Gotcha. Referring to Link 5 as the "kinematic toe" link was the confusing thing, since Link 4 is the kinematic toe link (according to the pic you posted above and everything else I've ever seen). Weird that the factory would refer to Links 1 and 5 separately when they're the very same lower A-arm.

Thanks for the pic from the service training book! I've been trying to get a better grasp of this, and I recently bought a Longacre Bump Steer Kit to experiment with the rear suspension. Not sure I'll ever get around to that...

p.s. looking at that Service Training pic, this lower a-arm (link 5; the radially soft bushing) does indeed fix the toe-out problem under braking. So that pic really makes sense!

It also shows why the outside wheel toes in when cornering. There are 2 effects: (1) the height compression of the suspension causes toe in, and (2) the side force causes additional compression in Link 5, which causes yet more toe in. The exact opposite happens to the inside wheel. Brilliant.

Thanks a ton Bill. :)

(but I'm still confused why both of the lower a-arm bushings look the same. I'd expect Link 5 would look more rubbery than Link 1, but no, they look identical.)

Here's some more food for thought: ERP sells a monoball cartridge recommended for Link 5, the same link that the factory says uses a radially soft bushing to cause the KT effect. So this ERP monoball idea makes absolutely no sense in light of the factory's explanation. http://forums.pelicanparts.com/uploa...1207176626.jpg

the ERP kits eliminate all of the rubber so that the driver does all of the driving w/ no input from the supension.

993RS uses harder rubber bushes as a compromise, but only on the A arm(#4) and KT arm(#5)
#s are from my pics in post #20

You wouldn't happen to have an A arm out would you?, Looking for the #cast into the stock bushes from different year 993

Bill, great info spells out everything.

I will comment you say the 964 turbo is tight running a 265 rear on 10" wheel in the rear. I run a 295/30/18 on the 10" speedline with tight but adequate room and a 235 up front with no issues at all. The car is lowered to 10mm above RS height with Bilstein HD's and H&R reds and I get no rubbing and it handles like it is on rails.

Also wouldn't you consider the kinematic rear suspension an upgraded version of the weissach rear used on the 928? Although it does not use the 3 drop links as the 993 it is very similar in design.

thanks!, I don't recall making that statement wrt to 964t. In this whole series I have been concentrating solely on n/b both for 964 and 993. The widebodies, especially 964 are just too different to include here.

Bill,

I am still working on getting those part #'s for you... I have all the control arms +1 A arm from my 95 to look over. I will try to get them soon.

Sorry my misunderstanding. You referenced the 964 turbo brakes and mentioned the 8 & 10 x18 wheels which are only authorized for use on the turbo so I assumed you were including the turbo info also. I run a 275 on the rear of my 964 C2 on a 9" wheel and use 15mm spacers no issues I also run a 9.5 x 18 with a 265 which the factory says I shouldn't could easily squeeze a 275 if I wanted to but the 265 works fine possibly even a 285 with proper offset and 10" wide wheel.

Again thanks for contributing. that's what this thread is for and what many owners will want to know.

My point was that from a wheel and tire perspective the 993 accomodates larger fitments w/ far less trouble.

It's the same w/ 911 tire & wheel fitments, what can be done and what can easily be done are 2 very different cases.

I sort of like using factory fitments as a guide for comparison, the factory only uses easy fitments even on track oriented cars like an RS or GT3.

I agree. They learned from the 964 and made some decent refinements to the 993.

Is this thread a sticky, if not it should be. A ton of valuable info.

This is terrific stuff. Thank you.

Here's what happens when you stuff 10 & 275/40 in a 964 wheel well
http://forums.pelicanparts.com/uploa...1209384967.jpg

http://forums.pelicanparts.com/uploa...1209384993.jpg

Not the end of the world, but it is tight

Looking at the table of aerodynamic performance Bill posted below I think it is interesting to speculate what the 964 RS America's configuration with its rear wing would have produced. I bet it would have produced something like:

Cd=0.30 Clf= -.01 and Clr = -.10 making it the most aerodynamic 911 produced with a low Cd and downforce front and rear.

http://forums.pelicanparts.com/uploa...1205964342.gif

I wonder, since the curves are subject to the compression of the elastomer components in the suspension which would vary with lateral loading, under what conditions the curves Bill posted are derived.

The 964 RS has a modified "control mount" in the trailing arm. This limits the axial motion and the "Weissach Axel" effect and produce a different curve than the normal 964 trailing arm.

From the 964 RS technical guide:

http://forums.pelicanparts.com/uploa...1209396098.jpg

Edited from the 964 technical guide:

http://forums.pelicanparts.com/uploa...1209396610.jpg

Gotta agree w/ both of those statements

It seems that the serious track setups eliminate or at least reduce the Weissach effect on both 964 and 993. I don't think it's even part of the 996 or 997 design, but I don't know enough about thoose cars to say for sure.

964 vs 993 Sort Of
 

This is really a series of questions for Bill.
Looking at the 964 front wheel hubs, the 964 uses a two-piece M22 x 100 bolt through a tensioner shim/ABS pulse wheel. The Carrera RS uses a one-piece "stub axle" with an integral ABS pulse wheel and a spacer ring. The 964 Turbo uses?

The Bentley Manual is slightly different than the Pelican drawing below.

Is there any advantage to using the one-piece rather than the two piece axle? Would one be stronger than the other? Would it be lighter? What are you using?

What is the P/N of the one piece axle? The drawing does not list the P/N. Which one of these axles is on the 964 Turbo?

Thanks,
Mark
http://forums.pelicanparts.com/uploa...1218766279.jpg

Some of the 964RS used aluminum bolts(#20) all the other 964 including turbos used the steel(#15), obviously the aluminum versions are lighter. They are also NLA.

964 use 45 tooth ABS wheel teeth, 993 use 48. either assembly may be used in either 964 or 993 hubs as a unit.

993 uprights are alumium 964 are steel, 993RS(aka GT2EVO) are also aluminum but modified to eliminate bump steer and need a different tie rod.

I use 993 axle/ABS w/ 993RS uprights

How much lighter are the aluminum uprights over a stock set of steel uprights off my 1991 964 turbo?

993EVO upright w/ bearings 7.50
964 steel upright w/ bearings 12.00

Damn for what I am doing I think I will spend my 1600 elsewhere. 9 pounds is not enough to justify it to me:)