Greetings, Brethren of the R129. I own a 1991 R129 500SL whose transmission won't shift out of first gear. Brought in a shade-tree mechanic who concluded that I'll need to replace the transmissions valve body and conductor plate assembly. Looked on ebay, and found a couple, but I generally tend to be a tad leery of buying used car parts from ebay, so I thought I'd ask here if there happens to be any reputable vendor of transmission valve bodies for this model and year R129.

https://www.ebay.com/itm/Z1024-R129-...T/133511611177

I sure would appreciate any thoughts on where to source this critical transmission component, so that I don't need to roll the dice buying a non-returnable ebay part for this car.

Thanks in advance for any pointers that can be offered.

 

You need to find a new mechanic because 722.3 transmissions don’t have conductor plates

 

Looks like I will be needing a bigger boat ha ha. This pointer is appreciated, sir. The village mechanic had singled out the transmission valve body as the part to replace, then an ebay seller claimed that the conductor plate is an integral part of the valve body, which I now know does not apply to the R129. I'll take down the vavle bodies' serial number, which ought to speed up my search. I'll report back here when this transmission defect is solved, in case anyone runs into the same thing.

Can't wait to get the transmission sorted out because the engine of this R129 runs smooth as silk. Looks can be deceiving though. My Clark Kent E420 4-door family saloon, upgraded to an E500 by dropping in an M119 5-iter V8, will always be much quicker off the line than this sleek and sporty-looking R129, With my lead-foot days well behind me now, I still look forward to seeing this 1991 500SL back to highway condition, to be driven in a suitably restrained manner.

 

My village mechanic called in a transmission specialist, who took apart two separate valve body assemblies, swapped parts between them to get one functioning unit, and reinstalled the completed valve body into the transmission of my R129. Because the car's brakes are inoperable due to the vehicle having been out of action for a while, the transmission was tested with the car stationary, in a hair-raising manner that defied logic as I knew it, yet worked to my amazement.

One of the car's rear wheels was lifted off the ground with a jack, leaving the other wheel firmly on the ground. My understanding of rear differentials has always been that the wheel with the greatest traction, gets fed the most power by the rear differential. This presumption was turned on its head when the transmission witchdoctor fired up the 500SL, shifted into drive, and stomped on the gas pedal. The wheel that was off the ground then proceeded to spin, while the wheel firmly on the ground was obviously not powered at all. I then watched in awe as the car shifted through all four gears smoothly, while rocking gently with each gear shift while perched atop the jack, due the momentum generated by that spinning wheel.

So, as far as I can discern, this R129 is ready for a road test, just as soon as the brake maestro shows up tomorrow to work his magic. I have always marveled at how African village shade-tree mechanics are able to solve the most complex of mechanical problems, using the most primitive of tools and techniques. The internal view of an R129 valve body reminds me of the structure of a human brain, with its bewildering pattern of fluid channels, valves, and tiny springs, yet this shirtless, oil-stained mechanic somehow managed to perform the intricate surgery that brought the transmission back to life, whereby this car can finally hit the road after 2 years of sitting idle and inoperable. Now I wish I'd known about these guys earlier.

When the road test is done, I'll add one final chapter to this story of an abandoned R129 brought back from the dead.