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Using a power steering rack without the power?
mr henderson - 30/5/09 at 10:59 AM

Power steering will still work without the power of course, as that is an essential safety feature. However, the unassisted steering is fairly heavy and presumably this is caused not only by the fact that the racks are usually quite 'quick' but also because of the mechanism itself causing some drag.

Does anyone happen to know if a power steering rack can be modified so that it is usable without the power? especially from a legal point of view?

Thanks in anticipation

John

tegwin - 30/5/09 at 11:02 AM

The ratios are usually differnt in asssisted racks...

And if there is any evidence that it was once a PAS rack... it will fail an MOT because "if its fitted it has to work" and ergo... a pas rack with no hydraulic feed is not cosher!

mr henderson - 30/5/09 at 11:11 AM

quote:
Originally posted by tegwin


And if there is any evidence that it was once a PAS rack... it will fail an MOT because "if its fitted it has to work" and ergo... a pas rack with no hydraulic feed is not cosher!


Indeed, but what I was hoping to find out was whether it was possible to modify a PAS rack so that that problem wouldn't arise.

mad4x4 - 30/5/09 at 12:51 PM

Saxo's and peugeot 106's have electric PAS pumps - Could use that to power it

HAL 1 - 30/5/09 at 12:54 PM

If you were to do this then i suppose you'd have to use some form of lubrication other than the fluid used in PAS, which i believe is quite highly pressurised, it's still under pressure when the engine is stopped hence the heavy steering, if you were to release the pressure then the rack should be easier to turn, I THINK !

HAL 1 - 30/5/09 at 12:56 PM

quote:
Originally posted by mad4x4
Saxo's and peugeot 106's have electric PAS pumps - Could use that to power it


i was thinking along those lines for my car but it's not too heavy so i'll stick with manual

mr henderson - 30/5/09 at 01:07 PM

quote:
Originally posted by mad4x4
Saxo's and peugeot 106's have electric PAS pumps - Could use that to power it


That's interesting, do you mean that the pumps are conventional (as in engine driven pumps)?

As you may have deduced, my problem is that I can't conveniently use an engine driven pump, I've got nothing against PAS as such (in fact, I like it)

John

Volvorsport - 30/5/09 at 01:12 PM

quite a few cars are now using electric PAS pumps , vauxhall being one of them .

the problem as i see it , is that you have seals in there to prevent fluid loss(hence making the rack work) , which if oil gets in or you havent got rid of all the oil - itll lock up when you dont really want to .

take all the gubbins out , and decide for yourself if teh rack will operate smoothly etc .

May we enquire as to why you need to convert one ?

turbodisplay - 30/5/09 at 01:24 PM

Some racks have external hydraulic rams which can be removed.
Next thing to be removed is the valve unit.
Darren

mr henderson - 30/5/09 at 01:28 PM

quote:
Originally posted by Volvorsport


May we enquire as to why you need to convert one ?


Yes, you may. I am working on a project that utilises various Ford bits, including the PAS rack. It incorporates a Duratec engine, and once the air conditoning pump is removed, it makes retaining the power steering pump particuarly problematic in terms of the belt drive. Another solution, although not easy, I should imagine, would be to modify the AC pump so that its pulley could be used as an idler.

John

Peteff - 30/5/09 at 01:41 PM

quote:
Originally posted by Volvorsport
quite a few cars are now using electric PAS pumps , vauxhall being one of them .


Vauxhall Corsa use a power assisted steering column not a pump to power the rack and they read the engine speed from the electronic dash to cut assistance when not needed.

snapper - 30/5/09 at 01:47 PM

Won't fail MOT if the power steering pump is not fitted.
The Sierra ratio is about 2.7 , the power steering rack is 2.4.

To use a power steering rack as a quick rack take off the flexi pipes, connect the fixed tubes on the rack together with one bit of flexi pipe, before connecting both pipes together add some power steering fluid, keeps things lubricated.

rusty nuts - 30/5/09 at 01:49 PM

But the later Astra's has the PAS electric pump mounted to the bulkhead complete with resorvoir .

