low speed manual downshift inop - Mercedes-Benz Forum

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post #1 of 1 (permalink) Old 07-27-2011, 09:29 AM Thread Starter
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Date registered: Jul 2011
Vehicle: 81 450 slc
Location: S. America (USA born)
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low speed manual downshift inop

I am driving a 71´ 280 se and it has only one small problem with downshifting. Above 40mph all manual downshifts work correctly, below 40 mph it wont downshift at all. It WILL downshift correctly with slight accelerator pressure at any speed. The problem is only on a decending road, no accelerator pressure shifting into 2 second for engine brake effect. If I tap the pedal, I get second gear and proper engine brake but no shift occurs otherwise. I have adjusted throttle control linkage to the tranny, I have replaced the copper gaskets in the vacuum line also. I have adjusted the modulator 3/4 turn clockwise (no gauge) and no result. I removed the modulator and confirmed free moving diaphram and slide pin. Any way to narrow this down for me? Trying to find the right oil pressure gauge but no luck so far. Thanks for any heads ups!
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