fluid drive tries to upshift

[jorg]

hello,

I have a fluid drive that tries to upshift, sometimes it succeeds but other times not and it is scraping his gears. when it does upshift it can suddenly downshift and not upshifting again.

what could be the problem?

 

Jorg

[Dodgeb4ya]

Check the transmission oil level .

[jorg]

the transmission was rebuild, and oil level was filled till it came out of the fill plug. it did work ok for a while.    

 

jorg

[joecoozie]

5 hours ago, Dodgeb4ya said:

Check the transmission oil level .

Check the oil level in the Fluid Drive coupling. That may be low.

Could also be faulty wiring/solenoids.

 

Try this , too.

http://www.imperialclub.com/Repair/Lit/Master/012B/cover.htm

http://blog.oldmoparts.com/fluid-drive-information/

[Dodgeb4ya]

Going around a corner and dropping out of high or not upshifting is a sure sign of low trans fluid.

Certain bare trans wiring can ground out causing a downshift or prevent a upshift.

Oily governor contacts will cause erratic shifting problems too.

 

[wagoneer]

The hydraulically controlled transmission uses similar principles standard transmission with solenoids and extra plungers to automatically push the synchronizers between the power gears (1 and 2), drive gears (3 and 4). 

 

First, your information tells a couple of things:  

    1. Rebuilt - there could be some error in the rebuild or in the adjustments necessary during install)

 

    2. Gear clashing - Synchronizer issues - could be related to gear teeth, front shift fork issues, or worst case the input shaft could be out-of-center causing improper synchronizer meshing that worked for a while but then eventually wears. Also depends on whether you have problems in drive (synchronizer issue -   https://youtu.be/wsuDpTADKZ4?t=500)  or reverse/first gear clashing (could be remote steering gear nut adjustment to push fork far enough).

                                                                          

 

    3. Worked well for a while and then stopped working - likely something got loose, and I would tend towards electrical problems over trans problems, though could be improper wear due to improper alignment of shafts.

 

    4.  Shifts successfully, but then Drops out of gear and won't go back up - synchronizer stop rings fails to remain locked and pops, possibly your idle is too high, or interrupter not working properly so the friction isn't taken off the input shift to allow the shift to go back up. 

 

 

Troubleshooting steps:

1. Oil level - as recommended elsewhere, the governor can't push the fork without having enough oil, but your symptoms don't sound like lack of oil because it tries to up shift indicates the check valve is pushing oil to adjust the shift fork.

2. Check your idle speed - too high would prevent the interrupter relieving enough pressure to allow the upshift; there may be some carb issues that might need addressing to get idle speed and performance proper. 

3. Electrical - follow the "up and down rule" in the Troubleshooting the Hydraulically operated transmission  

      A loose connection could mess up the whole system, or possibly the interruptor or the governor. 

4. Check remote control gear shift adjustment (see standard transmission video)

5. You may need to reopen the trans to check the synchronizer stop sleeves for wear, proper shaft alignment, and gear teeth.

    Last option for obvious reasons.

 

 

In 1949, Chrysler MTSC did segments on both types of transmissions. They are really excellent to understand how it works, and why it works, and symptoms of failures, that will give you the right intuition to understand your own failure scenario: https://mymopar.com/browse-mtsc-by-model-year-1949/
  

Definitely watch and read the following and read the corresponding MTSC.That's my first go-to for understanding. Interestingly, the videos have MORE information than the reference books. Shop manual makes a lot more sense then. 

 

 

1. Standard Transmission

https://mymopar.com/mtsc-1949-volume-2-6-transmission-fundamentals/

https://www.mymopar.com/downloads/mtsc/018.pdf

2. Troubleshooting standard Transmission

https://mymopar.com/mtsc-1949-volume-2-7-troubleshooting-in-the-transmission/

https://www.mymopar.com/downloads/mtsc/019.pdf

3. Hydraulically operated Transmission

https://mymopar.com/mtsc-1949-volume-2-11-inside-the-hydraulically-operated-transmission/

https://www.mymopar.com/downloads/mtsc/023.pdf

4. Troubleshooting the Hydraulically operated transmission.

https://mymopar.com/mtsc-1949-volume-2-12-how-to-service-the-hydraulically-operated-transmission/

https://www.mymopar.com/downloads/mtsc/024.pdf

 

 

 

 

 

 

[chrysler1941]

And what did you fill it with?

In 3 gear, what speed does upshifting occur ? The answer will make for easier diagnosing.

Edited July 2, 2021 by chrysler1941

[jorg]

I use 10w oil.

I lowered the idle rpm and that solved the problem mostly.

it still rattles a few second before it shifts to 4. it shifts when driving approximately 15 - 20 mph.

 

Thanks Jorg

[chrysler1941]

17 hours ago, jorg said:

I use 10w oil.

I lowered the idle rpm and that solved the problem mostly.

it still rattles a few second before it shifts to 4. it shifts when driving approximately 15 - 20 mph.

 

Thanks Jorg

RPM should be around 450. If it stalls, turn idle mix screw CCW.

Has it solved  staying in 4th ?

[jorg]

yes it does stay in 4th now.

only the rattling during the shift takes a few seconds.

 

Jorden

[wagoneer]

Hi @jorg  

 

     Glad to hear a simple idle adjustment resolved most of the issue.  The rattling issue sounds like something loose (better sounding than clashing, I guess) like possibly the front shift fork. You may try to just feel it with your hands underneath the car to see if it's unusually loose and adjust the linkage to remove slack. Maybe check to see if the interruptor switch and governor are seated in their positions snuggly through the interior access panel under the carpet.

 

A shift-rattle can only be a limited set of moving items, and any deeper you have to go internal.

 

You may consider putting the back wheels on stands, and recreate the shift rattle while listening carefully or with one of those automotive stethoscopes to pinpoint the rattle.