[Driving] Homebuilt Locost 7 - from Motorcycle engine to Leaf power!

[jrbe]

I'm so happy for you reading this!

See if you / someone can record your conversations both about the car and ev safety. They might help you get into races closer to home.

A friend of mine has a van she uses for her band and camping. There are racking rails on the sides to lay down a flat surface to sleep on above their gear. I was thinking you could do similar above the front of your car.

If you use combustion heat sources be careful with carbon monoxide.

[Zieg]

Ah thanks, yes I have a folding chair I'll be using at the track anyway. I also need to update my track checklist... Remove items like 'gas can' and add things like 'laptop'. Haha.

[Zieg]

See if you / someone can record your conversations both about the car and ev safety. They might help you get into races closer to home.

A friend of mine has a van she uses for her band and camping. There are racking rails on the sides to lay down a flat surface to sleep on above their gear. I was thinking you could do similar above the front of your car.

Sorry you must have replied while I was typing and I missed it. Yeah I can try to record whatever conversation. Not exactly sure what that will look like yet.

I had thought about a fold-down structure of some sort, maybe I can try and get something set up for next time. Is your friend's custom made or bought off the shelf somewhere?

[jrbe]

...custom made or bought off the shelf somewhere?

Its something like this on each side,
https://dccargo.com/products/e-track-ra ... 3253870786

and shoring braces like,
https://dccargo.com/collections/load-lo ... r-aluminum
Across from left to right. Then its plywood or some other lightweight but strong paneling to put something to sleep on above the shoring braces.

[Zieg]

Oh, E-track, okay! I think i have some of that laying around from my last trailer. I'll see if I can find those bars - never knew those existed!

[Zieg]

So my wife talked me out of the platform idea because she wants a hammock for the yard. I couldn't figure out a good way to span the back bay so I was about to buy some hinges and make a folding table that would work as a bed, but I guess the hammock is less work. I didn't realize you're supposed to lay in them diagonally though. Not sure that's going to work since it's necessarily so close to the wall. Feels comfortable enough to lay straight in it though...

Since I had already dug out the bits of e-track I saved, I just used them as anchor points for the hammock. Glad I kept the d-loops too because they are perfect for this.

There's a line in the rule book that states the battery must be within the structure of the car (I heard elsewhere it was mostly there to make sure people don't put batteries in the side pods of a formula car without some kind of structure around them). I was a bit worried someone would complain about the battery being above the level of the chassis, so I built this just in case.

Turns out finding a 6 point harness in town is a little less easy than I thought, but I found a place that could bring one in. It's HANS compatible if I ever want to do road racing or something. I do need to verify it's not REQUIRED that you use the harness with a HANS device though. Apparently some are like that. Need to phone the manufacturer on Monday. It also has to be a 6 point and not 5 because when I built the car, I welded two anchor points below the seat.

The 6pt: https://www.holley.com/products/safety_ ... /747007RQP

And what I currently have: https://www.schrothracing.com/item/rallye-cross/

Yes it's only 4pt, but one of the shoulder belts has a section that stretches in a crash and lets your torso turn slightly, like a standard 3pt harness. It's also DOT legal and easy to use, which is why I bought it. I may stop driving the car on the street though, so at that point it wouldn't matter. Especially if I also need to add the roll cage to run in BC. Still haven't heard back from them. I got a heads up they were going to discuss it yesterday and haven't heard anything since, so I'm thinking it might not be good news.

[jrbe]

A hammock is definitely less work. Less stuff and weight to store too

6 point is definitely more comfortable, especially when you tighten it up.

Is this your only seatbelt? Do you need a DOT (not sure what Canada uses) seatbelt for driving on the street?
My caged car has the original seatbelts installed if I drive it on the street because my 6 point harness isn't DOT. You can find everything but availability / manufacturers who offered them was pretty limited last I looked 12 years ago or so. It's definitely nice to be able to drive on the street to check things before a race. Did I get all the air or of the brakes, coolant system running properly, etc.

Does your current harness have provisions for the anti-submarine straps? Some do, those might be easier to find. And if you're driving on the street you can leave those disconnected.

[Zieg]

Just got back from an event in Montana. Had to move quickly to get ready and didn't have enough time to get everything 100%, but I made it work!

