# Considering 1950 Chevy 3100 conversion



## brian_ (Feb 7, 2017)

bwilliam79 said:


> 1. I'd really like to be able to turn the engine bay into a frunk, if possible. Given most conversions seem to use a non-Tesla motor mounted to the existing transmission, I'm curious to know if it's possible to place a RWD Tesla motor between the rear axles and forego the traditional transmission and drive shaft altogether? I believe this would require custom fabrication of new axles as well as a custom frame, but is there any reason not to consider this approach?


Just difficulty of design and fabrication. It's not just new "axles"; it's a complete suspension system for a driven axle.



bwilliam79 said:


> 2. If I were able to go the route of using a Tesla motor for the rear, does that make it more difficult to connect to some type of speedometer?


Yes, that's a difficulty, but it's a tiny issue compared to the other issues you would need to deal with.



bwilliam79 said:


> 4. I assume weight distribution is an important consideration from a performance and handling perspective. Would building a custom battery box under the bed of the truck put too much weight on the rear end, especially if there is no motor or transmission up front?


Weight distribution is a concern, but if you consider the battery to be the load that the truck is carrying, assuming that this is a recreational toy that will never actually haul anything, that's manageable. The stock truck is somewhat rear-heavy when fully loaded, and if you keep the battery as far forward as possible this may not be much different.

Serious electric truck designs intended for production have battery filling nearly the entire length between the front and rear axles.


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## bwilliam79 (Apr 14, 2020)

brian_ said:


> Just difficulty of design and fabrication. It's not just new "axles"; it's a complete suspension system for a driven axle.
> 
> 
> Yes, that's a difficulty, but it's a tiny issue compared to the other issues you would need to deal with.


Thanks, brian_. I appreciate you taking the time to answer these questions!


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## blwnhr (Apr 4, 2019)

bwilliam79 said:


> I have a 1950 Chevy 3100 Pickup in my garage


Awesome. I was looking for one of these but they are rare in Australia and ended up with a 1951 Ford F1. Mine has sat in the shed for 7 years untouched because I ran out of inspiration, I didn't want to do "just another LS conversion".
I started a job with very clever mechanical-electrical-process engineers and environmental scientists. These guys got me inspired on an EV conversion and I've been researching and acquiring bits ever since.
I have a toddler at home and needed to finish another car I have, but I'll be making a start in a few months.
Much like you, I'm using a Tesla large rear drive unit. I have good mechanical knowledge and fabrication experience, but don't quite have the fine knowledge of the electric drivetrain components.

To your questions:
1. This is what I'm doing. The track will be way too wide as you say. I've opted to design a new rear subframe, use the Model S suspension, maintain the factory geometry but make the track more narrow. This means nothing more than shorter half-shafts but does require a lot of fabrication. Below is my proof-of-concept 3D model that shows you can move the arms inboard by 120mm each side and still clear the drive unit. I haven't completed the subframe design so can't share that yet.

https://i.imgur.com/6Qgeh9U.jpg

2. Some (most) drive unit controllers come with some kind of display which includes speed. eg. this one from EV West.

3. The Tesla stuff is really hard to re-purpose and communicate with (the CAN control is encrypted). There are a number of good aftermarket options. If interested I can list what I'm planning on doing.

4. I would say yes. I'm planning to utilise the now-empty space between the chassis rails for the batteries with overflow under the tray (forward of the rear axle line) and maybe in the engine bay if required. I too want to run a frunk for closed, sealed, dry storage.

5. It depends on how much you can do yourself. I'm in Australia so the dollar values don't align, but I'm fully prepared to spend $35k on the driveline, batteries, control systems. But then this is going to be my daily drive and I want it to be robust.


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## brian_ (Feb 7, 2017)

blwnhr said:


> I too want to run a frunk for closed, sealed, dry storage.


I like the idea of a front trunk in an electric pickup truck, but the engine compartment of any normal vehicle is not sealed in any way, top or bottom. It would be easy enough to build an open-topped box that sets into the space, which would be keep the contents from splashing from the bottom, but sealing the hood of an adapted vehicle to the box doesn't seem reasonable to me. It is probably worth considering making this trunk a box with a gasketed lid, so you open the hood then open the lid of the box. You could even just use an off-the-shelf box, such as a large plastic tool box with a gasketed lid.

No matter how the front trunk is constructed, I think it's reasonable to plan for it to occupy only a modest part of the compartment volume, with equipment such as the braking system behind it, radiator ahead of it, and ancillary equipment such as the on-board battery charger and DC-DC converter around it somewhere. Assuming that there is an on-board charger and adapter for normal outlets (for when there is no charging station), the adapter cord should get a storage spot under the hood, too.


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## blwnhr (Apr 4, 2019)

brian_ said:


> sealing the hood of an adapted vehicle to the box doesn't seem reasonable to me.
> You could even just use an off-the-shelf box, such as a large plastic tool box with a gasketed lid.


Just because it doesn't seem reasonable to you doesn't mean it is not possible.
Using an "off-the-shelf box" would be more impractical than custom fabricating something. Old cars don't have a square engine bay like cars made post-1970, they are tapered. A square peg, triangle hole, so to speak.
Look at how OEM's do it; a flat face mounted to the bonnet and a pinch-weld seal around the top of the tub, easy. The tub could be steel or fibreglass, the latter would be a good option as you could mould it to clear all the ancillaries you mention.
Speaking of, while the engine bays might be tapered they are pretty cavernous, designed to handle large engines. There is ample room for the items mentioned, plus AC compressor et al.


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## brian_ (Feb 7, 2017)

blwnhr said:


> Just because it doesn't seem reasonable to you doesn't mean it is not possible.


