[bigshooter]

Im posting here because I’ve had no luck getting replies on my last 3-4 posts in the diesel forum. I’ve even tried posting on Reddit but got no replies there either.

Car: 2014 328d with stage 2 engine and transmission tune. 135k miles. Owned since 30k miles. Tuned since 75-80k miles.

Issue: my transmission is going. More specifically the torque converter. I have a nasty grinding scraping sound that doesn’t change with speed. I have an opportunity to buy a 8hp50 transmission with only 3k miles. I like the idea of replacing the 45 with the 8hp50 bc it holds +50nm more.

It should be plug n play, but I am planning on swapping the mechatronics to avoid having to clear the INS with ISTA but more importantly not to lose my custom tranny tune. FYI it’s not xHP.

Couple things I’m not sure about with the swap.

1 - I read that the gear ratios are slightly higher in the 50 as compared to the 45. My understanding is that ZF did this for emissions purposes.

Can I assume the mechatronics are identical between the 45 and the 50?

Will there be any issue with the difference in gear ratios? Hoping it’s not noticeable or the tranny just “learn” and adapt to it.

Ideally I’d like to just pull the tranny, swap the mechatronics, install new trans, flush fluid, and be done.

The tranny that I’m planning on buying comes from a M340i. So I believe I will need to buy a flex disc/flywheel for a B58. Either that or fit a torque converter to the tranny but that doesn’t make sense going that option. I plan on grabbing one from eBay or a junkyard. Am I missing anything? This seems very doable.

Originally I was planning on doing this but swapping in a 8hp70. However, I read a few posts where some people attempted a 8hp70 swap but could never get it to shift right. Maybe software wasn’t available at the time. That and this 8hp50 transmission only has 3k miles on it for a fair price


Any thoughts? Suggestions?

Forgot to mention that I was getting shudder or slippage when hitting it hard in 5th gear. I barely get on it but I think that was enough to cause it to self destruct over the last year. I have videos of the noise if anyone is interested.

[5w20]

Compare the Bellhousings and let me know what you think.

[bigshooter]

Originally Posted by 5w20

Compare the Bellhousings and let me know what you think.

They are the same. Identical

[5w20]

Originally Posted by bigshooter

They are the same. Identical

It's worth a shot, but honestly it isn't much of an upgrade.

[Polo08816]

Any updates on this? I would be interested in seeing how this turns out.

[bigshooter]

Originally Posted by Polo08816

Any updates on this? I would be interested in seeing how this turns out.

I did not end up doing it. At the time, a friend on here who works nearby my house was selling his 8hp50 from his 235M. But I would need a diesel torque converter.
I ended up changing my tranny fluid which was burnt to hell and about 1.5 quarts low. Prob burned up.

Drive fantastic initially. Then it started making noise again. I drove it hard one day and it’s been great since. Prob been like 1,500 miles now. I know I still need at least a new torque converter or a whole tranny. It’s hard to find a low mileage tranny. There’s a place in Old Saybrook, CT, Erikkson Industries, that will remanufactorer your torque converter for $385. They will do it via shipping too if you aren’t local. I will probably pick up a low mileage 8hp45 tranny from a gasser/petrol and have my torque converter rebuilt by them.

[Polo08816]

Originally Posted by bigshooter

I did not end up doing it. At the time, a friend on here who works nearby my house was selling his 8hp50 from his 235M. But I would need a diesel torque converter.
I ended up changing my tranny fluid which was burnt to hell and about 1.5 quarts low. Prob burned up.

Drive fantastic initially. Then it started making noise again. I drove it hard one day and it’s been great since. Prob been like 1,500 miles now. I know I still need at least a new torque converter or a whole tranny. It’s hard to find a low mileage tranny. There’s a place in Old Saybrook, CT, Erikkson Industries, that will remanufactorer your torque converter for $385. They will do it via shipping too if you aren’t local. I will probably pick up a low mileage 8hp45 tranny from a gasser/petrol and have my torque converter rebuilt by them.

I was looking at replacement costs for the ZF 8HP for the M2 and M3/M4 cars. It's really pricey... > $7000.

I think that's why I will eventually transition to domestic vehicles like the 7th Gen Mustang Dark Horse or the C8 Z51 to keep catastrophic powertrain failure costs down.

[Greg555]

How much for the 8hp50
Im looking for one

[bigshooter]

Originally Posted by Greg555

How much for the 8hp50
Im looking for one

$400-$1200 depending on mileage