1974 BMW CSE

Discussion in 'E9 Projects and Restorations' started by JetDexter, Oct 8, 2018.

  1. JetDexter

    JetDexter Member Site Donor

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    Hey guys,

    Well, after introducing myself over the weekend, it seems that there is enough of an interest in my electric coupe to carry on a build thread. I created a blog for this project so that various friends and clients around the country can easily follow along. But I will just try to recreate the blog posts here along with the photos so that you don't have to click to the other site. (I am doing the same process in my EV forum, so hopefully I won't wind up spending more time posting than I do building :)

    Here is my first post:



    My name is Paul Dexter, and I have a problem: I have been a lover of European cars as long as I remember.
    [​IMG]

    Sure, my dad and his ‘50s car club buddies built plenty of American muscle hot rods. But my mom opted to haul us around in various VWs and Volvos.

    As I came of age in the ‘80s and ‘90s I began to explore a string of my own European cars. Nothing fancy mind you, I would buy what I could afford, which wasn't much. Always a bit rough, I drove a string of Alfa and Fiat Spiders, Jensen Healey, Triumph, Saab. But German cars were my obsession for their combination of engineering, performance and personality. Plenty of BMWs, Porsche’s VW 16Vs, Audi Quattros, and a few Mercedes passed through my garage. The BMW straight 6 and the Porsche flat 6 engines were so intoxicating for me, they could literally wash away a bad day by joyously going through the gears.

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    Then Tesla came along.

    I was drawn to the refined stealthy, torquey, efficient power. I threw all financial caution to the wind to buy one and it ruined my love for internal combustion engines forever.
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    Manual shifting is fun sport, but it doesn’t match the gratification of having all the power you could ever dream of at your disposal - at any speed and any time you want it.

    But after a few years with the Tesla my soul longed for the one thing I missed from my early cars: Personality. Cars that were drawn by hand, with long hoods and chrome bumpers. Cars that mock wind tunnel tests.


    So That Settled It
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    As Ferdinand Porsche said “I couldn't find the sports car of my dreams, so I built it myself”. Similarly, I decided that what I must do is build my own modern classic for my daily driving enjoyment. Two cars that always topped my list were an early 911 and a BMW 3.0 CS. Both have seen remarkable - perhaps obscene - runs on values in the last ten years. The last thing I wanted to do was destroy the true value of a highly collectible car. Then again I wanted to drive my car, not store it in climate controlled environment and visit it on occasion.

    Since I still run the kids to school most days, the BMW coupe made most sense. My wife has always wanted a 2002, so building on its big brother checked even more boxes.

    Cheers,

    Paul Dexter
     

    Attached Files:

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  2. JetDexter

    JetDexter Member Site Donor

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    Sorry guys, this is from my blog, and in this post I am telling folks about the coupe.- you clearly know these cars better than I do so ignore that:)

    Finding the Right Coupe
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    I searched nationally for a good amount of time for the right car at a fair price. Because I want to convert it to electric, I was hoping to find a roller. Something with it's original motor and transmission missing, so that I could feel a little better that I wasn't the first person to cause harm to the collectable originality of the car. My car would certainly have rust, but I wanted to avoid a rolling rust museum. The overall condition of the car did not need to be high, but finding one as original as possible, and with as much of the trim intact was very desirable.

    I can not and will not unpack the mysteries of the collector car market and it's currently obscene values of certain cars. Many cars from the 70s and 80s are getting very hot, so what you could get for just $5k a few years back is suddenly costing $20k. In looking for my coupe I wasn't as concerned with value, but I did want to do the best I could to avoid getting caught up in all the hype.

    [​IMG]
    In the end I came a very interesting 1974 3.0 CS through a very off-the-radar listing (really helping with the aforementioned over-valuation hype). It was close-by in San Diego. It is a European market car, imported to the US in 1994. This is interesting for a couple of reasons: First, it was driven for many years by actual Europeans, most likely full-throttle on the Autobahn. Second, it means that it has the lovely small bumpers that by 1974 all US market cars did not. They received park bench units that hung well into the next county. What really pleased me is that she is a sunroof model. Those that know me know that if my cars don't have a sunroof, a convertible or a targa, I will likely find a saw nearby and take it to the roof. (You should have seen my 1978 VW Rabbit Targa- it really happened). Sunroofs were rare for the European market, so that's even more interesting.

