Looking for some input on a dogleg transmission swap?

General conversations about BMW E28s and the people who own them.
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David B
Posts: 520
Joined: Mar 09, 2008 5:43 AM
Location: Savannah, Georgia

Looking for some input on a dogleg transmission swap?

Post by David B »

First off, hello, I took almost a decade off from this hobby. I got bit by the audio bug, don’t even get me started on that, here’s my conundrum.
I have recently picked up a Euro E23 735 with a stock manual gear box. I have a dogleg box out of a 79 635 sitting around serviced and ready, does it make any sense to swap out the stock box for this dogleg in a big heavy car like the E23? I do not know what rear diff is currently in the 7, it does have the 10.1 motor in good shape, I’ll add some sport springs with new shocks etc.
So again is it a waste of such a sporty gear box on the 7 being a large luxury car or will the dogleg make it a more exciting drive? Will this add value to the E23 if I decide to sell in the future?
Regardless I’ll just list either tranny with a pedal box, new drive shaft and associated hardware as a 5sp swap for an E28. I would think value wise the dogleg is exponentially higher, but I was thinking a full euro E23 with a dogleg and all the other goodies I have around would be pretty dang dope too.
This is not to solicit sales so please do not reach out, I’ll list in the appropriate thread for that eventually.
Your thoughts, opinions, and experiences are appreciated, thanks.
wkohler
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Re: Looking for some input on a dogleg transmission swap?

Post by wkohler »

Given you can just swap the gearbox itself for the overdrive unit already installed it wouldn't really be too hard of an experiment. When you look at the numbers depending on the equipment the E23 has, it's not much heavier than an E28 or E24 and it might make for an interesting experience when combined with some suspension. Worst case, you don't like it and put the OD box back in. I imagine the car has a 3.07 rear end with the 10:1 so that would be appropriate for the dogleg as well. I think the deciding factor is really how much you want to row the gears in a car like that.

As far as selling the car, I'm sure it would make it more interesting to some but at the end of the day probably wouldn't add more value than the delta in value of the two gearboxes. Hell, there might even be one guy that might consider the car to swap back to an OD and sell the dogleg to recoup some cash. Stranger things have happened. Good luck!
David B
Posts: 520
Joined: Mar 09, 2008 5:43 AM
Location: Savannah, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by David B »

Thanks wkohler, I already have a new clutch to install so it does make sense just to drop the dogleg in and see how it drives. If the diff is a 3.07 that would work well, if I remember correctly that was what was in the 635 donor. I have a 3.25 in the 535 and had been worried it would be to short, not that that is pertinent anymore. I do wish there was an E23 specific forum as useful and layed out like MyE28.
wkohler
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Re: Looking for some input on a dogleg transmission swap?

Post by wkohler »

Well the good thing for you is that most all of the people that know their stuff with E23s are here. :D
Kenny Blankenship
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Location: NNV

Re: Looking for some input on a dogleg transmission swap?

Post by Kenny Blankenship »

Your diff could be either 3.07, 3.25, or 3.46. Better check. 3.46 is pretty stiff for a dogleg, 3.07 or 3.25 is appropriate. How many RPM does it turn at 70mph?

As far as the application, it depends how you drive the car. If it's a cruiser, it would be a waste to install it. If you enjoy some spirited driving, I can see how a dogleg can be worthwhile with the closer ratios.

You didn't say the year of your E23. If after 1981, it would be Motronic with 10:1. If it's an early one, it would have the M90 engine (9.3 compression).

By the way, a Euro E23 isn't that heavy depending upon equipment. Probably the same weight or even less than a US 535i, especially if the E23 doesn't have AC, power windows, power seats and/or power sunroof.
travisj
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Location: Arvada, CO

Re: Looking for some input on a dogleg transmission swap?

Post by travisj »

^^^^Kenny is your Huckleberry!

wkohler wrote: Sep 22, 2020 8:53 PM Well the good thing for you is that most all of the people that know their stuff with E23s are here. :D
David B
Posts: 520
Joined: Mar 09, 2008 5:43 AM
Location: Savannah, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by David B »

The E23 is an 86, I’m going to pick it up this weekend. As far as expected driving style in this car? I’ve never really layed in it hard in any of the BMW’s I have had. I’ll hit some twisties but short shift at 5k or so, I’m a fan of lowend torque. If I get that itch I have another car specifically for getting the poison out.
I do work in New Orleans but live in Georgia, I make the drive once a month, working two weeks on two weeks off and would like to drive the 7 from time to time once I get it sorted out.
This is why I started this post, going in I was just thinking (damn it would be cool to have a Euro e23 with a dogleg to boot), but I’m assuming they never came that way. It comes down to selling the dogleg and completely paying for the 735 possibly. Last night I was looking at comps online, they have gone up since the last one I sold 13 years ago. Besides making sure everything is in spec and running well these are the parts I will be swapping off the 535 to the 735 in the near future. I’ll order some sport shocks and springs, it’s sucks the E28 will not work I have a brand new set of complete Bilstein sports in BVA sport springs.
Dogleg transmission?
New clutch.
Headers.
Alpina steering wheel.
M6 Tach.
Alpine Deck.
A/D/S PS5 x 2.
A/D/S 200i plates up front.
NOS Boston Acoustic separates in OEM premium housing rear.
Euro headlights.
Style 19 wheels/PS4s
OEM Foglights.
OBC LED light installation.
Batteryless SI board?
Lighted switches.
I want to say I am absolutely giddy about getting this car. I haven’t felt this way about a new car in a very long time.
Mdreamer
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Location: Atlanta, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by Mdreamer »

How is the car coming along? Did you put the dogleg in it? If so, how do you like it?

