Sway bar size/adjustment and 3 wheel Porsches (long)

I have a question about sway bar sizes and adjustments.
I have a ROW 1984 Cabriolet. I purchased it 2 years ago, bone stock. When bought, it swayed radically in corners. Last year, after some research and consultation on this board, I installed 22mm front and 28mm rear torsion bars as well as Bilstein sport shocks, turbo tie rods and a shock tower brace. This spring I would like to do Suspension Upgrade Stage II and was planning on sway bars. This car still has the stock 18mm rear and 20mm front sway bars.
I read all the back threads on sway bars and still have couple questions and am soliciting advice and opinions.
Let me add that I am, by trade a farmer, and so drive a pick-up as a daily driver. I like autocross and will do some DE when time allows. However, 99% of the time I am on the street with this car, I like to take spirited drives into the mountains (sometimes rough roads) or out along the lettuce fields in the valleys where it is empty on a Sunday afternoon.
In my reading I am getting a lot of conflicting information. The 22F and 28R torsion bars are right out of Bruce Anderson’s book and he says “If your serious about good handling, the next step is 22mm sway bars front and rear.”
The 22F and 28R torsion improved the handling enormously. It seems to have gotten a bit looser in the rear end during autocross, or maybe it’s just me and I’m pushing a bit harder. On fast corners down in the lettuce fields it enters solid but the rear comes out a little if I boot it in second gear at the apex.
I had always thought I’d just install 22mm bars front and rear. But I started looking around.
Have you ever noticed how many 911’s corner on 3 wheels? We’ve all seen it. Look at the cover of Henry A. Watts book “Secrets of Solo Racing” a very low, obviously race prepared 911 with the inside front wheel off the ground. Now look on page 96 of Fred Puhn’s book “How to Make Your Car Handle” another 911 on three wheels and Mr. Puhn says “If your car lifts a front tire off the road in a turn it has too much front roll stiffness, too little rear roll stiffness or a combination. A car on three wheels generally cannot corner as fast as a car on four wheels” and “Adjusting roll stiffness to tune the suspension has no effect on a three wheel car”
So my question is: Why do we all do this? Are we so afraid of the big oversteer that we will corner slower on three wheels to avoid it? I’ve seen pictures of myself at autocross (before last year's suspension upgrade).. three wheels, and it did understeer.
And for my car, keeping in mind that it’s a cab and so not supper ridged along the long axis, will the 22mm bars work out? I would get adjustable bars, can I loosen them enough to take the wife on picnics without blowing up the Champaign bottle?
I read that you, Warren, have 19s front and rear, but my car is heavier and with the 20 already in front, I wouldn’t want the butt end any looser.
Any advice would be appreciated.
Best Regards -Andy


[This message has been edited by Andy Snow (edited 01-21-2001).]

I have also done all the changes you have and have installed 22mm adjustable sway bars. A few points. On hard cornering, the inside wheel is sharing little of the cornering force as opposed to the other, (hence the lifting). These cars are running very sticky tires with lots of negative camber. Having one wheel off is demonstrating just how much grip without body roll you have and not neccessarily a negative thing. I can tell you also, these cars are not cornering slow. Your ride quality may suffer but you have already done 9/10th to it by the other changes. Why do all that and continue to use the soft factory sway bars? You are right about mixed benefits in a cab. Although you will get an improvement, you will never have the stiffness in a coupe.

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8 9 9 1 1, The last of the line.

Andy,

First, Mr. Puhn is what I tend to call a chalkboard engineer ... he talks in generalities and platitudes, and I don't recall ever seeing his name associated with any winning teams in the '70s after his book came out. I bought a copy in the early '70s, read it, and put it on the shelf ... never to be referred to again!

Shortly after reading his book I recall seeing a cover shot from Autoweek with Richard Petty's Blue Plymouth cornering at Riverside sometime during a race that he won! The cover shot showed about 1.5" of air between the track and one of his front tires! I have also seen plenty of winning RSR's driven by Peter Gregg, Mark Donohue, Hurley Haywood, and others in the three-legged stance, so my belief is that it is not a serious handling problem for winning drivers! So, it must be OK for regular enthusiasts, too!

As far as my car goes, my 19 mm bars were the largest available when I bought them. And, the 'through-the-body' style bars have a shorter lever arm that the later, control-arm mounted bars, so are stiffer than the same size later-style bar. That, plus the lighter weight makes direct comparisons to '80s Carreras difficult.

So, my recommendation would be to get 22 mm bars, but make the front one the 'through-the-body' style! And, mount the rear bar in poly-graphite bushings to make it effectively stiffer!

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Warren Hall
1973 911S Targa