Putting manual steering in 84+ 944s

[G50]

So, from what I’ve been able to research, there’s no really easy or inexpensive ways to put manual steering in an 84 or later power steering car.

True?

It seems like some people depower the power rack, but that doesn’t seem like a good solution.

It seems like the easiest would be to get a rebuilt manual rack from a supplier (Pelican etc). But from what I’ve seen it’s unavailable.

Is there any substitute that can be used, like from a VW or Audi?

Is the only way to find a good used one?

[9FF]

No affiliation but I’ve heard good things about mwthemachineshop[dot]com

“Refurbished 924 manual rack, for use in 944’s. 3.5 turns = 119 mm ratio complete with new longer steering universal shaft, new tie rods, new ends, and new boots. $670 add $160 for solid mounts.”

[ERAU944]

I put a rack from an '83 in my '84. not very difficult at all and IMO well worth it.

looks like 9FF has done it more recently.

[LambInLionOut]

I converted a power rack to manual myself for about $20 in fasteners plus new end links and boots. I probably could have done it cheaper than that. Just about every single part of the PS was leaking and probably would have cost more than the car was worth to fix. So this was the only rational option.


You can follow the machine shop pdf for a pretty good general idea, but the basic process is to remove the lines, and put zirc fittings in their place. You will also need to disassemble the rack and put a spacer in place of the valve to Eliminate the slop in the steering that’s introduced. Fill it with grease and re-install it. I took a bunch of pictures, I’ll see if I can find them and post them here.

Ive had no problems, other than parallel parking, and it is much more direct feeling now.

[v2rocket_aka944]

^^ if OP or anyone is interested I have a spare PS rack I intended on de-powering that I won't be using after all, that I will sell for $50+ship.

I also have a brand new Rennbay u-joint shaft that I would add for another $125.

[LambInLionOut]

Here is a link to disassembly instructions to do the same.

http://www.cryogenicsmedia.com/Porsche/power-to-manual-steering-rack.pdf

I didn’t see where he puts the spacers in place of the valve though. I had forgotten how many parts need to be removed, but the instructions look correct from what I remember. The only picture I found is this one where i machined the little spacer to go in place of the valve. You could just as easily use washers though.

[G50]

Thanks, very helpful.
Everything seems straightforward, except for the “11 degrees of slop” issue.
That’s where people say the rack will have 11 degrees of slop on center.
He describes it here starting at around 7 minutes:

https://youtu.be/omUZHk-2quA

I haven’t seen anyone else put spacers in place of the valves like you did. What does that do? I’m having a hard time envisioning how that solves the slop issue.

Another concern I have is I’ve read some people who have done it and say the steering feel isn’t as good as a real manual rack, and the steering effort is way higher. What do you think?

[G50]

https://rennlist.com/forums/924-931-944-951-968-forum/741724-de-powering-the-steering-rack-2.html

This shows using washers instead of a spacer in place of the valves. He did it in 2 places. I still don’t quite understand the cause of the slop, and how this solves it. (Because isn’t the steering system from the steering wheel to the tie rods solidly mechanical?)

[G50]

https://youtu.be/amTnNkAhWgQ

Pretty cool, he saws a power steering rack apart so you can see all the internals.

At 4:40 he shows where the slop comes from. There isn’t a solid connection between the input shaft and the pinion.

But does putting those spacers/washers in really lock it up and make it solid?

[v2rocket_aka944]

theres a lot of mystery about this mod.
there *IS* a physical locked connection between the input shaft and pinion, a pin at the top where the U-joint attaches. at the bottom they are still connected but...

The "slop" on center is because there is some wiggle room for valves in the pinion assembly to move one way or another when you start to turn the wheel, to tell the PS fluid which port (which side of rack) to pressurize. the valves are what get spacers/washers stacked on the ends to lock them in place; in the original set up the valves have little springs but the valves can move maybe 3/16" back and forth before stopping.

so by adding spacers to the valves and taking up that ~3/16 (that's a rough number, you need to measure your rack's distance as they are not consistent) the valves are locked solid so when the input shaft turns there is no wiggle room before the rest of the pinion turns the rack.

[G50]

I think I understand it now.
For some reason, they want there to be some “flex” in the system.
This is achieved by using a very thin “torsion” shaft, as shown in this picture:

So that operates as a torsion spring, giving flex.
To prevent it from flexing too much (and also possibly breaking) the torsion shaft rotation is limited by these “ears.”

One way to secure it would be to weld those “ears” so they can’t rotate. But there’s not much room in there for that.
Does the washers/plug in place of the valve springs do the same thing?

[v2rocket_aka944]

Yes.

The "rotation" is just the 2 fluid valves having some free play before sending pressurized fluid to the right or left side of the rack...there's slop in the middle so the power steering assist is basically "turned off" when you're driving in a straight line. It's easier to understand when you actually have parts in your hands rather than relying on the rather poor summary from the website your images came from.

[LambInLionOut]

yup - you have it exactly right. The spacers take up the slop that the thin torsion rod and valves would normally require in operation with the pressurized fluid. Without the spacers, the steering torque would not be fully transmitted to the gears until rotating to the position where one of the valves would be normally fully open.

[LambInLionOut]

Originally Posted by G50

Thanks, very helpful.
Everything seems straightforward, except for the “11 degrees of slop” issue.
That’s where people say the rack will have 11 degrees of slop on center.
He describes it here starting at around 7 minutes:

https://youtu.be/omUZHk-2quA

I haven’t seen anyone else put spacers in place of the valves like you did. What does that do? I’m having a hard time envisioning how that solves the slop issue.

Another concern I have is I’ve read some people who have done it and say the steering feel isn’t as good as a real manual rack, and the steering effort is way higher. What do you think?

In regards to the steering effort - yes it is high when the car is not moving, and if I had to parallel park this car every day I would have kept the power steering. however, once the car is moving I think the steering is weighted nicely. I've not noticed any fatigue from it. I have not had it on the track though.

In terms of the steering feel - it is very direct. I've not drivven a 944 with a factory manual rack but, if anything i'd guess that once the 11 degrees of slop is removed, the de-powered rack is more direct than the porsche factory manual rack due to the quicker steering ratio.