i love porsche
Mar 5 2007, 08:32 AM
what size torsion bars are available for our cars?
ive been thinking abou it..and how do the sized equate to the springrates...just looking for some info and reccomendations here
Dr. Roger
Mar 5 2007, 08:45 AM
i think there's almost no resources for 914 tortion bars. please someone chime in if i'm mistaken.
almost everything i found was for 911's, hence another reason to switch over to 5 lug.
Joe Ricard
Mar 5 2007, 09:01 AM
You can get torsion bars for 914/4 al day long. 21mm and 23mm also hollow bars. from smart racing.
I suggest you do some soul searching before up grading to stiffer bars. 19 to 21 is like doubling the spring rate. 23 is pretty much race only.
TravisNeff
Mar 5 2007, 09:18 AM
You can go 19mm if you swap for 911 A-arms and torsion bars. You can do 20mm from troutman, powerbars in 21, 22, 23
Lou W
Mar 5 2007, 09:34 AM
I just installed 21's on my car, I ordered them through Glenn Sager at Pelican Parts, they carry "Sway A Ways". Im running the stock 914-4 setup with 914-6 struts.
woobn8r
Mar 5 2007, 09:54 AM
My '72 911 (street car) had 23mm up front and 26mm in the rear...firm but liveable
For the teener, it's tougher to guess the right size as you need to match to the rear spring rate...
Somewhere (on one of these boards) I saw a chart with spring rates corresponding to torsion bar size...if you can find that (I wish I'd printed it) your bar selection would be much easier....
please post what you find out!
Good luck,
Sean
shelby/914
Mar 5 2007, 09:59 AM
Pelican has 17, 21 & 22mm solids and 21, 22 & 23mm hollow torsion bars. PO had left in the origional 17mm bars but changed the sway bar to a 22mm which gave it a horrible bouncy ride. Switched over to 21mm torsions and a 19mm sway bay. Rides and handles a lot better.
Dave_Darling
Mar 5 2007, 10:06 AM
The stiffness of a torsion bar (or a sway bar) goes up with the FOURTH POWER of the diameter. Which means when you go from the stock 17.9mm bar to the 21mm bar, you are getting (21^4 / 17.9^4) ~= 1.9 times as much spring rate.
The exact rate depends on the "lever arm" that the bar affects the suspension through.
--DD
i love porsche
Mar 5 2007, 10:10 AM
QUOTE(woobn8r @ Mar 5 2007, 07:54 AM)
Somewhere (on one of these boards) I saw a chart with spring rates corresponding to torsion bar size
that is pretty much what im looking for...i should do a search
Dave, that is very helpful too..thank you!
Aaron Cox
Mar 5 2007, 10:17 AM
i run 22's with 225 lb springs in back....
very livable.
John
Mar 5 2007, 10:42 AM
I made a spreadsheet for determining equivalent front spring rate based on torsion bar sizes, but it is at home somewhere. It's not difficult to calculate if you know the distance from the center of the torsion bar to the center of the ball joint.
Let me know what that distance is and I'll make a new spreadsheet.
TravisNeff
Mar 5 2007, 10:47 AM
The smart racing products catalog has the charts for torsion bar size to lb sprin rate.
John
Mar 5 2007, 10:55 AM
QUOTE(Travis Neff @ Mar 5 2007, 08:47 AM)
The smart racing products catalog has the charts for torsion bar size to lb sprin rate.
That works as well.
John
Mar 5 2007, 03:34 PM
Here is a small table:
InstantG ChartThere is also a PDF on Rennlist. I would post it here but I didn't get permission. Here is a link
Torsion BarsI know it's 911 stuff, but our cars use 911 front suspensions (except the splines are different in number).
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