Petza914

My 79 has the sport springs (blue stripe), new Konis, and 18" wheels with Nitto Invo tires. Ride and handling are very good - definitely softer than either of our 997s but firmer than the Cayenne Turbo S.

Very comfortable GT ride but can still handle when needed.

rosenfe

hacker-pschorr

Not necessarily, there's a point of diminishing returns if you go for higher performance tires with stiffer sidewalls. That is what makes the reviews in The Tire Rack so helpful. See what people are putting on BMW's and Mercedes versus Corvette's could be a smoother riding tire.

Age is a huge factor though, check the date stamp no your tires. Tread depth isn't the only factor necessitating replacement. Not just for ride comfort, but also safety.

Run Flats are a whole different animal, horrible ride quality and those are some of the highest end tires.

rosenfe

BRB-83-911SC

Factory size for 1986.5 running stock wheels: Front - 225/50 16 / Rear - 225/50 16

Where did you hear they should be 205/55?

rosenfe

rosenfe

hacker-pschorr

I would check The Tire Rack. Maybe even order from there and bring your wheels into the local shop to change them. Assuming you have the capability to put your car up on jack stands.

Also make sure they use stick on wheel weights, not the ones that pound onto the outer lip.

When you buy new tires, always check the date stamp on the sidewall. Make sure you are not paying full price for something that's been sitting on the shelf for 2+ years:

https://www.tirebuyer.com/education/...-of-your-tires

Bertrand Daoust

+1.

GregBBRD

Although sometimes it seems like I'm preaching to an empty church, I'll throw this out, here:

More important that the condition of the shocks is the condition of the lower control arms. Check the rubber bushings carefully for deterioration. The front rubber must remain vulcanized to the control arm and to the outer mount. The rear rubber must be vulcanized to the control arm and not have chunks coming loose.

These rubber pieces are a major percentage of the front spring rate and are also a major part of the valving of the front shocks....in both rebound and compression.

While one person, with perfect lower control arms, may enjoy a certain brand of shock, the next person, with bad rubber on the lower control arms might hate the same shock. (The action of the front shock is radically altered by the lower control arm bushings.)

These arms must (well, absolutely should be) be replaced in pairs (if one is bad) so that the "set" of the front rubber and condition of the rubber are the same on both sides of the front suspension.

928 International offers excellent rebuilt lower arms at an extremely favorable price, compared to new control arms, from Porsche. (While there was a "learning curve" to the rebuilding of these lower control arms, all the issues have been resolved and this is now an extremely well done product.)

Do no make the mistake of changing these lower control arm bushings to a "free rotating designed for track use" bushing, for a street car. Substitution of the "captive rubber" for a free floating bushing requires a complete redesign of both the spring rate and the shock valving....something beyond almost everyone, except for well equipped race teams with high dollar data acquisition equipment and a suspension engineer.

BC

Lets say that someone was stupid enough to do this, or repeatedly attempt to, and is a very slow learner.

What would need to be done, in general for the shock valving and the spring rates?

GregBBRD

Take the lower control arms and the front mount pieces to 928 International and get some rebuilt arms....they will not care that the rubber has already been removed, as long as the pieces are not altered.

If you are working on a "late" model car.

Order a set of factory Boge Sport shocks from Porsche (yes, they are more expensive than any other "standard" replacement shock.) The special valving that Porsche called out for these shocks is fantastic!

Use the stock springs...or a set of the rare CS springs.

There simply isn't anything that gets remotely close to the level of performance and ride that his combination will give you, for street use.

Schocki

Another big factor with our cars is the correct ride height. Over the years, our cars drop significantly and with this, the geometry of the suspension is changed too.
When I changed to Bilstein B6, I raised the ride height back to factory specs and it makes a huge difference! For me it is the perfect combination of a sporty and comfortable GT ride.
I always adjust the geometry myself in my garage with a set of self made laser tools. When I adjust, I take some weights and put "myself" in the driver seat and footwell. With a full tank and the weights, this is the every day driving configuration.
Adjust ride height first, followed by the geometry. This process takes some time initially (correct ride height) but it is worth it.
Porsche BTW mentions a DIN norm in their instructions, it only calls for 70 kg a full tank, tool kit and emergency tire in place before suspension adjustments no driver weight.
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