The AC compressor has an electric clutch so that the compressor doesn't turn when not needed . Pity it's so bulky

bram boekestein - 30/5/09 at 02:10 PM

Miata people use it a lot, as a sort of quickrack. They remove the R&P out of it and remove the seals, put it back together and blank off the PAS fluid ports.

Here is a guide:
Miata PAS removal

MikeRJ - 30/5/09 at 02:21 PM

The valve assembly in PAS racks contains a torsion bar which operates the valve, under manual operation this will be subject to a lot of force, and will therefore add unwanted lost motion to the steering.

This has been covered dozens of times in the past.


[Edited on 30/5/09 by MikeRJ]

mr henderson - 30/5/09 at 02:50 PM

quote:
Originally posted by MikeRJ


This has been covered dozens of times in the past.



Tiny bit of exaggeration there, do you think?

Anyway, even if it has been covered 'dozens' of times, the answers tend to be different and knowledge does advance. A search on the subject will produce many different opinions, none of which are conclusive.

Are you sure that the Miata solution linked to above won't work in my case?

John

Wheels244 - 30/5/09 at 03:58 PM

Most MNR's were supplied with PAS racks ( if ordered from them ) up until recently when they've gone over to Escorts.

Mine has one fitted, has been modified by MNR to fit.
It doesn't have any pipes on it or anything else connected - the ratio of a PAS rack gives a quick rack.

It works fine - nice and light and passed SVA recently with it.

Ferg - 30/5/09 at 04:07 PM

I retro fitted power steering to our Saxo. Bought pump, rack, pipes and loom all off e-bay for £60.
We used a Saxo pump on our 6R4 with a Cavalier power rack.
The only thing to be careful of with the Saxo pump is that it uses a feed tied in with the alternator so that it doesn't run until the alternator is charging. Otherwise I suppose you might struggle to turn the engine over adequately while that pump is spinning.

Electric columns are good, but need a strong dash rail....

mr henderson - 30/5/09 at 04:16 PM

Thanks for all the replies, it would seem that the ideal solution would be for me to use the rack as is and obtain an electic pump. Power steering would be useful in this application so that's what I will go with.

John

MikeRJ - 30/5/09 at 06:32 PM

quote:
Originally posted by mr henderson
quote:
Originally posted by MikeRJ


This has been covered dozens of times in the past.



Tiny bit of exaggeration there, do you think?


No I don't. Look back through the archives if you can be bothered, it really has been asked many times before.

mr henderson - 30/5/09 at 06:47 PM

quote:
Originally posted by MikeRJ
quote:
Originally posted by mr henderson
quote:
Originally posted by MikeRJ


This has been covered dozens of times in the past.



Tiny bit of exaggeration there, do you think?


No I don't. Look back through the archives if you can be bothered, it really has been asked many times before.


I did, and found many different opinions. Are you in a bad mood or something?

John

britishtrident - 30/5/09 at 10:58 PM

quote:
Originally posted by snapper
Won't fail MOT if the power steering pump is not fitted.
The Sierra ratio is about 2.7 , the power steering rack is 2.4.

To use a power steering rack as a quick rack take off the flexi pipes, connect the fixed tubes on the rack together with one bit of flexi pipe, before connecting both pipes together add some power steering fluid, keeps things lubricated.


Instant MOT Failure

Because this trick was exploited to get unroadworthy vehicles through MOTs a specific MOT rule clarification was made on this a few years back -- if you have a powered rack it has to function as powered rack
This applies also to brake servos ---- if you have a brake servo it has to function as intended.

MikeRJ - 30/5/09 at 11:11 PM

quote:
Originally posted by mr henderson
I did, and found many different opinions. Are you in a bad mood or something?



No, quite a good mood as it happens. Just pointing out the facts.

mr henderson - 31/5/09 at 06:03 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by mr henderson
I did, and found many different opinions. Are you in a bad mood or something?



