'77 300D shift patterns (auto)

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'77 300D shift patterns (auto)

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Mercedes Forum >> Mercedes Benz Models >> Diesel Discussions >> '77 300D shift patterns (auto)

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'77 300D shift patterns (auto) - 7/22/2007 4:11:50 PM

gwooden

Posts: 3
Joined: 7/22/2007
Status: offline

Is it true for a '77 300D automatic, that upon launching, that it really starts off in 2nd gear? And that the "shift" points on the Speedo doesn't really matter?

I ask because my 300D revs very high in starting at 65MPH. And on the Speedo there is the 4th gear shift point at approx 68MPH. However, my car doesn't shift. It last shifts at around 40MPH (where the other shift pattern is).

I took it to a local mechanic who said the car's trans is just fine, and that it starts off in 2nd gear .. unless I punch it from the get go where it drops to first. I have tried to punch it launch but still only shifts twice ... around 20MPH and 40MPH.

So - I am crazy, that this is normal? I have just recently acquired the car and just now taking it to high-way speeds. What brought this to my attention is that while Driving on the interstate, I get only about 20MPG, where-as on the city I get around 27-28MPG.

Thanks,

-graham

Post #: 1

RE: '77 300D shift patterns (auto) - 7/24/2007 10:43:17 AM

Drrty240D

Posts: 154
Joined: 7/30/2006
Status: offline

We had a discussion relating to this topic not long ago that may be of assistance to you:

http://www.mercedesforum.com/m_74683/tm.htm

(in reply to gwooden)

Post #: 2

RE: '77 300D shift patterns (auto) - 7/24/2007 11:05:52 AM

gwooden

Posts: 3
Joined: 7/22/2007
Status: offline

Thanks for the reply.

So ... from a dead stop to approx 70MPH, the car only shifts twice. This is normal then? To have such high revs at the highway speed?
Again, shifts at around 20MPH and again around 40MPH.

If this is all true, then the shift indicator at the 68MPH mark doesn't even come into play here?

< Message edited by gwooden -- 7/24/2007 11:29:13 AM >

(in reply to gwooden)

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RE: '77 300D shift patterns (auto) - 7/24/2007 1:11:51 PM

Drrty240D

Posts: 154
Joined: 7/30/2006
Status: offline

It may be that first gear is hastily shifting into second so that you're not noticing the shift, but the transmission should be reaching top gear (4th) easily before 60 on a US spec car. How's your vacuum system? The trans shift points are controlled by vacuum via the Modulator -- maybe it's gone bad. Good news is the Modulator is easy and cheap to replace if needed. Here's a pic of the unit in question...

Thumbnail Image

Attachment (1)

< Message edited by Drrty240D -- 7/24/2007 1:17:04 PM >

(in reply to gwooden)

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RE: '77 300D shift patterns (auto) - 7/24/2007 1:16:15 PM

gwooden

Posts: 3
Joined: 7/22/2007
Status: offline

Thanks for the clarification Drrty240D.
Well, the vacuum system be somewhat at fault, since the locks don't really stay locked, cruise won't stay on, and the center vents barely blow any air.
The car is at the local mechanic as I don't have the time to work on it ... but he is soo slammed with other cars ... he's the only guy on the gulf coast that will work on them.
Thanks again,

-graham

(in reply to Drrty240D)

Post #: 5

RE: '77 300D shift patterns (auto) - 7/25/2007 9:43:47 AM

carnut

Posts: 157
Joined: 3/31/2006
Status: offline

The shift points marked on the speedo are there to refer to max RPM in each gear. If you were to manually shift it then those marks advise you to not exceed the mph in that gear.

_____________________________

1981 300CD. had a 72 280SEL 4.5, had a 66 250S

(in reply to gwooden)

Post #: 6