Non adjustable sway bar sizing for 69E
 

Hi all,

I am preparing a 1969 911E race car for Australian historic sports car racing. Apart from engine internals and gears the cars must run pretty stock. Drivetrain is MFI 2.0 litre and a short geared 901.

The car weighs about 1000kg (2100 lb) with fuel and wthout me and must run 6x15 wheels on all corners. Tyres are 205/60 R spec (Dunlop D01J).

Current suspension is 22 F and 28 R torsion bars, koni S/D shocks and 15 F and 15 R sway bars, -2 deg camber on the rear and a little less on the front from memory.

Adjustable sway bars are not allowed.

Whilst the overall balance feels good (a little low speed understeer at turn in), the car rolls a lot. What sway bar sizes would you suggest trying with this setup?

My first guess was to try 18 F and R?

(I should also mention that I prefer a stiff car and are used to a 2.7RS clone with 23/30 torsion bars and 22 adjustable sway bars set almost full hard.)

Adjustable in any form, or just not adjustable from inside the car? Sway bars alone will not get rid of the roll, you should also up the t-bars as well. The fronts look to be fine, but possibly a 30 in the rear of this car as well. These cars are probably not more then couple hundred pounds different in weight. If you like it stiff, make it that way.

hey john - thanks for the reply.

the sways can not adjustable in any form - they basically have to be the same style as the units available from the factory back in the day.

i was also thinking the rear t-bar could go up (based on the theory that you can not have enough rear spring in a torsion bar 911)

do you think 18mm sways F+R would be a good balance with 20 and 30 t-bars?

I am running 23 front and 33 rear tb's on my 920kg (including driver and minimal fuel) swb - it is not too hard (a lot softer than I thought it would be).

I think you should up the torsion bar sizes as far as you can go (drop the roll) before playing with the sways - I drove mine (briefly - maybe 50 laps) after putting the big tb's in with the factory stock (think it's 15mm - maybe less) front sway - generated very minor understeer - so I think you will be in the ballpark with 18mm sways (at best that's a wag).

Of course that setup did not last long - 23mm SRP adjustable got installed shortly thereafter (arrived in the same box as the tb's - but ran out of time to install before a time trial)

G

I have adjustable 22 F/R on my car, and I tend to run them close to full soft. I'm not sure how big of a stock sway you can get. If you can do 18's with big t-bars, it's a start.

thanks guys

just back from 3 days running at our longest/fastest local track, and starting to get comfortable in the car (even the 901 'box). handling is very neutral (some body roll aside) with a little power oversteer that is very catchable.

the only downside was some rear end bounce thru a very fast turn 1. initial suspect is rear shocks are too soft. i'll stiffen them first then look at t-bars and sways after that.