Early 1-2 Shift In My 300sd - PeachParts Mercedes-Benz Forum

85drtysthbenz · #1 11-07-2003, 03:29 PM

im having a problem with my 1-2 shift point....as far as i can remember its always been like this,so it hasnt just happened recently....

with WOT the car shifts from 1-2 at 3400rpm and at 20mph...all the other gears shift like they should,at the desired rpm,right at 4500rpm....and at the correct speed....

is there anything i can do to get the RPMs up to around 4500 for the 1-2 shift?

any ideas or suggestions welcome...thanks in advance
dave

85drtysthbenz · #2 11-07-2003, 08:02 PM

.....

#3 11-07-2003, 08:26 PM

Best to give the year on that SD.
For the early ones it may be as simple as adjusting the Bowden cable. On the 81-85, don't know about the later cars, the Bowden cable is mounted on top of the valve cover. It runs down to the trans. Has an adjustment at the point where the cable wire runs into the shielded cable itself. Just lengthen the cable right there to get the trans to shift later.
Otherwise there are a lot of complex adjustments to make on the vac system. You should run a search for those. Best article was written by Steve Brotherton. Explains all the details.

fahrgewehr2 · #4 11-07-2003, 08:40 PM

That's a funny user name.

85drtysthbenz · #5 11-08-2003, 03:09 AM

the car is an 85 model...ive tried adjusting the bowden cable,but when i adjust it to make my shift point higher,it makes my transmission sort of hang in the gear its in for about 2 seconds before it shifts when i let off the accelerator...say im in 3rd gear with wide open throttle,going about 60mph...when i go to let off the pedal to even the speed out,it doesnt shift up to 4th right away..instead it kind of hangs in 3rd for about 2 secs before finally shifting....also it did nothing for my 1-2 shift,i didnt notice that it was any later than before...it seemed to only affect the higher gears....so,ive adjusted the bowden cable back to where the car shifts rather quickly whenever i let off the pedal

i havent messed with the vacuum modulator on the tranny yet...i dont suppose i can get to it without lifting the car...although,im not sure that would do much good either...from what ive read,it only affects the shift quality as far as firmness or softness of the shift itself....

id like to get some feedback from other owners about where thier cars shift at full throttle,starting in 1st gear...it seems to me that every other gear is shifting properly,except for the 1-2 ....in every other gear,the car shifts at the points on the speedo,and at around 4500rpm....the only one that isnt right is 1st gear,which shifts 10mph and 1000rpm under what i think it should...the dots on the speedo say it should shift at 30mph,and the latest ive gotten it to upshift is at 20mph...any input is appreciated

haasman · #6 11-12-2003, 03:03 PM

You might want to visit this site:

http://www.mercedesdismantlers.com/diesel_vacuum_system

Be sure to follow the links also at the bottom of the page.

Haasman

WANT '71 280SEL · #7 11-12-2003, 04:30 PM

Mine is like that too. It is 6 years older and has a completely different body. It is a 1979 300SD Turbo. I think it is suppose to be like that though.
David

85drtysthbenz · #8 11-12-2003, 05:26 PM

its not really a problem..in fact,its probably making a lot less stress on my tranny....but,why would there be dot indicators on my speedo if it werent designed to shift at that speed at full throttle? its shifting 10mph slower than whats shown on the speedo....iiii dunno,maybe im better off just leaving it be,but itd be nice to see what kind of performance increase it would have if the car were to go to redline in all gears

haasman · #9 11-12-2003, 05:34 PM

85drtysthbenz

The speedo marks are there for really two reasons, used differently: Max. permissible speed, as in accelerating but also as a guide regarding shifting to a lower gear.

Good driving,

Haasman