ZF 4hp22 compatibility

Post Sun Oct 18, 2020 8:42 pm

Hello, so glad I found you. I have what may be a silly question about transmissions. The automatic in our 1989 325i has reached the point where it needs a rebuild or replacement. I still have the good 4hp22 (non EH) from my e28 528e I swapped to manual a few years ago. I was wondering is there any reason I can't use the auto-box from the 528e in the 325i?
Thanks for any help.

Post Mon Oct 19, 2020 7:01 pm

528 is an M30 engine which has a different bell housing bolt pattern to your M20 engine, if the bell housings will change then it may be possible but id ask an auto specialist if I were you

Post Mon Oct 19, 2020 7:44 pm

Thank you for the reply. My 528e (US spec) has the m20b27 "eta" engine. I know the torque converter has a lower stall speed than the 325i and I would need to swap the e28 cable actuated shift linkage for the e30 rod type. I just want to make sure I'm not overlooking anything, I very much wish to avoid having to pull the engine and transmission back out right after putting them in.

Post Wed Oct 21, 2020 2:21 pm

Where are you located as I had my auto box rebuilt a few years back in west London.

Post Thu Oct 22, 2020 9:02 pm

Hi, I'm in the U.S.. Rebuilding the original transmission is my plan "B", it can be done for about £1400.00 (a bit over $1800.00). Since I swapped my 528e to manual I still have its perfectly good 4hp22 so if possible I would like to use it.

Post Fri Oct 23, 2020 6:52 pm

I received a reply from ZF, I didn't miss anything they are effectively identical

. Just switch the shift arms. I've got the suspension, brakes and diff seals done, I'll do the center driveshaft support this evening and swap gearboxes this weekend. I'm still debating which torque converter to use, according to ZF the stall speed rpm for the e28 R2 is 1900-2050 and the W2 from the e30 is 2200-2400.