Living with an Automatic Transmission - PeachParts Mercedes-Benz Forum

llensart · #1 02-17-2018, 09:06 PM

Just recently acquired an 83 240 D with an Automatic Transmission and have a question , On a properly tuned transmission what is the top speed that you can have an Automatic Downshift ? Sorry wrong Part of the forum Admin could you please move to diesel discussion

Diseasel300 · #2 02-18-2018, 11:01 AM

Downshifts are not really "automatic" in the 722.3 Your "downshift" is your foot pressing the downshift button behind the accelerator pedal. Automatic downshifting usually only really happens below 30mph, once you're above that use the downshift button that's what it's there for.

llensart · #3 02-18-2018, 12:14 PM

Thank you for your answer , I really wanted to know at what top speed will the kickdown switch kick in and when is it safe to shift down to the S setting on the shifter without wrecking the transmission its been a learning curve to drive with an Auto coming from an 81 240 D Manual

Diseasel300 · #4 02-18-2018, 03:54 PM

You should have a series of dots on the speedometer showing where the top of the rev range is. The governor on the transmission won't let you shift into the wrong gear if the RPM's are too high. My SDL will downshift from 4-3 at 70MPH as a reference point. Your 240 has lower gearing, so your RPM's will already be pretty high at 70.

chrisgt · #5 02-19-2018, 07:28 AM

Put the transmission in S and run the engine up to full speed, then you'll know exactly how fast you can go in S.

oldsinner111 · #6 02-22-2018, 11:22 AM

these auto's are cool,you can push start them at 30mph.

llensart · #7 02-22-2018, 06:48 PM

Is First Gear in L position and 2nd gear in S ? Also do all downshifts involve the Kickdown switch ? my pedal does not reach the kickdown switch any idea on how to remedy this

Diseasel300 · #8 02-22-2018, 07:22 PM

L is 1st (low), S is 2nd. If you're travelling slowly enough, the transmission will downshift automatically if you give it enough throttle. The bowden cable needs to be adjusted properly for that to happen. If your pedal doesn't reach the kickdown switch, you need to adjust your accelerator pedal linkages. The FSM gives the lengths for the various linkages and is a good place to start.

chrisgt · #9 02-22-2018, 09:02 PM

Quote:

Originally Posted by Diseasel300

L is 1st (low), S is 2nd. If you're travelling slowly enough, the transmission will downshift automatically if you give it enough throttle. The bowden cable needs to be adjusted properly for that to happen. If your pedal doesn't reach the kickdown switch, you need to adjust your accelerator pedal linkages. The FSM gives the lengths for the various linkages and is a good place to start.

Does the 240d only have a 3 speed? My 84 300td isn't like that. L is 1st and 2nd, 1st revs out pretty high before shifting into 2nd. S is 1-3, and D is all gears.

DieselPaul · #10 02-23-2018, 05:40 PM

240Ds do not have bowden cables, they use 722.1 transmissions with the vacuum 2/3 valves.

Diseasel300 · #11 02-23-2018, 06:06 PM

Quote:

Originally Posted by DieselPaul

240Ds do not have bowden cables, they use 722.1 transmissions with the vacuum 2/3 valves.

Even in 1983?

DieselPaul · #12 02-23-2018, 08:29 PM

Unless someone back dated the transmission in my dads 1983, yes.

Diseasel300 · #13 02-23-2018, 08:38 PM

You sure those 3/2 valves weren't for the EGR? The 3/2's went away on 1984 Cali cars and 1985 Federals. '82-84 still used them for EGR. Everything else switched to the 722.3 sometime in 1982, seems weird that they'd have kept the 722.1 on a single model.

DieselPaul · #14 03-04-2018, 07:55 PM

There is no such thing as a 722.3 240D. The OP does not have a Bowden cable. The 722.117 is what was fitted to 240Ds. The 722.118 is very similar and was what was in non turbo 300D 3.0s.

Also consider the 200D and 220D were available and widely produced for other markets. So the 722.1 was not kept on for a single model.

Allegedly incredibly late (123 production lasted into 86 for some markets) got 722.4 gearboxes but that would never have been a USA delivered car and as stated is hugely uncommon even in Europe.

I’ve owned 5 240Ds myself and my father has an 83 currently, they do not have Bowden cables.

97 SL320 · #15 03-08-2018, 07:27 PM

I usually don't get to this side of the list but saw this thread on the main page.

Something to note if our guy has been brought up on manual trans and this is their first auto trans. Resist the urge to press the throttle farther _just before and during_ when the trans is up shifting ( 1-2 2-3 ) Re: in a manual trans the throttle is released, ( shift ) and rolled back into to continue the acceleration process.

The valve body can't react fast enough to raise line pressure and the shifts will be soft causing friction material wear and eventual trans failure.