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  #31  
Old 10-19-2012, 12:19 PM
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Quote:
Originally Posted by Govert View Post
If only the bowden cable/plunger doesn't work properly, you will take-off in second gear (instead of first gear) and there will be normal upshifts, only at the lowest possible speed. You will be in fourth gear at around 30 mph. This applies to D. In 3 the upshift will be to 3rd gear only, at lower speed, around 20 mph. If you use L (or 2), the car should start in first and stay in first until the maximum speed of the first gear, then it should shift to second gear.

Now if is something is broken, the transmission can behave unexpectantly, i.e. not as described above. Inspecting the bowden cable can be done easily, it attaches itself on the passenger side of the transmission. By turning the plastic connector, you can pull the cable from the transmission. The cable should be attached by a hook to the plunger. Clean the area before this, you don't want dirt to enter the transmission.

Are you only using the VCV or did you transfer the vacuum transducer too?
on my car with a 722.4 trans - If I shift to 2 it does achieve maximum engine speed in 1st before it shifts into 2.

My question in alignment with the above is that if I floor the accelerator from a standstill with lever in D and everything adjusted as the book tells, it should reach maximum engine speed before shifting to 2nd gear and subsequent higher gears thereon.

In my case it falls short 1000 rpm, even with bowden cable tight to the point that it will tight as a guitar string at full pedal.

What can be a cause?

btw ATF was clean and clear, almost as new colour when changed.

I was told that it might be a fuel issue - but according to experience and after consulting with others too, with having fuel issues the engine should balk and hang at some revs with pedal to the floor, bowden pulled tight which causes the trans not to shift unless the pedal is let go. This is not the case with my car.

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  #32  
Old 10-19-2012, 01:00 PM
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If you're going to rebuild.

I STRONGLY urge you to replace the governor gear, and the worm gear that drives the governor AND whatever that valve thing that goes bad on the secondary pump that can cause the governor to size.

Your 416 has a plastic gear as well!






Effected Transmissions!
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  #33  
Old 10-19-2012, 01:31 PM
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Originally Posted by JamesDean View Post
If you're going to rebuild. I STRONGLY urge you to replace the governor gear, and the worm gear that drives the governor AND whatever that valve thing that goes bad on the secondary pump that can cause the governor to size.
Good advice, thanks. That's what I was looking for.
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  #34  
Old 10-19-2012, 01:39 PM
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Quote:
Originally Posted by mach4 View Post
Good advice, thanks. That's what I was looking for.
Id replace the B2 piston too. Any plastic tubes as well. There is one that pours ATF on the output shaft area in the tailshaft.
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  #35  
Old 11-02-2012, 01:32 PM
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Update

The 722.4 transmission remains drivable, even quite normal, as long as you're either accelerating slowly, or manually going through the gears. The symptoms I'm experiencing do not match up with any of the normal problems I've read about and seem to point to a sticky valve internally. Since the tranny is eventually going to need rebuilding I decided that it wouldn't hurt to try some Trans-X as a last resort. I'm going to run it for another couple hundred miles just to see and then make a decision.

Rather than rebuild the 722.4x, I've got a line on a 722.3x out of an '83 300D that I'm thinking of swapping in. This strategy seems to have some benefits. This is the same model as what came with the 380SL originally and this is a stronger transmission than the 722.4x. I can eliminate my NSS adapter cable. And I can use the tail cone off the 380SL transmission and eliminate my kludgy (but effective) external electronic trigger wheel speedometer setup.




I've got two questions -

[1] can/should I run the 722.4 torque convertor (which I believe is a higher stall speed one) or the 722.3
[2] can/should I keep the vacuum transducer setup from 722.4 with the 722.3 or eliminate that

Anything else that I should consider or am missing in thinking through a solution?
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  #36  
Old 11-02-2012, 01:51 PM
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I'm not 100% sure what you mean by "vacuum transducer" - if you mean the vacuum dash pot then I say you are better off having the correct dash pot for the transmission you fit.

I would keep the 722.3 torque converter with the 722.3 transmission.


If you want to check the valves in the valve body you might find the information in this thread useful

http://www.peachparts.com/shopforum/diesel-discussion/323259-722-303-bits-photo-shoot.html

Some where in there I've got pictures of the outside of the valve body with information that corresponds to the position of each valve and what each valve does...

...so if you have a problem with shifting from one gear to another then you know where to look etc etc etc

722.4 might be a little different but it does remain the unwanted bastard child of the 722.3 so it is related...
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  #37  
Old 11-02-2012, 02:24 PM
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The vacuum transducer is indicated by the red arrow. Also known as the blue flying saucer.



The transducer has a different vacuum output (typically between -0,7 bar and -0,05 bar) and the transmission is probably adjusted for that. So if you put in a 83 transmission, it might not respond well to the transducer output. So you by-pass the transducer and hook it up directly to the VCV.
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  #38  
Old 11-02-2012, 02:32 PM
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Quote:
Originally Posted by Govert View Post
So if you put in a 83 transmission, it might not respond well to the transducer output. So you by-pass the transducer and hook it up directly to the VCV.
Great thanks.