I found a 6pt harness locally that I was able to install. It's not DOT, but I'm leaning towards not driving the car on the street anymore anyways. Before I started this conversion, I asked my insurance company if there were any issues with it being converted and they said no. Two weeks ago I got the car appraised again since you have to do that after any substantial changes. The insurance company said "hold on, it's not powered by flammable liquid anymore? Now we won't cover any loss or damage". I called around a bit and got the same story from every other company. Hagerty told me they have an agreement with the province that restricts them from insuring EV conversions of any kind. Are you KIDDING ME?! I guess if I stop driving on the street, I can replace my tires with slicks and add some aerodynamics without worrying about range.

Anyway, back to the trip. The car did amazingly, drivetrain-wise. Drove nice and smooth. Everyone thought it was really cool, and most had never seen anything like it before. I was having a lot of trouble with losing the rear end going into corners. I kept adjusting the brake balance forward, but in small increments it wasn't doing much. Finally I made a big change (15 clicks instead of 2 at a time) and that finally got me into the right ballpark. I had expected to have to shift it forward a bit and started out maybe 5-10 clicks ahead of where it was with the bike engine, but obviously that was nowhere near enough.

I also had to turn regen way down. Right at the limit of braking, any amount of regen seemed to cause a rear wheel to lock up. I never really thought about it this way, but because it's an open differential I think the regen torque can get sent to one wheel and cause it to lock? Just like how one wheel will spin when accelerating. At least, that's my best guess about what's going on. Turning regen way down made the problem mostly go away, so I think I should try turning it off completely.

I wondered if there would be any trouble with cooling, but with the big radiator it was perfectly fine. The batteries stayed around 25c which wasn't too much above ambient temperature.

And speaking of temperature, the extra weight and improved balance helped me get the tires up to operating temperature, which is something that I had struggled with in the past. I was hoping that would happen!

This venue was pretty cool. It's also used as a police training track so they have a big skid pad and a small road course. My runs were 80-some seconds long, and we got 12 runs through the car. Each run used about 0.8kWh of energy. It would have been good to charge at lunch because the drop in power was noticeable, but I did manage to get through the day. There's probably 3 hours or so between morning and afternoon runs. I could probably get by with a 2000w inverter and 5kWh of storage in the ambulance, or a 2000w pure sine generator so I could charge anywhere on site.

So, things to do for next time (or some point in the future):
-Consider buying a set of slicks
-Add rear downforce
-Get a generator
-Consider adding a front swaybar?
-Consider buying the Nismo LSD?
-Replace hammock with a fold-down sleeping shelf
-Add insulation to the rear door of the ambulance (5*c overnight temp, 1500w space heater couldn't keep up)
-Figure out why the ambulance has soot in the coolant/low coolant level (Please oh please let it be a failed EGR cooler and not a cracked cylinder head)

Pics:

Video (Sorry about the quality here, somehow my camera reverted back to a different mode and I didn't notice):


Also, one thing I did not consider when choosing the location for my new charge port, is that there isn't enough room to plug it in while it's in the ambulance. However, Foccci also isn't configured to shut off the EVSE when charging is finished, so I may reinstall the other charge port for L1/L2 charging. Oops.

There was an event photographer there, so as soon as I can find their photos I will upload some of those too.

[jrbe]

It's great you got to run it. The insurance side of things sucks.
Did you try raising the front end / lowering the rear? I'm guessing from your video, especially the end that your roll axis is off. Did you get to try the skidpad at all? I'm guessing the rear will let go first. You also need a bunch of extra rear roll axis bias because it's rwd. Are you able to throttle steer or does it just come right around?
Anti lift geometry / more of it very likely would help too but somewhat depends on what's going on.
It's looking like you have more front grip vs the rear as your main struggle after maybe too much rear braking. But if the roll axis favors one end too much this will also mess with your brake bias.
You may also find that a more progressive throttle ramp helps mid corner drivability. And if your throttle foot is bouncing during the video some more throttle smoothing would likely help too.
Regen is like slowing down with a parking brake in your case. You had a bike engine previously so not much decel as a comparison / reference.

[Zieg]

Hmm, lots of different opinions on RC that I can find online. I don't seem to have recorded my reasoning in my design notes, but checking my CAD files it looks like I've got a front RC 3.7" off the ground and the rear is 4.7". I guess my CG has changed too, need to factor that in. I did have to raise the rear by about 1/8" because the rear springs were about to loosen at max droop. Had to go stiffer than originally intended due to the rear weight being slightly higher than expected. I did get better launches with softer rear springs but also bottomed out over certain bumps and dips in the road. So that could definitely be playing a part as well. I could get some helper springs and try lowering the rear a bit?

