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Rear Suspension - Torsion Bars

Posted: Sat Sep 12, 2020 10:45 am
by MikeS911
Hi All. Hope everyone is staying safe, and still playing with the motors. I have a question for the suspension experts.
I have a 77 - 2.7 911 and I understand the standard rear torsion bars should be 23mm rated at 100lb, the spring plates free setting should be between 36*30' and 37 degrees as a starter for standard ride height.
My car was fitted with 25mm torsion bars which are rated at 140lb. Does anyone know or have a calculation to give me an indication of what angle to set these at or what the difference in ride height would be if the same free angle setting was used (I assume considerably higher due to the spring rate). I know the final adjustment will need to be made once things settle, but a starting point would be great. Is there any info on this forum, impact bumpers, or pelican.
Any help would be much appreciated.
Mike.

Re: Rear Suspension - Torsion Bars

Posted: Sat Sep 12, 2020 11:25 am
by AndrewSlater
Hi Mike,

Elephant racing have a calculator on their website - might be a good starting point.
https://www.elephantracing.com/tech-top ... alculator/

Regards
Andrew

Re: Rear Suspension - Torsion Bars

Posted: Sat Sep 12, 2020 11:53 am
by MikeS911
Thanks Andrew
Will take a look

Re: Rear Suspension - Torsion Bars

Posted: Sun Sep 13, 2020 9:11 pm
by Cortina
MikeS911 wrote:Hi All. Hope everyone is staying safe, and still playing with the motors. I have a question for the suspension experts.
I have a 77 - 2.7 911 and I understand the standard rear torsion bars should be 23mm rated at 100lb, the spring plates free setting should be between 36*30' and 37 degrees as a starter for standard ride height.
My car was fitted with 25mm torsion bars which are rated at 140lb. Does anyone know or have a calculation to give me an indication of what angle to set these at or what the difference in ride height would be if the same free angle setting was used (I assume considerably higher due to the spring rate). I know the final adjustment will need to be made once things settle, but a starting point would be great. Is there any info on this forum, impact bumpers, or pelican.
Any help would be much appreciated.
Mike.
Would the angle not be considerably LOWER due to the higher spring rate ? Stiffer , so same weight moves car much less , so start with car "lower" so it ends up at the same ride height .................. (I am assuming agle measured from horizontal ? ..... so long ago since I did one , that I have forgotten !!)