Parts Catalog Accessories Catalog How To Articles Tech Forums
Call Pelican Parts at 888-280-7799
Shopping Cart Cart | Project List | Order Status | Help



Go Back   PeachParts Mercedes-Benz Forum > Mercedes-Benz Tech Information and Support > Tech Help

Reply
 
LinkBack Thread Tools Display Modes
  #1  
Old 02-13-2007, 09:36 AM
Registered User
 
Join Date: Aug 2006
Location: Houston, TX
Posts: 450
Question adjusting shift firmness

'92 300SE

I think my transmission shifts a little too firm on the 2-3 shift. If I'm VERY easy on the gas it shifts like silk - normal driving gets a rather stiff shift. This is more pronounced with the A/C on, and I'll assume that's because the motor is working harder and the vaccuum signal is lower. Oddly, when I'm pulling out from a corner it seems to shift better - maybe that's because my initial acceleration rate isn't the same as starting out straight from a light?

The arrows on the throttle linkage align just fine.

There is no slippage at any point - all shifts occur when they should, just a little more harshly than I personally care for.

Is there an adjustment to the bowden cable, or perhaps the modulator that I should be looking at?

Does it matter where on the intake manifold I pick up the signal for the transmission modulator?

Thanks in advance.

Reply With Quote
  #2  
Old 02-13-2007, 11:20 AM
Registered User
 
Join Date: Aug 2006
Posts: 141
Adjusting shift firmness

The vacuum modulator is on the drivers side of the transmission. It can be one of two versions. The early version has a black rubber cap that cracks and changes vacuum signal, Just replace the cap and roadtest for shift ouality. If the shift is still firm remove the cap and turn the adjuster counter clockwise in small increments until you get the shift you want.
The second version has a white plastic cap and has limited range of adjustability. Turn the plastic cap counter clockwise until you get the shift you want.
Good luck
Mike
Reply With Quote
  #3  
Old 02-13-2007, 12:13 PM
david s poole
 
Join Date: Mar 2005
Location: dallas
Posts: 1,822
check the vacuum line from the manifold to the modulator.i have found one or two that had a hole chewed in them by creatures.the other thing as mentioned is the cap over the modulator which cracks and loses vacuum that way.i doubt you will needto adjust it ,it sounds as though you lost all vacuum to the mod.
__________________
David S Poole
European Performance
Dallas, TX
4696880422

"Fortune favors the prepared mind"
1987 Mercedes Benz 420SEL
1988 Mercedes Benz 300TE (With new evaporator)
2000 Mercedes Benz C280
http://www.w108.org/gallery/albums/A...1159.thumb.jpg
Reply With Quote
  #4  
Old 02-13-2007, 01:51 PM
Registered User
 
Join Date: Aug 2006
Location: Houston, TX
Posts: 450
I know I've got the black cap - remember it from when the transmission was out to R&R the rear main seal. I'll check it for cracks.

The hose is good - I checked that at the same time.

I'm assuming a quickie test would be to use a mity-vac on the engine side and see if I can pull any vaccuum at all. I don't know if the modulator would ordinarily "hold" a vaccuum, but if the cap is cracked, I'd think I'd be unable to pull any vaccuum at all.

Thanks for the suggestions.
Reply With Quote
  #5  
Old 02-13-2007, 06:56 PM
Registered User
 
Join Date: Jan 2003
Location: Dallas
Posts: 790
Brian, just as a suggestion on something you might check.
My '91 300SE started shifting a little harsher than usual last month.
Then I noticed the engine temp was running about 70-75C, about ten degrees lower than normal. The bad thermostat was replaced, the temp went to 85C, and the tranny started shifting normal again.
But, just like yours, my little engine can't handle hot weather and AC, and it always shifts harder in the summer, just trying to move that big car.

DG
Reply With Quote
  #6  
Old 02-13-2007, 09:00 PM
Registered User
 
Join Date: Aug 2006
Location: Houston, TX
Posts: 450
Thanks for the suggestion - I just replaced the thermostat - temp holds around 90c most of the time. Some times a little lower, some times a little higher.
Reply With Quote
  #7  
Old 02-15-2007, 11:53 PM
86560SEL's Avatar
Registered User
 
Join Date: Jan 2003
Location: east Tennessee (southeast USA)
Posts: 3,015
When warm, my car shifts very smoothly, with the 1-2 shift being more noticable, but not harsh by no means. The 2nd-3rd and 3rd-4th are very smooth, but not slipping. When cold, the 1-2 is really noticable, with others smoother, but harsher than when the car is hot.

I personally would like a smoother 1-2 shift.

Reverse? Huh... when hot, it harshly engages into reverse (after a hesitation), when cold, its smooth into reverse. Been like this since I have owned it... no changes, so I am assuming it is nothing to cause concerns.

Reply With Quote
Reply

Bookmarks

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is On
Trackbacks are On
Pingbacks are On
Refbacks are On




All times are GMT -4. The time now is 08:06 AM.


Powered by vBulletin® Version 3.8.7
Copyright ©2000 - 2020, vBulletin Solutions, Inc.
Search Engine Optimization by vBSEO 3.6.0
Copyright 2018 Pelican Parts, LLC - Posts may be archived for display on the Peach Parts or Pelican Parts Website -    DMCA Registered Agent Contact Page