Quote:
I would keep the 722.3 torque converter with the 722.3 transmission.
Ok
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  #39  
Old 11-02-2012, 05:44 PM
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Quote:
Originally Posted by mach4 View Post
.....

...

[1] can/should I run the 722.4 torque convertor (which I believe is a higher stall speed one) or the 722.3
[2] can/should I keep the vacuum transducer setup from 722.4 with the 722.3 or eliminate that

Anything else that I should consider or am missing in thinking through a solution?

The 722.4 torque converter is physically smaller than the 722.3. Plus the it will not fit the input shaft of the 722.3 trans. So you cannot swap them.
The only issue I would consider is since you are running a 2.47 rear ratio, the benefit of having a higher stall converter helps in stand still acceleration. So sourcing an '85 Federal torque converter maybe a wise move.

I would keep the transducer setup and try it on the trans, that is if it's working properly originally. It might respond very well with some modulator adjustments. You will never know unless you try it.


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  #40  
Old 11-10-2012, 05:33 PM
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I suctioned out transmission fluid to make room for a can of Trans-x, and added it to the transmission. I used this version.



The theory was that the transmission would need to be swapped/repaired anyway, so it was worth a shot.

After a week, there has been absolutely no change in the operation of the transmission.

I really think it is just a stuck valve or a clogged passageway that is preventing the proper shifting. To summarize:

With the selector in D the transmission shifts very quickly from 1-4
With the selector in S the transmission shifts very quickly from 1-3
With the selector in L the transmission starts in 1 and stays in 1

If I start in L and shift to S it shifts very hard into 3
If I downshift into L while the car is moving, it downshifts to 2 and if I then upshift into S it shifts to 3 quite smoothly.

It would seem that this set of functions would eliminate most major components e.g. the B2, the modulator, the bands, clutches, torque convertor, the pump(s)

The one thing that it could be pointing to is the Bowden cable, but the Bowden cable is adjusted reasonably and appears to function reasonably (meaning that there is good spring pressure when pulling it manually, indicating that it is pulling on something inside the tranny) and running it without the cable connected makes no difference in the operation.

Is it possible that the piston is stuck internally? but if so, why is there spring tension on the cable?
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  #41  
Old 11-10-2012, 05:44 PM
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More Data

I just had a friend disconnect the Bowden cable on his engine as a test. He got very similar results to mine which would seem to point pretty strongly to a pressure control valve problem. Since it isn't the cable it must be something internal.

That being the case, is there a possible fix short of a total rebuild?
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  #42  
Old 01-19-2013, 11:02 PM
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I thought I'd close out this thread with a description of the solution that I went with. I decided that the transmission was bad and needed rebuilding or replacing. I opted to replace.

I had a spare '83 617 with a 722.315 of unknown condition sitting in the garage. I also had the original engine from the 380SL with a known good 722.312 transmission. I thought long and hard about trying the gasser transmission as a test, but in the end chose the safer option of the diesel transmission even though it was a junk yard unit and untested.

I pulled the engine and transmission, swapped transmissions and put the combination back in the car. I was also able to eliminate my NSS pigtail and, by using the tailcone from the 380SL transmission, I was able to eliminate my variable reluctor bracket from the external speedometer pickup and use the stock mount in the tailcone.

Wow, what a difference. It was like a different car. I also swapped in the new filled motor mounts with the softer urethane and eliminated the filled transmission mount at the same time so the elimination of the vibration problems helped a lot.

Initially, the new trans did have the annoying 2-3 and 3-4 flare, but only under very light load. I put a pressure gauge on the modulator test port and found it was reading about 2 pounds light. After turning up the modulator to the 42 pounds spec, it now runs absolutely perfect. I am running the blue vacuum transducer from the 722.5 transmission and it appears to be running just fine. I may try eliminating this as a test in the future, but for now, it's just fine.

At first the transmission leaked fluid like crazy. One problem was a bad cooler flex hose that just decided to start leaking and the other was a leak around the cooler lines banjo fittings. Swapping out the hose and reseating the banjo fittings took care of the leaks.

Thanks to all for all the diagnostic help with the 722.4xx problem.
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  #43  
Old 01-20-2013, 03:14 AM
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Good to hear that you've got it sorted. I'm not that surprised to hear that the older technology came to the rescue...
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  #44  
Old 01-20-2013, 11:14 PM
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I have a 91 300d 2.5t with I think a 722.418 trans and it's seems to be toast.
It has basically has no forward gears or reverse, if you put it in drive or reverse and floor it will eventually start to drag enough to get the car to move some.
Fluid is smoked!
Thoughts?
Some have suggested changing the fluid and B2 piston?

DD
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  #45  
Old 01-21-2013, 12:09 AM
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Quote:
Originally Posted by DieselDummy View Post
Thoughts?
Some have suggested changing the fluid and B2 piston?
I think you'll have better luck getting responses if you open a new thread

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