Gearbox Jerks and Slipping

Among the many issues that I have on Rhino, one is on the jerks and slips on the gearbox. I have got this checked in a number of places and the diagnosis has been a faulty gearbox that either needs to be rebuild or swapped for a newer one.

What happens is that when I drive the car from a stop, from shifting of 1 to 2, the gearbox will jerk, the jerk is softened when the engine is driven aggressively, but there will be a jerk.

From 2 to 3 and 3 to 4, the gear starts slipping in between. This on the other hand becomes more prominent under aggressive driving, on regular driving, the slip is not as drastic.

Among the work that has been done were:
  1. Replacing the automatic transmission fluid to Mercedes original fluid - it took in 7 litres if I remember correctly
  2. The valve body was serviced
  3. The transmission filter was replaced
  4. Rear-axle bushes were replaced
  5. Gearbox mount replaced
  6. Long shaft flex disc on both ends replaced
  7. Long shaft mounting was replaced
However, the symptoms were reduced but not removed completely and I have lived with it thinking and believing that the issue was a gearbox issue and I was contemplating either a swap or rebuild of the gearbox.

However, I decided to take a drive to the garage for a consultation on what he thinks of the gearbox and what his recommendation is. He hoisted the car up and checked the pressure in the gearbox. He told me that the pressure was far too low and he needed to increase the pressure.

10 mins later, the car was ready for a test drive. What I immediately noticed was that the jerk is no longer there from 1 to 2, shifting is no longer slipping from 2 to 3 and 3 to 4. I did not know that improper pressure could cause a major issue, and ironically, the fix is also as simple.

While the gearbox was checked, I also requested that the throttle body seating be checked. Upon checking, he found a link to have been loose and happened to have a replacement that can be plugged in. He removed the pivot link of the old one and the replacement one was regreased followed by refitting, a 5 mins job.

He started the car and we went for a spin, the 1 to 2 jerk is no more there, slips from 2 to 3 and 3 to 4 is also no more there. Indeed the pressure of the gearbox sorted the issue. He did caution me that there was a delay in the reverse gear engaging and did tell me to not accelerate as soon as the reverse gear is engaged but rather allow the pressure to build which takes about 1 to 2 seconds.

It was a pleasure to drive it back after the work that was done. I will be monitoring the gearbox for a bit and if it is all good, I have one more issue resolved.

Final update:
The jerk from 1 to 2 is there but it only becomes prominent in a jam, when the car takes off with a steady accelerator, the jerk is mild to none. Slipping from 2 to 3 and 3 to 4 is no more there.

Pictures:

Gearbox pressure adjustment being done that made all the difference

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