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Discussion Starter · #1 · (Edited)
I'm really into rock crawling. It's super fun. Very technical driving, thats slow paced so for the most part there is low risk of injury while still keeping the adrenaline up. I had a solid axle swapped 1989 Toyota 4runner, locked differentials with lower gears, chromoly axles and 39" tires. It is great fun to go for a camping/wheeling weekend where you basically drive on trails, drink beer eat food and talk shit all day and night.

Part of going off roading with decades old, beat up and neglected trucks is that they are pretty much always on the verge of breaking down for lots of reasons. I think an electric motor and batteries, after a few bugs are worked out, will be significantly more reliable than the old Toyota ICE and supporting systems. More time having fun, less time broken on the few weekends a year we get together.

Rock crawling specifically is also well suited to electric drive, where low end torque is desired over sustained high output. You can have fun all day in a rock crawler and never go farther than a 5 mile radius from camp or go over 20 mph.

So I've been talking/dreaming about it for years, and finally overheated my motor earlier this year and its not worth repair. Lots of thought/research, including guidance from this site, plus budget constraints led me to the Leaf components. A running driving Leaf could be had in the ~$3500 range, which would yield a motor and batteries. Thunderstuck has the Leaf VCU for $500, and I knew there would be more components to buy but I figured this was the most economical way to get my 'runner de-ICEd with a modern, powerful AC motor(regen) with Li-ion batteries. I knew the capacity wouldn't be great, but I decided it was a compromise I was willing to take for now. The idea being get the thing running and driving, and in time upgrade the batteries. So I bought a donor September '20, a 50k 2015 Leaf salvage title running and driving for $4000 and started collecting parts.

Then I got a call that there would be a new EV only class at the February 2021 King of the Hammers event. KOH is the largest rock crawling event in the world, over 50,000 attend annually for a week of racing in the So Cal desert.

Element of Survival is a really cool video to watch to get an idea of the cars and terrain, lots of other videos documenting the race can be found easily.

That's when the plan changed, I knew I had to compete. A team was made of coworkers, friends and family. We don't have time to turn my beat up Toyota into a racecar due to what's required for safety. A friend who had an old 4600 class 4runner racecar that has previously competed in KOH offered his chassis to convert. So I sold my crawler and am all in on converting this car.

The challenge is a ~90 mile loop, with 2 pit stops. There will be about a 20 mile section, pitstop, 45 mile section, pitstop, and a third ~20 mile section. It will include steep sandy hills, rock crawling, and long straight flats. The 24kwh pack that came in the car will not be anywhere close to accomplishing this. We decided swapping discharged batteries for charged ones at pit is how we will tackle the problem. Based on napkin math, two fully charged 24kwh packs cannot be relied upon to take the vehicle 45 miles. So we need to used the later model higher capacity packs. Sticking with Leaf modules because I've already invested in the Dilithium 96 cell BMS and am somewhat comfortable with them. I like the simplicity of the aircooled design, even though it compromises performance.

The late model packs are hard to find. I found a salvage yard that has a 40 and a 62, and they are charging the same price. I know the 40 will bolt into what we built, but I couldn't bring myself to pay the same price for ~50% less capacity. I am also actively searching for two more packs, ideally 1 40kwh and 1 24kwh. That would give us lots of battery options, and those packs would have basically no more unknowns when it comes to packaging/wiring. Also, after the race, the loose plan is to get myself another rock crawler chassis, another Leaf motor, and split the batteries between the two vehicles, on an agreement that owner of this car will purchase the batteries/electronics that stay in his car.

Pictures of Hammertown and race action on the trail Backdoor, roughly 2015 perhaps earlier.
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Discussion Starter · #2 ·
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2015 Nissan Leaf. Chosen for its AC motor, air cooled batteries, aftermarket conroller support, and cost effectiveness. $4000 bought the nicest, newest vehicle I have ever owned. Drove it everyday for a few weeks before I tore it apart it, these are great little cars.
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LeafSpy app connects to the OBD 2 port of the car and runs in depth diagnostics of a Leaf battery. Our car had around 50,000 miles, so it was important to check the state of the batteries to be sure they are useful to us. 78% state of health is acceptable, especially considering the price paid.
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Battery pack out
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Too bad i couldnt use the Nissan charger and dc-dc. would love to use DC-DC fast charging at pit.
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Pickup up the race truck. Its an 86 4Runner that has raced for years in the Ultra4 4600 class. Its raced King of the Hammers a few times, multiple series races, and has been down and up the Baja penninsula. Its a little tired, but a great platform for conversion.
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Thats the easy part...
 

