bilstein or koni for daily driver auto-x

[bento]

i'm pretty certain that my 88 carrera is going under the knife for some 21mm and 27mm torsion bars and some other goodies (turbo tie rods, bushings, etc.) but i still have one more question.

The local suspension gurus at Smart Racing advise that the best set up w/ the 21 27 combo is the bilstein sports with the front ones revalved to their specs. I plan on using the car for auto-x, DE and hopefully, in the not too distant future time trial. I can get konis for my boge oem strut housing 88 as well as bilsteins, but the konis are adjustable. given the fact that i probably won't put bigger sway bars in for a while, should i go with the adjustability of the konis or should i trust the guys at Smart Racing w/ their revalved bilsteins?

i guess i like the idea of adjustability of the shocks given the fact that i live in san francisco and the roads are in a complete disrepair at times.

any thoughts are appreciated,

david benett

[Randy W]

I prefer Bilsteins (HD Front and Sport Rear) to Konis, especially for a car that is driven as a street/track car. IMO the Bilsteins are just as firm but with faster compliance, for a ride that has better "feel" than the Konis. This is a bit difficult to explain, and you may want to drive or ride in differently equipped 911s to see what you think. For an economic and competitive autocross car, the double adjustable Konis are probably a better choice due to your ability to adjust them according to course layout. Serious autocrossers will often upgrade to Penske, JRZ or Moton, though. So if your goals and budget allow, you may also want to consider these as an option.

I have Bilstein Sport gas dampers and I love them. Really nice ride, quite firm but not hard.

[Clark Griswald]

I have basically the same setup you are planning, 21/27 bushings, etc. I have konis and I am very pleased. However, you won't go wrong with either choice.

One thing I like about the konis is I tighten them up at the track, then loosen them a bit for the street. At least I do this for the fronts.

I am in San Jose. If you'd like you can come down and take a spin to see what the konis are like.

[Tyson Schmidt]

Boy, I feel your pain man. I live in Seattle, the home of broken pavement. Bilsteins, like Randy said, give the best ride-to-stiffness feel. Koni's are adjustable though, and can be softened down for the ride home. Tough decision.

I'd definitely take Clark up on his offer and drive the Koni's. Then see if Smart Racing will let you demo a car with the set-up they have. That's really the only way to know for sure.

I'm going through this same dilemma on my C2. Still haven't decided yet.

[Jack Olsen]

You may also want to test a car with 22/28 bars, since that's what Bruce Anderson recommends for your car.

However:

I have a pretty stiff setup on an even lighter car (21/30 torsion, 22/22 adj swaybars, Bilstein Sports all around, revalved in back to match the 30mm bars -- on a 2430 lb car), and my experience is that the downside isn't the potholes and expansion joints so much as it is the little things -- textured road surfaces, lane-divider reflector bumps and stuff like that. The stiffer suspension produces more vibration than heaves and lurches. I hardly notice it, sitting on a cushioned seat, but it made a big difference for my camera mount (suddenly much more jittery, and even the CD player (those lane-divider reflector bumps, especially). Road noise is also more pronounced.

[72SMFI]

In a narrow body car would it be a improvment on the track to switch from HD fronts to sport fronts. I get some oversteer and I cant afford 911r wheels. Running 205 50tires 21 29 tbars 19mm front sway and 21rear lowerd balanced in fact way to low somtimes it will bottom out on the front.It has the tie rod drop links so bump steer is not a problem. rear monos front monos. It just feels greesy in back mybee I just need more seat time.

[Randy W]

72SMFI, I wouldn't recommend going to a stiffer shock for the front of your car. Your 911 has 60% of its weight in the rear, and with your rear torsion bar already being too big for your tire/engine (27 would be better), your damping would not match your spring rate combo with a front sport shock. Your front bar is also smaller than your rear, and even if this is a through the body type front bar, it is set up more for autocrossing than the track. You have an oversteering baseline, even without factoring in tire pressures and sway bar adjustments.

You may want to see a respected 911 suspension shop in your area (Jeff Gamroth at Rothsport comes to mind) to have them look at your suspension/alignment and give you some options.

[72SMFI]

Randy I pulled my records I was a little off. 22 and 28 tbars and 19 22 sways sport rears and hd front. Is that still a over steer battle? If I bought a bigger front sway bar that would help/ The rear is a weltmeister and front is a racers group. I got em used so the price was nice. ANd I did get this car done by Rothsport. Which sold me the stuff.. I also an tending to a tranny leak mybe thats whats making it slip

[Randy W]

You are certainly in a better situation than what I thought based on your previous info. Not necessarily an oversteering baseline now - if you can tighten your front bar and loosen your rear bar enough, you may be able to obtain a slight understeering nature, which is what you want for the track. You will always have a bit more final oversteer than you want with equal size front and rear tires in a 911. Since Rothsport set you up, I would go back to them and tell them what you are experiencing - maybe they have a set of Revolution R-offset wheels that you can mount 205 F and 225 R tires on. If your tranny leak is due to the input shaft seal going bad (not good on a '72), you may have oiled your clutch a well.

[72SMFI]

That is why I was woundering since I am going to replace my front shox would sports help any. ofcorse I read someware about mods That need to be done to the "Bilstien" strut if you go from hd to sports. Somthing is wrong with the shox the bottoming on the street gos Bang... My tranny leak is from the front cover.. Gordon dos not belive in sealents.. I bought a lsd 915 from him. With those guys they will fix it if you ask em. But they are the only show in town and the best in town I hate to be a pain in the A$%. It is an easy fix 'Kinda'. I leaks about a 1/2 quart on a long track day. Not so bad on the street 3 months or so . But on the track she leaks to much. I was thinking that might also be my oversteer problem going around a tight corner pulling some Gees might get the oil to the outside tire the one that needs all the traction on a early 911!

[Randy W]

You may have the front end to low. Best advice is to go see Jeff and Gordon. Tell them to make it right. If it's their fault, they should admit it and fix it. If not, go to someone else recommended by someone you trust. If you want to see someone in Seattle, email me and I will give you a recommendation.

Best wishes,

[bento]

while we're flushing out the subject, which bushings are you guys using for street/auto-x/DE work? is everyone using polygraphite? if so, did you get them from a particular retailer?

thanks,

david

[Randy W]

David, it all depends on the car's primary purpose. If you want the best possible response and predictability for autocross/track use, then most tuners will recommend replacing all bushings with plastic ones, except for the inner control/trailing arm. Depending on the rules of the class you run in, you want either stock rubber or steel monoball bushings there. If the car spends most of its time on the street, then you will have some noise, not to mention feeling every ripple in the road, with the above. So, for a compromise setup you would probably be advised to replace all worn stock bushings with new rubber ones, and use the Neatrix bushing for the rear spring plate, since factory stock rubber is NLA there. The aftermarket products are available from a number of suppliers - try our sponser, Pelican Parts!

[Clark Griswald]

The rubber replacements for the front control arms are not widely available and I've heard some things that indicate they may be a bit sloppy.

There are two grades of the poly bushings available. The full-on hard plastic ones that Randy is talking about are best for race cars. There is also a "street hardness" version that is slightly softer, though still much harder than stock rubber. The street hardness ones are less inclinde to squeak and I recommend them for street cars.

I've got them on my '77 and am preparing to put them in my '86.