M50 manual swap

[bimmerd00d]

So it's that time, the wagon's tranny is starting to show its age. It's sluggish from Park to R or D when it's cold. I'm not even going to mess with the auto anymore. I have an 89 525i donor car i can snag the pedal assembly from, but i'm leary about the tranny in it. They're the Getrag 260, and putting that behind an M50 puts it all cockeyed i believe doesn't it? I found a '91 318i 5-spd on craigslist that's a Getrag 240, which would work nicely with the 4.10 LSD that the wagon already has. Ultimately i need to find a '91-92 525i 5-spd donor. I do need to change the driveshaft as well don't i?

[Blitzkrieg Bob]

M50 powered E36s may be easier to find

[genphreak]

Beware ratios. I popped a 5 speed (ex M50, not sure if e36 or e34) in replacing the factory 5HP18EH. With the 3.91 it was mad.

My calcs show a factory ratio would be more like 2.93 (basd on 5th gear crusiing speed/rpm) which is strange as the old auto was a 5 speed also. Presently am running a 3.65 diff from a 530i auto, it is much better but still a stupidly low ratio. 3.23 might be an ideal option to have good pickup and highway-ability, however I suspect that the internal ratios can change between the e36 and e34 boxes... they always do this to control economy between models and engine outputs.

Kinda cool tho, if you go 5 speed it's good idea to get a cheap barely abused LSD diff from an e32 as they all have those less desirable ratios.

[bubba966]

Beware ratios. I popped a 5 speed (ex M50, not sure if e36 or e34) in replacing the factory 5HP18EH. With the 3.91 it was mad.

A factory ratio would be more like 2.93- which is strange as the boxes are both 5 speeds. Presently am running a 3.65 diff from a 530i auto, it is much better but still a madly low ratio. 3.23 might be an ideal option if you want some pickup, however I suspect that the internal ratios can change between the e36 and e34 boxes...

Kinda cool tho, if you go 5 speed it's good idea to get a cheap barely abused LSD diff from an e32 as they all have those less desirable ratios.

Yeah, I think the gear ratios are different between E36 & E34 boxes. Hence why you usually want the diff with the tranny out of the donor. And you'll want the driveline as well.

And if you want an E32 diff you'll need one out of a 735 as the 740 & 750 used large case diffs. 735 was the only one that had a medium case diff that you'd want.

I suppose you could also change everything over to a large case diff setup. But that'd require a good amount of parts swapping.

[Blitzkrieg Bob]

I think the issue is the difference between the auto diff ratio and the manual diff ratio.

The gear boxes should be the same, only difference was Getrag and ZF boxes.

[bimmerd00d]

I think the issue is the difference between the auto diff ratio and the manual diff ratio.

The gear boxes should be the same, only difference was Getrag and ZF boxes.

I had a Getrag and ZF in my old E34, they were the same ratios to my eyes/ears. I have the 4.10LSD in the wagon now, which would be nice if i could use the Getrag 240 from the '91 318i....it would be alright with that. There are plenty of E34 manuals floating around the yards here, but they're mostly 535's. I'll have to find a 3.23 or something later.

[Blitzkrieg Bob]

I had a Getrag and ZF in my old E34, they were the same ratios to my eyes/ears. I have the 4.10LSD in the wagon now, which would be nice if i could use the Getrag 240 from the '91 318i....it would be alright with that. There are plenty of E34 manuals floating around the yards here, but they're mostly 535's. I'll have to find a 3.23 or something later.

Check the bell housing on the 240...the M42/4 in the 318 might be different then a M50

[bimmerd00d]

Check the bell housing on the 240...the M42/4 in the 318 might be different then a M50

the M42-based 240 fits, the M10 one does not. There's a whole '91 318i near me for $350 :) Could EASILY part out most of that car to pay for the rest of the swap :)

[bimmerd00d]

back from the dead! If i source the S5D-310Z from an early 525i or M3, would the driveshaft work from a '94 530i? They share the same diff/tranny as the 525i, albeit with a different bellhousing.

[bubba966]

back from the dead! If i source the S5D-310Z from an early 525i or M3, would the driveshaft work from a '94 530i? They share the same diff/tranny as the 525i, albeit with a different bellhousing.

As long as the length of the driveline & bolt pattern on the tranny end is the same it'd work just fine. I don't really recall bolt patterns being different if at all on the tranny end of E34 drivelines. I know that guibos are different thicknesses between different E34's. So it should only be a total length issue if there is one at all.

[WarrenBrown]

I'm pretty sure the 318is from a 90/91 E30 will fit the M50. That trans will not fit the M10 motor without being cockeyed. Having said that, my 318is trans went at about 70K with bad shift forks. Bought a used one from a junkyard, it also was bad also. Ended up rebuilding the 1st and it has about 150K after the rebuild. The 318is has aluminum shift forks that tend to wear. Maybe I have no luck because it doesn't get mentioned often on forums. I think ratio wise it might be a good match. Taking a E34/E36 trans might not be a good match for present diff. E34/E36 transmissions use a 1:1 5th gear where the E30 cars had a overdrive 5th. Years ago I thought about doing a conversion and ended up dreaming about a 6 speed from an even newer car. The 6 speeds use an overdrive. 6 speeds are common in E46 and E39 (I think) cars. Do they fit and if what drive shaft to use is another question. I've lost interest in the conversion (it was only pipe dream anyway), the car suffers from rust on the doors, the motor sounds like a diesel with a bad lifter or 2, the trans is beginning to scare me.

Warren
88 325iX
91 318is
95 525iT
01 525IT