    It was originally Polaris Metalic (silver) with blue leather. At some point the car was painted white, along with it's factory alloy wheels. White wall tires were fitted to complete the interesting look. The car is very complete, with a fairly tidy interior. The power windows work with a little assistance. The car runs and drives. With no working clutch, the driving experience is even more exciting.

    Bringing Her Home
    [​IMG]
    With Trailer in tow I headed in her direction. I hadn't actually been able to see the car in person. I had to buy based on photos, more detailed photos, and answers to my many questions. Then I had to pay for the car, then come pick it up at a third party. Highly aware of the common scams, this was clearly not that. It was just a seller that did not or could not deal with the process of showing the car. Since the car was nearly half the price of others I were looking at and in far better overall condition I did take that chance. When I pulled up I was greeted with a clean California Title, a bill of sale, an original BMW key and a car that looked better than the photos I had been reviewing.

    Getting her on the trailer was fun without a clutch or a winch. We tried disconnecting the coil and driving up the trailer ramps with the starter, but that wasn't enough power to make the climb. So I had to drive it up and try to remember to turn off the engine once on the trailer. Things were going swimmingly until the car jerked to a stop with a loud crash! The exhaust (which was attached to the car only at the manifold and the tailpipe) was hanging just a bit too low. We thought it would clear, but just enough of it caught the hard edge of the trailer that it ripped away the entire system right at the manifold. We gathered the parts and put them in the truck then gave it another run. This time she sounded like a terrific track runner. I drove it to the top of the trailer so easily that of course I forgot to turn off the motor until I just about drove off the front of the trailer. But I found the key just in time and avoided any more excitement for the day.

    In the Shop
    Back at the shop we pulled her down and settled her in. We will likely weld the exhaust back to the car so that we can drive her around a bit and have some fun before she's completely disassembled. We also want to weigh the 4 corners of the car with the exhaust in place so that we can design the weight balance of the new system with this in mind.

    With the couple snuggled in for the night, I leave you with this little video of how great she sounds with no exhaust.

     
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  3. JetDexter

    JetDexter Member Site Donor

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    Today we finally took some tools to the CS. Before we tear it down, we thought we would repair the exhaust and service/adjust the clutch just so that we could run the car some. We will be selling off the entire drive train and wanted to shoot a driving video - running through the gears around town. Once we got the car up and took a deeper look, it was clear that a quick repair wasn’t going to happen. One of the downpipes bends had been pulled out of shape enough that it no longer lined up on each end. The other downpipe had taken a portion of the rear manifold with it. While it is all repairable, we decided that it was too “exhaustive” and time consuming. Any time spent here is going backwards from our actual goal, so we decided to move forward. With bailing wire we attached the exhaust to the car for the purpose of weighing her in.

    [​IMG]
    Weighing the CS
    We want to weigh the four corners of the car so that we have a good basis for our new weight distribution. Our electric motor, batteries, and associated systems will replace an engine, a tranny, drive shaft, differential fuel tank, etc. The weight of our new systems can be equal to the items we remove , depending on the number of batteries we end up using. The minimum number of batteries to achieve the voltage and minimal driving range will weigh a tad less than our current drive train, but additional batteries to increase that range will add to the weight. We are somewhat flexible here, as we are not requiring a 300 mile-range car. We also don’t want to settle for 50 miles. Thus we need to weigh the car now, then weigh it again with it’s drive train removed. We can then begin that engineering. The good news here is that the CS is a fairly light car, weighing around 3100 lbs. It’s current successor can weigh 4500 lbs. Naturally our chassis and suspension is not built to handle that kind of weight, but we certainly do have a bit of room to play with and maintain a fairly light car.

    [​IMG]
    To be economical, we built a pair of scales using some basic parts. Our scales are capable of measuring 600 lbs, so we configured them to measure half-weight. We verified our rig’s half-measurement by weighting an item directly, and then using the scale. Once satisfied, We rolled the front wheels onto the pair, keeping the rear wheels elevated the same amount as our scales. We swapped the scales around a couple of times to verify that the readings were coming back the same. I assume that our final measurements will be off by a very small amount, but certainly within just a few pounds at each wheel which is certainly close enough for our needs.

