Hello folks. My 85 300 SD turbo takes a long time to shift into 4th gear, usually not below about 42 mph, and then will drop down to 3rd if speed is reduced. Any quick fix ideas out there, like modulator, or an adjustment?
Thanks.
Mike

What are the exact speeds for the 1-2 and 2-3 shifts under the same conditions as when the 3-4 is at 42 mph?

Brian,
Firstly, it's not an SD, and I've edited my post. Just a 300D turbo. I'll have a look tomorrow if I go out driving. I work 5 doors from my house and ususally don't take the diesels to work.
Another thing about the trans, the car downshifts(not a kickdown) to 3rd from 4th very easily thus it appears that it won't hold 4th at lower speeds. Today I put about 100 miles on the car and the trans seemed to bang into 4th a few times. When the car is cold it shifts a bit hard, and it mostly smooths out when warmed up. Would a trans fluid and filter change help? I'm sure it won't hurt. Valve body? Don't know much about that yet but heard it discussed. I'm gonna guess that there's no "magic" tranny flush that would be any good for the car. Correct me if I'm wrong.
Mike

The SD got a 2.88 diff in 85. I'm not sure about the D, 123 diff ratio that yr.
I've noticed the 85s with the 2.88s will 'hunt' for an efficient rpm speed when cruising right at the 3rd to 4th shift point.

This may be good reason to re-evaluate the "benefits" of changing out the diff to a 2.47.
If the engine is running way below its torque peak rpm, it will take more on the throttle to maintain speed. Now if one was cruising at 75+mph on flat roads most of then I could see the advantage. Otherwise, I believe the 2.88 is about as tall a ratio practical.

I'm confused here...... 116 300SD wont touch 4th gear at anything less than 55. According to tachometer narrow power band engine favors 3000 rpm's at least. What's engine speed at 42mph in 3rd with your 1985?

Let me clarify this post. My car is not an SD. It's a 123 300 turbo diesel.
I'll get back to you all with the rpms at shift points.
Thanks.

SD's are being mentioned for 2 reasons:
-Your initial post calls out an SD and,
-the D and SD drive trains are nearly identical.

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'83 300D Turrrbo 295K miles