Didn't get to mess around outside of my 12 runs but during the long corners at the beginning of the course I did notice I could throttle steer reasonably well. Plenty of front grip, yeah, so that's why I'm thinking it's time for a sway bar. It was especially evident to me on the slalom section.

Hadn't thought about throttle smoothing.. Next time I should set it up to log potnom (among other things) so I can go back and see if I'm doing anything I shouldn't. I guess, as the day went on, my torque at higher speeds dropped along with my voltage so that could have somewhat masked any issues early on in the day.

[jrbe]

How harsh is the bottoming you mention? When the suspension bottoms hard that bottomed spring rate goes infinite which can cause snap steer and other suspension gremlins. My suggestion would be to raise the rear 1/4 to 1/2 to make sure you have enough travel and raise the front 1/8 to 1/4 more than how much you raise the rear. Getting away from bottoming should help you see what the suspension is truly doing. And roll axis can vary a lot from expectations. I usually try to balance the vehicle without swaybars first then add the swaybars in and then balance them into the mix. You could maybe use swaybars to mask the issue but it's still there. You can chase suspension quirks that are masked under layers..

And for clarity adding swaybars may solve the bottoming and solve the issue. But if adjusting ride height isn't too much work it's worth trying. Swaybars will help slolom once you get things right. They also make the suspension stiffer so could make it snappier if they don't mask the issue(s) well. And you'll likely be able to lower it again but this should help you find it's balance.

Tire pressure could help some too, especially if it's bottoming.

You have some impressive cornering g's in the video, how does this compare to the bike engine?

I didn't mean you sounded rough on the throttle. Bumps look a bit harsh from the video. If you are bouncing it makes it very hard to be steady on the throttle.

[Bratitude]

I also had to turn regen way down. Right at the limit of braking, any amount of regen seemed to cause a rear wheel to lock up. I never really thought about it this way, but because it's an open differential I think the regen torque can get sent to one wheel and cause it to lock? Just like how one wheel will spin when accelerating. At least, that's my best guess about what's going on. Turning regen way down made the problem mostly go away, so I think I should try turning it off completely.

this is a good insight, just got my Datsun back on the road, with regen now, and already started noticing some lock up on wet roads.
This makes a lot of sense. I have been researching lsd options, and the Nissan h233 has a clutch pack type, which means I can rebuild and adjust lockup/break away torque. Which for a daily driver, is going to be important.

From my understanding the nissmo diff is from quafie, meaning it’s an atb.

[jrbe]

Limited slips come in different flavors. Moist people's focus is on acceleration but there is usually a decel aspect as well. You'll often see a 1.5 if it's a clutch pack style lsd. This is 100% limited slip forward and .5 (50%) in decel. They have different cams to give different % as well as different stack options.

Note that an open diff will drag the inside / unweighted tire on too much decel, you still have cornering grip on the weighted wheel. Adding limited slip in decel distributes the torque more between the 2 tires which can get you more decel grip but can trade it for cornering grip / grip snap. It can also try to force similar torque between the 2 wheels which can have a stabilizing effects up to a point.

It depends on what you're looking for but I'm not sure a limited slip will help with decel oversteer / skidding.

[Zieg]

I have a theory about that too. When braking near the limit and the regen torque locks a wheel, it's going to be the wheel with less grip. In a straight line it might just be the one with less weight on it, and very likely the same one that would spin when accelerating in a straight line. The instant that wheel locks up, the regen torque has to go to the other wheel, adding to its net braking torque and possibly locking it as well. Maybe it wouldn't lock if you are already turning and there's a bunch of weight transfer already on that wheel? I wonder if I could somehow add wheel speed sensors that would alter the regen if a wheel stops?

Is the Nismo diff the only option for the Leaf reducer box? It's the only option I can find anyway. I think it would be fine for my application (at least from my other experiences with a torque sensing diff). Just have to actually get my hands on it.

About the bottoming out, it doesn't do it at all now that I went one step stiffer with the springs. It wasn't bad anyway, just the tires rubbing the inside of the rear fenders on big bumps/dips. I think I just underestimated the rear weight when I was selecting new springs. Could try going back down I guess, would help with launches too. It was happening while both wheels were going over bumps so the swaybar wouldn't help that situation, but I still do want a front swaybar. I think it would help how the front end feels in the slaloms. Tried disconnecting it on my RX8 just to understand exactly how it all worked and the feeling on the locost kind of reminds me of that.

