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#1
06-09-2008, 05:08 PM
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Transmission downshift behaviour - is this typical
We are very new to the 107 SL's, having just bought a 1982 380SL.
I have a question about normal transmission shift patterns. I've noticed that on a steady but reasonably gradual uphill section, the transmission is reluctant to downshift from 4 to 3 and requires flooring the gas pedal to kick it down or using the shift lever to force it into a lower gear. RPM and speed will drop because of the ratio mismatch if the gas pedal held about half to three-quarters of the way down. Floor the pedal to kick it down and all is OK. I am NOT talking about a mountain road here. My diesel 126 downshifts more cooperatively than this. I am wondering if I have a vacuum problem but I do not know what normal is for a 380SL. Can anyone comment? 
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#2
06-09-2008, 05:21 PM
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Shift points can be adjusted.
Mercedes transmissions look for input from the linkage and/or vacuum input to decide when the transmission downshifts. Sounds like you need to go over the linkage/vacuum systems and ensure everything is adjusted to spec. If you floor it and it downshifts, the switch under the accelerator is working. Jim
__________________
14 E250 BlueTEC black. 45k miles 95 E320 Cabriolet Emerald green 66k miles 94 E320 Cabriolet Emerald green 152k miles 85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles
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#3
06-09-2008, 05:39 PM
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Quote:
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#4
06-09-2008, 05:58 PM
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I suspect you have a simple adjustment issue, not a major problem with the transmission.
Look at the linkage at the back of the intake manifold. You should see a link going down to the transmission. Jim
__________________
14 E250 BlueTEC black. 45k miles 95 E320 Cabriolet Emerald green 66k miles 94 E320 Cabriolet Emerald green 152k miles 85 300TD 4 spd man, euro bumpers and lights, 15" Pentas dark blue 274k miles
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#5
06-09-2008, 09:09 PM
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Follow the cable coming from the transmission to the linkage on the manifold. It is a little slide adjustment. Take a screw driver and go for a ride. Move it in VERY small increments, as it doesn't take much, at least on my car, to adjust it. Stop, adjust, drive, and so forth until you get it just right.
Glenn
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#6
06-09-2008, 09:24 PM
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It could be a simple adjustment but then again it may be just right. It depends on your perception of what you feel is normal.
__________________
To see my 129 parts for sale visit: John Roncallo
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#7
06-10-2008, 06:48 AM
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When I floor the gas pedal of my 380sl and activate the kick-down switch, I find that my car shifts at higher rpm's for a while after I leave the hwy. I don't floor it very often, so I haven't tried to fix the problem. But now I'm wondering if this could be caused by the linkage sticking, or a bad modulator. Has anybody had this problem, and solved it?
Thanks for any help.
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#8
06-10-2008, 08:34 AM
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On the 722.3 transmission, vacuum will NOT effect the shift point, only the softness of the shift. The Bowden cable controls the shift point and is adjustable.
__________________
All the best, J. P. Mose 1968 250SL 1970 280SE 3.5 Cabrio 1987 560SL 1990 560SEL
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#9
06-10-2008, 03:00 PM
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I won't get to this for a while as I'm heading to Seattle on business tomorrow for a few days. When I get to it I'll bump the thread and let you guys know how it worked out....
Thanks for the tips guys!
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