# MR2 power steering experience.



## tj4fa (May 25, 2008)

Does it run all the time or do you have a switch to turn it on and off at will?


----------



## Tom W (Jun 9, 2008)

Yes, it runs all the time.


----------



## booksix (Aug 26, 2008)

has anyone yet wired it to only run at low speeds or other specific conditions? It seems wasteful to run it all the time and having to switch it on and off simply won't do for me personally (I'd never be happy with a setup that is anything short of how a major manufacturer would set it up)...


----------



## dimitri (May 16, 2008)

All it needs is a VSS signal, according to the diagram. I can't believe no one has tried it yet. I would have , but Miata didn't have compatible VSS signal and I was too lazy to mess with it. 

BTW, it takes about 70 Watts of power when idle, which is 99% of the time. 70 Watts is a drop in a bucket compared to main motor, so its not that big of a deal.


----------



## booksix (Aug 26, 2008)

this makes me wonder how a simple dc motor/belt drive could compare in power usage... Maybe I'll look into a small DC motor that can run my PS full time and have a enough power when the a/c clutch kicks in. What motor could I use? And would it need a controller?

edit: I was looking at this motor. 

http://surpluscenter.com/item.asp?UID=2009011121520731&item=10-2435&catname=electric

Could it be run off my 144 pack with a relay and voltage regulator? If so, where would I get the regulator? I can't seem to find any in the voltage range.


----------



## subevo (Aug 23, 2008)

just finished installing mine very happy .used a company called pirtek who say on their website they can make power steering hoses( branches in the uk)to fabricate the required fittings and hoses cost £70.thought it might be cheaper.you can hear it whirring away even though its mounted where the petrol tank used to be.just passed the mot yesterday.now for the road tax(dvla glasgow office tomorrow).im using a 30amp relay and its ok so far.


----------



## Tom W (Jun 9, 2008)

Update: After two weeks I am very happy. The PS works perfectly, couldn't ask for more. There is no noticeable effect on range. My opinion is that this is the way to go, don't mess around with trying to hook up a belt driven system. This is easy to do and not too expensive, about $200. I spent almost as much on belts and pulleys. 
Tom


----------



## electricmini (Oct 21, 2008)

Hi guys - glad to hear the MR2 pump is working well in people's EVs.

I've just got one myself, to go into my Supra-EV project, but I've
come across something that might be a concern:

Mine's a mark 2 MR2 pump - the kind with separate electronics and a
remote reservoir (no mk3 units on Ebay for ages, then as soon as I've bought this unit, one pops up... grrr)

Anyway, according to the mk2 MR2 Toyota service manual I've seen, it
uses different fluid ( "toyota EHPS fluid" whatever that is) rather than
the Dexron II ATF that the Supra system uses.

What fluids are others using in their systems?

I certainly don't want to use something different from the ATF that the Supra's steering rack expects (not sure what the other stuff will do
to the seals, replacing a steering rack is harder than replacing a pump!)

Anyone had an MR2 pump fail because they're using something different?

I can't imagine much difference, as the Supra's steering system is high-pressure hydraulics, just like the MR2, but Dexron II ATF is red and the MR2 pump's fluid isn't....

Am I just worrying too much? (this has been known to happen..;-)

electricmini


----------



## Zemmo (Sep 13, 2007)

Do you think your acceleration has improved a bit? I drove a Ranger EV that has the PS pump, AC and alternator on a pulley system from the tail shaft. I thought it pulled a lot of amps to be able to turn all of that stuff over. It does seem like the MR2 ps pump would be the way to go. Does someone make an equivalent pump for the AC? The alternator could be removed and just replace it with a deep cycle battery and charger.


----------



## electricmini (Oct 21, 2008)

Zemmo said:


> Does someone make an equivalent pump for the AC?


Yes, Masterflux make motor/compressors for aircon systems, that have a brushless motor & integrated electronics.
Various voltage ranges suitable for EVs, but they ain't cheap!

I thought about it, but don't use the aircon much, so might just pull it out to make better use of the space under the hood.


----------



## Tom W (Jun 9, 2008)

Zemmo, on my ranger there is a significant improvement in acceleration.


----------



## Zemmo (Sep 13, 2007)

Thats great news. I didn't think to leave the Ranger out of gear and just spin the motor to see the load on the motor at different RPMs. I could ask the person to perform this test for me and report back what the readouts say. I bet it is quite a few amps.


----------



## Tom W (Jun 9, 2008)

Zemmo. I can't give you any exact data but in additon to the improved acceleration the amps at a steady 55mph dropped from a little over 200 to less than 200 - I would guess about 10 to 15 amps. This amp improvement is offset to some extent by the PS draw that does not show on my ampmeter.
Tom


----------



## Zemmo (Sep 13, 2007)

Right, that is just the amp draw off of the main motor. But the new PS pump runs at 12 volts doesn't it. So it no longer draws from the traction pack.

I took out my DC-DC converter and just put a deep cycle 12 volt battery in its place. Taking that DC-DC converter off of my traction pack removed a constant 7 amp draw (just the car on). The savings was even better at night because of the lights, I think at night it was almost 15 amps. But your change would have been something you could actually feel while driving.


----------

