Bull

No power steering on the Cup Car, and I like it better than the PS that was on my 993s. I run 245 Hoosiers on the front and have no problem. I like the feel of what the car is doing, or about to do, better without PS. Maybe that is because my first 20+ Porsches had no PS.

JM993

That's a good point. The 993 assisted rack has the quickest (but not too quick)ratio (which is one of the things I love about my 993). The slow steering in my BMWs drives me nuts.

Bill Verburg

Would it be possible to get a lock to lock turns on your non assisted Cup?

cfdarch

....my power rack started leaking around 100K. Thought of it as an "upgrade". My 993 is a daily driver. The parking deck is decidedly more challenging these days. The more I drive it this way the more I like it. The turning radius on the 993 sucks and the lock to lock numbers Bill Verburg quotes don't surprise me. At very slow speed it is way more work. Have not auto-X'd since installing but get the feeling I made the car more difficult to drive fast.

Bull

Bill, I will get to the car tomorrow or Saturday and report back.

LA964RS

Most junior formula cars run w/o power rack as a cost savings or because they don't generate enough downforce to need it....or the races are so short you should be able to tuff it out. But you won't find a Chap Car, IRL car, NACAR (any division) F1 Car, ALMS, Grand AM w/o it....and let me tell you, those drivers tell you about it when they have a power steering failure during a race....and they are usually in exceptional shape.

Tom W

In the end it's a personal preference. You have folk with opinions for both options. Let us know what you decide (and let us know later in the year what you think).

I decided to leave mine assisted. The guy who runs the shop that maintains my car consitently wins his race class (in non-assisted cars) and has won the 25 hours at Thunderhill. While he agrees that the feel may be a bit better with a manual rack, having driven my car multiple times, he thinks it's best to leave it as it is - especially if I do any enduros (which I plan to do).

chris walrod

Both Champ Car and IRL cars have manual racks. I say this, but just this off season IRL has been testing a variable ratio rack due to the two girls driving (Danica Patrick and Darren Manning).

The four years we designed and manufactured Champ Cars we never had power steering.

Steering effort is a result of front suspension geometry mostly. Downforce does play a small role but because any real amount of 'lock' is applied at very low speeds, caster, trail and king pin inclination determine the force required to steer one of these beasts.

Bull

You all do understand that a failed power steering car is much more difficult to steer than a true manual rack car, right?????

Droops83

Ha, yeah my power steering belt tensioner rod on my 951 broke when I was at Buttonwillow a couple months back, it was a bit of a workout in the tight turns, but even though it wasn't a true manual rack and I was pushing through all that fluid I was still surprised at the increased road feel. I have been toying with putting in an '83 manual rack but in a front-engine daily driver/weekend track car may be a bit much.

The 964 RSA is one of my favorite Porsches, largely because of the PS delete. The steering feel is wonderful since you get all the feedback of an older 911 with the slightly more modern front suspension/increased caster of a 964. Not to mention the #6 topside spark plug is easier to get to! Although 964/993 heavier than old 911s, the front is still light enough to be fine on the track w/ sticky tires, though for an enduro, maybe not.

NineMeister

Thanks for the thumbs up. On my RS I used the GT2 Evo solid steering arms with the original RS uprights but these have a different geometry to the standard 993 as the track rod mounting point is relocated. for your car you should just fit the stock 993 steering arms off the original rack (or preferably buy new ones).


All joking aside, for the short track and hillclimb blasts I do where there is precious little margin for error, the manual rack communicates more through the steering wheel, hence I can accurately feel what the car is about to do before it happens and use pro-active correction techniques. Obviously this suits my smooth and fast style and helps me to avoid going beyond the limits of grip. That said, whenever I take the car to a practise day on circuit my shoulders let me know that I have had a workout by the end of the day, so if my focus returned to racing I would definitely refit the power rack or use electric assistance on the manual rack.

As an aside I believe the 964RS manual racks are no longer available from Porsche so we are giving consideration to having some made in both LHD and RHD for the 9mRS build program. Would there be any interest for 2.75 lock to lock manual racks?

Bull

Bill, I have checked the lock-to-lock turns on my USA Carrera Cup car, and after several tries it looks like something between 2.5 and 2.75, and I would say it is closer to 2.5. Maybe 2.6x?

FWIW, I shuffle steer a MS equiped car in slow speed, tight turns, while I used to not move my hands on my PS equiped cars.

Bill Verburg

Thanks!

964RS

This is an old thread I know, but anyways...

Is the standard 993 rack quicker than the 993RS? It sounds a bit odd.

Measured lock to lock on my non assisted 964RS. Some 3.1 turns on the steering wheel. :-/

/Anders

Bill Verburg

yes, the standard 993 rack is quicker than the 993RS.

the only model to use the slower 993RS rack was the 993RS and 993RS/CS. The 993RSR and 993GT2EVO both use the standard quicker 993 rack

Here is the data on steering that I have collected
911 is ~3 turns lock to lock, non assisted
964 is ~2.81 turns lock to lock, assisted
993, 993RSR & 993GT2EVO is ~2.47 turns lock to lock (2.73 for 993RS), assisted
964 manual ~2.6