CyberSeven: Martin's Lotus Inspired, Tesla Powered Roadster

[Lonnie-S]

Congratulations on all the axle wizardry, Martin. You're certainly very resourceful there.

I'm looking at the motor sitting in its cradle and wondering what kind of power and torque it puts out? The new standard world-wide now is kilowatts, I guess. I'm still a horse power guy, so is there an HP rating for that motor? How about the torque? Do you know what it is in lb-ft?

It looks very powerful relative to that steel tubing it sits on.

Cheers,

[hassleweed]

Congratulations on all the axle wizardry, Martin. You're certainly very resourceful there.

I'm looking at the motor sitting in its cradle and wondering what kind of power and torque it puts out? The new standard world-wide now is kilowatts, I guess. I'm still a horse power guy, so is there an HP rating for that motor? How about the torque? Do you know what it is in lb-ft?

It looks very powerful relative to that steel tubing it sits on.

Cheers,

Thanks Lonnie. Well depending on the battery output the motor is good for up to 300hp, 248 lb-ft torque. It spins to 18,000 rpm!
I'm aiming for 10 inch wide rims on tbe rear to stand a chance of utilizing the torque as that all kicks in straight away. If only the car would hurry up and build itself so I can go play!

[hassleweed]

Just a little bit of work done this weekend. I received two inner bearing races through the mail (all the way from France!) that will do the job perfectly of aligning the Model 3 hub with the Model S axle.

So as I work my way out, I've made the decision to stick with the Model 3 multilink uprights. There's just no way I'll be able to fabricate an upright that will have the tight tolerances needed to hold the hub (at least for a reasonable cost). Those are being shipped from eBay land and will arrive this coming week.

I'm also going to see if the NC Miata rotor will work on the rear of the Model 3 assembly. I know I will at least have the stud diameter difference of 14mm versus 12mm to contend with. The Tesla rear rotor and caliper are monsters and just not suited for this application.

Finally, I took a trip to Goodwin Racing on Friday and chatted with Greg and Rocky about wheel and brake options. Looks like I will stick with the NA front spindles instead of the NC spindles. The advantages in brake sizes I thought the NC option would give me were short sighted as there are plenty of options available in the NA as that is the same bolt pattern as the ND Miata! (duh) That will save me from the insanity of finding balljoints for the NC.

As for wheels, now looking at 17x10 for the rear and 17x8 for the front. I'm not making any purchases yet as there's no guarantee the 17s will fit the Model 3 rear end - I need to assemble that first then take it along to Goodwin for a trial fit.

[ohmite]

Martin,
This is great! I’ve been interested in Electric vehicles for some time and the challenge you are tackling is one i have dreamed of. I definitely agree learning something new is a huge part of things. As an engineer this ticks lots of boxes. I will be following your progress and solutions with interest. Maybe someday copying you shamelessly.

You might have said and I missed it, did you get your drivetrain from a wrecking yard? I suspect they are more common in your neck of the woods than mine (near Buffalo NY). I see Teslas everywhere when I travel out there for business. So far only a few here.

Thank you for forging the path!
Regards,
Eric

[hassleweed]

Martin,
This is great! I’ve been interested in Electric vehicles for some time and the challenge you are tackling is one i have dreamed of. I definitely agree learning something new is a huge part of things. As an engineer this ticks lots of boxes. I will be following your progress and solutions with interest. Maybe someday copying you shamelessly.

You might have said and I missed it, did you get your drivetrain from a wrecking yard? I suspect they are more common in your neck of the woods than mine (near Buffalo NY). I see Teslas everywhere when I travel out there for business. So far only a few here.

Thank you for forging the path!
Regards,
Eric

Thanks Eric! Hopefully I can save somebody some headaches in the future. I did find a local Tesla breaker - he's on 60+ Model S and X cars already. He is very knowledgeable and helpful and sells through eBay (Autobahn Tesla). There are others out there too. All the Model 3 parts have been through eBay - they seem to be fairly reputable as there is a big outlay to purchase a wrecked Tesla ($20k+).

