Enigmatic Transmission Complication

[almamater78]

Greetings to all,

This site has assisted me numerous times with my gearbox issues previously; but, for the second occasion this year, my gearbox is malfunctioning.
This time, I have discovered no information on the Internet, and I also left the local gearbox shop perplexed. They merely intend to dismantle the gearbox.


Before pursuing that option, I would like to enquire if anyone has experienced these concerns.

The gearbox shifts abruptly into Drive, both when cold and heated, while the shift into Reverse is typical. All shifts are generally challenging, but the primary challenge is the transition from the 5 to 4 shift.
When I maintain 5th gear for an extended period, such as while travelling on the interstate, downshifting to 4th gear results in a jarring engagement, producing a noise so severe that it causes the inside to groan. It is as if someone momentarily engaged the brake. When I decelerate from higher speeds, there is a slight jolt when shifting from 5th to 4th gear.
Strangely, after the initial abrupt transition, I can seamlessly alternate between 5th and 4th gears as frequently as desired.

It only downshifts abruptly after driving in 5th gear for 10 to 15 minutes.

The fluid is new, and the level is accurate.

I would greatly appreciate any assistance offered. Thank you!

[James_Rover99]

This may not pertain to your issue, but here is information regarding difficult 2-to-1 downshifts on the 2002 to 2005 5HP24 gearbox, linked below.

A simple yet unconventional suggestion to implement promptly: If you utilise air cooling, deactivate it for few days when driving. If you do not utilise it, consider employing the air conditioning for several days of driving.

[almamater78]

The air conditioning is now inoperative. Thank you for your counsel.

[n1mrod]

You have not specified which gearbox you possess, but I will presume it is the ZF 5HP24.

Your description suggests an A-clutch engagement problem. The A-clutch engages when Drive is chosen and throughout the 5-4 downshift.


I am curious whether your EDS 5 solenoid is malfunctioning. This solenoid supplies pressure to the spring side of the A-clutch cut-off valve, specifically for Drive engagement and the 5-4 downshift.

[n1mrod]

If you do not possess the 5HP24 gearbox, disregard my message.

[almamater78]

Indeed, that is the 5HP24 gearbox. Is there a method to inspect the solenoid, and where is it located within the gearbox? A connector may have become loose.


Thank you for your contribution!

[n1mrod]

Upon further consideration, the EDS 5 solenoid is utilised for engaging the E-clutch/brake in 2nd gear; hence, if 2nd gear operates without trouble, the solenoid is likely functioning properly. Nonetheless, I firmly believe that you should thoroughly investigate potential defects in the valve body assembly prior to considering the removal and disassembly of the gearbox. The valve body assembly may be extracted while the gearbox remains installed in the vehicle.

[n1mrod]

The issue may pertain to the EDS 5 solenoid, the pressure spike damper, the cutoff valve (Abgeschnittenventil, abbreviated as Absch-V-A), the clutch valve (KV-A), or the clutch accumulator/damper (D-A).

[n1mrod]

The valve bodies are a pleasure to work on; I now have almost twenty in progress, which I remanufacture for enjoyment. I will gladly examine yours at no cost; but, I am uncertain about the practicalities of transporting it from Germany to the UK and back.