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Kermit - Hillclimb Buggy Tesla Swap

RadialDynamics

Yellow Skull
Joined
Dec 22, 2020
Member Number
3165
Messages
161
Loc
Greenfield, MA USA
It's time to start documentation of my latest major automotive undertaking. For the past 5ish years, my personal motorsports projects have largely taken a back seat to growing the business. Any free hours that I previously would have spent working on buggies or race cars turned into R&D on steering pumps so my personal buggy has gotten nothing more than oil changes and basic maintenance. Now that the business is in a healthy and steady place, it's finally time to dive into a new project that will also support R&D and marketing of my latest high voltage power steering pump system.

First a little history, back in 2015 (2 years before Radial Dynamics was even a concept) I had a habit of collecting too many projects, like most people here. I was in the middle of building a new chassis for my Toyota truggy and had just finished building a Bro Lite Ford Ranger short course truck when this 2WD Hayabusa powered rail/mini buggy popped up on Craigslist a few hours away for short money. The want was strong so I jumped on it, ultimately selling off my Toyota project to a local guy that I was glad to see finished it and still wheels it today.

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I could tell the buggy had been originally built professionally but the previous owner that I got it from was a major hack and it took years to eliminate most of his half assed fabrication. It was a kick in the pants to drive and there was a lot of cleaning up to do but I eventually fixed it up to the point of prepping it for the Mint 400 in 2017. The motor was too large (1300cc) to be considered a UTV and it didn't fit into any car classes so I ended up racing in Unlimited Sportsman. The Mint was a bucket list item for me, absolutely brutal but the experience of a lifetime. Ended up with a DNF after blowing the motor and catching on fire around race mile 80. What a trip!

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I spent the following year tearing the buggy down to bare chassis to clean up more of the PO's hack fabrication, got a replacement junkyard engine, and re-wired most of the car. In the meantime, I was doing a lot of motorsports photography and one event that I shot that year was the Mt. Washington Climb to the Clouds (CTTC) hillclimb race which got me wondering if the buggy could even remotely be a hillclimb car. When I got it back together in 2018, I slapped some Hoosiers on it and brought it up to a New England Hillclimb Association race at Burke Mountain in Vermont. I had no idea what to expect for handling on pavement but the buggy exceeded my expectations and I was instantly hooked on hillclimb racing.

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Mt. Washington CTTC is only run every 3-4 years and I was fortunately able to get an invite to the next race in 2021 which was without a doubt the most intense thing I have ever done. This was also two weeks after I had just left my job to go full time with Radial Dynamics so it was a pretty big moment in my life.

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This brings us to the present. The Hayabusa motor was getting tired and I was already making plans to do an electric conversion to have an in-house development vehicle for my high voltage steering pump system. I currently have two operational systems, one being the Hypercraft Ultra4 Spec EV car and the other being the Tes-Ten Ultra4 car with a few electric comp crawler buggies also nearing completion.

The problem is that none of them are near me in New England so having my own dev vehicle will make it easier to test program changes. Plus, I don’t think there is a more ideal application for electric than hillclimb racing. So the plan is to use the Tesla small front drive unit out of a Model S (220 kW/300 HP), Chrysler Pacifica Hybrid battery modules in 6S1P configuration, and one of my 2.5kW high voltage pump setups going to a Fortin 2.0 power steering rack which will be setup as full hydro.

Through a stroke of luck when I was at Mint in 2017, someone recognized my chassis and I found out who designed and built it. Turns out there were a few made by a now-closed shop in CA in 2007 and I was able to come across a couple pictures from when they were first built. I'm pretty sure mine was the black one on the left.
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Fortunately the designer still had a CAD model of the chassis after all these years, with a few later revisions but close enough to make accurate again and start laying out the new drive unit, moving the seat back to the original center position, and the steering pump which will be the centerpiece sticking up through the hood.