I had a dogleg put into my 535i a couple of months ago and I'm willing to trade notes if you'd like.
David B
Posts: 520
Joined: Mar 09, 2008 5:43 AM
Location: Savannah, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by David B »

I dropped the 7 off at a techs a few months ago, waiting for him to sort it out, just basically make it a solid driver as far as mechanics. If for some reason the stock 265 has been compromised I’ll certainly drop the CR in there given it’s what I have. The tech suggested I live with the stock box for awhile before committing to a swap.
What are your thoughts after the swap?
Mdreamer
Posts: 526
Joined: Feb 12, 2006 12:00 PM
Location: Atlanta, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by Mdreamer »

David B wrote: Feb 26, 2021 12:22 PM
What are your thoughts after the swap?
For what I have in mind for my 5er, the CR is a bit "hyper." If your driving consists of driving no more than 80 mph, it may be enjoyable if you have a 3.25 rear differential. Higher speeds will have the revs pretty high up there, however. Unfortunately, I have yet to have my tachometer repaired, but 100 mph sounds like I'm turning 4,500 - 4,800 rpm, which is more than I prefer for extended drives. Once I get my tachometer fixed, I'll chime back in with more specific numbers.

It's great to hear that your car is coming along!
Mike W.
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Re: Looking for some input on a dogleg transmission swap?

Post by Mike W. »

Mdreamer wrote: Feb 28, 2021 8:36 PM
David B wrote: Feb 26, 2021 12:22 PM
What are your thoughts after the swap?
For what I have in mind for my 5er, the CR is a bit "hyper." If your driving consists of driving no more than 80 mph, it may be enjoyable if you have a 3.25 rear differential. Higher speeds will have the revs pretty high up there, however. Unfortunately, I have yet to have my tachometer repaired, but 100 mph sounds like I'm turning 4,500 - 4,800 rpm, which is more than I prefer for extended drives. Once I get my tachometer fixed, I'll chime back in with more specific numbers.

It's great to hear that your car is coming along!
That would make sense. With a 2.8 Bavaria and a 2.8 E12 in my history, both of which saw over 100K in my ownership the stock 3.45 with a 1:1 a 4 speed was almost a little buzzy. Probably the right overall diff, but I would have liked at least to try a 3.25. And that's with 2.8 in bodies of essentially the same weight.

There is a but however... at 3K, 3.5K it felt buzzy, if I rant it up to 4/4.5K doing 80-90MPH it no longer felt buzzy, just kind of hummed along like it was happier than at lower RPM.
TheE28Ranch
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Joined: Feb 12, 2006 12:00 PM
Location: Marquette, MI

Re: Looking for some input on a dogleg transmission swap?

Post by TheE28Ranch »

I had a 3.46 in an E28 paired with the close-ratio transmission - did it specifically for short-track purposes. Was buzzy as could be. Drove it from southern OH to northern MI once upon a time, couldn’t get over 110 mph iirc. So high-revving. Rowed the gears constantly, appeared/sounded like I was gearing to race anyone from any stop. Drove by friend working at house (in a neighborhood) one day - I overhead his coworker say “that guy needs to shift”. 😆

Anyway, I’d suggest (to anyone) considering the dogleg swap to check the diff (compatibility), as pointed out prior. Have fun, regardless.
austin8753
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Re: Looking for some input on a dogleg transmission swap?

Post by austin8753 »

my e30m3 came with one installed, paired with a 3.25 limited-slip. perfect transmission for that engine, IMHO. the close gearing, with a low horse, high compression, high revving 4 cyl, is perfect, in my eyes. sure, the overall top speed is significantly less, but i rarely go above 80mph, anymore. i could see how that bothers some, though.

i would imagine that a CR box, would be plenty of fun, paired with the 10:1 M30. were it my car, i'd do it. i'd love to have one for my e28m5.
David B
Posts: 520
Joined: Mar 09, 2008 5:43 AM
Location: Savannah, Georgia

Re: Looking for some input on a dogleg transmission swap?

Post by David B »

Wow that’s some great info. I think I’ll keep the stock box in there especially given the comments, I do plan to drive the 735 from GA to Nola a few times a year. If I remember correctly the rear end in the 79 635 I pulled the transmission from had a 3:07 rear I think? I wish I had kept that. I really appreciate the input, that’s what I was looking for.
Blue Shadow
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Re: Looking for some input on a dogleg transmission swap?

Post by Blue Shadow »

The 79 E24 diff won't fit an 86 €E23 and the 7 should have a big diff, 3.25

Gearing would be 3.25 in 5th with the CR With the OD 5th at 1:0.81 this is 3.25 X .81 = 2.63 a comfortable rpm needed for up to an 80 or so mph cruise.
I have a 3.46 in my €7 and appreciate its ability to pull a bit more out of a corner and don't hate the increased cruising rpm, 3.46 X .81 = 2.80.
A CR would be way too buzzy and the car would be too much on its toes ready to go. Maybe great for twisties but not for highway. And between Savannah and NOLA you have no twisties. Not even much in southern GA. First gear would not be used except on hills.

My 5 currently has a 3.64 and it is a bit too short for long highway hours but not terrible. This one gives you 2.95 vs the 2.80 and 2.63 for the other options I've own(ed). 3.25 diff with 1:1 5th gives that 3.25. Ouch.
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