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Discussion Starter · #3 ·
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Figuring out how these things go together..
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Decided to put the pack in identical racks of 12 in series. So two of these guys make one full pack.
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Four of them side by side fit perfectly between the wheel wells. this way we can carry two complete packs. Its alot of weight but we need the capacity for the longer stretches during the race.
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Some detail on how the racks will fit into the frame we made for them. Not pictured, the handles of the racks will fit snuggly just beneath a 2x2 tube, which is welded directly to the rollcage and vehicle frame.
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Starting to shape up. the first one we did is on the right, we wired the Dilithium Design bms leads straight to the modules. The one on the left I tried sorting out which wires go to which cell, and using butt connectors to attach to the factory terminations. I like the second way better.
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Made a HV box. basically all HV connections and the Leaf contactor is located in it, keeps it sealed from a stray tool or misplaced pit crew hand. Was able to get and orange one as well, right at Harbor Freight. Those are Amphenol connectors, that what our battery rack's leads will have on them.
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We are driving the contactors with 12v. Signals between the VCU, Precharge circuit and + contactors shown. We also have a separate circuit of 12v driving the negative contactor, it is powered by key on and runs to vehicle shutdown switches on either side of the car.
 

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Discussion Starter · #4 ·
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Part of the race is 45 miles long between pit. So we needed more capacity. Found a brand new 62kwh pack that was damaged at the pack manufacturing facility. Adnvance Auto Salvage in Murfreesboro TN had it.
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Detail of the laser welding on the cell terminals. These modules are three different sizes, and arent coming apart. There are 4 big ones, 4 medium ones, and 8 small ones. So they split evenly 4 ways, and will fit into the same racks we already made for the 24kwh battery. So when we install the 62, it will take all four racks in the bed.
 

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Discussion Starter · #5 ·
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Made our coupler from clutch centers. Thank you user mainsource for the Fiat part number, the splines fit pretty dang well onto the Nissan splines. Big help there bud thanks for the post. The other side is the Toyota clutch center. Turned this dowel so that it aligns the centers and the tube pretty good. Tube is 1 1/2 inch od, .250 wall DOM.
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We welded both sides, and cleaned the OD back to 1 1/2 inch...
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Then sleeved the whole thing with 1 3/4 .120 tube. Welded that up. should be strong enough for 200 ft-lbs. While we were at it and had it all figured out, we made a second one. So if it fails, we can get the spare in while we figure out the next one.
Installed with antisieze on the splines.
 

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Discussion Starter · #6 ·
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The adapter was pretty simple, Leaf bolt pattern cut out of 1/4 plate, forget where i found the design pretty sure it was a google search. Same for the Toyota trans. Had a large hole cut in the middle of each for the center tube. This gave a hollow center for the coupling to pass through, and the large diameter helped make the the thing rigid and sturdy. The small pieces of tube were originally on there during assembly to make sure everything was true, and it looked good so we burned them in. 17 mm hardware all around for easy service. tons of room to get tools in.
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Motor mounts fabbed up, was able to use Leaf bolt holes for the original motor mounts. drivers side mount had to get a little creative. Ended up throwing a tube across them making it into a cradle, might help take some stress off the aluminum motor casing.
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Mounted to the Stock Toyota frame side mounts with 22re ruff stuff specialties mounts that we modified to fit our cradle. We're really happy with how it came out.
 

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Discussion Starter · #7 ·
That about brings the project to the current date. We have gave it its first test drive, check it out on Instagram @willspecgarage. Hopefully testing in the dirt this week. Still figuring out the charger.
If you have any questions ask away. I'll update as we go. The race is in 3 weeks so we will be working on it alot.
 

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This is great! Do you have any more shots of the 62 kWh modules? I like hearing that they fit where the 24 kWh modules are...This is the first I've seen of them being repurposed.
 

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First the earlier pack...
Decided to put the pack in identical racks of 12 in series. So two of these guys make one full pack.

