325e/528e auto transmissions interchange?

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Fedaykin528e
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325e/528e auto transmissions interchange?

Post by Fedaykin528e »

I can't seem to figure out if the 4hp22 from a 325e is plug and play in a 528e. My e28's needs a rebuild which I would like to do on a donor vs. having a car on blocks for weeks.

I've searched around and not found a definitive answer. One post was saying that the e30 has a different length output shaft and a 3 bolt flange to the e28 4. However I'm looking at photos of a possible donor that has a 4 bolt flange. Maybe the post was about an i, it doesn't specify.

So, does anyone know? Do they swap between e30 and e28 etas? Thanks!
Mike W.
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Re: 325e/528e auto transmissions interchange?

Post by Mike W. »

I don't know, so take this for what it's worth.

My guess is they do interchange, but the output flange appears to be different. The output shaft appears to be the same which would suggest the overall length is the same, not counting the flange. I found this by poking around Realoem, but they won't list the trannys as being the same as I'm sure there were minor differences given the weight difference in the car, at the least the valve body and torque converter are likely to be slightly different. And just using 1-84 as a production date, they list 6 different 4HP22 variations for a 528e.

Tape measure? Can you see the prospective doner?
Fedaykin528e
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Re: 325e/528e auto transmissions interchange?

Post by Fedaykin528e »

Thanks Mike. Good point on weight and valving, and I don’t know enogh to make the judgement call.

Looking at realOEM again, it looks like the trans in my 528e was phased out right when the one in the e30 came in. ‘84 vs. ‘87.

So I’ll pass on this one. Looks like it’s narrowed to a pre-87 528e donor.
Fedaykin528e
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Re: 325e/528e auto transmissions interchange?

Post by Fedaykin528e »

Dug into this a bit more, I think there's just two types of 4hp22's which are described on Wikipedia and verified with internet sleuthing. There's an A and a B version with different ratios, for big and little engines. A went in m20s and B went in m30's. The differing model names and numbers on RealOEM might just be different output flanges.

These flanges are removable without opening the case, and swapping them around shouldn't be an issue. I'll verify all of this when I replace seals and clutch A in the e30 unit I found.
turbodan
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Re: 325e/528e auto transmissions interchange?

Post by turbodan »

The drive shaft lengths will be different between the e28 and e30 on account of the different chassis. As long as your output flange is the same I fully expect you will be good to go.

I think the autos got a four bolt flange and the manuals got the three bolt with the flex disc.
Mike W.
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Re: 325e/528e auto transmissions interchange?

Post by Mike W. »

Fedaykin528e wrote: Aug 16, 2022 11:59 AM Dug into this a bit more, I think there's just two types of 4hp22's which are described on Wikipedia and verified with internet sleuthing. There's an A and a B version with different ratios, for big and little engines. A went in m20s and B went in m30's. The differing model names and numbers on RealOEM might just be different output flanges.

These flanges are removable without opening the case, and swapping them around shouldn't be an issue. I'll verify all of this when I replace seals and clutch A in the e30 unit I found.
M20 and M30 trannys used different bellhousings/oil pumps and probably torque converters. Maybe output flanges too, aside from the A/T-M/T part.
gadget73
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Re: 325e/528e auto transmissions interchange?

Post by gadget73 »

Looks like the bellhouse is removable based on observations of mine behind an M21. Also lots of non-BMW applications ran this transmission.
Mike W.
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Joined: Feb 12, 2006 12:00 PM
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Re: 325e/528e auto transmissions interchange?

Post by Mike W. »

gadget73 wrote: Aug 18, 2022 11:44 AM Looks like the bellhouse is removable based on observations of mine behind an M21. Also lots of non-BMW applications ran this transmission.
Yes it is, easily I might add.
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