400E- late 1-2 upshift (transmission 722.3)

[werminghausen]

Since some time my 400E does not want to upshift as usual (at 1500 with low gas). All other shifts are normal. I tested the solenoid (Kick down) and it works properly. So the reason for late 1-2 upshift (at 2500 -3000rpm) is NOT a stuck kick down solenoid.
I think it must have to do with the valve body (VB) .
Unfortunately I don't know a lot about the details inside the VB but I know the 1-2 shift points are controlled here. I have seen this is a very complicated diagram.
It might be that a spring is broken or a piston does not move?

The 1-2 upshift problem happened over time , started last year with a few late upshifts and has become worse so that now the transmission won't upshift 1-2 normally any more.

Any help or information about the transmission is welcome.

I have a spare 722.3 transmission and I could fool around with swapping the VB but I wanted to hear the opinions first before I do the VB swap.

Martin

[party]

Perhaps cold shift delay vacuum actuator is malfunctioning?

[werminghausen]

Party,

1-2 cold start upshift delay is executed by the kick down solenoid... only with cold engine.
I disconnected the solenoid and this did not change anything for the late 1-2 shift. So I assume the problem might be in the Valve Body
Martin

[werminghausen]

I found a diagram in some information Nicholas sent me.
1-2 upshift is controlled by #17/18/19
Does anyone know if the problem is in this area?

Martin

[Sugar Bear]

Sorry I don't know about 17, 18, or 19. If your thinking it may be in the valve body, I've had success with Lubegard transmission additives improving shifting with what I believe was a sticky valve. Might be worth a try.

Good luck!!!

[werminghausen]

Hey Bear,

I don't believe much in these additives. I have tried Trans tune from Seafoam with no result.
I'd be happier if I did understand the interiors better and find the reason for the weird behavior.
Martin

[Frank Reiner]

w:

In addition to the very distinct possibility of a sticky 1-2 command valve, there is a similarly distinct possibility of a sticky governor. For a given road speed, the transmission output shaft speed, and hence the governor speed, is quite low due to the 2.24:1 final drive ratio. The internal 1st gear ratio is short (~3.7:1), and so engine speed is high for a low output shaft speed. If the governor is sticking from a stop, and then "pops" free, any subsequent shift behavior will be normal.

[werminghausen]

Hi Frank,

thanks... great,
you said the late 1-2 upshift might be the case because of the low output shaft speed and governor stuck until it moves?
Any idea how to tackle a 'sticky' governor? Is there any access....well with the transmission in place.... ?
Or do I need to remove the transmission [again].
Martin

[Frank Reiner]

Originally Posted by werminghausen

Hi Frank,

thanks... great,
you said the late 1-2 upshift might be the case because of the low output shaft speed and governor stuck until it moves?
Any idea how to tackle a 'sticky' governor? Is there any access....well with the transmission in place.... ?
Or do I need to remove the transmission [again].
Martin

When the trans was new, the governor weights moved smoothly at low rpm; as the trans gains miles the weights will wear a bit, and may develop small notches/grooves that tend to hold them from prompt movement. As a result, higher output shaft speed/road speed, and attendant higher engine speed is required to achieve the initial governor response.

The governor is accessible from the outside of the trans; it is on the left side towards the rear. If the trans can be tilted down a bit by removing the rear mount & crossmember, and the driveline, there may be enough clearance below the tunnel to extract the governor.

[werminghausen]

Thanks Frank,

I was lately changing a leaky (vacuum leak) control cable unit at the 400E....what a pain because there is just no space around the tunnel on a W124.
So my fear is that removing and reinstall the governor is no easy task with the transmission installed.
I'd need to take another closer look.
I guess the left side rear governor cap has to be clear and this access is enough to remove the governor?
How difficult is this job assuming there is access to the governor port ?
But even if I can remove the governor is there a method to see the wear and see if i can get a better governor...assuming they are available new or used?
Martin

[Frank Reiner]

w:

If access to the governor is too difficult in the 124 chassis, the default first step would be to remove the valve body and inspect the 1-2 command valve(s).

[werminghausen]

Originally Posted by Frank Reiner

w:

If access to the governor is too difficult in the 124 chassis, the default first step would be to remove the valve body and inspect the 1-2 command valve(s).

Frank,
what would you look at when removing #17/18 and 19?
is there any obvious wear or damage to expect in springs and pistons?
I am just curious.

Governor: the W124 tunnel is much tighter as the one on the W126.
Still I'll have a look.
How difficult is the removal of the governor. Can it be done through the one opening? I know before I installed the replacement transmission I replaced the rubber ring at the governor but did not touch the governor.
Martin

[Frank Reiner]

Originally Posted by werminghausen

Frank,
what would you look at when removing #17/18 and 19?
is there any obvious wear or damage to expect in springs and pistons?
I am just curious.

w:

In inspecting the valve components, look for any grooving, scoring, ridges, burrs, notches, etc.; that is, anything that would appear to be the result of wear, and that might cause the piston to catch in the sleeve, or the valve in the bore of the valve body.
Anything that might impede the free, smooth movement of the valve components would have the effect of raising the governor pressure (and thereby road speed/engine speed) required to initiate the shift sequence.

[werminghausen]

Thanks Frank,

I was driving the 400E last weekend for testing... that car is so much fun... if there were not the late upshift.
Weirdest thing happened when I started. The engine had to rev up to 4k (cold0 until it shifter 1-2.
WOW that scared me with cold engine... that cannot be healthy.
After the engine warmed up I had the now 'normal' 1-2 upshift between 2500 and 3000

I then remembered that my wife reported last year (it is my wife's car) that she had a situation when did not want to upshift and I did not believe her then.
Because I could never reproduce this until the late upshift was established as a new normal.
I just wanted to report this and maybe there is a hint (VB or governor ...that is the question) for those who know.

Martin

[werminghausen]

Upshift 1-2 Problem Solved!

I did finally remove the Valve Body from the transmission. Removal was very simple: remove approx. 15 bolts and the VB will fall into your hands.

Then I opened the plate where the 1-2 upshift valve parts are hiding, inspected #17/18/19 Parts on the bench under clean conditions but could not find anything suspicious at all.

Then I removed the VB from my donor transmission and put it on the bench (next to the other VB) and did the same thing. I did not find anything suspicious in the donor VB either. Everything was clean, nothing damaged or sticky. I put it back together.

Then I decided to install the donor VB (This VB is from the transmission that was damaged, metal chips in the oil pan).
Since the VB swap my transmission is shifting 1-2 correctly at 1500 rpm with low throttle.

I am very, very happy for this but I did not find the cause for the late upshift in the
Bad VB that is still on my bench and I want to renovate it.

Can people give me any advise how to open and clean this VB. I wanted to take the time and inspect the VB and possibly find some clues.
What is the process of rebuilding the VB?

Can you help me?

Martin