I didn't suggest that anything was "not possible".



blwnhr said:


> Look at how OEM's do it; a flat face mounted to the bonnet and a pinch-weld seal around the top of the tub, easy. The tub could be steel or fibreglass, the latter would be a good option as you could mould it to clear all the ancillaries you mention.


Almost nothing in a DIY conversion is very much like the way OEMs do anything; that is, in part, because the OEMs are working with body parts designed for the purpose, instead of adapting body parts designed for a very different purpose. Yes, you can attach the lid of the trunk box to the hood, instead of hinging it to the box, if you want the fabrication challenge. 

And yes, if anyone is custom-building a box, fiberglass is a good way to go.


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## blwnhr (Apr 4, 2019)

brian_ said:


> Almost nothing in a DIY conversion is very much like the way OEMs do anything


I notice this is a mindset common among EV enthusiasts across the world. Coming from a hot rod and modified car background, enthusiasts in this hobby approach things with a mindset on improving on the work of OEM's, repurposing elements from other vehicles or taking inspiration from OEM's. Just because the driveline is bespoke doesn't preclude the utilisation of other components.
I'll stop there for risk of derailing the purpose of this thread.


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## P.S.Mangelsdorf (Dec 1, 2014)

bwilliam79 said:


> 1. I'd really like to be able to turn the engine bay into a frunk, if possible. Given most conversions seem to use a non-Tesla motor mounted to the existing transmission, I'm curious to know if it's possible to place a RWD Tesla motor between the rear axles and forego the traditional transmission and drive shaft altogether? I believe this would require custom fabrication of new axles as well as a custom frame, but is there any reason not to consider this approach?


I just finished adding IRS to a 1940 Chevy coupe so that I can put a Tesla LDU back there. It's possible, you just need to find a donor car and be halfway decent with math and a welder. I used a 04-06 GTO rear subframe, narrowed three inches with QA1 coilovers.

Another guy on the openinverter forums is using the whole Tesla rear subframe under his 72 Plymouth.




bwilliam79 said:


> 2. If I were able to go the route of using a Tesla motor for the rear, does that make it more difficult to connect to some type of speedometer?


Most aftermarket gauge companies make a GPS speedo that matches their other gauges. (Autometer, Speedhut, etc) That's what I'm planning on using



bwilliam79 said:


> 3. If using a Tesla battery and motor, I assume a Tesla battery management system would be desirable, along with the HVAC system, power steering, brake booster, and battery/motor cooling setups. How does one begin to operate things like HVAC unit or is that something better off sourced from a non-Tesla vehicle? I'm trying to avoid using anything reliant on the Tesla display or MCU and believe the HVAC system may be the only thing listed above which would require that.


There are a few different BMS systems that work with the Tesla units. Orion BMS2 likely gives the most options (built in CHADEMO and J1772 charging support) but is also pricey. Thuderstruck EV also carries a system that looks good, it's likely what I'll be using with Chevy Volt packs.

Brake booster can be handled with a vacuum pump available from Jeg's or Summit for use on ICE cars with big cams.

I'm deleting power steering on my car, but there are electric PS pumps available from a variety of cars (such as the MR2) or electric PS columns from stuff like Priuses. Hot Rod has an article on their website about using a Prius column in a muscle car.

I haven't worried about AC for my build (drag car) but several people have used Prius or other hybrid/ev ac compressors.



bwilliam79 said:


> 4. I assume weight distribution is an important consideration from a performance and handling perspective. Would building a custom battery box under the bed of the truck put too much weight on the rear end, especially if there is no motor or transmission up front?


A big concern with weight distribution will be spring rates. Be prepared to need to tweak what springs you have for a good ride. As others have mentioned, many OEMs run batteries under the whole floor. Lots of pickup conversions build battery boxes between the frame rails.



bwilliam79 said:


> 5. Am I just way out in left field here and looking at a $100k+ project? I don't mind sending the vehicle out for some of this work to be performed by professionals, but before I go asking traditional hotrod shops to do things they may not be used to, I'd like to get some understanding of the level of effort.


No, this shouldn't cost 100K unless you want a show car restoration along with a conversion. Batteries will be the biggest cost. For the range you want, a Tesla based pack makes the most sense. A Tesla pack will run 8-15k depending on the source. Depending on how much you are willing to do your self (i.e. openinverter vs HSR motors) the motor and controller could be anywhere from 2k-10k. Chargers, BMS, contactors, Fuses, will put you back another 2-8k, depending how top of the line you want, how fast you want to charge, etc.

The cost of fitting it all in the truck depends on how much you can do yourself. The parts don't cost an arm and a leg, but it takes time.


Here's my two cents: a lot of people, in the ICE world and the EV world tend to make it more complicated than it is. Take the time to read forums, ask dumb questions, make a plan but most importantly just start. So many people will tell you to make sure everything is perfectly planned before you start. The problem is as soon as you start you will run into road blocks and begin learning. And everything you learn will give you new ideas and new lessons on how to do it.

Provided you understand basic safety concepts (how not to shock yourself and die), just jump in.


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## blwnhr (Apr 4, 2019)

P.S.Mangelsdorf said:


> Brake booster can be handled with a vacuum pump available from Jeg's or Summit for use on ICE cars with big cams.


Alternatively the Bosch iBooster (used in Tesla's) has small packaging and you don't have the vacuum pump noise.

The reference to the Hot Rod Prius steering article was a big help for me too, thanks. Link for those interested.



P.S.Mangelsdorf said:


> Here's my two cents: a lot of people, in the ICE world and the EV world tend to make it more complicated than it is.


Amen!


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## P.S.Mangelsdorf (Dec 1, 2014)

blwnhr said:


> The reference to the Hot Rod Prius steering article was a big help for me too, thanks. Link for those interested.


Thanks for linking it. I lost track of it but remembered seeing it recently.


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