No, quite a good mood as it happens. Just pointing out the facts.



You are Mr Cross-patch grumpy pants, AICMFP

In any case, to make what you said a 'fact' there would have to have been at least 24 threads on the subject, and I think you will find that that is not the case, if you can be 'bothered' to search.

Quite honestly, I am surprised at your attitude, Locostbuilders is the virtual home of repeated subjects (and threads in the wrong sections!), and it really doesn't hurt anybody, also new people join the forum all the time, and any one of them might have something useful to say about the subject.

John

PS, I must confess to having a quick search to see if I could find any threads you had started which were on repeated subjects, but couldn't (within a reasonable length of time) find any that you had started? Is this true? Do you not start any threads?

Starting threads is also a contribution, if nobody does it then we will have nothing to discuss, and therefore no forum.

Go on, ask a question about something, surely there must be something you don't already know?

NS Dev - 31/5/09 at 09:15 AM

Right, back on track for a mo!

I looked at doing this many many years ago (well, 1997) on my self built RWD pug 205 rally car which used sierra struts and rack.

I thought I could use the sierra pas rack as a quickrack with no fluid connections and the piston machined off the rack bar.....

It certainly did work, BUT I didn't like the look of the torsion valve, and there was no apparent way of dismantling it to make it rigid. It doesn't twist much at all, but it bothered me so I just fitted a sierra quickrack kit into a normal manual rack and used that (they are only cheap anyway)

There you go, a paractical answer, if not one that will solve your query!

I would go for an electric pump. I know of a LOT of autograssers using either those, or electric assisted columns like the fiat and corsa ones, on the class 6 huge power front drive class cars with very tight diffs.

MikeR - 31/5/09 at 09:46 AM

Keeping on track ..... anyone any idea how you make sure when using an electric pump that the power steering isn't incredibly light?

I like heavy steering, means I can 'feel' the road. I just worry if you fit random bits together you may get too much assistance.

mr henderson - 31/5/09 at 10:36 AM

quote:
Originally posted by MikeR
Keeping on track ..... anyone any idea how you make sure when using an electric pump that the power steering isn't incredibly light?

I like heavy steering, means I can 'feel' the road. I just worry if you fit random bits together you may get too much assistance.


That could indeed be a problem. I think I will just have to experiment, hopefully by choosing bits from similar cars I might get lucky. It would be good if it were possible to control the amount of assistance in some way, but I'm not really expecting to get that lucky

John

C10CoryM - 31/5/09 at 03:30 PM

You may not like what Mikerj has to say, but he is correct that de-powering a power rack is not a good idea. The torsion shaft is a skinny little spring that is designed to twist allowing the spool to work smoothly. It is also used as an emergency manual connection.
It is in no way designed for the extra load of constant manual operation. Torsion shafts are usually all of 0.25" thick VS the 0.75-1" tube that is normally used for steering shafts.
You will also get slop because the torsion shaft will flex before turning the wheel as it is designed to.
Custom racks really aren't all that much money and you will get a faster ratio so you aren't flapping your arms like an idiot while racing.
Cheers.
Cory

mr henderson - 31/5/09 at 05:09 PM

quote:
Originally posted by C10CoryM
You may not like what Mikerj has to say, but he is correct that de-powering a power rack is not a good idea. T


Au contraire, I am happy to read and take in what Mikerj has to say, if I showed any annoyance it was his crack about the "dozens of times before" that I felt I had to reply to, not the mention of the torsion spring.

In any case, I have already said, based on the information received in this useful thread, that I will be using an electrically powered pump so the issue of using a power rack without the power will not arise.

John

MikeCapon - 2/6/09 at 07:01 AM

Just one other alternative for you. On the works 6R4 we ran a standard PAS pump off the front diff driven with a poly-V belt. Worked well (except for parking ) and, as far as I am aware, passed MOTs.