Four of them side by side fit perfectly between the wheel wells. this way we can carry two complete packs. Its alot of weight but we need the capacity for the longer stretches during the race.
...
With 48 modules in a pack and 24 modules (12 pairs if using the glued-together pairs) in a rack, that works. :)

Then the 62 kWh pack...
These modules are three different sizes, and arent coming apart. There are 4 big ones, 4 medium ones, and 8 small ones. So they split evenly 4 ways, and will fit into the same racks we already made for the 24kwh battery. So when we install the 62, it will take all four racks in the bed.
So half the pack, consisting of 2 big (rear) modules, 4 medium (front) modules, and 8 small (middle) modules, has a total length too long - too much longer than 24 earlier modules - to fit in one rack? What is the total length of half or one-quarter of modules stacked this way?

This is great! Do you have any more shots of the 62 kWh modules? I like hearing that they fit where the 24 kWh modules are...This is the first I've seen of them being repurposed.
They fit in two dimensions, but the stack height appears to be so much longer that half of the modules from the 62 kWh pack don't fit in one of the truck's racks.
 

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Discussion Starter · #10 ·
Brian

Good catch on the earlier style pack, you're right its 24 modules per rack, two racks make 48, a complete pack. We have two complete gen 2 packs this style, so we will load the truck with 4 racks set up like this for hopefully 40 kwh in total. Both packs are used so we will see how they do.

The 62kwh style has 16 complete modules. 4 Large(9 cell), 4 Medium(7 cell), 8 small(4 cell). Each "cell" is actually 3 cells, but they are in parallel so we treat them as 1.

These could be arranged in two racks, but they would be so long they would almost stick out of the vehicle.

This presents a few issues. In desert racing there are lots of times when a racer is following right behind another car and bumps into the back, due to dust or rough terrain or to say "Get out of my way I'm comin through!". We really don't want our batteries right at the end of the car.

We are also adding alot of weight to the back of this little truck. The long racks would put our weight bias even further back.

Each long rack would be so heavy, they would be very difficult to move around with 2 people. I'm pretty sure we would have to look at our rack structure as well, I don't think the way we've been making them would hold up to that weight across that length.

Lastly, We would then need to devise a locking mechanism to hold two styles of rack at the same time.

So, we decided to set up the full pack in 4 racks of 4 modules, each rack getting a large, medium, and 2 small module.

It works out great for a few reasons, the + and - terminals alternate from module to module, so we can line up the HV cables for short, straight runs to tie the modules together in each rack. And we have 24 cells in each rack, which matches our wiring leads for each BMS. So each rack will have a set of leads that perfectly corresponds to a BMS module. Plus, they fit well in our existing rack dimensions, so we just need to make more of the racks that we already have.

I'll get more pictures of all this over the next few days, I'm in the middle of my work week. Still figuring out the chargers. Generator showed up yesterday. Hopefully putting in some miles this Saturday.
 

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That all makes sense - thanks. From the original style to the 62 kWh pack, Nissan increased capacity by about 50% (versus the 40 kWh) by increasing the cell count by 50% (by going to 3P instead of 2P). To fit them in they stacked them differently, with much less wasted space, and made the pack case a bit deeper as well. The total stack length is reduced somewhat by using fewer modules (less packaging overhead), but it looks like it is still much longer than the original design (which has essentially the same dimensions regardless of capacity - 24, 30, or 40 kWh).

The highest-capacity for this truck would be two 40 kWh packs if you could get them, but a single 62 kWh pack is 3/4 of the capacity for a bit less than 3/4 of the weight, perhaps better placed in the vehicle.
 

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I love that you can tell you guys are racers. Slamming parts together with big-picture perspective on why. "We made a coupler", "So we made 2 couplers!". Etc.

Good luck, can't wait to see it racing!
 

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Has this shaft coupler been run at speed yet?

Normally the transmission input shaft end is supported by the pilot bearing in the flywheel, but in this case it is apparently floating in space, with the female splined end of an coupling shaft slip-fit over the end of it, and the other end of that coupling shaft supported by the motor shaft. If the coupling shaft were absolutely true with the transmission input shaft and rigidly mated to it this would just be a long input shaft extension, but as it is it looks like an invitation for a shaft whipping around to the point of failure or at least bearing destruction. A reasonable design could be to mount a bearing in the transmission side plate of the adapter housing to support the transmission input shaft end and the transmission end of the coupling shaft, but that's not included here. Am I missing something?
 

