Removing Power steering

[S.H.]

Next project, removing the power steering.

 

This was a quick 1 hour job that will save you 7,1kg.

 

Power steering and air con removed in this pic. Use a Gates Micro-V XF belt part no. 6PK985.

http://iloapp.toyspeed.dk/data/_gallery//public/0/1281355562_resized.jpg?width=540&height=405

 

Feed line directed into the return line.

http://iloapp.toyspeed.dk/data/_gallery//public/0/1281355575_resized.jpg?width=540&height=405

 

Leftovers from the operation.

http://iloapp.toyspeed.dk/data/_gallery//public/0/1281355568_resized.jpg?width=540&height=405

 

Related project, IC removal.

http://www.mkivsupra.net/vbb/showthread.php?t=223606

[EdMorris]

What does it drive like now? Is it not very heavy?

[barneybrendan]

are you changing the rack then to a manual one, as said bet the steering is heavy.

[Jamesy]

air con removal i can understand, power steering ...

[Digsy]

You've also now got the belt tensioner on the tight side of the belt which is totally wrong.

[S.H.]

It's not that heavy. When not moving it's actually easyer to steer than my other car (89 Corolla with 205/17" tires).

 

On the tight side, what do you mean? Alle wheels turn clockwise as they shall escept the tensioner. The tensioner coud have ribs like the other wheels but this is a small detail. A new tensionerwheel can easily be made from a piece of aluminium.

 

I will keep the rack for now and maybe change it next year.

Edited August 9, 2010 by S.H.
Info missing. (see edit history)

[Digsy]

FEAD belts have a "tight" side and a "slack" side.

 

If you start at the crankshaft and work anticlockwise around the belt you will generally find that the high-power components come first (ACU, PAS), followed by the lower power ones (Water pump, alternator). Actually, the alternator can sap a fair amount of power but it is usually positioned last in the chain and used to "return" the belt back towards the crank pulley. Thus you get almost 180degrees of belt wrap. If you think about the power the components sap from the belt drive you usually find that larger pulleys have less wrap and smaller ones have more. The amount of power each compoentn draws is roughly proportional to the length of belt wrapped around the pulley. The crank pulley will be large and have lots of wrap because if has to have enough grip to supply power to all the other components.

 

The belt spans between the crank and each subsequent componant will be tight because they are tensioned by the drag that the components apply to the belt. The final span - the one between the alternator and the crank pulley - is the "slack" span because there is nothing there to tension it. This is where you put the belt tensioner.

 

In your setup you have the belt tensioner first in the chain. This means that if you apply a sudden load to the belt (i.e by revving the engine) it is far easier to simply compress the tensioner than to impart that drive to the other pulleys.

 

Modern engines with "starternators" (alternators that double as starter motors) when in alternator mode the belt tensioner functions normally. However when in starter motor mode the belt tight and slack sides swap over, effectively putting the tensioner on the slack side. These engines have special tensioners that sense the reversal and lock solid so that all the drive torque goes into turning the pulleys and none into compressing the tensioner.

 

Depending on how you have arranged your belt run (its not totally clear from the pic) you may have problems with belt slippage, particularly when revving the engine hard. You'll probbaly get away with it, but from a belt run design viewpoint its wrong.

[S.H.]

Now I see what you mean,- thanks for the good explanation Digsy.

To be honest I haven't thought much about beltslippage or the reason why the belt is routed the way it is. But now I know.

 

Let's see how it reacts when I start it up, hopefully there will be no slippage?

[Chris Wilson]

Now I see what you mean,- thanks for the good explanation Digsy.

To be honest I haven't thought much about beltslippage or the reason why the belt is routed the way it is. But now I know.

 

Let's see how it reacts when I start it up, hopefully there will be no slippage?

 

The belt may well even come off in that format. It MUST have the tensioner on the "slack" side. I am also unhappy about the amount of belt wrap around the damper. A MKIV with no PAS though? You must be some sort of muscle man Have you removed or welded the quill shaft in the rack? Without this little publicised mod you will have lost motion at the steering wheel for a few MM either side of clock and anti clockwise movement, and the quill shaft could break.

[Terminator]

I remember how my car felt when a PS hose collapsed, it was OK when on the move at road speeds, but slow manoeuvring was bloody awful.