    With a full tank of gas our CS weighs in at:

    Front: 1743 lbs. (Drivers 916 lbs, Passenger 827 lbs.)
    Rear: 1427 lbs. (Drivers 719 lbs, Passenger 708 lbs.)
    Total: 3170 lbs.

    [​IMG]
    Hood Upright Repair
    The drivers side hood upright arm had been poorly repaired at least a couple of times and had failed again. We will likely move to a more modern and lightweight approach of gas-charged struts, but for the time-being we figured we should properly fix the stock setup. The sledgehammer that we had been using to prop the hood up has far more important jobs to do.

    So that’s it for today. We hope to get in there again next week and have a drivetrain removal party.

    Cheers,

    Paul
     
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  4. Markos

    Markos Well-Known Procrastinator Staff Member Site Donor $$

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    Great thread Paul! I’m excited to follow this one. I’ve always wanted an electric 914. You have a lot of opportunities to lighten the load with an e9. The front seats are very heavy. You have all of that wood and cladding in the trunk. You can remove
    the heavy rear regulators and install lexan windows. You can also buy fiberglass hoods and trunks, although fitment can be tricky.

    I’m sure that you have seen the audi with a tesla drivetrain.

     
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  5. autokunst

    autokunst Well-Known Member Site Donor $$

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    Hi Paul. Loving this thread already. I can see that not only will this be an interesting build, but a great story will be told. Thank you for sharing! Love the scales, by the way.
    I met a guy who owns a company that makes a lot of carbon fiber parts for, among other things, cars you'll see at SEMA. At the risk of being banned from the forum :eek: I considered approaching the group regarding a bulk investment of hoods and trunk lids for our cars. I thought that would be a great way to shave weight from the cars while maintaining some level of quality. I have not followed up with this idea since its inception, but perhaps there will be a newly inspired interest with this topic.?.
     
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  6. JetDexter

    JetDexter Member Site Donor

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    Setting Up Shop
    New post https://bmwcse.com/buildblog/2018/10/12/setting-up-shop

    Last week was mostly spent setting up the shop. My A/V company has some extra warehouse space so after moving various pallets of amps, speakers, theatrical lighting, we found a nice corner for the project.

    [​IMG]
    We aren’t swimming in money, but we do like the safety and efficiency of a hydraulic lift. It made sense with the amount of fabricating that needs to be done top and bottom, in addition to the typical restoration work.

    To save $400 in freight, I opted to pick it up in Los Angeles. Using my short-bed Tundra only half of it hung past the tailgate so wheelies were enjoyed in rush hour traffic on the 405.

    [​IMG]
    Once the lift was setup, we finally got to get a good look under the car. We found various rust repairs that appear to have been performed in decade intervals. I was surprised not to see any duct tape. This is going to be more fun than we thought! :)

    Finally, we printed out and posted a reminder of the goal on the wall. When we find ourselves elbow-deep in rust, welders, batteries and wires we may risk losing sight of the dream. I assume that a poster will be all it takes to get us back on track :)

    [​IMG]
    Until next time,

    Paul
     
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  7. teahead

    teahead aka "Rob" Site Donor

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  8. JetDexter

    JetDexter Member Site Donor

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    Yes thanks! I am probably more competent in the Electric universe than I am a mechanic, so I do feel confident there. Still, I am aware of those risks even when you do everything right...

    I wasn't aware that that car went up in smoke though!?
     
  9. JetDexter

    JetDexter Member Site Donor

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    Out with the Old

    New Post: https://bmwcse.com/buildblog/2018/10/19/out-with-the-old

    This week we saw our first real milestone: Removing the 3.0 straight-six motor and drive train. It was bittersweet to be sure. It is not lost on me that this (and every) BMW straight six is a beautiful piece of engineering. I have had a number of people remind me that I am ruining a classic combination of coach and motor by converting her to electric.
    [​IMG][​IMG]



    On that note, last weekend I rode along with a friend on a two-day rally through the Southern California mountains and deserts. In the group were some of my favorite gas-burning vintage cars: Porsche’s, BMWs, Austin Healeys, Triumphs and more. We drove my buddy’s terrific vintage Alfa Sport Sedan. These great cars offer their drivers the enjoyable chore of working the clutches, gears and non-electric steering through the curves and the grades. The feeling returned from this enthusiastic driving is pure joy.

    I wanted so badly to take the coupe on this drive before it’s disassembly and restoration, but neither exhaust nor clutch it was pretty much out. All weekend long I kept thinking about what I was giving up by removing the soul of the vintage machinery for the advantages of the electric. But the CSE is to be my daily car. A weekend of smelling like exhaust, fuel and coolant is awesome with a bunch of car guys, but not ideal for a board meeting or date night. I am trying to build something that can give me a slice of the vintage soul in a “scent free” edition, so that I can enjoy it every day.


    Out with the Old

    [​IMG] [​IMG]

    Before we strip the car all the way down for it’s proper restoration, we wanted to find out just how much the drive train weighs. The engine, transmission, drive shaft, differential and cooling system weigh far more than our little electric drive unit. But the tank of gas weighs a fraction of our new fuel: Batteries. In order to achieve our goal of 250 miles of range we need quite a few of those heavy beasts. A few posts back we weighed in the coupe in at 3170 lbs. We are hoping that the drive train is a large amount of that weight.

    Things got off swimmingly. We started at the rear with fuel tank and the differential. We thought the diff would be maybe 40 pounds or so. We were happy to discover it a beastly 85 lbs! We were off to a good start. We left the half-shafts going to the rear wheels in place as those (or replacements) will connect to the Tesla drive unit. We then removed the drive shaft and the shifter. Finally we unbolted the transmission and motor mounts and lowered the car. We then removed the radiator and anything else involved in making the car go. Everything else stays in for the moment. We drained and properly collected gallons of various liquids, but somehow still had to mop up gallons more. A pesky tie rod that was interfering was just not interested in coming loose. Perhaps we could have pressed her apart, but it was more fun to whip out the grinder. At least we used safety glasses.

    After a few careful hours and one forklift, the motor and tranny were safely out of the car and on a pallet for it’s future owner.


    What’s the Verdict?

    [​IMG]

    With no drive train our coupe weighs in at:

    Front: 1020 lbs. (Drivers 576 lbs, Passenger 444 lbs.)
    Rear: 1140 lbs. (Drivers 588 lbs, Passenger 552 lbs.)
    Total: 2160 lbs.

    Drive train approximate weight: 1010 lbs.

    In rough numbers, our Tesla drive unit weighs 295 lbs, and the battery modules weigh 55 lbs each for a minimum of 550 lbs. This brings us to 855 lbs. Add to that the weight of our fabricated mounts, battery enclosures, battery management and charging systems, and it appears that we should be able to end up about the original weight of the coupe. If needed, we still have the option of lighting up other portions of the car such as seats, carbon-fiber hood and more. We are exploring some suspension options that could be lighter and more friendly as well.






    [​IMG]

    Meanwhile, we have a bunch of stuff for sale! A nice running 3.0 sixer, tranny, driveshaft, differential and so forth. Reach out for details if you are in need.

    Until next time,

    Paul
     
    Last edited: Oct 20, 2018
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  10. Bmachine

    Bmachine Well-Known Member Site Donor $$

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    Mike told me the culprit was that he did not use a BMS system. It overcharged one night...
    You have to remember that this build was still very much a science project at the time as many of the parts or techniques we now have access to were not available back then.
    Nevertheless is was an awesome experiment.
     
    Last edited: Oct 20, 2018
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  11. Bmachine

    Bmachine Well-Known Member Site Donor $$

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    Congrats on starting this project. This will be really fascinating.

    Before I started my resto, I seriously considered doing exactly this conversion. I talked at great length with Mike Pethel about what he learned in the process and established a game plan. I also wrestled with the dilemna of whether it was "right" to rob an e9 from its storied powerplant. But then I realized that BMW itself was already thinking in that direction at the time...:
    https://www.topgear.com/car-news/first-look/meet-all-electric-bmw…-1972

    My goal was to have at minimum the triple 200: 200 miles range, 200hp and 200lbs/ft torque.
    But at the time (2015) the cost for those parts alone was going to be significantly above that of a 3.5 conversion. On top of that, I just didn't want to run the risk of Chris Macha never wanting to shake my hand again. So I made a bargain. I would first get a proper coupe with a shiny M30 as its beating heart and after that, I would look into doing an CSE.

