vt951

I'm currently trying to decide what to buy for my '86 951 suspension upgrades. I'm looking for roughly 50% autocross / 50% street. I want something that handles very well and that I can be at least competitive in autocross, but that will still be somewhat comfortable on the street. I know this setup probably won't put me in running for ftd in autocross, but I at least want to be close!

Also don't want to spend much. For the setup below, I'd only have to spend about $1000 (excluding wheels and tires). One of the major online merchants is having a 15% off suspension sale this week, so I want to decide soon.

So far, this is what I'm thinking of going with:

Fronts:
Koni Adjustable Sport Gas Shocks
Weltmeister Heavy Duty Performance Springs, 250 lb
Stock sway bar (22.5 mm)
Ball joint rebuild kit for lowered suspension

Rears:
Koni Adjustable Sport Gas Shocks
28 mm solid torsion bar
Stock sway bar (18 mm)

Wheels/tires:
993 replicas, 17x7.5 +23 front, 17x9 +15 rear
Goodyear Eagle F1 GS-D3, 215 front, 265 rear

I've chosen this setup mostly based on advice on Clark's Garage, using his guidelines for the High Performance Street/Track. My only real deviation is staying with the stock sway bars, but I figure I can upgrade those later to fine tune the car's balance.

Any advice would be greatly appreciated before I make the purchase... especially if I'm way off on anything. Thanks!




Example Suspension Setups (from www.clarks-garage.com )

Sport Suspension

A good sport suspension setup for a car that is primarily driven on the street might include 220 lb. front springs, 27 mm torsion bar, 30 mm front sway bar, and 19 mm rear sway bar. Personally, I like a car that has very neutral steering characteristics. If you prefer to maintain the understeering characteristics of the stock 944, you might prefer a 26 mm sway bar to the 27 mm. If you prefer a car that oversteers, you might choose a 28 mm torsion bar. Just realize that a car that oversteers is much more sensitive to steering corrections and can you into trouble during a panic maneuver. With regards to the sway bars, I really like the 968 M030 sway bars. The reason I like them is that the 19 mm rear bars are 3-way adjustable which give you another option when it comes to changing the steering characteristics.

High Performance Street/Track Suspension

A good high performance suspension for a car that it used on the street and track might include 260 lb. springs, a 28 mm torsion bar, 30 mm front sway bar, and 19 mm rear sway bar. Again, if you want more understeer, you might choose a 27 mm torsion bar. And, if you want some oversteer, you might choose a 29 mm torsion bar. As I've already cautioned you about oversteer we won't repeat that again.

Full Race Suspension

While I've seen this suspension setup used on the street, I don't recommend it. A good combination for the track might include 400 lb. front springs, 31 mm torsion bar, 30 mm front sway bar, and 19 mm rear sway bar.

Gator_86_951

Who is having the sale?

Porschefile

250# fronts and 28mm TB's is a pretty good match, and it will handle decently well. Personally, I felt that 250# springs were too soft so I did the Paragon coilover conversion to my Koni's and went with 400# fronts. Something between 300-400# fronts and 29-30mm TB's would be a good match, and IMO would handle much better. I'd also consider 968 M030 sways if you can afford it.

vt951

performance products, www.automotion.com

vt951

yeah, I was thinking maybe the M030 sways would be a good future upgrade. Thanks for your advice. I've had an extremely firm Tein coilover setup on a previous car (240sx), and it was almost unbearable on the street. I think they were somewhere in the area of a 400 lb spring rate on a 2800 lb car. I don't want to go there again. Maybe 300 lb would be ok on the 951 since it's a little heavier.

Anyone else have any input? Thanks!

Porschefile

Hehe, I've experienced plenty of those kinds of setups on 240's, and actually that stiff feel is what I prefer. To me, the stock 951 suspension feels more "Caddilac" oriented than I prefer. The best thing you could do is to find someone that already has a 951 with modded suspension and get a ride or see if they would be nice enough to let you take it for a spin. Determining what type of suspension and ride you prefer is all that really matters. Almost everyone's opinion on what's "best" with topics of this nature end up being a bit biased with personal preferences, so it can be a bit tough to determine what would suit you best without experiencing it. Sounds like a 250# front / 27mm TB setup would probably be closer to what you're looking for.

Skip Wolfe

I would recommend 300# springs with the 28 mm bars. As long as you are still running rubber bushings they are fine on the street.

ninefiveone

I'd ditch the heavy replica rims and tire sizes that will give you a lot of understeer.

vt951

Well, my car oversteers like crazy now with the stock rims. Could be just the tires or worn out rear suspension I guess. Anyway, I eventually plan to use the stock rims for autocross and put some hoosiers on them. In the meantime, I thought putting wider tires in rear would reduce the oversteer.

RKD in OKC

Ok, here goes.....

As long as your springs are not bottoming out I would go this path...

Start with fully adjustable swaybars, I like the weltmeisters (heavy but cheap). It will give you a lot more control over how the car transitions than the 3 position M030 bars.

The adjustable ride height shocks are the next big plus. This will let you tune out that oversteer two ways, raising the front ride height with respect to the rear, and adjusting the rebound so the rear sticks better when throttle is applied and boost hits in the corners.

Lastly I would do the springs...I like the 180-410 progressive for the front as they don't lift as much as straight 400# springs under acceleration. For 400 in the front the biggest rear torsion bars you can get will match great.

This is the recommendation that Andial made to me for street/autocross. They were the suspension tuners for the factory 917 race cars.

Overall a great compromise for street/track/autocross. And very tunable to your driving style which is the most important part.

Tune the ride heights to get a good balance with the shocks and swaybars set to full soft. Then tune the swaybars to refine the balance slowly accelerating around a circle the size of your course turns. Once balanced, increase their firmness until it breaks loose at slower speeds. Then adjust the shocks rebound, fronts for acceleration and rears for braking. Fronts stiffer until it stops pushing, rears stiffer until rear quits coming loose under braking. This will provide a good all round setup that is well balanced in the apex under slight throttle.

RolexNJ

You posted the same post back to back RKD!

RKD in OKC

opps

RolexNJ

And wow, he is a paid member too now, wow!

RKD in OKC

Paid up to legally sell stuff in my posts. Notice my join date?

Need a knife edge 2.5 crank, 3 coated stock pistons, set of club sport wheels, an eBoost boost controller, or a Nakamichi MB VI reciever CD changer?

The assembly started on my car and they will be wanting money soon.

ninefiveone

RKD - Andial advice aside, do you have a lot of suspension tuning experience?

I ask because your suggestions are counter to a lot of standard suspension tuning basics.

Also, Andial made their name through engine tuning/building, not suspension tuning. While some of the engineers that founded Andial and work there did work for Porsche racing, I would stop way short of saying these are the guys who tuned the 917 suspension.