Author Topic: W111 auto transmission suddenly can't upshift past 2nd gear  (Read 5785 times)

ohgee001

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W111 auto transmission suddenly can't upshift past 2nd gear
« on: December 01, 2013, 03:01:53 »
Hey everyone, I'm new to this forum and hope to get to know you.  I have a 1967 registry 250se cabriolet that has been in the family for 13 years. I took the car out to exercise her today and was driving about 30 mph when it felt like the trans had slipped out of gear. I wiggled the stick, shifted to 3rd and then back to 4th. Power returned but it was in 2nd gear. I slowed down and manually shifted through the gears but could not get anything but 1st and 2nd, also my speedo stopped working. Reverse works and there was no obvious warnings or sounds associated with this event. I had the trans rebuilt 6 years and about 4000 miles ago and have only has good performance from it. Has anyone any experience or thoughts on this? Thanks and best regards, John O' Kansas City section MBCA

Pedrocamp

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Re: W111 auto transmission suddenly can't upshift past 2nd gear
« Reply #1 on: December 01, 2013, 03:46:44 »
John,
Sounds like the governor gears have stripped their teeth, happened to my trans a while back. These gears are in the back of the box, inside the rear tail cover... they are helical gears that drive the governor (tells the trans when to shift), speedo and the secondary oil pump. These gears seem to be a weak spot on the K4A auto trans, so I'm told. I replaced mine with used gears from a parts tranny I purchased. The used gears looked OK but were crack checked, bead blasted and finished with a micro media REM process to remove any stress risers. The Classic Center can supply new gears but they are quite pricey, relative to my 230 sedan anyway.

Beautiful car by the way!

Pedro Campuzano
Mooresville,NC

ohgee001

  • Guest
Re: W111 auto transmission suddenly can't upshift past 2nd gear
« Reply #2 on: December 01, 2013, 04:08:47 »
Wow that was quick! Thanks Pedro, it sounds like you had the same experience as me. Also, small world, I lived in NC for over 25 years. I suspect this happened because I bragged on the car recently. The town where I live has some very good German car mechanics. We just have to get this fixed, thanks and best regards, JO

Pedrocamp

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Re: W111 auto transmission suddenly can't upshift past 2nd gear
« Reply #3 on: December 01, 2013, 10:01:46 »
I'm in trouble! I brag on mine all the time!

Hope your repair goes smoothly and quickly so you can enjoy your car again soon. While they are in there have them check the secondary pump gears, I had one gear with slightly damaged teeth... Must have happened when the helicals let go I assume because it wasn't bad enough to cause the helical failure though maybe unrelated, worth a look. I replaced with good used as well.

We've been here in NC 5 years, pleasant weather compared to Chicago!

Best of luck,
Pedro

Marrs

  • Guest
Re: W111 auto transmission suddenly can't upshift past 2nd gear
« Reply #4 on: December 13, 2013, 00:25:46 »
Hey everyone, I'm new to this forum and hope to get to know you.  I have a 1967 registry 250se cabriolet that has been in the family for 13 years. I took the car out to exercise her today and was driving about 30 mph when it felt like the trans had slipped out of gear. I wiggled the stick, shifted to 3rd and then back to 4th. Power returned but it was in 2nd gear. I slowed down and manually shifted through the gears but could not get anything but 1st and 2nd, also my speedo stopped working. Reverse works and there was no obvious warnings or sounds associated with this event. I had the trans rebuilt 6 years and about 4000 miles ago and have only has good performance from it. Has anyone any experience or thoughts on this? Thanks and best regards, John O' Kansas City section MBCA

Before you pull a trans apart check the two bushings on the top where the rods actually connect to the transmission. As I recall there are two rods with ball ends, one is responsible for half the shifts and the other rod controls the other half, if one of these is loose, broken or fell off you could potentially have access to some of your gears but not all. This image is borrowed from another forum but you can see the two ball end rods near the green ribbon and follow them each back to the transmission to see the rubber bushings. Either end could have failed. At least you can diagnose this by sight and feel without spending any money just yet.

« Last Edit: December 13, 2013, 00:36:48 by Marrs »