How does 126 #3 compare to 123 "S"?
 

My indie mechanic has suggested that I drive around in "3" in my '87 300SDL,when I'm cruising around the city,up to around 40 mph...use "D" for higher speeds and rpms.Can I take this suggestion to mean it's not a bad idea to use "S" while cruising around in an '83 240D??Are the "'3" in the 126 and the"S" in the 123 comparable??TIA for the usual variety of good advice!

why not just put it in drive? why does he want you to put it in 3rd and "s"?

Good suggestion from that mechanic. I always drive in slow traffic in "3" in the '87 300D. Keeps the brakes from wearing and warms up the engine better if its cold. Engine dynamic braking. I can't seem to teach my wife to do that however :mad:
the 240D is a different set of conditions however

I agree with the mechanic. The SDL will perform better in third around town. It's a dog when it shifts to fourth.........when you want to accelerate at 30 mph it's a PITA unless you downshift. The engine will be happier and you will be happier.

The 240D, with its 3.69 gears, will be screaming in third at 40 mph........you won't be able to stand the noise.:eek:

I always cruise about in 3rd in my L and the SD up to about 45mph. After that it is 4th (D, 1:1) to get RPM back down.

Turbo will be on the boil and less wear on the trans. :)

personally
 

i put it in drive in my 350sdl and leave it there.

but the 350 is pretty torquey.

tom w

Just leave it in drive. There's no real benefit to leaving the shifter in "S" around town. You don't just need higher RPMs and more fuel flow, but you need more air flow as well to clean out the engine, which you get best at a high load, like high speed driving, or Italian Tuneups.

45 is fine for a 300D in 3rd. For a 240D, 35mph is better for the gearing

A thread like this comes up from time to time on another board I'm on-http://www.crownvic.net. On that board, it's generally known that the Ford AOD tranny has a weak 4th (overdrive) gear and should not be cycled more than needed. With the 722 MB trans, I am aware of no such weakness. My Benz goes in D before I leave the parking lot and there it stays.

BTW, my Sammy has an even better setup. It goes into whatever gear I choose, when I choose-manual 5 speed. I wish all my cars were manual (pauses for poetic reflection about slushbox-loving American new car buyers):mad:

Yeah it only has a 1.5" OD band stock. :eek: :puke: I have a 4R70W OD setup in mine currently, still on stock 2.40:1 first gear which is a bit lame but the close ratios (1.47:1, 1:1, 0.67:1) are nice with a decent rear gear and a 28" tire. :D

I drive in S generally in the city for to/from school driving, up till around 40, then I'll drop to D so its not such a high rpm. My car will go from 18mph to 110 in 4th without much complaint, its got enough torque to be "fine" in D at all times, but I enjoy the more sudden "surge" you can get when cruising in S, way more torque. Its likely also better for the engine than going along at 30mph and 1,250 rpm.....

Ever since I mentioned driving in "S" to my dad as an option, he tried it, and now does it for most of his driving, even up to about 50-55mph!! :D

I just stick it in D and go... around town youre at about 1800-2000 RPM or so in 4th gear which is perfect for low rpm torque/diesel engines.

I'm so glad I don't have to fight my tranny for control anymore. Now I choose when I want to change gears! :D All I need now is to find a 5-speed for the highways.

"warms up the engine better when cold"

wouldnt this have the same effect as flooring it? holding it in 3rd just makes the engine turn faster. i dont like to really open up the throttle when the engines cold.

Turning faster creates more internal friction in the engine and requires a bit more fuel......so.......it will warm faster in 3rd than in 4th......everything else being equal.

Flooring it will warm the engine very fast........but.......it's not all that pleasurable for a cold engine.