball spring for 3rd/2nd gear valve" in Bentley) in the transfer plate didn't have a spring (I am 99% sure I didn't lose it; it didn't seem to be there when I opened it up. What do these ball check valves do? I can't imagine this is my issue if it came on so acutely; Is there any way a spring could have disappeared or it could have been functioning fine without this spring and then all of a sudden stopped shifting to 3rd?
- the 1st gear band piston and accumulator fell out and they had a fair amount of 'metal silt' on them so I clean them out. seals were in good shape.
- I am assuming I probably need to disassemble the valve body and clean it in a solvent to really have an impact correct? There's little change to the functionality if I am just cleaning the exterior. There were some pretty alarming chunks of metal (see image below) that were sitting on top of the valve assembly. No idea where they came from.

- I pulled off the governor cap but couldn't pull it out all the way with the dipstick in the way so I will have to do this when I drop the pan again. From what I could see, it looked in pretty decent condition, but who knows if I couldn't pull it out all the way.


Questions //
Am I on the right track? I think I probably need to take some time to clean the valve assembly properly, inside and out. And when I am doing this, I will pull out the governor as well. Is there something else I should be looking at? How terrified should I be about those metal bits? Is the D/R clutch a problem? Does this problem seem like something I can address myself in a week or should I be planning on getting someone to do a full overhaul of the transmission.

Thanks in advance for any help or suggestions!!




Chucks of metal sitting on top of valve assembly

Image may have been reduced in size. Click image to view fullscreen.


Sitting in this cavity here
Image may have been reduced in size. Click image to view fullscreen.


Other images of the disassembly
Image may have been reduced in size. Click image to view fullscreen.

Image may have been reduced in size. Click image to view fullscreen.
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rugblaster
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PostPosted: Fri Jan 15, 2021 9:32 pm    Post subject: Re: Automatic Transmission not shifting into 3rd Reply with quote

I'm leaning more toward the governor. It controls the upshifts. If there were a problem with the direct/rev clutch pack, you would not have reverse either. First I would quit taking the valve body apart. The dealerships had location trays to put all the balls, springs, and spool valves in to keep them organized. I'd check the governor and make sure the valve inside it moves freely with the flyweights. If it is free, the next thing I would check is the 2/3 control valve and spring in the valve body. There is probably some shit lodged in one or the other

Those loose pieces are worrying. Are you sure they are metal? Some of them look like a lip seal....in other words, rubber. If the fluid doesn't have a burnt smell and just dirty fine particulate in the pan, you're probably ok and just have a sticky or lodged control valve.

It's been 30 years since I worked on these so..........????
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'09 MB E350 '18 MB E400, '65 Plymouth Valiant convertible and a '19 Ford F250 King Ranch (nicer, but dirty, farm truck)

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airschooled Premium Member
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PostPosted: Sat Jan 16, 2021 1:13 am    Post subject: Re: Automatic Transmission not shifting into 3rd Reply with quote

After a routine flush & fill, do not attempt any surgery on a 003 until you have verified your vacuum modulator is a) holding vacuum and b) adjusted correctly.

For B, hydraulic pressure must be measured at two ports under different conditions. It is helper to have a helper, or the most secure wheel chocks you can muster. You'll need the "hydraulic pressure test kit" from Horrible Freight or Jeff Bezos, unless you're testing frequently in which case quality tools are more accurate.

The bus 003's also appreciate a functioning kickdown switch under the throttle pedal. If buggered, the transmission could keep the engine wound out but good.

Lastly, it's important to check all vacuum connections in the engine compartment, regardless of induction. The vacuum modulator treats a vacuum leak or plugged hoses as "full throttle" and shifts late and hard even under lighter loads. (Those with aftermarket carbs, confirm FULL manifold vacuum at all times to the 7mm vacuum line. Balance tubes mandatory on duals, progressives can tap the brake booster hose.)

It's been a few moths since I've worked on these… Occam's razor! Wink
Robbie

PS, NONE of that applies to late 010 bus automatics Smile
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timvw7476
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PostPosted: Sat Jan 16, 2021 2:04 pm    Post subject: Re: Automatic Transmission not shifting into 3rd Reply with quote

just have experience with 010 autos.
that metal right in the middle of one of your images would worry me a bit.
seeing as you just changed fluid, did you measure capacity with a warmed
engine/trans while idling? VW autos need full capacity to access all three
forward gears. Low fluid would keep it in lower gears.
Good luck with it. They are simple not-so-modern transmissions.

also, if you do strip this down, just order a new diaphragm spring for the
forward clutch, they do break eventually & prevent the FWD piston from returning. then no forwards, just reverse. $2.85 part.
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rugblaster
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PostPosted: Sat Jan 16, 2021 2:24 pm    Post subject: Re: Automatic Transmission not shifting into 3rd Reply with quote

The auto part is as simple as it gets. It's that ATF through the final drive and into the torque converter that is kinda hairy legged. I was digging through some of my junk the other day and found a new oil pump drive shaft if anyone needs one of those.
_________________
'69 Karmy, '69 Camper, Meyers clone, '65 drag bug, 10.78 @ 128 (sold it) '51 Dodge farm truck,
'09 MB E350 '18 MB E400, '65 Plymouth Valiant convertible and a '19 Ford F250 King Ranch (nicer, but dirty, farm truck)

VWoA factory trained line tech 75 till 90 or so
ASE Master Certification
VWoA Assoc. of Quality Technicians inductee (One of 25 in the five state southwest region)
La Confrerie des Chevaliers du Tastevin (San Angelo Chapter)
TCU ......GO FROGS!!!!!!
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raygreenwood
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PostPosted: Sat Jan 16, 2021 5:56 pm    Post subject: Re: Automatic Transmission not shifting into 3rd Reply with quote

Ok....I have been inside more than a few 003....but like the others its been a long time.

Some observations:

In this first picture:

Image may have been reduced in size. Click image to view fullscreen.


1. The blue arrow part looks like a chunk of allen key. If its actually square it "could" look a little like a governor shaft but if it fell out it should be in the differential section.

2. The yellow arrowed part...looks a little like part of a flat snap ring. More on this in a minute.

3. The yellow circle...look at that little hook shape. Keep that in your minds eye.

4. The big red circle I kind of matched up to the curvature of those two broken aluminum pieces.....and they look like something about as big as that red circle I drew.


So.....looking at the type 3 book at the 003 exploded view:


Image may have been reduced in size. Click image to view fullscreen.


Look at that "hook" shape in the yellow circle. Its part of a boss...that contains a big flat snap ring shown by the red arrow. It keeps your servo piston locked in place.

Here is a close up:

Image may have been reduced in size. Click image to view fullscreen.


Pure BS speculation....but could the hooked end curved piece be a cracked off boss that allowed part of teh snap ring to escape and are messing with the servo piston?

Ray
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