Automatic Transmission not shifting into 3rd
Posted: Fri Jan 15, 2021 6:19 pm
Greetings IAC! First time posting here, long time bus owner, perpetual student of the aircooled. I have an automatic transmission issue that arose this week and I thought I'd try to get some extra thoughts as I haven't really monkeyed around with my transmission ever.
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!! (Hopefully this is not too verbose; attempting to be detailed and comprehensive)
Chucks of metal sitting on top of valve assembly
Sitting in this cavity here
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!! (Hopefully this is not too verbose; attempting to be detailed and comprehensive)
Chucks of metal sitting on top of valve assembly
Sitting in this cavity here