5HP18 ball (one-way check valve) diameter needed

I hope someone can help, I need the ball diameter of ZF part number 1043 226 028 Valve, "D" CLUTCH ONE-WAY CHECK VALVE ASSEMBLY made of plastic, for that also a modified
"Replacement" ALLUMINUM CHECK VALVE is available http://www.europeantransmission.com/...MWtechinfo.htm

also in the parts catalog shown on page 27 of 42, Position # 51.200

BMW ZF-5HP-18 "BIND-UP" WITH SELECTOR IN MANUAL "2" POSITION, 1st GEAR
COMPLAINT: Before or after overhaul, vehicles equipped with ZF-5HP-18, may exhibit a "Bind-Up" condition in the Manual "2" position, 1st gear.
CAUSE: The cause may be, the plastic "D" Clutch One-way Check Valve assembly located in the Lower Rear valve body, shown in Figure 2, may be broken allowing the "B" Clutch (Reverse Input Clutch) to be on while the "D" Clutch (Low/Reverse Clutch) is on in 1st gear.
CORRECTION: Replace the "D" Clutch One-way Check Valve assembly , as shown in Figure 1, with a new assembly from ZF, or a new "Aluminum" check valve assembly offered by: Mario Aristides. Phone (305) 666-3544 or Fax (305) 666-8238.

"Original" PLASTIC CHECK VALVE ZF Number 1043-226-028
"Replacement" ALLUMINUM CHECK VALVE

whiskychaser measured it: quote
4.56mm is as accurate as I can be. If I set my digital callipers at 4.6mm the ball slides through the jaws. The check valve isnt part of a kit so I would be tempted to get a new one from ZF, particularly as it is not the easiest thing in the world to remove.
unquote

updated links
here a copy bulletin of that http://www.europeantransmission.com/....BMW/01-34.pdf
from this main link http://www.europeantransmission.com/...MWtechinfo.htm
https://www.transmissiondigest.com/november-2001-issue/
Before or after overhaul, vehicles equipped with ZF-5HP-18 may exhibit a bind-up condition in the Manual 2 position, 1st gear.
The cause may be that the plastic D-clutch one-way checkvalve assembly in the lower rear valve body (#15 in Figure 4) is broken, allowing the B clutch (reverse input clutch) to be on while the D clutch (low/reverse clutch) is on in 1st gear.
Replace the D-clutch one-way check valve assembly (See Figure 5) with a new assembly from ZF, or a new aluminum checkvalve assembly offered by Mario Aristides (phone 305-666-3544 or fax 305-666-8238).

https://aftermarket.zf.com/remotemed...fc-5hp19fl.pdf
https://www.bmwe34.net/E34main/Troub...ch%20Guide.pdf

I'm looking into this kind of thing too. D clutches. One of the E46s began losing its reverse over the last week, an early one (2000 330i). Now it's gone altogether.

First it was delaying engagement a second, then a couple.

Then no reverse at all. You can feel some kind of connection straight after selecting reverse (1/2 sec) like normal, but the engine runs free like in neutral, no power transfers. This is bad, its the second one I have that needs fixing. The first is a 325 that blew the hydraulic pump's input shaft bushing, leaking fluid all over. I feel it will be all contaminated and need a complete rebuild so haven't touched it...

Lots of work is coming up!

Possible the basket busted, that happened on the one my boy was driving. We replaced that and the pump pressure valve thing so it never happens again.

ZF 5HP18 parts lists and diagrams https://www.vaglinks.com/Docs/Catalo....com_5HP18.pdf