E46 M3 gearbox swaps

[snaponbob]

An interesting discussion popped up on a Facebook M3 group. It centered around replacements for the stock 6 speed manual. Some took the position the non-M3 manual 6 speed is STRONGER than the M3 box. Also, and argument ensued about if these gearboxes are ZF designed and contracted to Getrag for production. Also, the really interesting nugget was the the gearbox behind the S54 in the Z4M is different (part number and some slight differences in and outside) and actually more stout that the box in the M3.

Who is aware of any of this, and what is factual about it?

[dworthy]

I didn't know that the Z-4M used a different box, not sure if it would be stronger, but as it was built after the E-46 that's a possibility. I do notice that most Getrag boxes have issues with 2nd gear, and ZF seems to be better in that department, perhaps that's why the M Division switched over?

[snaponbob]

I didn't know that the Z-4M used a different box, not sure if it would be stronger, but as it was built after the E-46 that's a possibility. I do notice that most Getrag boxes have issues with 2nd gear, and ZF seems to be better in that department, perhaps that's why the M Division switched over?

The 06-08 Z4M 6 speed is a different part number and designator.

I have replaced a couple M3 manuals due to 1) 1st gear syncho, and 2) there were gold colored flecks on the drain plug of another (and the owner THEN said he wanted a fluid change because he was having gear change issues). A third came out of a donor M3 that I bought the engine from. The gearbox had REALLY crashed -- no reverse, three gears, and was making ALL sort of ugly crunching noises. Mine is not shifting like it did when I bought the car, and I am searching for a replacement.

Over the past 15 years of working on hundreds of 3s (30s, 36, & 46s) I have replaced a dozen (ish) Getrag 260s, and few 250s, and NO ZF320s. The bulk of my work over the past 6-7 years have been E36 ZF box cars. Many were seeing track use. I have a 328 and M3 that a codriver and I beat the hell out for 5 years in SCCA Solo with no issues. That said, ZFs have detent issues. It got to the point that I refused to replace a 328/M3 clutch without allowing me to do detents - saved "come backs". Also I know a lot of guys with 46 M3s who killed Getrags and replaced them with ZF320s. Lighter, same gears 1-5, and all have been issue free.

I can't "prove" ANYTHING about these various boxes except personal observations and input from others with similar background and history.

One interesting bit of info surfaced a couple months ago. It seemed that Getrag 420s M3 boxes were not serviceable. Well, DiffsOnline sells remans !! https://diffsonline.com/transmissions/

[dworthy]

Nice link!

So yeah I have heard about the issues with the ZF detents, and as a result I have been keeping all my BMW's in 3rd gear when I park them. The tough part is trying to remind the wife to leave it in 3rd or 4th and not 1st, and this has been going on for like 15 years.

I just have the hard to put into 2nd gear with the M3 while cold, and a short shift kit doesn't help much either on that. I don't track the car, as it's a sunny day type of car that gets taken on the Autobahn now and ago to clean out the carbon.