87 i manual trans into an 87 eta auto?

[jc1000]

Hi there,

I just sourced a manual trans from an 87 325is (M20B25) and was hoping to swap it into my 87 eta automatic (M20B27).

I saw this thread but it was still not clear to me whether these will be compatible. Can anyone confirm?

[AWDBOB]

All m20 g260s will bolt up to all m20s. You just need to match flywheel and TOB to the depth of the bellhousing. The trans you have should be p/n 260.0.1346.90 and thus a shallow bellhousing trans. Will work perfect with a single mass flywheel and normal TOB.

The thread you linked has some bad info in it. This one is the updated one:

https://www.r3vlimited.com/board/forum/e30-technical-forums/engine-drivetrain/transmission-driveline/181528-the-official-transmission-thread

[jc1000]

All m20 g260s will bolt up to all m20s. You just need to match flywheel and TOB to the depth of the bellhousing. The trans you have should be p/n 260.0.1346.90 and thus a shallow bellhousing trans. Will work perfect with a single mass flywheel and normal TOB.

The thread you linked has some bad info in it. This one is the updated one:

https://www.r3vlimited.com/board/for...mission-thread

Thanks. What about the crank position sensor? Won't that be an issue?

Here is a pic of the trans. Yes, the part number you provide matches:

[AWDBOB]

Thanks. What about the crank position sensor? Won't that be an issue?

Here is a pic of the trans. Yes, the part number you provide matches:

I assumed that because you didn't post about the crank sensor holes that you weren't planning on using them haha.

Yeah, you'd need to drill those bosses out and run a flywheel with a reference pin for crank pickup. 84-85 325e had heavy single mass flywheels with a crank pickup tab, and the early 528e had a lightweight single mass with a crank pickup tab.

[jc1000]

I assumed that because you didn't post about the crank sensor holes that you weren't planning on using them haha.

Yeah, you'd need to drill those bosses out and run a flywheel with a reference pin for crank pickup. 84-85 had heavy single mass flywheels with a crank pickup tab, and the early 528e had a lightweight single mass with a crank pickup tab.

Do I need to use them? Someone mentioned that I might be able to use an i front crank sensor?

In other words, if I don't use the bosses, what do I do?

[AWDBOB]

Do I need to use them? Someone mentioned that I might be able to use an i front crank sensor?

In other words, if I don't use the bosses, what do I do?

To not use the bellhousing mounted crank sesnor setup you would need to do a full Motronic 1.3 conversion which is its own research topic for you.

The easiest thing to do is just find an 84-87 325e g260 that'll have the bosses already drilled out for the bellhousing mounted crank sensors.

Just make sure you use a flywheel with a reference tab for crank pickup or your car won't run and you'll have to pull the trans back out.

[jc1000]

To not use the bellhousing mounted crank sesnor setup you would need to do a full Motronic 1.3 conversion which is its own research topic for you.

The easiest thing to do is just find an 84-87 325e g260 that'll have the bosses already drilled out for the bellhousing mounted crank sensors.

Just make sure you use a flywheel with a reference tab for crank pickup or your car won't run and you'll have to pull the trans back out.

Thanks. I should have mentioned: I am doing the 2.7i budget stroker - 2.7 eta bottom end with 885 i head. So I will already have the i "top end". I am planning on turboing and using a Speeduino ECU. Does that make it any easier?

[AWDBOB]

Thanks. I should have mentioned: I am doing the 2.7i budget stroker - 2.7 eta bottom end with 885 i head. So I will already have the i "top end". I am planning on turboing and using a Speeduino ECU. Does that make it any easier?

Yeah, you *should* be using the Motronic 1.3 parts with that setup, which will use a front crank trigger at the harmonic balancer, and thus you won't need the bellhousing mounted crank sensors any more.