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E9 3.0 CS M5 engine swap

Discussion in 'E9 2800CS, 3.0CS (1969-1974)' started by Lostagn, May 24, 2008.

    Lostagn guest

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    Hi

    First post here.

    Took a while but managed to pick up a CS with 90% of
    the body restored.(motor gone).
    Then got lucky and got a 1991 M5 (rear end hit).
    I heard from another forum that there was some info here
    on this swap. Being new to this I have not found any reference ?

    Any and all help to loacate info would be much apreciated.

    First question I have is with the rear end.
    Should I upgrade it to a newer unit ?
    I thought I read some where that a 1980 ish 525
    unit with subframe will partially bolt in then some retrofit required ?

    I want to start with this so I can figure out which trans to use.
    with or with out speedo gear.

    thanks ahead of time for any advice.

    Dale Peddie guest

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    M5 engine in E9

    In case you have not had a reply to your post I would suggest you contact Carl Nelson of La Jolla Independant (Google for phone & email) in California. He has been involved in most conversions with E9 coupes and also sells a full range of parts. I have converted my '73 from an auto to 5 speed and installed a 3.5 litre from an early euro M535 (single cam). FYI, still using the stock diff and have not had any problem in the last 10 years. The fuel injection saves alot of fuel vs. the twin carbs and the performance is great although not twin cam great! Good luck!
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    EuroWerkz1

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    Yes

    I second that advice, in fact I met a guy that did this very swap and he was surprised how almost bolt in it was mechanically. Carl is your man for E9's and just a great guy too.
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    mooseheadm5

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    Stream of consciousness post:
    I put in a 3.5 from a 91 535i complete with the Motronic. I can dig up my wiring digram (it will be almost identical.) I am not sure about the S38, but all M30 engines after 89 were missing a couple mounting bosses for the passenger side of the engine block which necessitates fabrication of a custom engine mount bracket. Also, the bell housing may be different, so manual trans only. I know that the E12 has the same dimensions as the E28 where it counts for driveshaft placement, so you may get very lucky if you can get an E28 M5 driveshaft. I never got around to conversion of mine to a manual before I sold it. You must fabricate a clever cable throttle because the CS has a linkage throttle (but I can give you tips on that, having done it for my family's old E12 530i auto to E28 motronic manual swap.) You will probably have to change the brake booster. You may need to go hydraulic boost to get it to work, which means you need an E23/24/28 parts car with working boost stuff (easy to do.) If you have any questions, just let me know. I love motor swaps and think they are "easy" but that does not mean they are fast or require no thinking or custom fabrication. Also, your temp gauge will go nuts because it will think your car is always overheating. I never did install a resistor, but that is all it would take to fix that issue. You need to install a fuel pump assembly. You can go in tank, ot pull the pump/filter cluster from an E28 or similar and bolt it under the car, which I did. I made a custom pickup that went into the tank and used the existing feed line for the return, running a new steel line under the car for high pressure to the fuel rail. If you really feel like it, you can even install an E28 rear subframe and diff. Use a trans with speedo gear definitely. Otherwise you need to do lots of wiring for an electronic speedo. I suggest a Getrag 265 gearbox from a 528i (1981?, I think.) Where do you live?

    Lostagn guest

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    Thanks for the advice

    Hi, thanks for taking the time to reply.
    I'm in Calgary, Canada.
    Had a 1986 535i parts car....pulled all kinds of parts off it.
    and found a posi out of a 1980 ish 730...good shape...still tight.
    flanges don't match on the 535 rear end.....looking for a fix.
    Still looking for the 265 trans...
    Have not started to do the M5 swap yet...to busy with work...sad sad.
    still have a couple other BMW's to fix to create some more Hoby cash flow.
    Looking forward to the project ....looks like fall and winter.....
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    mooseheadm5

