Power steering pump options

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Richard Ward
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Power steering pump options

Postby Richard Ward » Thu Sep 04, 2008 12:24 pm

Hi all, I've been thinking about possible donor cars for a while, and was restricting myself to ones without power steering, for obvious reasons. However, I will soon have available (for nothing!) a V-reg Seat Arosa 1.0, which would be quite suitable in a lot of ways (esp. the price).
The question I would like to ask is: what are the options for applying power to the power steering pump? How have others done it?

Richard
Bristol

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qdos
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Postby qdos » Thu Sep 04, 2008 12:31 pm

One option is simply not to use it at all. With such a small car it's very unlikely its actually needed and that it's just there so that the manufactures could list it in the brownie points game that manufacturers play these days to keep cheap cars out of the showrooms.

Synic errr yes but I ask you how many needed Air Con this summer for example or how many got lost because they didn't have a SatNav?

GregsGarage
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Postby GregsGarage » Thu Sep 04, 2008 3:16 pm

Find out if that car model was ever offered without power steering. If it was then you should be able to find a used manual steering rack at a local car breakers. You may need to get the mounting brackets as well, but if you can find a suitable manual steering rack it will be a little easier to turn due to different gearing in the rack. This is the option I chose with my Volvo conversion and it works well. You may have to look at earlier models, sometimes the manufacture will make PAS standard as a model nears the end of its life.
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

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Jeremy
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Postby Jeremy » Thu Sep 04, 2008 6:00 pm

A popular option (if you really must have power steering) seems to be to use the electric power steering pump from the Toyota MR2. These are usually fairly readily obtainable from scrapyards, I believe, although I have no direct experience of using one.

Jeremy

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Postby GregsGarage » Thu Sep 04, 2008 6:55 pm

Actually quite a lot of newer cars use an electric power steering system,
New MINI
Most Vauxhalls
A class Mercedes
Fiat Punto
to name a few.

May require some clever plumbing and some electronic trickery to get it working but a possibility. If I remember correctly, the Corsa has a electric motor attached to the steering column, so no hydraulic fluid. 8)
Greg Fordyce

Daewoo Matiz
http://www.evalbum.com/4191

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geekygrilli
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Postby geekygrilli » Thu Sep 04, 2008 7:38 pm

Hi Richard

I've been looking at this for a Daewoo Matiz. I have been speaking with my mentor from when I was at Nissan - he has been designing strg systems for 20 or so years, and its what I used to do. We have been discussing flow rates, pressures, catch up (is there enough flow for really fast strg movements?) and stuff like that...

Citroen Saxos have an EHPAS (Electro Hydraulic) system. Pumps are readily and cheaply available on e-bay. I consider this to be the best option for a smaller size car.

You could have a switch to turn the pump on when required (draws about 16 Amps, I think) but the friction in the strg gear when the pump isn't running is huge, so the strg will be really heavy.

You could easily disassemble the strg gear to make it into a manual system; remove the piston o-ring etc and weld up the torsion bar, and you'll reduce the friction. Do away with the pump. PAS strg gears are usually higher ratio than their manual counterparts, so it'll be like having a quick-rack (!).

HPAS used to take 2 or 3mpg to run and about 1.2 kW.

EPAS systems like on the corsa and new micra are really clever as you can program the assistance at different speeds, the damping and resistance. All good, if you can overcome their dongle functions, fit them to your car and hack into the program. Will make a mess of your interior.

My cinquecento is fine without powersteering, and its got over size tyres. So my opinion is that for small cars its not needed, but nice to have!

Er, hope this is helpful?

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Jeremy
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Postby Jeremy » Thu Sep 04, 2008 8:19 pm

Interesting stuff, I'd not realised quite so many cars had electric pumps.

It makes me wonder why more manufacturers didn't opt for the same solution as the Toyota Prius, with an electric motor built in to the steering column and no hydraulics or other complications. It makes for a pretty easy system to adapt, I should think, as all the assistance is contained within one simple unit.

Jeremy

Richard Ward
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Postby Richard Ward » Thu Sep 04, 2008 8:52 pm

Yes, very interesting, thanks for the replies.
This Arosa has been in our family since new, and I remember a couple of times when I stalled it (!) the steering was definitely too heavy for normal use. Till now, I had not thought about all the extra friction in the system due to the seals, etc. I guess without that, it may be OK, difficult to test though first.
Also, useful info about the MR2 and Saxo systems, I will start to investigate those right away!
I do have a suspicion that car manufacturers in general these days don't have any regard for steering weight when designing the geometry, they just rely on the PS system providing however much assistance they need to make it light-weight.

Richard
Bristol

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geekygrilli
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Postby geekygrilli » Thu Sep 04, 2008 9:28 pm

Column mounted electic assistance is becoming more and more popular. They took a while to come down in price and for maufactures to be convinced of their reliability.

There are other concerns too, such as one person trying to lift and fit a 12kg mass inside a car on a production line. Plus the motoring press hate electric systems, saying they feel false, when in fact they can be tuned to feel exactly the same as manual systems, which is what the pres say they want (rant over, sorry).

Anyway, EPAS is a good, efficient system, only powering up and assisting when required.

Back to pumps - the saxo one looks nice and simple, +ve and -ve in for the motor, and a flow and return on the pump side:-

http://cgi.ebay.co.uk/Saxo-Power-Steeri ... 286.c0.m14

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qdos
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Postby qdos » Fri Sep 05, 2008 2:29 pm

It's pretty difficult to find a car these days without power steering even the Citroen C1 Pugeot 107 Toyota Aygo have it


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