Very rough shifting into gear after fluid change

[Ahealey12]

Update- i guess i never really shifted from reverse to park. That is where it’s rough sounding in first video. I did adjust the throttle blade yesterday and adjusted back and now is not shifting as hard into gear. Also posting videos of it shifting on road. It’s always had a rough shift, that has somewhat improved with the fluid change. Any ideas? I ran through pressures last week below

Used non synthetic dextron 2 and after fluid change it shifts a bit better but after it’s hot it jolts the car when i put it in gear. Any ideas? Fluid level is at top. No more leaks which it had. I had checked and have good pressure at each point if solenoid (a bit under 10 at idle maybe 8, but other two are perfect 40 at part throttle and 60 when kickdown activated). Is my pressure too low at idle maybe? Can hear the shift toward end of video https://imgur.com/a/qdludKS

Driving videos shows the harsh up shifts. Never has had harsh downshifts at all kinda hard to tell in video but def shifts hard from 2-3 and less from 3-4.

https://imgur.com/a/dDd8dYf

https://imgur.com/a/fhXmFXX

[MartinK]

Please check the switch at the throttle assembly. The switch has to be closed up to 1200 rpm. Above 1200 rpm it should be open. The switch has 12VDC current on both contacts and when it is open only on one of the contacts. If the switch is not well adjusted, it causes rough shifting. And please check this together with another person sitting in the car with running engine at idle. The person on the driver's seat should be on the brakes and shifts in R or 4 and the switch has to remain closed!

[Ahealey12]

Finally got a buddy over that could help me test this. Switch does operate as it should. I had also cleaned contacts a couple weeks ago as well.

Another update- it is rougher shifting going uphill vs downhill or flat, not sure if that affects anything?

[WRe]

Another update- it is rougher shifting going uphill vs downhill or flat, not sure if that affects anything?

Hi,
that sounds that your oil level isn't correct. Did you check it with warm engine and running motor or cold one thumb above highest mark?
Does your Dextron II oil have the TASA (Type A/Suffix A) specification?
...WRe

[MartinK]

All DEXRON fluids up to Dexron III  are downwards compatible with TASA.

Edit:
See ATF220 data sheet: it fulfils the TASA requirements: https://www.mobil.com/en-gb/passenger-vehicle-lube/pds/gl-xx-mobil-atf-220
even the high performance Mobil ATF SHC fulfils Dexron IIe and is applicable for TASA purposes: https://www.mobil.com/en-gb/passenger-vehicle-lube/pds/gl-xx-mobil-atf-shc

From the technical point of view it is no matter which Dexron fluid you use up to Dexron III.

[MartinK]

Hei,

concerning this videos it is obvious for me that the idle speed solenoid on the air intake manifold is pushing too hard. The perfect adjustment is, when the idle speed does not rise when setting P or R. Please adjust the solenoid to less idle speed.
https://imgur.com/a/qdludKS

The hard shifting could be caused by an old and hardened diaphragm in the modular pressure assembly on the right hand side of the transmission. If the diaphragm is too stiff it cannot follow the vacuum changes inside the air intake and reacts too sluggish. After changing the diaphragm it is obligatory to adjust the modular pressure. Please take care that the maximum pressure is not above 2.9 bar (42 psi), this causes hard gear change, too.

Talk soon, Martin

[Ahealey12]

Hi yes i adjusted the solenoid right after this video i had adjusted one linkage and hadn’t adjusted that one yet as well.

 Could the diaphragm be reason my pressure is lower at idle but spot on at part throttle and when kick down is pressed? Haven’t heard much about the diaphragm on forum except now reading if it leaks into the intake.

[Ahealey12]

Oil level has been checked many many times. Hot and cold. And after 40 min drive

[MartinK]

8 -10 psi (600 millibar) is a good number at idle speed (vacuum at the diaphragm housing disconnected).

[Ahealey12]

Any way to test the diaphragm before pulling apart?  I did another drive at lunch and it shifts much better while manually shifted

[MartinK]

Hei. No, you have no chance to check the diaphragm. I changed several of them and all owners mentioned smoother gear change afterwards. If the rubber part is 60 years old it is stiff and does not follow the vacuum changes in the air intake manifold that quick. The exchange is a matter of one hour and maybe some pressure adjustment. Its worth a try.

[Ahealey12]

Awesome thank you! I’m making an order tomorrow at Mercedes so I’ll add that to order

[Ahealey12]

Ok did some more digging today.

Tried to adjust the modulating pressure as it was very low at idle and still a couple psi short while driving (about 7.5 at idle 40 at part throttle) The modulating pressure bolt didn’t do anything. It was as if it was loose, do they sell that piece still? The part that actually screws in and out will turn, but it wasn’t going any tighter if that makes sense? Almost as if it’s not the right size for the threads. The nut tightened up but never got fully tight either.


Video of the pressure currently also did verify that kick down works too just didn’t get it on video while driving.
https://imgur.com/a/7aWa4IZ

[miked_md]

The adjuster screw is left threaded into the small metal disc in the modulator.  The spring sits between the disc and the diaphragm.  Turning clockwise the screw will eventually become unthreaded.  There are around 5 turns from the fully counter clockwise stop until the threads are no longer in the disc.

[MartinK]

Did you disconnect the vacuum line off the air intake manifold? The 0.6 bar (8psi) is not adjustable. The only number which is adjustable is the 2.9 (-0.1) bar (40psi) maximum pressure. The kickdown pressure results from the adjustment of the maximum pressure.  Are you sure that you have installed the diaphragm and the spring in the right order?

Turning the bolt clockwise results a rising pressure, turning the bolt counter clockwise lowers the pressure. 0.15bar per full turn

Talk soon, Martin.