Author Topic: Stabilizer Bar  (Read 1804 times)

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Offline Abarthfan

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Stabilizer Bar
« on: May 16, 2007, 08:26:30 AM »
Hi all,

please let me know diameter of rear stabilizer bar which you use in your Abarth 850,1000 TC,TCR. I know that somebody use rear stabilizer from F850 special (diameter 14mm) but i would like to use stabiliser which is made just for this car. I think that diameter around 16mm -18mm could be OK.

Thanks for answers.

Offline zippyfiat

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Re: Stabilizer Bar
« Reply #1 on: May 16, 2007, 05:14:50 PM »
Hi, got to the Scuderia Topolino website.  Paul has an excellent tech. section on stabilizer bars.  You can get Abarth replica ones from Berni Motori.  Maybe Guy has them too?


Offline Paul vander Heyden

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Re: Stabilizer Bar
« Reply #2 on: May 31, 2007, 02:15:51 AM »
Ref: stabilizers

Just a note on stabilizers.  Some stabilizers, particularly original Abarth ones, were heat treated AFTER they were bent.  This considerably changes the bending modulus of the steel, and therefore these bars will respond differently that ones that have not been heat treated.  This does not mean that it is required to heat treat the bar.

The resistance provided bij a stabilizer is the result of three factors.

1.  The straight distance between the two fulcrums on the chassis
2.  The diameter of the bar and beding modulus of the material
3.  The length of the actuating arm, measured from the center of the fulcrum to the attachment point at the end of the arm.

With reference to Item 1.  The longer the distance between pivots the lower the rate of the bar.
With reference to Item 2.  The larger the diameter of the bar the higher the rate og the bar.
With reference to Item 3.  The longer the arm, the lower the rate of the bar.

Therefore, if we say that Item 1 stays the same and we have two bars that are equal in diameter, but one has longer arms, then the one with the shorter arms (less mechanical advantage) will have the higher rating.

You can mix and match any of the factors to come up with a solution.  The way that I achieved a good result is to bend up 4 bars that are all the same diameter  at the fulcrum points (makes mounting them easy) and all have the same length arms.  Leave one bar full diameter in the area between the fulcrum points, and this will be your stiffest bar.  Take the next one and machine a "flat" on the bar in between the two chassis fulcrum points.  The next one machine two flats, and the last one machine three flats.  You now have a progression of 4 bars that provide you with quite a bit of adjustability. 

You would use the stiffest or next stiffest for dry track racing conditions/hot street.  The two softer bars would be for use on the track in rainy/wet conditions, when in conjunction with softer shock settings you would want greater suspension compliance so as to maintain maximum tire/road contact. 

All of this is on the front of the car.  ONLY after you have the front dialed in do you need to worry about the rear bar, as this is strictly for fine tuning.  On by own car I have done away with the rear bar altogether, as it interferes with keeping the rear wheels in contact with the ground, and the resultant loss of traction.

Hope this helps.

Scuderia Topolino