i have search this forum and come up with that the 993 C2 has the shortest ratio steering rack,
considering that 993c2 one on my 964 combined with new uprights from BBI or TARETT what is your opinion on that to fast?

i also read about that the servo assistans is more on the 993 is that so?

anything else to think about regarding this modifications?

 

I am not sure however the pump AFAIK is the same so any additional assistance would have to come from the rack. Have yo access to a 993 rack? Last I checked they were $15k. Also there are always pros and cons with making changes the aluminum uprights are nice but add a lot of additional vibrations through the wheel you don't have with the cast iron uprights.

 

How does $15k for a steering rack even make sense?

 

I'm mistaken? They came down in price. Now only $8k. Unless things changed this is for a rebuilt unit and there is a hefty core charge. As parts become scarce the pice goes up. When Porsche re released the 993 RS uprights I grabbed a set for under $1k today I think they are at least $2500 ea and hard to come by.

The 964 units both manual and power are NLA so I guess $8k sounds better than nothing. I have 5 964 units in stock but 4 need rebuilds. I did not realize the 993 RS used the 964 power rack. I always say I learn something new everyday.

 

I've done this modification and am also running Elephant Racing uprights. I don't find the front end to be too quick, though it definitely took some dialing-in to get it to a good spot. I'm super happy with the results. I was able to source a rebuilt 993 rack. One FYI, the turning radius on the 993 rack is much wider than the 964 rack so you get pretty good at 3-pt turns.

 

What are you trying to accomplish?

I don't see a benefit of coupling the 993 front end parts honestly, the 993 front end / rack / tie rods would need appropriate components to make it all work right, the rack, the longitudinal, etc are about 10mm wider per side, which may also influence your wheel offsets if you are running an aggressive setup.

What you'l experience on the 964 is that the updates to the front end (ie gt2 style uprights) solid bushings etc is that the front end is WAY more competent than the rear end of the car as they 964 continued to use swing arms with a coil over vs. the 993 which introduced multi link rear suspension.

So I would not want the front end super fast. I find my cars balance perfect, I run a hair of toe out, and I have the front end softened a bit to bias some more to the rear. It drives like a slot car on rails.

Also, tire selection greatly influences that overly aggressive front end feel.

 

I trying to achieve a better front end balance
i am experiance racing driver and the car i a 964 turbo with over 500hk at crank but still the front end grip is very low,
turn in is slow, and understeer at turn in and midcorner. and i have tested everything with, camber, 0-4mm toeout less toe in in rear, spring rates, adjusting the damper even change damper setting inside. swaybar, tires, different LSD settings and more
so with the correction of the rollcenter, i hoping to get much better grip in the front end, i have elephant racing bumpsteer kit, is better but not good. so with the new uprights i can adjust the bumpsteer to perfect.
i already have powerflex but going to change to monoballs in LCA, and 993 longitudals to get wider track.

The question was when i am there should i swap to the 993 c2 rack or what is the expertise of preference here when change to different uprights with shorter steering arms
if it gets to fast or if it feels better than the 964?

 

I found on the widebody using the 993 longitudinal pushes the front end out by 12.5mm per side and changes how the car handles. I have no issue with front end grip but run 9" wide 245 and can fit 9.5 265 rubber up front. My engine is going on the dyno for tuning this week and will see 600 whp. Unfortunately it will need to wait till next season for me to test.

 

Thats nice to hear looking forward to a much better front end!

 

I can agree with @cobalt . The 993 longitudinals make a real difference even on my narrow body car. Only running 225's up front, but I never have a problem with under steer with warm tyres. Depending of how I set the sway bars I can move towards under steer, but it's never a problem to find a neutral balance. Rest of the front end is RS uprights, manual rack, cup sway bar etc.

 

993 longitudinals push each front wheel out 12.5mm more than 964 longitudinals this widens track which by itself increases grip, the wider track also reduces roll by increasing the effectiveness of the swaybars, this tends to reduce grip but also reduces the geometric changes that lead to reduced grip.

the worst effect is limiting tire width and wheel O/S, a narrow body 964 can fit a 245/35 x18 on an 8,5 ET40ish wheel as long as stock 964 longitudinals are retained

 

Bill agreed but I believe we are discussing wide body 964 front end. This shouldn't limit the front wheel O/S or tire size. The added fender width allows for a wider tire and wheel using the 993 longitudinal and IMO adds additional grip. Although it requires some additional parts to make work. On my narrow body cars I stay with the 964 longitudinal.

 

Then you have the decision of inner or outer holes which are 30mm apart

993 long in the outer holes are a +42.5 mm change per side

that's a big track increase
not sure how the s/r is affected

maybe use 993 longs w/ the inner holes then get the track w/ wider more o/s wheels, that for sure makes the S/R go positive which ruins the ABS function, as ABS needs 0 to negative S/R to works correctively

Guess that must be why the factory used outer holes and more negative o/s wheels

 

I run a full 993 RS front end in my 964 and love it. I drive a lot of super tight twisty back roads so the increased ratio is welcome. It doesnt bother me on track at all.

The issue is that the wider track causes the tire to hit the front fender and bumper where they meet on bad bumps. This is with castor maxed, of course. Even with this area ground away past the TSB recommendation and going from a 1.5" E88 lip down to a 1" lip (8" total vs the 8.5" I started with and prefer), I cant go as low as I want with a 350lb front spring or it will rub, particularly on the drivers side. At my current height it's really no problem, but ideally Id like to be a few mm lower front and rear. My avatar is at the height I liked, Im currently higher.

Ive considered going back to narrow uprights, but I think the wider track vs the lower height cancels out mostly and I love the way the car drives at the moment. Plus, not needing a jack to get the lift arm under it is a nice plus.

I do think the rack I bought and had rebuilt is on its way out. It feels much heavier than my 993s and I had 2 bad experiences with Rack Doctor getting it rebuilt then promptly re-rebuilt. I may just go manual because I dont mind the extra effort. I just run a 225 up front and there's nothing in the frunk.

 

Sorry, what is S/R? My ABS has never worked since going to 993 front end, and yes I used the 964 ABS ring. Ive tried all 3 sensors (964, both 993 P/Ns.)