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Discussion Starter · #14 ·
Brian,
Thought about this a bit, we decided that having that rigid coupler between the motor and trans is sufficient to support the trans input shaft.

The fact is, I don't know if it will work. At this point, we don't have enough time to do something different.

I think it will work for the mileage we are asking, which is likely far less than 5,000 miles, albeit rough miles. We'll see
 

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I have been thinking a bit about shaft couplers lately myself, so this topic is interesting to me. It seems to me that the coupler is doing 2 things: It is extending the motor shaft, and it is supporting the trans input shaft.

I agree that if there is too much run-out, the tip of the input shaft is going to be forced to turn in a circle, which will likely get worse as speed and centrifugal force increases. You could measure the run-out with the coupler only connected to the motor, and also check if there is any vibration when spun up? If it turns within the spec for a flywheel, it seems like it should not be a problem, right?

And while you are no longer supporting the transmission shaft with the pilot bearing, this function it seems to me is now going to be taken up by the splines. The only reason the shaft needed a pilot bearing was so that the splines could be disengaged, but without the clutch, it really does not serve any purpose.

For what little my opinion is worth, I think it will work. At least long enough for you to destroy the rest of the truck trying to drive over a mountain, or some such craziness :)
 

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I have been thinking a bit about shaft couplers lately myself, so this topic is interesting to me. It seems to me that the coupler is doing 2 things: It is extending the motor shaft, and it is supporting the trans input shaft.
Yes... and a splined joint is questionable at best for supporting the shaft in the middle.

I agree that if there is too much run-out, the tip of the input shaft is going to be forced to turn in a circle, which will likely get worse as speed and centrifugal force increases.
I agree with this part, but...

You could measure the run-out with the coupler only connected to the motor, and also check if there is any vibration when spun up? If it turns within the spec for a flywheel, it seems like it should not be a problem, right?
The flywheel is rigidly supported by the crankshaft bearings, but in contrast the female splined end of this coupler shaft is hanging out is space far from any bearing, and connected to bearings only through slip-fit splines.

And while you are no longer supporting the transmission shaft with the pilot bearing, this function it seems to me is now going to be taken up by the splines. The only reason the shaft needed a pilot bearing was so that the splines could be disengaged, but without the clutch, it really does not serve any purpose.
While the clutch is engaged the clutch supports the shaft, in the position determined by the pilot bearing. While the clutch is disengaged the shaft is supported by the pilot bearing. The splined transmission end of the coupling shaft isn't located by anything other than a slip fit on the short splines of the motor shaft, so it can't positively locate the transmission input shaft.

Thought about this a bit, we decided that having that rigid coupler between the motor and trans is sufficient to support the trans input shaft.
But is it really rigid?

The fact is, I don't know if it will work. At this point, we don't have enough time to do something different.
A steady bearing mounted in a plate bolted into the transmission-side plate of the adapter housing could support the rear end of the coupling shaft, which would need a machined outer diameter to match the bearing. That's a one-day thing to build if you can get a suitable bearing and have the tools and equipment, but a long-term project for the average DIY builder - I don't know where your current situation falls in that range.

I think it will work for the mileage we are asking, which is likely far less than 5,000 miles, albeit rough miles. We'll see
For what little my opinion is worth, I think it will work. At least long enough for you to destroy the rest of the truck trying to drive over a mountain, or some such craziness :)
If it works, great. If it works for the first hour, it will probably work for a long time. If it ceases to work, it could go from working to destruction in a fraction of a second. The coupler shaft is inside a steel housing, so it's unlikely to hurt anyone if it fails, but its failure could be the end of the transmission input shaft, maybe the motor output splines, and the race. Jamming the input shaft could lock the rear wheels, which is always an exciting thing to have happen at speed.

I hope it works. :)
 

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Discussion Starter · #17 ·
Brian,

All very good points, I agree with your concerns and thoughts. For sure, the trans input shaft is not located in the way it was intended to be. For sure, the slip fit splines on the Leaf motor, of which are not even the exact correct ones, is not a suitable way to control runout on the coupler, and in turn the trans input shaft. Especially since the coupler is 6 inches long, the length amplifies the issue. The coupler itself is rigid, but the end of it is not rigid.