    Best of luck!

    PS: I'm sure you are in contact with EVWest down in San Diego. An invaluable source of parts and experience for just this type of conversion.
     
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  12. Cornishman

    Cornishman Member Site Donor

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    Paul
    I find this fascinating and wish you the very best of luck and fun with this project. I will be watching carefully.
    Can you tell us about how you plan to get the components, motors, brakes / regenerators or whatever they have connected to the wheels to slow down and charge the batteries, the control system and loom would also be interesting. Is it a situation of finding a crashed Tesla and putting it into the E9 shell, or will you Source new components, perhaps with alternative designs?
    In the UK a Tesla is not a common car and the price of a new one is massive, so I imagine that the chances to find a suitable crashed one are few and far between. My limited knowledge of Tesla’s is that you can get different levels of performance, which level will you go for?
    Looking forward to the next post.
    Regards
    Charles
     
  13. Cornishman

    Cornishman Member Site Donor

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  14. teahead

    teahead aka "Rob" Site Donor

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    Getting rid of the rear differential? Interesting what you'd replace it with.

    LSD? If so, worth some $$.
     
  15. JetDexter

    JetDexter Member Site Donor

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    Thanks guys- here's some lumped-in replies:

    True that just 3 years ago the gear was just too costly. EV kits were low-powered DC types (good for modest VW/P{Porsche conversions using the existing tranny). But by now there are a BUNCH of Tesla drive units available to buy- salvaged units from cars in total loss accidents, etc. (we all know that it doesn't take much of an accident for Insurance to total out a car. My wife's 2018 VW Atlas was very minor looking front end damage and they totaled it out to avoid the liability, etc. It is still very pricey, $5k for questionable history, or $8k for refurb drive units. Battery modules are $1100-$1500 depending on history. So maybe $20k for drive unit and batteries then another $5-$8k for BMS, Control, etc. Not cheap- BUT you wind up with an extremely proven reliable setup.

    Point is- I JUST about did what you did Bmachine, and restored this one to gas then do another electric down the road. But I think the tech has finally stabilized just enough that it is worth doing and JUST affordable enough.

    I do assume that in UK they would just be too rare to afford quite yet. but I assume that will all be changing in the next couple of years with VW, Porsche, Jag and all the rest REALLY diving into EV.

    Regarding the Differential- the Tesla drive unit has a diff integrated. One can even swap the guts for limited slip which is interesting, and I assume I will do, as I will have so much torque.

    A couple of folks have asked about my BMW diff- I don't know how to check if it is LSD. Any way to check from the outside or do I need to open her up?

    thanks again guys-

    paul
     
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  16. autokunst

    autokunst Well-Known Member Site Donor $$

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    Absolutely. On the right (passenger) side, there should be two numbers stamped in it. 39/12 (3.25 gear), 38/11 (3.45 gear), 40/11 (3.64). Then, there will either be a large letter "S" stamped in, or not. S = LSD. At least that is how I understand it. Here's a pic of my 3.64 non-LSD casing for location reference:
    20180322-rear diff ratio.jpg
     
  17. JetDexter

    JetDexter Member Site Donor

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    Okay, here's what I have- Looks to be a 3.45 non LSD, but I don't know about the 11 and the 4.

    dif-stamp.jpg
     
  18. autokunst

    autokunst Well-Known Member Site Donor $$

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    I don't know that actual answer, but I have a theory. I wonder of the "4" on the tab is the year of manufacture (of the rear end). Your car is a '74, and it has a 4. Mine is a '73, and it has a 3 stamped in the same place. Not sure about the 11 (or the 2 on mine). Maybe the month? My car was from April 1973, and I could see the rear end being manufactured 2 months before delivery. Again, just a theory. ;)
     
  19. teahead

    teahead aka "Rob" Site Donor

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    Wouldn't hurt to open up the case just to confirm it's non-LSD. Sometimes there's just a painted "S" rather than a stamp. Paint can wear off of course.
     
  20. Bmachine

    Bmachine Well-Known Member Site Donor $$

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    Great link.
    Jaguar has made this process legit. Looks like the Brits are leading the way!
     

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