Steve PH

In reply to Chriss.

[How can the shaft make a difference in the mechanical advantage? I think you're talking about the gear.]

The shaft doesn't make a difference, I was just trying to explain how my rack differs from a normal power rack ie its been converted properly and not simply disconnected.

Re-jigged??? What do you mean by "re-jigged"? Did they have to cut, jig, and weld it?]

Good question I really don't know how they carried out the alteration I don't believe it was cut and welded, I don't intend to take it apart though! All I know is that although my rack looks like (and is) a power rack the part that connects to the steering shaft is distinctly different.

With regards the numbers quoted for turns lock to lock, these are the figures provided by the people who put the rack together and I carried out my own slightly unscientific test when taking out the old original manual rack and replacing it with the new one.

Yep I counted the turns! The real proof was in the driving and its a much better steer than on a standard manual rack.

Steve PH

In reply to Robby.

[I'm just curious.... I drove a 931 awhile back & I did not like thte manual at ALL... it was much easier to turn the wheel on-center... BUT, when I would get past 1/6 turn or so, it would start to get much heavier... the weight was non-linear... the feel was not linear at all either... the whole thing just didnt give a good feel.... i'm wondering if this is anything like the way a manual is supposed to feel....? Everyone says they are heavier, but, again, on-center to ~1/8 turn or so was MUCH easier... If something was wrong w/the car, then, it was not a good example for me to rely on... I wanted manual, but, after that, not.... I'd like to try another.... anyone near Knoxville TN? Atlanta or Charlotte, etc? I would LOVE to get rid of the leaking probs.....]

I think you'll find the rack on a 931 is different to a manual 944 one so you really need to try a 44 !

tifosiman

No offense intended, but..........

That makes absolutely no sense whatsoever. It's a very simple gearing equation. The standard power rack has a high ratio with a power assist. The manual rack has a lower ratio with no assist. If you have a power rack that has been modified and seems easier to turn than a manual rack, then it must have a lower gear ratio than the manual rack and thus more turns to lock. It can't have the same or less turns to lock and feel easier. We are only talking about a single set of gears, a rack gear and pinion gear set-up.

You need to spend a little more time with the manual rack and get used to it. It will take a little more effort at low speeds, but the reward is in the feed back. Those people that complain about the extra turns and wheel effort have not become accustomed to it. Once you spend time with it, do some spirited twisty roads, and a few events, it will become normal to you, and your driving and steering wheel input amounts adjust to it to where you never notice any difficulty.

Steve PH

I never said the modded rack was lighter, its not ! It takes marginally more effort to turn but smaller inputs (less steering angle but more effort!) make a more pronounced difference in the direction of travel.

BTW parking in tight spots is pita, more trips to the gym are required ! My rack is noticeably heavier at parking speeds than the normal manual rack.

Robby

The point about power vs manual's as I understand it is: IF you have a POWER rack w/OUT power, the manual rack would be easier to turn b/c of it's geometry.... obviously a power rack WITH power would be easier than a manual, only, not on-center in a 931- the manual 931 was much easier to turn for the 1st 1/8 turn or so... it was very annoying & not as connected- thanks for the heads-up on the 944 manual being dif... I was not aware of this...

tifosiman

The 931 and 944 manual racks are the same ratio.

M758

The biggest advantage from a manual rack is feedback. It is much better and on track this makes a difference. The other advantage is weight and simplicity. No power steering pump to leak or carry around and a bit more space in the engine compartment.

For street driving I perfer a Power rack. It just works better at low speeds. On my race car I prefer the manual rack. Great feedback and simpler. I use a non powered power rack or while, but the low speed (paddock) turn effort was real pain.

Stan944

Just to elaborate on this: when you are in a turn at the limits of (sideways) traction, the steering wheel pulls to make the car go straight, but when you've lost traction and already going sideways, the steering wheel becomes very light. This is a very effective mechanism of controlling the car in turns. I like it a lot in my 944.

Travis - sflraver

To receive more feedback at high speeds you could always put in lighter springs at the pressure relief valves.
This is the part of the rack that gives it the variable assist. The higher the RPM, the more pressure the pump puts out. When the pressure gets high enough, these valves open up to bypass the power assist. By putting in lighter springs, you make these valves start to open sooner, which cuts out the power assist at a lower RPM. You could feasibly set up the rack so that it has full assist at idle speeds but goes to full manual just over 2000 rpms this way.
Also, keep in mind that the actual drive gear on both the manual and power racks are virtually the same. There is a slight gearing difference on the manual but they both work the same way. Gear to gear with no damper in between. Without the assist kicked in on the power rack, there is no reason you should get anything, feedback related, less than the manual rack. The only dampening effect would be that extra 1/2 turn, lock to lock.

Stan944

I never drove 944 with PS, but I would think that pumping the PS fluid through the rack would kill some of the feedback effect.
But it's very interesting how much you can tune the "assist effect" with these springs.

Robby

Travis- is it tough to get to this part of the rack to change the springs? Are the lighter springs easy to get? Can you get them? I am about to replace a hose or two under there to correct a leak & am wondering if I could do all this at the same time...?

As for the manual I drove, there was definately no more feedback- I DID notice the "wanting to straighten out when cornering hard" feeling, but, the worst part was how unlinear it felt... would like to drive a few others to see if there was something wrong w/the one I tried.... could have been....

Manning

Travis,

How is it that the lighter springs improve feel or feedback? I only ask because I was of the impression that the fluid in the system is what damps the feedback. Lightening the springs doesn't remove the fluid from the system, it only reduces the pumps effect on the fluid flow, right?

I know from my experience that the fluid does seem to numb road feel. The first experience was when my Scirocco dumped is steering fluid and I had to drive for a couple days without until I could replace the blown hose and the other was when I swapped to a manual rack in my 924S. What I noticed was that with the VW system intact steering was calm and smooth, but when the fluid blew out I could feel every bump and rut in the road and what the tires were doing against the pavement. Pretty much the same thing with the manual rack in the 924S. I guess a way to think about it is like how gel gloves damp vibration through your handlebars on a bicycle.

M758

Manning has the perfect description of manual vs power steering. The fluid in the power rack damps out those imperfections in road surface so the steering feels smooth. On a manual rack you feel all those little jolts and things.

Stan944

you should try driving other examples for sure. Probably the manual steering rack on the one you drove was mostly worn out, and somebody tried tightening the screw to remove play from the rack and pinion, but it was at the expense of the overall smoothness due to worn out parts.
don't judge the design after driving a bad example. Porsche knew what they were doing when they released early 944 with a manual rack!

Robby

That's what I keep hearing- IF only there were a few more examples here in Knoxville- for now, I think I'll concentrate on fixing my power steering leak, my power draw (somehow frome fuse 39- stereo), power locks cycling incorrectly, horrible suspension, non-working horn, removing passenger AB, getting 6.5" speakers up front (maybe impossible?), etc, etc, etc- that's about 1/3 of the things I've got going on.... pretty overwhelming, but, I'm really hating new cars nowdays, so, I think I'll stick w/it....