W124 89 300E Transmission Shifting Repairs
 

My 300E transmission is starting to shift really badly. Imagine a beginner on a manual transmission that lets the clutch out too fast between shifts and you get that jerking back and forth. I am getting that between gears 2-3 and 3-4 on an automatic transmission.

If I put my foot down all the way and try to drive it harder, the shift from 2-3 is just gone, engine revs and the transmission never catches into third gear. I have to come to a complete stop in order to move forward again.

Is this a sign to replace the K1/K2 springs as well as the ATF fluid and filter? Anything else I need to look at replacing while I am in there?

So have you checked the obvious... the fluid level? These cars are notorious for leaking from the front pump bushing and various case seals. Excessively stiff shifts are almost always due to modulator issues dealing with line pressure, sometime vac line off others bad modulator. The bowden cable just deals with shift timing.

Do you have the 722 PDFs? If not, PM me your email address and I will send them.

I did check the fluid level and it was fine. The fluid was dark though. I'll send you a PM with my email.

Check this: https://www.youtube.com/watch?v=gM4KZvwsCW0
I have the same problems. I am intending to check the vacuum valve.

I spent some time today and started taking things apart. I started with the K1 and K2 springs for my 722.358 using these part numbers:

K1: 126 270 44 77
K2: 126 270 05 35

Despite what a lot of posts read, the K1 and K2 springs are not interchangeable on my transmission (722.358 / 1989 300E). The larger spring from K1 is too big to fit inside the plastic bore on the K2 spring.

Next, I decided to take the B2 piston out. I was able to do this with transmission in the car by removing the driveshaft support bracket, loosening the motor mounts from underneath the car, and finally jacking up the oil pan with a wooden block for clearance.

Everything looks fine to me and it looks like it's even updated to the later version already with the plastic bushing?

http://i.imgur.com/2RJ1rEel.jpg
http://i.imgur.com/dVBkgMol.jpg

Should I just leave the B2 piston stuff alone and reassemble/move on to the vacuum modulator? Or should I look at replacing the orange seal ring before putting things back together?

P/N on my B2 piston reads: 126 277 11 38

Edit: I forgot to note, when I was removing the B2 piston cover, I did not need to apply constant pressure on the cover to remove the clip, is this normal? Pressing on the cover allowed the cover to remain "stuck" in place for me to remove the clip. Is this a sign of sticky B2 piston or should I not worry about this?

Edit 2: My thrust pin measures at 47mm, is this already an oversized replacement?

Good Info, but I would change the B2 Black - Bore seal as that gets rotten hard...If you have a metal inside bore, change that sucker like on this thread. The new bore is made of plastic..

How to Replace Your Oil Cooler Lines

The "thrust pin" the dog bone, make sure to put it back in the way you took it off as it has a stripe on one end...

Here is the service manual that may help:

www.bayhas.com - /w140manu/Service/

All the best,

Martin

Thanks Martin, this page is something I was struggling to find earlier, B2 adjustment measurements.

Alright last weekend I was finally able to put everything back together and drove the car around for the last week. All of the old problems are gone and transmission seems to be shifting correctly. I'm not sure what I exactly I did fixed it, but I went through the following items:

B2 piston (seal replacement and thrust pin clearance check)
K1/K2 springs replacement
Vacuum modulator replacement
ATF fluid change

It's been a crazy experience, but thanks to all the resources, I was able to pull it off! I did a huge knowledge dump on my wiki, hopefully this can be of some use to someone later on: 722.3 - Star Wiki