Prius power steering

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BZOOK
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Prius power steering

Post by BZOOK »

G'day. Just watched a dude on YouTube add an electronic power steering unit from a Prius to his samurai. Looks too easy to be true.Thoughts?
https://youtu.be/DeujFu__rFA
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neofitou
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Re: Prius power steering

Post by neofitou »

This is actually what they have done in the new Jimny.
It is so they can jun the driving aids like lane keeping and esc etc though it. I believe it's under the dash on the column like the prius unit.

Luke is looking at running an electric hydraulic pump and a normal power steering box on his race truck.
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gwagensteve
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Re: Prius power steering

Post by gwagensteve »

The other reason electric power steering is now used is CO2 emissions.

ANYTHING manufacturers can do to lower CO2 via lower emissions is a win. Consider that the Jimmy in current form won't be sold in Europe but the end of the year as it's too polluting.

for something like a Prius it's required so the car can have power steer while the engine is off.

Despite the ease (if not legality) of fitting these systems, I don't believe they're suitable for an off-road application. The readily available systems aren't (currently) adequate for steering a large tyre in a rut or against a rock, for example. It's possible with vehicles like the chevy silverado using electric power steer (the LT1 V8 isn't designed for hydraulic steering) this might be solved soonish

However, the effect is like being the strongest man in the world and hanging off the steering wheel. Power steer boxes are designed to cope wth the hydraulic forces being developed inside them, and in an off road application it's not all that hard to retrofit a bigger/stronger steering box from a larger vehicle, such as a jackaroo box into a Sierra, which wouldn't be a bad fit at all.

However, putting all that assist force into the input side of a Sierra box isn't a great idea. The shaft and splines are tiny, as are the universal joints. they weren't designed to transfer assist force. In a road car its probably OK, but the shafts, input and rack have been designed for the application.
michaelpiranha2000 wrote: The rear is in great condition. but has a broken crown wheel and pinon
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gwagensteve
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Re: Prius power steering

Post by gwagensteve »

Oh, and I just took the time to watch the video. I'd never given much thought to how these systems would be fitted but golly, an engineer would have a fit at that. They don't like to see any non-factroy welds at all on a steering shaft. I'm also curious about how that would fit on the RHS of the car - there's a lower radiator hose, alternator etc all competing for space there.

Additionally, it doesn't look like the end result offered all that much assistance. Whilst the driver could sort of palm the wheel when stationary, it wasn't all that convincing. I imagine offroad and at low tyre pressure there would still be pretty high effort, which is a concern in itself - if the system is running flat out* and there's inadequate assistance, it's basically being overloaded - how will it deal with kickback and other large forces offroad?

*associated question - is it running flat out? There's clearly feedback being provided from the Prius ECU to the steering ECU about the conditions the car is running in. As the youtube poster comments - "it's running in dumb mode" which I bet isn't full assist, because that would make the car feel odd at speed - conventional power steering boxes have a torsion bar that controls assist force - the harder you pull on the wheel, the more assist is provided at high speed, there's little demand for assistance so hydraulic power steer boxes pretty much just idle. I bet that's not the case with the electric steering ECU isn't seeing speed/drive mode data from the car ECU. Prius have very, very light steering at parking speeds.
michaelpiranha2000 wrote: The rear is in great condition. but has a broken crown wheel and pinon
BZOOK
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Re: Prius power steering

Post by BZOOK »

Damn it. I was just heading to the wreckers to find a totalled Prius :lol: Excellent and interesting info Steve. I'm running a standard box in my Zook and with 31's off-road it would be nice to 'palm' the wheel! Now if I swapped in an auto trans or 'when' I get bigger tyres I might be forced down the power steering path. I see no reason not to copy everyone else and use a Vitara unit. I've got the engine in but it didn't come with power steering. It's on the list. I'm sure there are a host of new options out there.
Brenton.
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gwagensteve
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Re: Prius power steering

Post by gwagensteve »

Yes, the common Astra electro/hydraulic pump (R50 minis used these too) could be used with a Vitara steering box, and these are easy to mount, but these systems are fairly heavy and power consumptive when being used hard. They also don't really adhere to the idea that the simplest option is the best being a kind of interim solution on the way to full electric steering - the alternator converts crank power into amps that then drives an electric motor to turn a hydraulic pump that then drives the steering. There's one too many steps in there.

I understand the idea for reducing emissions/increasing economy when the steering isn't required (which is why these systems were developed) but I don't get it in our application.

JDM sierras had electric power steering since 1996. Consider they were only turning a 195 section tyre and the system had a 70A fuse(!) It was basically a parking aid and turned off once the car was in motion. Late K engined cappuccino's had the same system.

The jimny hydraulic power steer box is the best option.
michaelpiranha2000 wrote: The rear is in great condition. but has a broken crown wheel and pinon
BZOOK
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Re: Prius power steering

Post by BZOOK »

I think I'll just swap my stock Sierra steering wheel for something out of a Mack truck and focus on upper body strength in the gym :D But then again I guess if you can't turn your tyres then something else is going to let go. A torn bicep is not fun.
Side note. What's happened to auszookers??
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gwagensteve
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Re: Prius power steering

Post by gwagensteve »

I think someone forgot to pay the bill. :D

This morning I was getting an "account suspended" message and now it's back but about a week behind. :roll:
michaelpiranha2000 wrote: The rear is in great condition. but has a broken crown wheel and pinon
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