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1974 BMW CSE

eriknetherlands

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What an amazing achievement.
I do like the "old" feel, and did drive my car for five years, nearly every day, but i get the thrill you describe from enjoying the silent hum as it glides along.

You know, once you get to the point where all that is left is prep&painting, then realise that that's just standard. Anyone can do that; themselves or pay someone. I mean to say, you've come so far. Again amazing. Who cares that its just in primer?

And it gives you more time to contemplate on the color...
 
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This is the most entertaining read! Absolutely fascinating. Not for a purist e9 buff but in my mind, a logical and worthwhile exploration. Hats off!
 

JetDexter

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Trying to get more (nearly) free stuff done on the car:).

Last week I started working on the analog gauges. While the digital display in the old Tach position is nice, I still want to see the traditional Speedo, Temp and Tank gauges function (along with the clock of course).

The speedo took some patience for this hack engineer. A lot of measuring, 3d printing, then remeasuring, then printing, etc. But I've got it working and it's fantastic. I took the speedo apart, removed the mechanism.

IMG_2420.jpg


Using a common Stepper motor (this model is used by several manufacturers) I needed to extend the shaft to reach our needle (since it passes through the Odometer). Also, our shaft is larger diameter. I cut off our old shaft, then printed a small extender section which very snugly creates a nice single unit.

New Shaft.jpg


Then I took some circuit board and cut out a shape that would fit. I installed a small motor driver board, then wired up the motor to it, and our leads which will exit the cluster, and wrapped those nicely.
wiring back.JPG
wiring front.JPG


My 10th iteration of this mount worked perfectly. None of the holes are really aligned to anything, so it was tough to find a reference, but PLA material is cheap (and Jeff tells me recyclable) so I just kept printing and adjusting until I got this nice mount. There is a top cap which then bumps the top inside of the can.

Housing.jpg


Next up was the Odo. I do not have a transmission to feed me miles, so I have to do it electronically. Once removing two layers of worm drive, you are left with this 22 tooth gear. (22 spoke for this unit, the older unit I landed on using is a 19 tooth gear). I printed up a shaft that surrounds this gear on one end, and the output of a stronger, geared-down stepper motor on the other.

Odo Gear.JPG


Here's a nice shot of an old and new (at least that's my assumption) of debossed printed unit and flat printed newer unit. Both with very low miles I might add. I am going with the classic unit.
IMG_2544.jpg


I had to cut away the side of the can for the motor. It is a tight fit to the next can, but it works well. The motor very slowly, and very smoothly turns the odo. Notice the driver board fo this motor inside this cap.
Odo Motor.jpg


After everything was assembled, it is all enclosed in this cap. This is a first iteration, so it should be cleaner once complete.
cap installed.jpg


After all that was done, I am now forging my way into the Temp/Tank gauges. Pretty good progress there, but only one pic so far. I'll get those dummy lights working as well. I don't even know what they all originally did, but I might change that up anyway. For sure, a high temp, a low fuel (battery), but I don't know the others. I'll leave the original printing alone, and just insert LEDs in the tunnels.

temp.JPG


Oh- one more thing. I did buy a couple cans of vinyl dye spray, and paint my aging blue rear seats and door cards black for my temporary solution. The rear seats also had terrible sun damage so I used large sections of patching tape to seal them off. It's not perfect, but it will get me by until I can reupholster the whole interior.

It's fantastic to have an interior that is all the same color! The rear headrests now match the seats as well.

Seats.JPG


That's it for now.

Cheers!

Paul
 

JetDexter

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Last week we made some good progress:

We got the power steering and power brakes functioning. If you've followed this thread, you are aware that (for better or worse) the steering and brake setups were completely re-engineered. Mostly to make way for the humungous Tesla battery box in the engine compartment. We installed a VW GTI power steering rack, a Bosch hydroboost brake booster (since we have no vacuum) and a Wilwood master cylinder and big brake setup.

Since we have been driving the car the last 6 months, we have ran these systems without power. Steering felt fine on the road, but turning those big tires in a parking lot was just as you would expect. Brakes were very weak since the setup simply requires boost to properly function. Lucky for us, the regenerative braking of the Tesla setup means that you step on the brakes very rarely. If you have ever driven a Tesla you would agree that there are many drives where you simply don't put your foot on the brake at all other than for a full stop. The drive unit provides remarkable braking. At speed it is the equivalent of sporty downshifting, and coming to a stop it does all the work up until the very last few feet to a complete stop. Letting your foot off the accellerator is what triggers this (as opposed to a lot of smaller EVs where it is triggered by the brake pedal). This feels strange, and even "Autopia-like", this one-pedal driving. But once you get used to it it is addicting and very responsive. This is also how we have been able to drive the car without issue for so long.

Luckily we have sorted out so many details with the conversion that it was finally time to tackle this one. To power both steering and brakes I had selected a BMW/Mini 12 volt power steering pump. It fit nicely between the PS rack and the bottom of the firewall. I gave it the 100amp service it wants (30 amps constant, but it will pull 80A or so if a soccer mom were to hold the steering at limit for extended periods of time).

PS-Pump-Installed.png


The pump feeds the brake booster, which then feeds the power steering rack, which feeds the reservoir which feeds the pump. This all looked really good on paper a year ago, but I have been cautiously optimistic that it would all function and feel nice. I had done a lot of research, based on parts of this design working with other parts of other designs, but there was no real comparison as a whole.

Installing the pump was easy- we've done a lot of that. Fabricating brackets from various nearby mounting points, which mate to the Mini pump. Running the electrical was easy, but when it came to the high pressure lines I was literally lost. Tyler (who you know as the metal finishing master from this thread) called a mechanic buddy who told him of a guy he had heard of who used to work at Mesa Hose. Tyler called them and they said "That's Mike Swan, here's his number". I'd never heard of Mike, but he and his dog Stanley live in Nebraska and come out a few times a year to work on very nice hot rods for a few weeks at at time. He and Stanley were busy with a project but couldn't resist the story of this Tesla BMW, so he came by the next day to check it out. He instantly knew all the devices, connection sizes, etc. He measured for what he would need and said that he could come back after the weekend to fabricate and install the hoses at our place.

Pump Plumbed.JPG


Mike fabricated the custom braided lines and fired it up. We bled the system (which requires several repeats of letting the bubbles die off with long delays). In the end we now have fantastic brakes. The stock brakes were already amazing for their day, but I am quite proud of this setup which feels wonderful and stops the car immediately. I feel like they are a great match for the type of Tesla conversion we've got going here.

The steering feels good, but I need more drives to see if it might be a bit soft. If so, Mike will do what VW does, which is insert a thin sleeve into a hose to reduce the pressure before the rack. It is suprising that there is not an adjustable valve (there may well be but Mike hasn't come across one that handles this high of pressure). Inserting sleeves is what manufacturers do for reliable pressure reduction. Once again- this is not my world, but I find it fascinating.

While all of this was going on we were able to get our gas-charged struts in place to hold the hood up. I think this gained us about 40 pounds from the front of the car as the revered stock system is quite weighty. I'd read some threads here which had used some various designs. Some more obtrusive than others. I think that mine are quite out of the way. Of course the only thing I even need to do under here is check my 3 fluids.

Hood Support.JPG


I'll be backed up now the next couple of weeks so I won't be able to get much done, but it's been quite a run this last month.

Cheers,

Paul
 
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