[EV-FAN]

I am converting my grandfather's M38A1 Jeep Willys to electric (as well as restoring the jeep).

Some features include:
Tesla Model 3 drive unit;
narrowed Dana 44 axles from a 1975 Jeep Wagoneer;
Jeep YJ leaf spring conversion;
Orion 2 BMS 132s; and,
a Chevy Volt battery pack.

I am just finishing mounting the Model 3 drive unit sideways in the middle of the jeep. The front and rear drive shafts will each connect directly to the stock drive unit differential outputs. I plan to mount the entire battery pack (stock fiberglass shell and all) in the cab with the top of the "T" sitting where the rear bench seat normally would go. The car should be VERY torquey!

 

[remy_martian]

Unless you're planning to install ABS, it's going to be absolutely horrible in low traction conditions.

What you'll get is opposite to the Subaru commercial, with your setup: "Transfers power from the wheels that grip to the wheels that slip."

I know Qaife make a limited slip for the Model S LDU, but I haven't followed what's out there for Model 3. You might want to contact them to see if anything is in the works, if it isn't out already.

 

[G00se]

Love it!

 

[Chris_W]

I believe Zero EV are working on some solutions but haven’t released them yet.

 

[remy_martian]

I saw that episode. They've changed the gearing, which is great, but they didn't say anything about torque biasing. They know what they're doing, so maybe they're keeping torque bias control under their hats, but, as I said, unless you're a dry pavement AWD poser, an open diff as a transfer case is a disaster when traction goes to heck on one or more wheels.

This is where the Plaid drive unit (>>$) would shine...

 

[brian_]

Zero EV's differentials come from Quaife; Quaife differentials are their ATB gear-type limited-slip. There is a Model 3 unit from them (Quaife, presumably only via Zero EV).

 

[EV-FAN]

Thanks, Remy Martian, Chris, and Brian! My dad had offered to make a spool but a limited slip differential would be way better since I would like the jeep to be somewhat streetable.

 

[Chris_W]

NP…I just noticed Zero EV has the gear sets and the model 3 diff listed in their store now (a bit pricey)

Quaife Tesla Model 3 Differential - Zero EV

Quaife Tesla Model 3 Differential

zero-ev.co.uk

Tesla Model 3 Rear Drive Unit Reduction Gearset 3.54:1 - Zero EV

Tesla Model 3 Rear Drive Unit Reduction Gearset 3.54:1

zero-ev.co.uk

 

[EV-FAN]

That reduction gearset could be super helpful, too! Based on rough math, I think with the stock 9:1 Model 3 gearbox, 2.72 axle gears, and 30” tires, my max speed would be about 58 mph.

 

[remy_martian]

Jack it up and get it shod with 35's 😂

 

[Chris_W]

Even with 33’s the motor would have to do 15000 rpm to do 60 mph
Here’s a good tool…

Tire Size, RPM, Speed, and Differential Ratio Calculator

Describes the process for converting a gasoline powered car to electric power

www.advanced-ev.com

 

[EV-FAN]

Jack it up and get it shod with 35's 😂
[/QUOTE
Haha!

 

[EV-FAN]

Here is a chart I compiled comparing different Tesla motors for my M38A1 Jeep build. (I also included a couple hypothetical ICE drivetrains for comparison.) I thought the information might be of interest for similar jeep/ 4x4 projects.

 

[remy_martian]

Up to you, but the spreadsheet source might be useful for people with differing tire sizing, or vehicle weight, for example. You also have enough info on there to add a 0-60 time approximation column...

 

[eWillysBoulder]

I am converting my grandfather's M38A1 Jeep Willys to electric (as well as restoring the jeep).

Some features include:
Tesla Model 3 drive unit;
narrowed Dana 44 axles from a 1975 Jeep Wagoneer;
Jeep YJ leaf spring conversion;
Orion 2 BMS 132s; and,
a Chevy Volt battery pack.

I am just finishing mounting the Model 3 drive unit sideways in the middle of the jeep. The front and rear drive shafts will each connect directly to the stock drive unit differential outputs. I plan to mount the entire battery pack (stock fiberglass shell and all) in the cab with the top of the "T" sitting where the rear bench seat normally would go. The car should be VERY torquey!

View attachment 124807

View attachment 124806

Hey EV-Fan, your project looks great. I could have used your welding talents when I converted my 1948 CJ2A "Chick Magnet". Question: have you run torque and power calculations under various driving conditions? I developed a set of calculations in MS-Excel when I planned my Willys conversion, it turned out to be very helpful and reasonably accurate. Lots of nail-biting staring at the Excel spreadsheet before taking the plunge and tearing the Jeep apart but it paid off. I would be happy to run your numbers on my spreadsheet if it is of any interest to you.
Oops, I see now that you did your homework. Never mind. Cheers!

 

[EV-FAN]

Project Updates:

I ended up moving the motor mounting location rearward so that the front and rear driveshaft will be the same length (the attached picture is still of the old motor mounting location). Now the the driveshaft angles will be less harsh. I currently plan to use the stock tripod joint on the drive unit side and a double Cardan cv joint on the Dana 44 side. We're currently making an adapter so we can use the stock tripod joint with a 2" drive shaft.

I got in my Orion BMS from Evolve Electronics. I still need to wire it up to my Volt pack. I went with the 132 S Orion BMS 2 because I plan on maintaining the stock Volt battery layout with the fuse/shut-off part way through the pack (if I counted correctly, the stock fuse is between parallel cell pairs #45 and 46).

I got in my 3.3kw Elcon Charger from Evolve Electronics--the helpful people at Evolve told me that I can use the 3.3kw charger to start with and I can add a second charger in parallel down the road if I want faster charging.

I have the front and rear leaf springs mounts tacked in place (converted to YJ leaf springs).

Other components that arrived:
Volvo power steering pump (after seeing a post from Electric Land Cruiser); 2.72 gears for the front axle; Dutchman custom length front axle shafts (the front axle is a narrowed 1975 Jeep Wagoneer axle).

Regarding the open diff/locking diff topic: after more thought about what I want to do with the car I am currently leaning towards eventually putting a spool in the drive unit. I plan to either drive the car around town (Southern California roads) or trailer the jeep to the desert on the weekends for short off-roading around the campsite. My current thinking is that with a spool in the center I can pull the front drive shaft out around town and just have rear wheel drive. For desert trips I could put the front driveshaft back in and have 4wd. My friend suggested for short road hops I could unlock the front hubs and drive the car on the road with the center diff locked.

 

[remy_martian]

Yup - I'd just go with the locking hubs. Driveshaft pulling is a PITA and you know you won't do it because you're only driving a short/minimal 😉 distance

 

[EV-FAN]

Up to you, but the spreadsheet source might be useful for people with differing tire sizing, or vehicle weight, for example. You also have enough info on there to add a 0-60 time approximation column...

Here is a link to Excel file. I could not figure out how to upload an Excel file directly to the forum page. Feel free to edit, add, repost, etc. I will try to add to the Excel file in the future and repost any updates:

Reference_Comparison_Chart_for_Tesla_Motor_in_4wd_car_DIY_Forum.XLSX

Shared with Dropbox

www.dropbox.com

 

[EV-FAN]

 

[EV-FAN]

Working on wiring up my Orion BMS 2 to my Volt pack this week. I found the following video very helpful when spec'ing out and wiring the Orion BMS to a 2017 Volt battery: