Mercedes W126 560 transmission woes - losing reverse. - Auto-Trend Repairs and Service Information Forums

SELLC · CERTIFIED POST WHORE

Mercedes W126 560 transmission woes - losing reverse.

Date: 04:22 PM Jan 3, 2010

RE: Mercedes 560 transmission loosing reverse.

SELLC · CERTIFIED POST WHORE

Right now we are not offering any for sale. I have seen a few of them being sold on e-bay second hand at almost twice the cost!

The next revision of the CD is going to be NICE. I have done a lot of video footage with all the parts cars we have had over the years, in addition to much more information and photos. I am dedicating the CD to my kids, in an effort to ensure they will always be able to fix what they are certain to be passed down. For that reason alone I feel it will be the BEST that anyone has ever seen.

SELLC · CERTIFIED POST WHORE

RE: Mercedes W126 560 transmission woes - losing reverse.

SELLC · CERTIFIED POST WHORE

Finally got the new transmission in. The last one I replaced was on a hoist and it seemed to go much faster, but I have really spent some quality time cleaning everything up underneath and treating many seamed area's to prevent rust.

Pulling the transmission basiclly requires for throttle rod to be removed. This will require you to remove the three allen head bolts that attach the bracket to the manifold. After this you will want to remove the kickdown cable or TV cable. Do this by poping off the ball from the linkage and removing the C-clip. From there it will push right out of the braket. You will also want to remove the two clips that hold the fan schroude to the radiator, as the engine will tilt back. Finally, do not forget to remove the brake booster vaccum line. Its a 17mm and 19mm where they join together right behind the fuel distributor. Be sure to take the crank sensor wire out of the clips to give it some slack as well. Now disconnect the positive and negative battery cables and be sure they wont make contact with the battery.

From there jack the vehicle up with a big jack using good 6 Ton jack stands. All four wheels must be off the ground. If you are not used to working with jacks and stands you may not want to do this because it can be very dangerous if not done properly.

You will need to drop the exhaust. Really it will be most easy to zap the bolts at the manifold collector, and then the ones holding the converter support rod that mounts to the bottom of the trans. Then you will remove the 4 round rubber hangers to let the exhaust down. Slide it out the back. If you can not get the vehicle 2 feet off the ground safely, you wont be able to perform this job as you need ground clearance to get the exhaust and transmission out and back in.

From there you want to zap the driveshaft flex disc bolts loose that connect to the
transmission. You only need to remove 3 at this time, the ones that connect to transmission. Once them three are removed the driveshaft will slide back and off the transmission.

Zap off the stabalizer brace up twards the bell housing. This will be six 17mm bolts. Then you will need to drain the transmission. After that you will need to put your transmission jack under the trans. Zap the two bolts that hold the trans mount to the trans crossmember. Lift the trans jack till you see the trans mount lift off the crossmember. Now zap off the crossmember. It is 4 17mm bolts.

Lower the trans down a little so you can access the round electrical plug that attaches to the neautral saftey switch. Push the tab downward and wiggle it off. You will also need to un-plug single wire going to the modulator. From there remove the banjo bolts attaching the trans cooler lines to the trans. Then zap the starter. The starter bolts are 10mm Allen heads and VERY TIGHT. Might have to break them with a breaker bar. Just push the starter back and leave wires connected. Be sure to save the shims. The ground strap is attached with 1 of the 2 starter bolts. From there get at the front of the vehicle and remove the bell housing inspection cover. There are two, one held on at the bottom by 2 10mm and one at the 3oclock possition on the drivers side. The one on the drivers side is a small allen, perhaps 5 mm I think. Turn the engine to gain access. Remove the six 13mm torque converter bolts. Usually you can get two at a time before moving to the next set.

After that you want a long extension and a 17mm universal socket to zap out the 4 top bell housing bolts while the engine is tilted. It will take a long extension and they are rather tight until busted loose.

Leave the bottom 4 bolts as they are the easy ones to get at. Now you will need to remove the dipstick bolt from the transmission. This will either be a 5mm allen or an inverter torx (I forgot the size but hey). Now remove the two clips that hold the shifter rod to the trans linkage. Remove the bar.

Now all you have to do is have someone to help while you zap out the bottom 4 bolts. Shake the tail shaft from side to size and it will slid out and onto the trans-jack. Lower trans-jack, swap transmissions and reverse the process.

Trust me, it's much easier on a hoist but not impossible without. Either way you will need a good trans-jack. In my younger years I would use a regular jack and wood, but that is risky and not advised.

SELLC · CERTIFIED POST WHORE

Here are some other shots I took of the throttle rod, and the transmission to flex disc area.

SELLC · CERTIFIED POST WHORE

Well the transmission is finally all bolted in and done. While I did get tied up on some other jobs it took about 8 hours to R/R. Not very good time, but I also did a lot of cleaning up and treating of the underside.

Now I am working with the gear box and brake support/guide rod bushings. Lots of oil had been pooring out of them. Lucky me I just happen to have a leak free gearbox and another brake guide rod support unit with bushings and all.

Administrator · $y$Op

Well everything is all finised up. Very glad that my low mile (20,000) Mercedes-Benz reman transmission shifts wonderful. Changed the oil, and finished up the suspension and steering.

I had to make a custom exhaust system for this vehicle since not long ago we had someone steal our stash of cat. converters.

One thing is for sure, had anyone else had to get this work done the bill would have crested the $3000-$3500 mark! This includes the transmission, and front suspension and steering. Even then many of the parts would not be new, as a new transmission for a 560 is well over $3000 from Mercedes in of itself! doh

The good news is that we plan on busting down our 722.350 transmission to inspect and rebuild. While it's not a priority, you can bet it will be at least a year before that ever happens. Let's hope our new used replacement can hold out that long.

-- Edited by Administrator on Saturday 13th of November 2010 01:34:17 PM

SELLC · CERTIFIED POST WHORE

Well it appears this alleged "Factory Rebuild Mercedes Transmission" was not a good unit, or it wasn't actually the proper unit for the 1990 560 SEL that it was removed from.

An in depth write up can be read about here-

http://autotrend.activeboard.com/index.spark?aBID=91042&p=3&topicID=23026173

In that thread we discuss using an early model 722.324 transmission in a later model 1991 560 SEL, and the subsequent 1-2 flare that can result by using a 420 transmission in a 560. More research is being done to rectify the problem should you ever find yourself in a "Pinch", but I wanted to update this thread.

I should also add that I noticed a very strange "Pinch" in my plastic vacuum hose that goes to the modulator with evidence of teeth marks from some kind of needle nose pliers. So who knows, maybe it was sabotage. I know them kinks were not in there when I installed it, but then again I guess I could have overlooked it. Too bad that didn't seem to be the problem and more details can be learned in the thread above.

I am going to see what the numbers turn out to be on this 1990 Factory Re-manned transmission as it appears it was lacking any of the traditional part numbers found on 1986-1991 V8 Mercedes. I never really checked them and assumed since the trans come out of a 1990 560 SEL that it had to have been a 722.350. My bad.