[Bratitude]

Limited slips come in different flavors. Moist people's focus is on acceleration but there is usually a decel aspect as well. You'll often see a 1.5 if it's a clutch pack style lsd. This is 100% limited slip forward and .5 (50%) in decel. They have different cams to give different % as well as different stack options.

Note that an open diff will drag the inside / unweighted tire on too much decel, you still have cornering grip on the weighted wheel. Adding limited slip in decel distributes the torque more between the 2 tires which can get you more decel grip but can trade it for cornering grip / grip snap. It can also try to force similar torque between the 2 wheels which can have a stabilizing effects up to a point.

It depends on what you're looking for but I'm not sure a limited slip will help with decel oversteer / skidding.

Yes for sure, I’m just not familiar with the Quaife atb units with how they work/ behave. Are they just a worm gear set? Are they multiway? I wonder how locked down the nissmo units are, if we can adjust the breakaway?

[Zieg]

Not sure you could adjust a helical diff at all, unless you got creative with shims maybe.


Doing some digging and apparently Cusco makes an LSD for the note e-power. Now the Nismo catalog seems to indicate the Nismo LSD is the same between the Note/Leaf and just the seals are different. I wonder if this Cusco would fit a Leaf reducer box? It's a clutch type, and they say it's a 1-way but the RS series also appears to have the ability to function as a 1, 1.5 or 2 way. Now since my motor is mounted backwards a 1-way would be more like a negative-1-way. The chart they have shows the 2-way configuration functioning the same in both directions but from the shape of the cross shaft I'm not so sure about that. At least it looks reversible from the exploded view.

Damn, that's kind of tempting. I can only find the Nismo on ebay for like $3k CAD, but the Cusco... https://atomic-shop.eu/products/cusco-l ... -note-he12

[jrbe]

I don't know the fitment answer. Nissan may have used the same diff in the note/ leaf but a replacement diff may have clearance issues based on it's shape / size.

Most diffs won't be reversible but the cusco diff looks modular and may be able to be put together backwards. They will likely have at least a pin to prevent installing it backwards. It's definitely worth digging deeper into. You may also be able to buy the inner cross / cam to adjust the lockup profile - if they're willing to sell parts. But for the price you could buy a second unit and mix and match.

Helical diffs have different designs. From driving a few some do a little in decel and some seen to have no real effect in decel.

But some more anti lift in the rear suspension along with maybe more anti squat could help to make it more predictable. Correcting Anti lift is how Porsche tamed the 911 lift snap oversteer.
I'd suggest turning off regen and doing some skidpad testing on the balance front to rear. Once that's sorted do some late braking turn testing in an open area and get your brake bias set well. Orings on the shocks / sliding bump stops / some travel indicators could help see what's happening. And cameras or datalogging with position sensors could help too.
Once it's sorted and you can easily throttle steer and power out of corners you can add in regen and see how it behaves. If regen is still like pulling the ebrake, you'll likely need more anti lift for the regen you want to run. You won't be able to get a lot of regen from the rear. That's why formula e uses the front for the bulk of the regen.

And swaybars will definitely help slalom from what I saw in the video as long as they're balanced. OEMs also usually add at least a bit more compliance on the rear bar vs the front to help soften transitions.

[jrbe]

And it may be worth adding in a positioning sensor on the brake pedal to activate regen. This way the regen won't be trail braking on you.
The regen setting will also change your brake bias. When you adjust one you likely will have to adjust the other.

Edit 3, you may be able to look at suspension positioning sensors and lower regen when you see a difference between the 2 sides or different wheel speeds as you mentioned. This can start to get pretty complicated as it becomes stability control.

[Zieg]

Oh, yeah actually my shocks do have a rubber bumper on the rod that I could move down and see how far it goes after some hard cornering. Is anti lift controlled by the angle of the upper wishbone? I'm pretty sure I set those level. I could adjust it but I'd have to cut the brackets off and reweld. Don't remember how much antisquat it has but I know it has some. A few degrees or something like that.

Also found a teardown video of the Note transmission. It's definitely different to the Leaf reducer but the differential LOOKS the same to my eye? The Nismo catalog gives the same dimensions for the carrier and stuff, only the ratio is different.. which shouldn't matter if the ring gear is being replaced? Kind of want to email Cusco and ask..

[jrbe]

It's more about how the suspension moves with the tire.
Moving one pivot point will mess with the camber gain, anti lift, and anti squat, at least a little. I think some F1 teams have designed their suspension so they can move 1 pivot without effecting the others too much but it's not very straight forward, especially with rubber bushings at the ends.

