Upshifts at what speeds and what rpm ? - PeachParts Mercedes-Benz Forum

MVK · #1 07-20-2002, 06:59 PM

Hello there:
Can anyone please tell me on a 1985 300D Turbo
( Automatic Tranny), under normal driving conditions what are the speed sequence for upshift of gears from 1 to 2,
2 to 3 and then 3 to 4.
Also at these shift points( just before the shifts from one gear to another) what should be the RPM reading.

Now again this is not pressing the pedal to the floor. I am talking about the Normal Driving Conditions.

Thanks

MVK

Holson Adi · #2 07-20-2002, 07:14 PM

I usually drive with around 1/2 throttle and the transmission shifts around 2000 +/- 250 rpm from 1-> 2.

Other shifts are about the same. I can't be exact as it seems to change every now and then. However it's usually that way. 7/8 throttle usually makes the tranny shift at around 3500 rpm.

Full throttle makes it shift at 4500rpm and it sounds amazing and shifts amazingly nice when floored. Kinda weird...

People who ride in my car think the turbodiesel engine sounds nice when floored.

I can't really say what the speed is when it shifts. However when it's floored, it usually upshifts right at the I , II, III marks on the speedometer.

sorry that I can't be more of help. I'll pay more attention when I drive later (before it's dark.. otherwise you know what it's like to read the instruments when it's dark)

240Joe · #3 07-20-2002, 07:35 PM

I don't know if this helps or not, but somewhere I read that at full throttle, the transmission should shift at about 90% of the dots on the speedometer.

It seems that if you make your bowden cable adjustment to that, it should be ok at less (more normal) throttle.

I assume you are adjusting the cable, or thinking about it.

Joe

psfred · #4 07-20-2002, 08:38 PM

Your car should sit in 2nd gear, downshift to first as soon as you open the "throttle", and then shift into 2nd at about 15 mph, into 3rd at about 20, and into 4th about 30 mph under light throttle. Shifts should be fairly soft, although perceptible.

Shift points should be higher the farther down the pedal is, and with the kickdown switch activated, should be about 90% of the speed marked by the dots on the speedo. Shifts should be firm, with no flare between gears.

Any variation from this pattern of speeds suggests a broken or misadjusted bowden cable or, more likely, leaking vacuum lines on the vacuum modulator system.

Peter

MVK · #5 07-20-2002, 09:53 PM

Thanks Holson, Peter And Joe:
Thats really helpful. Yes I am trying to adjust the bowden for right shifts. The shifts are pretty nice no flares etc. Shifts from 1 to 2 very quickly, then 2 to 3 is a bit slower than 1 to 2 but I still feel that the time spent by the car between 2 to 3 should be longer and finally 3 to 4 seems to be ok.
However by the time it falls in 4 th gear its about 45 or so under normal condition.

Why am I doing the adjustment? Well I try to make the story as short as I can.
The PO had the valve job done and at that time they must have detached the throttle linkage, when they put it back, the cruise control link and the connecting links were messed up and attached in wrong way. But amazing all things were working well including cruise. only problem was the emergency stop was not working as it had no room to press. I did the look up in 123 CD and found the problem- reattached all links the way they are supposed to be, emergency stop works, amazing thrust of power now but the shift is a bit messed up so the bowden needs to be adjusted. Amazing story huh. I am really impressed by these work horses- works well even if the linkages are misattached.

I thank you all for your quick feed back. Holson hope your newly fixed AC is keeping you cool.

MVK

engatwork · #6 07-21-2002, 10:42 AM

I have been working with my 300D every since I have had it trying to get it to shift "later". It is in high gear by the time I get to 30. I recently drove a 300SD that shifted GREAT compared to mine. Anyway, I feel pretty certain that the kickdown solenoid is inoperative. I will start troubleshooting the switch/solenoid over the next couple weeks and see what I can find.
thanks

MVK · #7 07-21-2002, 11:19 AM

Ok I will be watching for your results.

MVK

JoelS · #8 07-22-2002, 10:30 AM

engatwork said:

"I have been working with my 300D every since I have had it trying to get it to shift "later". It is in high gear by the time I get to 30. I recently drove a 300SD that shifted GREAT compared to mine. "

Remarkably similar experience to my 85 300td...it shifted way too early, which didn't allow the turbo to kick in until highway speeds. After driving an 85 300SD (126), I was blown away with the way the transmission behaved. Knowing that both cars have the same engine and transmission (I think...), I figured mine had to be capable of the same. I, too, had suspected that my kickdown switch was inoperable. Previously, mechanic had mentioned that the shift linkage on my car had been turned around (backwards). He reinstalled it properly and adjusted the cable after replacing the vacuum switch on the transmission. Presto! MUCH better shifting characteristics - at light to moderate throttle the shifting is smooth and the car winds out slightly but not excessively. At full throttle, it stays in gear to 3500-4000 rpm and feels quite a bit more powerful with a bit of a kick as it shifts between gears. Also, the kickdown switch now works fine. I think this is a case where there was more than one thing going on and that the vacuum switch replacement and trans. linkage bracket being turned back around worked in concert to dramatically improve things.

And, as Holson mentioned, 617 engines sound great when they wind out. I get a big grin on my face at full throttle!

Joel

190D22 · #9 07-22-2002, 11:59 AM

Well for what it's worth, MVK, my car shifts out of 1st gear very quickly at around 2000 RPM then 2nd to 3rd holds out until around 15mph and then 3rd to 4th right around 30 mph. Very smooth shifts between them all. I've decided that my 1st gear is so short because my engine is only 70hp and it needs that to get going... My only beef with it is I have to be careful in rain and snow because it's so easy to get the tires spinning in 1st gear. I wish I had that selectable sport and economy transmission that the later 190s had. But comming home from work lastnight I re-affirmed my love that car: it started so smooth, the shifts were perfect (not rough at all) and it was just a very comfortable ride. That car never ceases to please and amaze me.

I love mercedes!

engatwork · #10 07-23-2002, 08:00 PM

Joel
I am interested in finding out about the "vacuum switch" that your mechanic replaced on the tranny. I am thinking he is talking about the vacuum modulator. I will probably replace it before the kickdown switch and see what happens. Could you please email me the p/n that he replaced?
thanks

MVK · #11 07-23-2002, 09:09 PM

Hi guys:
I just posted another post regarding a technical bulletin on our Diesel car trannys. See that post some one has posted a nice reply to that with tranny pictures. etc.

MVK