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Chassis torn down, first order of business was removing the last of the previous owner's hackjob

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Cleaned things up a bit then brought the chassis over to MN Offroad, aka Nate Gilbert, for some help with fabricating a new main X
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I also decided since I am building this thing for the sole purpose of going stupid fast up mountains, it was time for another seat upgrade. The Momo containment seat that I swapped in for Mt. Washington was a good seat but I wanted even better containment and after going down the seat research rabbit hole recently, decided on the Sabelt Spine which is one of the first seats to meet the newest FIA 8855-2021 spec. It is beefy! Weighing in at 35 lbs, it is nearly double what my previous Momo weighed.
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I chose the Tesla small front drive unit for two reasons, first the motor sits at an angle up from the diff which worked perfect with my chassis layout and second, because they are less desirable than the small rear drive units, the front units are dirt cheap. I also bought a set of Porsche 930 cv stub adapters since the car was originally setup with 930 cv's I could re-use my original axles.

One snag was that the Tesla to 930 adapters are stated as not being able to fit the front drive units, only the rear small drive and the large drive. Reason being the front units has a mounting tab for the oem half shaft and a motor cover mounting bolt that interfere with the 930 CV. Nothing a grinder can't solve.
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Before shaving
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After shaving
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Yeah, but I think I can make a few aero concessions. My second year hillclimbing was when tech told me I had to fill in my firewall to the roof. It used to come up only to my shoulders so that the cab was open. I immediately felt the drag of closing that in and also immediately started having overheating problems due to the rear radiator. Hence the roof scoop which will no longer be there since I will be containing around the battery box and will open up the upper half of the cab again.
 
All of the torque of the drive unit gets transferred to the chassis through the four bosses on the side of the motor cover while the brackets on the opposite end of the unit strictly provide vertical support
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So I designed a boxed mounting bracket to tie the torque transfer into the nearest node and vertical chassis tube
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And got those parts all laser cut and tacked up last night
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Drilled slugs will be welded through both plates that the drive unit will mate against
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I bet you get it done before Chirs gets his Volkswagen done.
 
Just added to the watch list. This thing is gonna be sweet!

Any thoughts about testing at Josh's next lawnmower race?? :grinpimp:
 
Hell yeah! This is bad ass. Excited to follow along.

Make the light bar removable? Take it off for races with high speed sections?
 
It's been struggle finding time to work on the buggy with business picking up lately but progress does continue, just slower than I was hoping. First, batteries arrived. As mentioned previously, these are Chrysler Pacifica Hybrid batteries, 60V each so 360V in series for 16 kWh of storage. I still need to design a box for them but will be doing two stacked banks of three modules each, roughly as shown.
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I also finished welding the motor mounts so the drive unit is now in the chassis.

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Seat mounts done
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And just last night finished up the mounting plate for the HV steering pump
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Got any rally races in your area? Would be a fun rig to do rally with as well.

You say those small front motors are cheap...how much we talking?

Same with the batteries, what does a set of those batteries go for?

Got me thinking a setup like that would be fun in a crosskart.

Really dig what you're doing, looking forward to seeing it in action.
 
There is a pretty healthy rally community here in New England. SCCA actually just adopted new EV supplemental rules not long ago so I am going to be following those with my battery box design and all of the safety provisions to keep my racing options open.

The Tesla small front drive units can be had for $1000 on ebay which isn't bad at all for an integrated 300 HP electric motor with inverter, gear reduction, and differential. The 930 CV adapter flanges were an additional $500.

The Pacifica batteries are also reasonable, EV West sells them for $800 each but I found them from GreenTec for $600 each so $3600 total for my modules. Of course, I just looked this morning and Greentec is running a 50% off sale on these modules... part of me wants to buy another set just because. Chrysler Pacifica NMC 60V 45Ah 2.6kWh 16S Battery Module | Greentec Auto | Energy

While the drive units are quite reasonable and even the batteries aren't terrible if you are keeping the pack small, the controls are where the costs add up fast. Between the drive unit control board, VCU, BMS modules, dash, onboard charger/DC-DC converter, and a single 8-channel PDU, I'm up around $10K with AEM alone. There are cheaper ways to do it all like using a T2C controller instead or even an OpenInverter board but for this project, my focus is on developing the steering system so I am willing to pay more to make the drivetrain as plug-and-play, not to mention tunable, as possible.
 
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