[jevansio]

I love weight loss, but even I admit I couldn't manage mine without it, 255 888's on the front mean turning the wheel when stationary/slow is VERY difficult

[Swampy442]

I love the idea of ditching the PS and a/c pumps off the engine, looks alot less complicated but Id have to fit an electric system from an MR2 for practicallity. Great if you dont have much slow speed manouvering to do I suppose

[S.H.]

Haven't removed or welded any parts in the rack, just removed the lines.

 

Maybe a new rack without power steering will be prioritated a little higher now . Just to keep it all safe and sound. Don't want any accidents.

 

Ps. My Sup is not a daily driver. More a project car that only comes out off the garage on summer days.

[Chris Wilson]

There's a quill shaft in 99% of hydraulic PAS rack stems. It is a small torsion bar that is twisted when load is applied via the steering wheel. As it twists it uncovers a slit like window in the spool valve, allowing an appropriate flow of high pressure PAS fluid to the appropriate side of the rack bar seals, and "assists". The quill shaft only moves about one, two or three degrees before the window starts to open and assistance is given. Without hydraulic pressure this shaft will keep on being twisted until safety stops come into play and the steering column then starts to turn the rack pinion directly. This can be as much as 10 degrees. Constant excess flexing of the quill shaft will either change its properties or it could snap. You won't lose the steering, as the aforementioned safety dogs come into play, but it will have what will feel an alarming amount of free play to a sensitive driver. A correct scenario is to strip the rack stem, fully clean and degrease the components and TIG up the quill shaft dogs to make the coupling solid.The welding needs to be excellent, and some machining in a lathe may be needed afterwards. It's good practice to remove the rack bar seals to remove internal rack friction at the same time. Somewhere out there on the Internet there may be a detailed and illustrated account of how I do Mazda RX-7 FD PAS racks, which will show you enough to do most other makes. A hydraulically castrated PAS rack without this mod will have lost motion in both directions that may or may not bug the hell out of you, but is undeniable bad engineering practice and needs addressing. Doing it can transform how a car drives.

Edited August 9, 2010 by Chris Wilson (see edit history)

[S.H.]

Thank's Chris, your posts are very informative.

 

It's very interesting working with theese things. Seeing how it's made and maybe making it more suitable for my needs.

[Chris Wilson]

Your English is perfect, are you a native English speaker, or just here to make me feel bad?

[S.H.]

Thanks for the kind words Chris Your serious right?

 

Born in Denmark, lived in the USA between age 4-7, that's all..

[Nodalmighty]

There's a quill shaft in 99% of hydraulic PAS rack stems. It is a small torsion bar that is twisted when load is applied via the steering wheel. As it twists it uncovers a slit like window in the spool valve, allowing an appropriate flow of high pressure PAS fluid to the appropriate side of the rack bar seals, and "assists". The quill shaft only moves about one, two or three degrees before the window starts to open and assistance is given. Without hydraulic pressure this shaft will keep on being twisted until safety stops come into play and the steering column then starts to turn the rack pinion directly. This can be as much as 10 degrees. Constant excess flexing of the quill shaft will either change its properties or it could snap. You won't lose the steering, as the aforementioned safety dogs come into play, but it will have what will feel an alarming amount of free play to a sensitive driver. A correct scenario is to strip the rack stem, fully clean and degrease the components and TIG up the quill shaft dogs to make the coupling solid.The welding needs to be excellent, and some machining in a lathe may be needed afterwards. It's good practice to remove the rack bar seals to remove internal rack friction at the same time. Somewhere out there on the Internet there may be a detailed and illustrated account of how I do Mazda RX-7 FD PAS racks, which will show you enough to do most other makes. A hydraulically castrated PAS rack without this mod will have lost motion in both directions that may or may not bug the hell out of you, but is undeniable bad engineering practice and needs addressing. Doing it can transform how a car drives.

 

I had to do this when I removed the PS from my MK3 Supra.

[S.H.]

Finally had the opportunaty to do a quick testdrive between the rainshowers.

 

The steering is very heavy and not advisable for driving around the streets. Besides being heavy when driving it's also slow reacting witch can be dangerous.

 

On the drag strip this mod is acceptable but not optimal.

 

To summe things up, a new steeringrack is high on my new priority list

[jevansio]

Good to know I suppose

 

Thanks for posting the results