Why did Turbos get smaller rear sways

[Jcon]

Porsche used 20mm rear sways on 86-89 Turbos, but 21mm rears on 86-89 carreras. Any reason why?

Jeff

[Bill Verburg]

The wanted to reduce oversteer or put another way increase understeer.

[Jcon]

Sounds reasonable...so a better match for my 81 SC / 3.6 would be the 22/21 combo from the carerra rather than the 22/20 from the turbo?

Jeff

[Lukesportsman]

I'm going along with Bill, but adding reputation on the street. 911's had bad rap about going off the road backwards and the turbos were known to be off/on switches. I'm not necessarily supporting either of these urban myths, but they existed. Look at Detroit, understeer might be slower but safer for the unaware/unexpecting driver. Snap oversteer on the street with little tires and wet dirty roads is a marketing nightmare. Racer's could/will improve the balance anyway.

Was there ever a class to race a "stock" 930 competitively? I can't think of a class that would allow this monster in as a pure showroom competitor.

[Bill Verburg]

so a better match for my 81 SC / 3.6 would be the 22/21 combo from the carerra rather than the 22/20 from the turbo?

Dunno, it depends on so many other things, not the leasty of which is driver preference.

I like adjustable bars, if you suddenly don't like something it's easy to try something else.

[JonT]

Tell us how the smaller sway bars increases understeer. Is it because with the softer rear suspension the rear end squats on accellerating thus increased traction in the rear causing the front to plow?

[Quicksilver]

Originally posted by JonT
Tell us how the smaller sway bars increases understeer. Is it because with the softer rear suspension the rear end squats on accellerating thus increased traction in the rear causing the front to plow?

Acceleration increases understeer by planting the rear tires as you have mentioned. Sway bars (anti-roll bars) do nothing on acceleration and deacceleration. They only act when the car is leaning to the side. Basically when the loaded side compresses it tries to limit the droop of the unloaded side.

The reason the smaller rear bar will increase understeer is it allows the rear wheels to be a bit more equally loaded so that end does more work. The front sway bar ends up doing more of the roll limiting and the tendancy towards more unequal loading between the 2 front tires will limit its grip.

Wayne

[Eric_Shea]

I'm using 1976 Turbo bars on my RS clone, front and rear. For this lighter tub they seem to be fine.

[Jeff Alton]

The relative stiffnes of the suspension on each end of the vehicle has an impact on oversteer/understeer. A softer front end/stiffer rear will give more oversteer. A stiffer front end/softer rear end will give more understeer. Swaybars are just one factor in the stiffness eqaution. Don't forget the Turbo had larger rear torsion bars to go with that slightly smaller rear sway bar.

Jeff

[Wil Ferch]

Turbo had larger rear torsion bars...yes indeed... ( by itself causing less understeer) as well as a wider rear track (....by itself increasing understeer).

Let's now add that the Turbo also has a wider front track ( by itself causing less understeer)....and you'll conclude.....

...There were a number of pro-con changes compared to regular 911's that you need a scorecard to understand the "net" effect....

Wil

[Oldporsche]

Was there ever a class to race a "stock" 930 competitively? I can't think of a class that would allow this monster in as a pure showroom competitor.

The "934" developed for racing in "group four". (1974-1978?) The 930 basically was the street version of this car. Some 934's actually were delivered with power windows.

A very interesting heritage.

David Duffield

[Wil Ferch]

The weight class that the 934 raced in, not allowing it to be below porker weight...allowed Porsche to keep many comfy items on-board ( like power windows, etc)...

Wil