If you spot anything I am doing that seems dumb, please let me know - I have no idea what I am doing!
Thanks again
Martin

[hassleweed]

Well today was quite productive. So far I've been able to get Tesla Model 3 (TM3) hubs to work with TMS axles.

The TM3 uprights came in from across the country. One of them was badly damaged so I'm currently organizing a replacement.

The next big task was getting a rear brake rotor to work. The TM3 rotor is a beast and is as big as most cars' front rotors. So with the 5x114.3 bolt pattern I went searching for a rotor. I discovered that Autozone's website is good for rotor dimensions. I tried a rotor from an NC Miata but its hat would not fit (I assumed the hat dimension was ID but it was OD on the Autozone website). Next up was to try a rear rotor from a Mazda 3.

There seemed to be promise as the rotor's 14mm holes (designed for 12mm studs) were just big enough to fit over the 14mm studs. However the taper on the studs meant that the rotor would not seat against the hub.

20200215_133330.jpg

20200215_133400.jpg

So a touch of redneckery was required. I discovered my step drill might be the perfect solution:

20200215_133955.jpg

20200215_134346.jpg

The rotor seemed to seat well, but I wanted to be sure so I used a small machine screw in an existing threaded hole to ensure there was no gap:

20200215_135709.jpg

20200215_135734.jpg

The rotor seated well and left just a hair of a gap on the inside of the hat:

20200215_135527.jpg

With the rotor successfully mounted, time to see if an NA Miata brake caliper will fit:

20200215_150924.jpg

20200215_151913.jpg

I might just get away with it. I'll need a 10mm thick plate and attach the caliper using countersunk M10 machine screws. Then I can bolt the plate to the TM3 upright.
To the drawing board...

[Miatav8,MstrASE,A&P,F]

The rotor ID to the hub OD is the important part to keep it turning true. You can use larger rear rotors with dual masters and a balance bar. Not that redneck, as a commercial drill press was involved.

[Trochu]

Not that redneck, as a commercial drill press was involved.

And a caliper.

[hassleweed]

Ha ha! 21st century redneckery!

[hassleweed]

I forgot to mention my little side project which is my break away from metalwork at the end of the day. The tool chest is the perfect height.

20200215_160053_compress15.jpg

[ohmite]

Martin,
I checked out Autobahn Tesla’s store, lots of nice parts . A few power plants there, but none like yours, I will have to keep my eyes open. If you don’t mind saying, how much did the power plant as it sits set you back?

The rotor mods look great! Nice to know the Miata parts look to be compatible.

I forgot to mention my little side project which is my break away from metalwork at the end of the day. The tool chest is the perfect height.

20200215_160053_compress15.jpg

Is that an emulator of the original game, or did you raid a console? The pieces look pretty clean and up to date, so I’m thinking emulator.

Regards,
Eric

[hassleweed]

The small drive unit goes for anything between $2k and $4.5k. I got mine for $2.5k. Not locost but $/hp a reasonable deal.

The arcade is diy with a Raspberry Pi running RetroPie.

[ohmite]

The small drive unit goes for anything between $2k and $4.5k. I got mine for $2.5k. Not locost but $/hp a reasonable deal.

The arcade is diy with a Raspberry Pi running RetroPie.

Martin,
Definitely very reasonable for the $/hp! I’m spending way more than that so far on my Miata motor rebuild.

I figured it was something like a RaspberryPi. I have one sitting doing nothing, I should see if I can do something similar. My sons have several emulator base games they play with.

Regards,
Eric

[KB58]

...Definitely very reasonable for the $/hp! I’m spending way more than that so far on my Miata motor rebuild...

Adding in the cost of batteries will help you feel better.

[ohmite]

...Definitely very reasonable for the $/hp! I’m spending way more than that so far on my Miata motor rebuild...

Adding in the cost of batteries will help you feel better.

Good point, will wait for that shoe to drop. They will have to be pricey though, for the smaller capacity Martin was thinking of, the price may be easier to swallow. Definitely looking forward to how this develops .
Regards,
Eric