Comment by red369
1 day ago
I once expected an aftermarket industry to pop-up to hybridize old cars. Old rear-wheel drive manual cars sound easiest.
Generator attached to the flywheel instead of the starter motor, and then find some way to squeeze a drive motor by the rear diff (probably more complicated, but surely not impossible). I thought something might pop up once companies like Bosch started making generic e-axles for manufacturers to use.
With a small Li-ion battery (and all the usual inverters, etc.), it could work like a manually operated version of the dual-motor Honda hybrid system. Put it into neutral, and whatever energy is in the battery could drive the motor on the rear axle. The engine could automatically kick-in and drive the generator if there's not enough in the battery.
It would never be as economical as a purpose-built hybrid, but old manual cars are often reasonably economical on the open road, and terrible in city traffic. Targeting only the urban fuel consumption would go a long way towards keeping them useable, with the added bonus of making manual shifting optional in stop-go traffic. Small motors would be enough for city speeds, and with a small battery, it sounds cheap to me at least.
I doubt it could ever be a simple kit, but I thought people would have a go.
The problem is that environmental regulations kind of act like a double edge sword with regards to hybrid conversions. They prevent Jim Bob from selling his environmental disaster kit, but they also prevent Bob Jim from selling his Hybrid drivetrain conversion without expensive approvals. This is why most people do BEV conversions. The kits are available because they are zero emissions and don't fall afoul of the environmental regulations.
People probably are having a go. Here's one for pickups: https://edisonmotors.ca/trucks/pickup-conversion/
> Generator attached to the flywheel instead of the starter motor, and then find some way to squeeze a drive motor by the rear diff (probably more complicated, but surely not impossible).
Some vehicles have this as a “battery starter generator” where the “hybrid” functionality is entirely on the accessory belt.
https://www.bosch.com/stories/48v-hybrid-battery/
https://hackaday.com/2025/01/24/bosch-starter-motor-freed-fr...
We had a guy give a talk at our local nerd meet-up about doing this to an old landrover with the hopes of commercialising it. Did a good job, but it was only for someone with money to burn.
Looks like he did commercialise it: https://www.jauntmotors.com/series
I recognise some of the photos from back then.
Automotive engineer here. One consideration for the diff motor is that it would REALLY sag the diff. I think the only way to go would be a front and rear generator/motor combo in one housing to replace the transmission, powering the rear end with a driveshaft. A direct drive clutch between the front and rear motor/generator would economize driving and assure high power at high speeds.
How about a front wheel mounted drivetrain with the motors built into the wheel hubs?
That would effectively add 4wd to old cars and allow the onboard engine to work normally with an option for eboost/edrive with the only extreme modification being adding the battery and control modules.
You would have to provide custom replacement hubs, for all the vehicle types you want to support. Plus, adding a clutch system to a hub drive is not feasable. So, the hub engines are engaged all the time.
I've considered it as a modification for FWD track performance cars. It is much easier to add a hub into a stiff rear axle. Turns out, that adding an electric motor, which is not part of the main engine assembly, ads way too much complexity in controlling the whole thing and weight to power ratio, that it stops quickly stops making sense.
Wouldnt the weight of the old chassis be a impedement to mods , older models tended to be more robustly buildt. Or what cut-off date for mods would be appropriate (last 10 years?) as beyond a certain cutoff would not be cost effective and most likely would be a hobby project done for the love of it.
I was thinking of a “feature” on manuals that ran electrical and accessory-belt stuff full blast during engine braking.
The best time to run your a/c or turn the seat warmers: when you’re trying to expel energy.
Would give you some extra braking without heating up the engine and take a small load off your brakes.
That or turn any vehicle into a mild plug-in hybrid for all electrical loads and flywheel the alternator until that time. Gasoline-powered generators are not very efficient.
Might get a few percent extra efficiency without having to touch anything mechanical.
My guess:
1) New cars are too cheap to make at scale.
2) Old cars are quite unsafe to drive, comparatively (airbags, backup cameras, lane departure alerts, blind angle alerts, etc)
2) cars have had airbags for a pretty long time. Backup cameras are a simple retrofit. Lane departure alerts are not universally loved, mine is turned off...
To be fair to the person you're responding to, airbag systems in modern vehicles are a lot safer than the single airbag per front passenger in older cars. The original airbag systems were just a single bag that deployed at a single rate based on an inertia sensor. Modern systems have several bags with multi-stage deployments that are inflated depending on seat belt and weight sensors.
But yea, as for the rest of the "safety mechanisms" the only modern change that I can think of that's not easy to retrofit but is a huge safety boost is blind spot detection. As someone that drives older (and smaller) cars, being able to see the blind spot detection light on other cars' mirrors is always a bit of a relief that their car will notify them if they try to change lanes.
Aerodynamics as well, new cars and especially ev/hybrids are slippery compared to many/the average if we take old cars to mean 50’s through 70’s.
Does that matter much if you only drive around town at 30mph?
An older sedan-style car might still be more aerodynamic than a modern SUV, simply because the frontal surface area is smaller. The less air you have to push out of the way in the first place, the better.
The big one is probably cost and scaling.
Cameras are a mitigation for high waistlines, and only a partial one. Keep your cameras and alerts, and give me a car with better fields of vision.
I think there are important dimensions of safety that go unmeasured. You have much less road awareness in new cars.
Survivability is great and all, but not at the expense of children and pets becoming invisible.
All the focus on survivability provided another incentive for makers to put ever larger pieces of steel on the road. I disagree that new cars are safer.
I have experienced driver aids glitching, and i want none of it. Anything that can take control of the car needs to be bulletproof, and it isn't.
Stuff like this exists for bicycles. For mopeds and motorcycles there are electrification kits.
It should be possible to just replace the flywheel altogether with a generator/motor that both brakes and powers during each cycle, cancelling vibrations. Then more generation during deceleration, and more power during acceleration.
In the US RWD manual cars have been exclusively sport/GT for decades. They aren't cheap and a hybrid swap and/or daily driving miles would destroy their value.
There are hybrid packages, which are very good for performance applications. A performance oriented conversion, done well, should boost the value.