[W126 Coupe] 560SEC acceleration

[Vance Rowley]

Hi Tim,

At what RPM does the upshift to the next gear occur? The reason I ask is apart from these cars starting in 2nd gear (although you can do a manual 1st gear start) more on that later, if your throttle/vacuum link is incorrectly adjusted then your upshifts will be taking place far too early thus giving quite poor acceleration performance. There is a metal link behind the air filter (between the air filter and the firewall) this metal link is in two parts bolted together (I think with a 10mm bolt) which can be lengthened or shortened by loosening the bolt and sliding them apart (or together) so it becomes longer or shorter. The length of this link will depend on where your shift points will be. this link is fastened at each end with a ball joint as such and can be removed completely (just clips off and on) to adjust the length easily, then replace. It's been many years, so I can't remember if it is a shorter or longer link that will lower or increase your shift points, but you can easily experiment as it is very easy to get to and adjust. You ideally will need a nice clear straight road for a test as once you get close to the adjustment to get it spot on, you will need to floor it from a standing start and make sure your shift points are spot on the red line (or just before in your case if your tachometer is slightly out of calibration) or better still, go off your marks I, II, III on your speedo.

As far as doing a 1st gear start manually is concerned, this can be done from a standing start by having your foot on the brake, select the shift lever all the way back and across to the right to low (you hit a microswitch) then all the way back to drive. As long as you don't take your foot off the brake while doing this, as soon as you take your foot of the brake and hit the gas, the car will do a 1st gear start without needing to floor it. You can also purchase a 1st gear start module which will have a switch fitted to select the option of having 1st or 2nd gear start automatically.

Hope this helps. Let me know what you find out and at what RPM your shifts under WOT are taking place at the moment.

Cheers,

Vance.
  ----- Original Message ----- 
  From: Tim Schmidt 
  To: mbcoupes at mbcoupes.com 
  Sent: Tuesday, June 06, 2006 4:27 AM
  Subject: [W126 Coupe] 560SEC acceleration


  Good evening,
  I just received a 1989 560SEC as a result of an Ebay bid.  I had never test driven one, so I took my chances on it.  Mechanically, the car is in great shape after taking it in for an inspection.  The only problem I have is in the way it accelerates.  It seems like I practically have to floor it to get it moving.  I know it is a large sedan and heavy, but it seems extremely sluggish, especially for having an engine the size it does.  My mechanic adjusted the throttle a little, but said this is typical of Mercedes.  I had previously owned a 93 300E and it seemed more peppy than this car.  Is there anything that can be done to improve how it accelerates??  I guess I really do like more power or torque from the get go.  The specs say it goes from 0-60 in 7 seconds.  It certainly doesn't feel that fast, though I haven't timed it.   Would getting it supercharged help considerably?  If so, can anyone make any recommendations for a supercharger?  I would hate to have to get rid of it for this reason, because I absolutely love everything else about it.  Hopefully there is something that can be done.  Thanks in advance for your help.




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