Non adjustable sway bar sizing for 69E

[obrut]

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.)

[barney911rs]

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.

[obrut]

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?

[V12man]

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

[barney911rs]

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.

[obrut]

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.