722.120 shifting issues
 

Hello all,

New to me owner of a 78 300SD T/D. PO seemed to take very good care of the car and even with 340K on the clock it's a pleasure to drive. So I'm trying to make sense of my shifting problems. I'm finding that in order for it to shift upwards, I have to let off on the throttle. Is this considered a "hard" shift of a "soft" shift? Any advice as to why you think this might be so. I will check all my linkages and see what's what...but a general idea of why this is happening would be most appreciated. My locks all work well, car shuts off quickly and all vacuum items "seem" to work. I've checked my fluid and it's not burnt and looks and smells good. Car goes down the gears no sweat. There seems to be little to no lag time when I shift into gear or reverse. Also...what RPM's should I be looking at with this trans and engine (617.9) I'm getting 3000RPM at 65 and about 3200 rpm at 70, does this sound right?

Your help is appreciated.
Thank You
Duke1

Rpm's are correct. Do a search on 'bowden cable'. You don't have a cable but a rod. The function is the same. It controls shift points. Vacuum controls harshness or softness of shifts. It doesn't sound like you have any problems there, just in the shift points. A stuck kickdown switch will also push shift points upwards.

Both my 722.1 have no cable or rods....

Its all done with vacuum on mine....

Vacuum is critical to their operation....

I don't know what the number of my tranny is, but my 79 116 SD has a rod. His is a 78 so I assumed it would also have a rod. I know there are transmission solely controlled by vacuum but I thought all of them were on non-turbo models.

Ah, Maybe....

All mine have been and are N/A....

We never got the Turbo in the UK, for some daft reason!:mad:

Kerry,

Thanks for the reply...I will search for Bowden Cable. I do have the rod from the top of my valve cover to my transmission. So by searching above words..this should tell me how to adjust this rod? Also wondering what the dots are for on the speedo. I'm assuming their shift points? One dot means out of 1 and into 2 and so on?

Thanks,
Duke1
(Mike)

The dots are the MAX speed for that gear. Not when they would shift. After all, the shift point is based on rpm, speed, load, etc. Not just speed alone.

Yes, tightening or loosening the nut at the end of the rod at the valve cover changes the length of the rod and moves the shift points.

Thanks for the info. So should I adjust it in or out so to speak to make it shift without taking my foot off the pedal?

So I adjusted my control pressure rod in (shorter), and adjusted the trans modulator to less pressure and it will now shift nice and smooth. My question now is shift points. 2 to 3rd gear does not shift until 35mph @3500 rpm. 3-4 shifts at 55mph @3500, unless I back off on the throttle. It shifts briskly, but not harshly. Are my shifts points too high? If so, I would adjust this with the contol rod?

Your help is appreciated.
Mike

you could have a stuck downshift button under your fuel pedal.