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    19?? 730? The parts catalog shows 79 as the last production year. 9/81 is a production break for the different styles of rear diff on the E23. I am not sure what you can use that drops in, but my guess is any sideloader rear will fit. If you wanted to do the entire rear suspension, you can do the E28 rear subframe, control arms, dampers and springs, brakes, diff, axles, etc. Otherwise, not sure what you can do. I had also contemplated doing the front suspension too, but never got there, and will probably never own another CS due to the rust issues. You haven't lived until you have cut the rocker panels apart to replace the inner stiffening metal piece. It is obvious why these things rust so badly!

    pingtsao guest

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    Cs/m5

    Hello from Ping Tsao in San Luis Obispo, CA. It has been over 17 years since my CS/M5 conversion was published in European Car magazine (Dec '91) and Roundel. It has appeared at numerous BMW Festorics at Monterey Historics after being built by a maverick local mechanic, Tim Rayner (who now lives in Camino, CA). It took hime 600 hours. I think that the project can be reproduced with the right collection of donor parts. We had a whole M5 wreck. My advice is that the more M5 parts you have, the easier the project. Key to the conversion is using the front and rear subframes from the M5 so that the suspension, steering, ABS brakes, and engine mounts are there. Everything lines up, and the bolt sizes and patterns are the same between CS and M5. No sheet metal fabrication work was required except cutting off the front frame rail pads for the old subframe. It is also probably wise to reinforce the differential mount by boxing in between the rear frame rails.
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    mooseheadm5

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    There you have it. That must have been the one I read about. So you do not have to worry about the engine mount brackets if you use the E28 front subframe, and you can use a much better differential and drive axles if you use an E28 rear subframe. All rear E28 subframes are the same, IIRC (except maybe the 4 cylinder.) The fronts should be virtually identical. I recommend E28 stuff over E9 stuff. Also, reinforce the steering box inboard mount. Get a whole wrecked E28 is the best advice. Should be able to come up with one for about $100 or less. Then you can use whatever you want and recycle the rest.

    37759 guest

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    When was it published in the roundel? Thanks
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    mooseheadm5

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    Don't remember, but I do have an E28M5 drivetrain for sale.

    37759 guest

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    Thanks. Just interested in the process, at this point. I looked at my Roundels from around Dec 91, without success. Thanks again.
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    CSBM5

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    Korman has done a number of conversions over the years. At TechFest 2004, I met the owner of one E9 that had been converted at Korman Autoworks. I can't recall his name at the moment, but I saw him and his brother again at O'fest 2005. I believe he was from Maryland, so probably a National Capital Chapter member. Here are some pictures I took of his car:


    [IMG]

    [IMG]

    [IMG]
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    mooseheadm5

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    Pretty car. I wouldn't let them work on mine, though.

    37759 guest

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    Thanks for the info and photos. I started reading about the DOHC heads of the early 70's that were used for racing with the Kugelfischer MFI, and eventually got to the M88. Any tech info or whereabouts of DOHC heads or Kugelfischer for the 6-cylinder would be appreciated.
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    mooseheadm5

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    It is essentially an Alpha-N style fuel metering system, similar to what was used on the 2002tii. It is good for racing, but not great for the street. It meters fuel based on engine speed and throttle position and has a temperature compensation circuit and that is about it. It cannot correct for real engine load or air density.

    BlueAngel M3 guest

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    Where did u get a strut tower brace for that car from?

    wgf3 guest

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    Did someone really do that???

    I realize that this thread is several years old but I just got off the phone with Carl Nelson and he says that the e28 to e9 front subframe swap is NOT a bolt in and is 'a project with diminishing returns' due to the complexity. I am looking to convert my e9 race car to the e28 front set-up as I have already done to the rear. And reading the several comments here that suggest it's a bolt-in sounded great. But the guru says otherwise. So if anyone knows of someone who did such a conversion (and since I am doing a race car I have a little more flexibility as to how it gets done than someone doing a street car) I would love to know who did it and how.

    Thanks
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    CRKrieger

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    You might want to contact Bill Arnold (Golden Gate Chapter) to see if that was one of the things he did in his Targa Newfoundland E3.
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    John in VA

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    granthr

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    Not that it is helpful, but I saw that car in Pittsburgh in 2009 at the Vintage Grand Prix. Awesome car!! :D

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