Author Topic: Missing Buffer or Misaligned linkage  (Read 4379 times)

w113abudhabi

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Missing Buffer or Misaligned linkage
« on: March 04, 2015, 15:12:27 »
Hello

My engine is not downshifting properly and my mechanic has worked through a few things. One question please: should there be a buffer to enable the accelerator pedal to engage the kickdown switch? I am guessing that either I have a missing buffer or a misaligned throttle linkage and probably the latter.

All comments gratefuuly received.

Many thanks,

Pierre

ja17

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Re: Missing Buffer or Misaligned linkage
« Reply #1 on: March 04, 2015, 21:23:22 »
Hello Pierre,

The kick down switch should have a small rubber/plastic button on the end of the unit, which contacts the pedal when depressed. If the accelerator pedal does not reach the kick-down switch then the engine linkages could be set incorrectly. Check out "The linkage Tour". If the accelerator pedal does contact the switch, then the switch could be faulty. Check it with a test light. If both of these check out OK, then check the engine timing. Engine timing can cause a change in engine vacuum. Kickdown may not occur if engine vacuum is not correct.
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

ctaylor738

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Re: Missing Buffer or Misaligned linkage
« Reply #2 on: March 04, 2015, 21:54:48 »
In addition, you may need a modulator pressure check and/or adjustment.
Chuck Taylor
1963 230SL #00133
1970 280SL #13027 (restored and sold)
1966 230SL #15274 (sold)
1970 280SL #14076 (sold)
Falls Church VA

Benz Dr.

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Re: Missing Buffer or Misaligned linkage
« Reply #3 on: March 05, 2015, 15:19:00 »
I find low engine vacuum will affect shift quality. The better your engine vacuum level is the better it will up shift. High vacuum will soften up shifts - the higher the vacuum the softer the shift will be if you lift off the throttle to affect an up sift. When you have WOT and the engine shifts into next highest gear, the shift should be quick and firm so that the trans doesn't flare as it's shifting. The modulator will self adjust according to RPM, load, ( vacuum ) and throttle position.
1966 230SL 5 speed, LSD, header pipes, 300SE distributor, ported, polished and balanced, AKA  ''The Red Rocket ''
Dan Caron's SL Barn

1970  3.5 Coupe
1961  190SL
1985   300CD  Turbo Coupe
1981  300SD
2013  GMC  Sierra
1965  230SL
1967 250SL
1970 280SL
1988 560SEC

w113abudhabi

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Re: Missing Buffer or Misaligned linkage
« Reply #4 on: March 12, 2015, 12:09:00 »
Many thanks to all those who responded.

Please find attached pictures from my car.

You will see the temporary solution that the mechanic has strapped onto the throttle pedal to ensure the kickdown switch engages. He reports it is now functioning well with the assistance of the temporary and unsightly solution. Based on JA17's response am I right in thinking that my issue may well be that there is a plastic button missing from the kick down switch which may have resulted in the gas pedal failing to engage the switch?

Don't worry about the dirty carpets - they are covered in my plan!

ja17

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Re: Missing Buffer or Misaligned linkage
« Reply #5 on: March 12, 2015, 13:47:18 »
First make sure all parts are in place, looks like the small plastic cap on yours might be missing. After confirming this and installing any missing part, the pedal height is adjustable vial the engine compartment linkages. The linkage tour should shed light on this if you have an issue there.  The two possible places to adjust the pedal height are the slip adjustment on the firewall linkage (near the booster) look for the spring and 13mm hex head bolt. This is a slotted connection. Remove spring before any adjustment or the linkage will adjust itself too far when the bolt is loosened. In addition changing the length of some of the primary engine linkage rods (before the cross-over rod) will also change the pedal height. In any case after any linkage adjustment for pedal height, you should confirm two things:  the accelerator pedal engages the kick down switch when fully depressed, and the intake venture is all the way open when the pedal is fully depressed (if not, you are not getting full throttle power).
Joe Alexander
Blacklick, Ohio
1969 Dark Olive 280SL
2002 ML55 AMG (tow vehicle)
2002 SLK32 AMG (350 hp)
1982 300TD Wagon turbo 4spd.
1963 404 Mercedes Unimog (Swedish Army)
1989 flu419 Mercedes Unimog (US Army)
1998 E430
1974 450SLC Rally
1965 220SE Finback

w113abudhabi

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Re: Missing Buffer or Misaligned linkage
« Reply #6 on: March 12, 2015, 18:22:40 »
Thanks Joe. It would be very helpful to see photos of the equivalent area from an automatic with well functioning linkage and  kickdown, if any users have time to share theirs.

w113abudhabi

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Re: Missing Buffer or Misaligned linkage
« Reply #7 on: March 20, 2015, 16:11:59 »
Can anyone confirm if the automatic 280SL should have the cover shown in the below link:

http://pages.ebay.com/link/?nav=item.view&alt=web&id=181292182427

wwheeler

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Re: Missing Buffer or Misaligned linkage
« Reply #8 on: March 20, 2015, 19:54:56 »
Does anybody have a picture of the plastic cap on the kick down switch? My W111 never had one and has just the metal stem protruding like the above pictures. My kick down works fine, just curious about the cap. Is it just a W113 part? 
Wallace
Texas
'68 280SE W111 coupe
'60 220SE W128 coupe
'70 Plymouth Roadrunner 440+6