NP993

I have an RS America manual rack in my 993 (993's have the same front suspension as 964's) and am looking for ways to lighten the steering feel a little. Happy with the mod, but looking at the alignment specs it looks like there's a lot of caster that could be taken out, and this would reduce the feeling of resistance you get in sharp corners.

Problem is, there isn't that much adjustment range in the caster setting -- you can only take about a degree out of the stock setting. Looking at the lower a-arm, it seems to me that by enlarging the hole that the caster eccentric bolt fits through, you could take a bunch more caster out of the alignment and lighten up the steering feel a bit more.

Crazy idea?

Caster eccentric is #18 in the diagram below -- looks like there's a lot of room in the a-arm to widen the adjustment range.

Geoffrey

993s do not have the same suspension as the 964. They have similar suspension, but some of the components are different.

The 911 wants as much caster as you can put in the car. We run as much as 6 degrees and the handling improves. On a street car you should be able to move it several, as much as 3 degrees, but we always install to obtain the most caster.

I do not recommend the manual rack in any situation. The power rack is so much better and when combined with an electric pump, eliminates all of the engine mounted power steering issues.

NP993

Well, that train has already left the station -- have had a manual rack in the car for four years, and I like it.

Seems to me that taking some caster out of the settings would reduce steering effort a bit. Am I wrong, or does reducing caster have other serious downsides in how the car handles?

Also, what electric pump do you recommend if I wanted to switch back to power -- do you have any pictures of the setup? Sounds pretty straightforward, I'd imagine the pump mounts in the front trunk and you'd have to make a couple of hydraulic lines. Where do you tap in for electricity?

Bill Verburg

You use a 996/997 Cup pump, this is one in a 964, 993 install would be similar


I'm w/ Geoffrey here, this is the way to go, Get your seat closer to the wheel or put an extender on the back of the wheel to get it closer to you, Don't mess w/ the dynamics of the car because you made a poor choice

NP993

I'd imagine there are lots of good-quality electric PS pumps out there -- does one from a Cup car have to be used?

Geoffrey

Actually Bill, that install is one of mine. I bought the parts and compliled the install components including wiring for that car.

You'll need big power through a fuse, big ground, and terminal 61. Some of the newer pumps also require terminal 15.

I've used several different pumps, but keep comming back to the Porsche Motorsport pumps in either RS or Cup.

Bill Verburg

I know, that was why I posted it, all that's missing is the usual rag around the cap

evoderby

Very elegant Dutch solution:

http://www.ezpowersteering.nl/index.php?p=0&lang=us

NP993

What are the ones you've used other than PMS?

Steve Weiner-Rennsport Systems

Just to fan the flames,...LOL,.....

I'm totally with Geoffrey (and Bill) here,.......we've converted a lot of RSA's to PS using the PMS stuff and its really good. Porsche's power steering is the best in the business and these cars need caster. That's precisely why they equipped all of the factory race cars since the 993's with it to lower the workload.

You can reduce the caster a bit to help your objective, however its a step in the wrong direction for good handling and manners.

If you were here, I'd talk you back into the PS,......

NP993

Heh, thanks Steve. I'm going back and forth. I kind of like the manual rack -- but a nagging wrist injury is making me think about going back to PS...

Geoffrey

I've used the Toyota MR2 pump - heavy, ugly, multiple components

A customer of mine used a Mini Cooper - Nice small package, had to do some welding for fittings

Mercedes pump - needs to be pre CAN

I'm just a fan of the Porsche stuff, it works, is readily available, and easy. Now I won't use anyting else.

KaiB

At Weiner's instance, and because I'm weary of leaving the track exhausted, we are installing the above in my car. I've sold the manual rack to an experienced Rennlister who nevertheless wants one.

Because of the new rack, the boys can now increase caster and I really look forward to the new system. I won't miss the manual rack one bit.

Oddly, my RSA is no longer as absolutely nothing exists on her (beyond the two decals) which differentiates her from a '93 C2...oops, the R&P are different.

NP993

Thanks Geoffrey -- sorry to keep asking questions but what is "pre CAN"?

Mini Cooper part has the advantage of being almost $1,500 cheaper than PMS.

race911

And yet another power steering in 911s fan. After 3 years of racing the RSA. One thing I will say is that the manual steering was almost tolerable when running Hoosiers and my lightest modular wheels, versus the Kumho V700s of the day on replica Cup 1s.

If a Motorsports pump dropped in my lap, sure I'd consider converting the 993. Not holding my breath though.