I would argue your thoughts on the likely failure mode. I think if there is excess runout, which there likely is, that the parts would wear over a considerable period of time and miles. I think an audible grinding, clunking, or some kind of "gear" noise as the clutch centers walked worse and worse on the splines, would present itself and become louder as the part continues to fail but still operate. Probably start to see trans fluid leaking from the front input seal, down through the coupler and visible under the car, well before it mechanically ceases to function.

The reason why I say this has to do with my specific, personal experience. These trans are pretty robust units, for the most part all Toyota 4x4 drivetrain components(especially 80's mini truck parts) have been proven to continue functioning way, way past what would be expected of them under serious abuse. Myself and my friends have beaten the ever-loving shit out of multiple Toyota offroad rigs for years. Based upon what I've seen, I have alot of faith in the Toyota parts, and this particular trans is the most desirable r151f turbo trans. It was rebuilt and had aftermarket components installed(don't know if anything was done to the input shaft or bearing) by Marlin Crawler, which is one of the most respected names in Toyota 4x4 drivetrain. All this leads me to believe the part will still work for awhile, even if its wounded and getting worse.

That said, its still totally possible it will fail catastrophically and quickly, I just don't think it will.

Today is Sunday, I have 3 days of work, then a day of loading on Wednesday and a day of driving to the desert on Thursday. We still dont have all of our batteries completed, or the locking bar fabricated on the back. I get to the shop around 5:15pm, work till at least 9:00pm on the car, get home get to bed and wake up at 3:30am for the next days shift. There isn't time to make a proper support. But you definitely have me thinking alot more about this part. It will be really interesting to dismount the motor and inspect after the race, and see what we got going on in there, I'll be sure to share what I find. Of course, that's if it holds up the whole week and doesn't require us to make repairs in the field.

OR-Carl,

Our adapter is solid, we cant get a dial indicator in there while its all assembled to check runout. We talked about cutting a window into the side of the adapter, we might just do that after the race. Would be nice to get an actual measurement on this and report back for other interested parties.

Great conversation, thanks for the feedback. I will get more pictures when I get to the shop today and update the thread on where we are currently at tomorrow. Here's a pic of what we got going on with the chargers. More about this on the next update.
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I would argue your thoughts on the likely failure mode. I think if there is excess runout, which there likely is, that the parts would wear over a considerable period of time and miles. I think an audible grinding, clunking, or some kind of "gear" noise as the clutch centers walked worse and worse on the splines, would present itself and become louder as the part continues to fail but still operate. Probably start to see trans fluid leaking from the front input seal, down through the coupler and visible under the car, well before it mechanically ceases to function.
I agree, as long as components just bend slightly and/or the spline fit just gets sloppier. On the other hand, I was thinking of the worst case... and have you ever heard of a driveshaft which failed nicely, rather than whipping to destruction?

It was rebuilt and had aftermarket components installed(don't know if anything was done to the input shaft or bearing) by Marlin Crawler, which is one of the most respected names in Toyota 4x4 drivetrain.
Good, but assuming that the lack of a pilot bearing isn't a common problem, there wouldn't be any reason to expect the modifications to address this issue - they're usually about harder gear teeth with better finish, bearing grade or lubrication, reinforcing weak points in the shift mechanism... stuff that does fail in hard use.

Our adapter is solid, we cant get a dial indicator in there while its all assembled to check runout. We talked about cutting a window into the side of the adapter, we might just do that after the race. Would be nice to get an actual measurement on this and report back for other interested parties.
Yes, I was going to suggest the window (ideally a removable access panel). You can check runout with an indicator when turned by hand, check runout visually while it is turning in neutral, and with it stopped you can just manually push on the shaft at the joint and check for compliance. You could cut a small window now, and just close it up with tape until you have time to do it properly, but obviously just leaving it alone is the straightforward approach. :)
 

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Hey guys, congrats on your KOH finish! Can you talk about how things went and what you think worked and what you’d do differently? I would really like to build an EV Ultra4 car.

Thanks!
 

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CONGRATULATIONS!!!!!

You have now created a monster inside my lol. I have been gathering parts for a suzuki based 4600 car............... now........ I need to see what the rules will be for the new EV class!
Thank you for being innovative in our sport!
Andrew
 
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