Automatic upgrade- which one?...don't want a manual swap.

lytebrite

lytebrite

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Hey Everyone -

I was Speaking with Carl at the BBQ over at La Jolla Independent on Sat and told him I liked the idea of an automatic, just not this one (I have the stock BW unit). All of my newer BMWs are 6spd MTs.

As many of you know, it downshifts at odd times and just isn't a good performer. He mentioned an auto trans replacement from a 5 series (which would also give me an extra 35hp) that would be a drop in, but I'm not sure which one.

What is the preferred model year 5 series to do this with?Has anyone done this? I tried searching the forum, but everyone went the 5spd route.

I'll post some photos of the event. too. Great time and Carl is the coolest.

Thanks -Wyndham
 

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lytebrite said:
Hey Everyone -

I was Speaking with Carl at the BBQ over at La Jolla Independent on Sat and told him I liked the idea of an automatic, just not this one (I have the stock BW unit). All of my newer BMWs are 6spd MTs.

As many of you know, it downshifts at odd times and just isn't a good performer. He mentioned an auto trans replacement from a 5 series (which would also give me an extra 35hp) that would be a drop in, but I'm not sure which one.

What is the preferred model year 5 series to do this with?Has anyone done this? I tried searching the forum, but everyone went the 5spd route.

I'll post some photos of the event. too. Great time and Carl is the coolest.

Thanks -Wyndham
Click to expand...
I was not aware there would be a drop-in automatic transmission alternative. The 5/6 series of the 80s used the ZF 4HP22, of which there is a mechanical vs. electrically controlled. The first advantage would be that it has 4 instead of 3 speeds. I have no idea if it fits r the E9, and I do not know if it has 35HP less of power loss. The torque converter does have a lockup clutch that kicks in 3rd and 4th gears, that could save power over the E9 BW.
 
1985 318i 4hp22 non-electronic should work.

Been custom fitted on 2002s with an M10 bolted to it

THey also came in (again, get a pre-86 to get non-electronic):
    • 1983–1989 633CSi M30/B32
    • 1983–1987 635CSi M30/B34
    • 1981–1987 518i M10/B18:[2] Type B
    • 1981–1987 525i M30/B25:[2] Type A
    • 1981–1987 528i M30/B28:[2] Type A
    • 1983–1984 533i M30/B32
    • 1984–1988 535i M30/B34:[2] Type A
    • 1983–1984 733i M30/B32
    • 1984–1987 735i M30/B34:[3] Type A
 
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If you use a 4HP22 in a coupe I would suggest a shorter differential ratio to operate 4th gear in a sweeter part of the power band. 4th gear is really overdrive in the 4HP22 at 0.81, which is lower revs than a 5 speed OD Getrag 5th gear... On my E24 I went about 11% shorter differential ratio I think, and I wish I would have gone even shorter.

And here is the trick question that experts smile and don't answer when I ask: if I use a shorter differential do I get to higher revs on the lower gears (as if the shifts were based on speed) or the shifts happen at lower speeds (as if shifts are triggered by RPM alone)?
 
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Arde said:
If you use a 4HP22 in a coupe I would suggest a shorter differential ratio to operate 4th gear in a sweeter part of the power band. 4th gear is really overdrive in the 4HP22 at 0.81, which is lower revs than a 5 speed OD Getrag 5th gear... On my E24 I went about 11% shorter differential ratio I think, and I wish I would have gone even shorter.

And here is the trick question that experts smile and don't answer when I ask: if I use a shorter differential do I get to higher revs on the lower gears (as if the shifts were based on speed) or the shifts happen at lower speeds (as if shifts are triggered by RPM alone)?
Click to expand...
Then, are any of Rob's pre 86 diffs mentioned fit that bill?..and fit?
Personally, I love the auto of later model Mercedes Benz's...great fuzzy logic with up and down shifts. In an e9, that would be transformative (if that's a word). But I guess that any improvement to the 3speed auto's is good.
 
www.bmw2002faq.com

4HP22H project...

This is my semi blog for the transmission swap for my bone stock 1974 Automatic 02. The goal is to get out the poor venerable 3HP12 3 speed in favor to a 4HP22H 4 speed overdrive unit. This transmission is only found on the 1985 318i, it is a non-electronic unit so it is a perfect swap in a carbe...
www.bmw2002faq.com www.bmw2002faq.com

Anything that fits an m10, should fit an m30.

Wiki page says it can handle 380NM of tq. That's ~280ft-lbs. Sounds plenty strong enough for most E9s.

I wouldn't worry about speedometer. You can get one of these:

https://www.bmw2002faq.com/forums/topic/221329-speedhut-speedbox-on-stock-‘68-speedometer/
 
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