300sd transmission won't up shift Help

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brujan@electrotex.com - 01 Jul 2006 15:32 GMT

I have just finished changing my transmission out on the floor of my
garage and now with a stiff back I drive the car, the test drive
reveals that my replacement tranny
won't shift to top gear. It shifts quite fine and smooth untile at
55 I am doing 3000 RPM and there is a solid back lash as I let off the
gas. I have checked my linkage and I know for sure that I am driving
with the shifter lever in the first detent past neutral. I have
disconnected the wire to the kick down solenoid, I swapped the solenoid
from the old tranny, the vacuum hose is on the modulator (with
vacuum), I have checked the the detent cable is relaxed and not
providing too much tension. Before I
go raise hell with the junkyard that I bought this perfect $800
transmission from dose any one know what I could have done to cause
this or what I should check that I have not already checked. This is
quite depressing and I would rather the problem be my stupidity some
how rather than that this transmission is bad.
Thanks,
Bruce Buchanan

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T.G. Lambach - 01 Jul 2006 19:12 GMT

Did you count the shifts?

Starting out from a dead stop in L, is 1st, shifting up to S and
immediately BACK to L will hold 2nd, then on to S for 3rd and D for 4th.

My 300SD runs at 3,000 rpm at 65 mph (70 on the speedo).

I believe you have done all the right things to check the installation.

Suggest you disconnect the pressure rod or cable to the throttle linkage
to force early up shifts.

There's a problem for sure if it's then unchanged.

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brujan@electrotex.com - 01 Jul 2006 21:07 GMT

I have done that. I have had this car out for several drives, all with
the same result. I completely disconnected the pressure rod or cable at
one point and no change. There are two shifts, they feel normal and at
the right speeds but at about 38 mph I would expect a third shift, that
shift never takes place. As you reach 55 the engine is 3000 RPM (way
too fast), I have run it up to 3800 or so the engine starts to surge if
you push this. At no point can I get it to shift to 4th. Even with a
tight pressure rod you would get a shift at some eventual speed I would
think. I would think stuck kick down but I think I have eliminated
that as the cause. What is bad, I turned down several transmissions
over weeks of searching that all wear about $500 and finaly was willing
to pay $800 for this one that came from a quite reputable parts
supplier and has 98K on it. The transmission looks like the genuine
article, is still shinny. It was quite a shock to find it will not
provide as good a service as looks good. Well thanks for your thoughts
Tom and if you have any others send them over here.
Bruce Buchanan

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Richard Sexton - 02 Jul 2006 01:00 GMT

>I have done that. I have had this car out for several drives, all with
>the same result. I completely disconnected the pressure rod or cable at
>one point and no change. There are two shifts, they feel normal and at

It starts off in second, not first. So, one shift is to get to
third, the next one to fourth.

If you hold it in low manually then let it go and shift up
you should feel three shifts.

This is all perfectly normal.

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T.G. Lambach - 02 Jul 2006 01:10 GMT

I don't know what internal parts trigger the shift to 4th gear. No
creative thoughts to add.

Suggest you talk to the yard that sold you this box. I'd suggest
willingness to first change / flush the trans oil and filter at THEIR
expense (incl. torque converter) as a final attempt to make a success of
this box. A failure thereafter is return for a refund - thank you very
much (for wasting a lot of my time!)

In fairness to the yard THEY know nothing more about this box than I do
- and that's zero!

So their warranty is a crap shoot; they know some parts will come back
but since they haven't invested any labor in installation it's not
particularly painful to "eat" a return.

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Tiger - 02 Jul 2006 15:49 GMT

Everything is hydraulic control... so your tranny is bad. Did the tranny
part number match? or has a higher last digit? 722.3xx? It cannot be lower
number than you have...

I am guessing that it is the wrong tranny... possibly one from those that
85MPH max speedo.

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brujan@electrotex.com - 02 Jul 2006 20:34 GMT

Well I checked numbers. Original number 722 303 02 053794 new number
is 722 303 02 222285 is said to be out of an 81 300sd. My car is one
of those only 85 MPH cars but it used to do 85 quite well.

I just came back from another drive. I hooked up a push button switch
to my kick down solenoid and 12 volts so I could energize the kick down
any time I wanted, took it for a drive, I found that I can put it back
into 1st by pushing the button while pulling away from a stop, and I
can put it from 3rd back to 2nd by pushing the button. I figure the
kick down system must not be stuck. Tranny just don't like 4th

I will just wait till tomorrow and take it up with the company that
sold this to me. My biggest fear is that they will want to refund or
exchange the transmission with out a diagnosis and it would be a shame
if there was some simple thing that could solve the problem while
tranny is still in the car. I will at least see a transmission shop
befor I change that box again, I am getting too old for this under the
car stuff, though I enjoy it, my neck is still stiff.

Thanks to all who have answered my post, I appreciate you.
Bruce Buchanan

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