It's worth asking if there's something preventing the Cusco diff from fitting a Leaf transmission and if the internals could be reversed.

[Zieg]

Okay, haven't had much time to work on the car this past week but I have been able to do some research.

Update on the Cusco diff, I spoke with Cusco USA and they told me this diff only functions as a 1-way (no cams for 1.5- or 2-way). However, they did say they confirmed it will fit the Leaf reducer box (which I expected) and they think it should be fine to flip the internals so that it at least functions as a 1-way in the correct direction for my application. Should be getting a shipping quote soon and we'll see what that comes out to. I also want to do a bit more research to satisfy myself that a 1-way is worth the cost and effort.

Found a picture on the Japanese Amazon listing which might show the actual diff rather than a generic photo of a RWD diff.

Also working on a front swaybar design. It's going to be a little tight fitting it around the rest of the suspension but I think I have a plan. I'm going to go with 3/4" OD tube and get several different wall thicknesses. Then two holes on the ends for the endlinks so I can make lots of adjustments to dial it in. That should be easy enough to achieve this season, then over winter I can look at adjusting my suspension geometry.

And I'm looking at trackside charging options. Looking at the timestamps from my videos I had almost 3 hours elapse between the end of my morning runs and the beginning of my afternoon runs. I used about 5kWh in the morning so if I can get most of that back into the battery in 3 hours that would be great. Getting a 240v system seems difficult/expensive, but even L1 charging at 1500w would be pretty helpful. I've been advised by Thunderstruck that I really do need a pure sine wave fed to my charger, so that rules out conventional generators and MSW inverters. Trying to see what I can find on the used market in terms of inverters and batteries, or a portable generator. Looks like I want something rated for at least 1800w continuous if charging at 120v.

[Romale]

and why not use a charging system using an OI board??
in boost mode, you can supply any constant voltage to the input, even 75 volts, and an inverter with a motor will raise it to your battery level.

[jrbe]

Do you have room on the ambulance roof for solar? There are some cheaper inverters that should be able to give you the 220v like a Deye. You could add batteries to the system too.

Fred Puhn has a pretty simple swaybars calculator equation if you want to see what the different dimensions do.

[Zieg]

Ah, admittedly I don't really understand how the OI charging works, but the rulebook also has a few things to say about charging - including something about using common charge ports with an EVSE and the BMS has to control charging and all that. I'll double check though, and maybe I can add some code to my Arduino that's already on the CAN. Thanks for the idea!

I do have room on the roof for solar, yeah. Eventually it would be awesome to have some panels on there charging a bank of batteries. Maybe like a 230v/50hz inverter if I can find one cheaper than a 240/60 unit? One with a 12v input might be handy because I could start with smaller batteries and supplement by running the engine if need be, but that's a lot of current - even for my dual alternators.

As for the swaybars I have done some calcs but it's really hard to know what kind of numbers I should be shooting for. I know a Caterham uses a 3/4" bar, possibly solid, and the dimensions are going to have to be in the same ballpark based on the photos I have seen. The thicker wall options are going to have almost the same characteristics as a solid bar.. So I'm not sure what else to do other than make 2 or 3 and try them. After I have my exact dimensions worked out I will put it through the calculators again and try to make it so that the stiffness increases linearly from one endlink position to the next and then one bar size to the next. Not going to try swapping a bar on the grid but if I do it right I should be able to swap a bar over break easily enough.

[jrbe]

This would be a perfect candidate for the clamp style swaybar adjusters. Instead of forming the bar ends they stay round. The clamp is like a motorcycle fork clamp with one bolt to clamp to the bar and the other to attach the end link. This gives you a lot of adjustment on the bar. Depending on your travel you may want a few spots on the control arm to attach to so the link angle doesn't get too high.

One of the things to look at with the calcs is what the ID of the swaybar contributes to the bar strength. Below 5/8" to 3/4 ID it doesn't make much of a torsional strength difference going from solid to hollow. Basically, going hollow with different wall thickness and a small OD may not get you any real difference between bars. You need enough thickness for bending strength.

You can also adjust the width of the swaybar clamps to the chassis as an adjustment technique. You'll likely need clamps on the bar to keep it centered.

You can calc total roll resistance with your springs and proposed swaybars. Has lots of inputs to get it right though.

Going junkyard / eBay swaybar shopping could work out. You'll sometimes find swaybar dimensions on eBay.