Autox Spring rate help, Too Stiff? Options

[nolift914]

Is my Autox 914 too stiff?
I am currently running the PO setup, the 914 was set up for club racing with front and rear coil overs. The front is at 330lbs/in which I believe is the equivalent to 25MM torsion bars and the rear is at 230. The 914 is a 4 weighting approx 1780lbs with bias ply slicks. I plan on switching to Dot-R radials. I have always thought for autox go soft on springs and big on bars. Does the paddock crowd have any suggestions for a setup. The autox sites in NYC tend to be on the rough side. I was thinking either 175 lbs/in in front and 140 lbs/in rear or 200 lbs/in front and 180 lbs/in rear.

[nolift914]

Is my Autox 914 too stiff?
I am currently running the PO setup, the 914 was set up for club racing with front and rear coil overs. The front is at 330lbs/in which I believe is the equivalent to 25MM torsion bars and the rear is at 230. The 914 is a 4 weighting approx 1780lbs with bias ply slicks. I plan on switching to Dot-R radials. I have always thought for autox go soft on springs and big on bars. Does the paddock crowd have any suggestions for a setup. The autox sites in NYC tend to be on the rough side. I was thinking either 175 lbs/in in front and 140 lbs/in rear or 200 lbs/in front and 180 lbs/in rear.

Currently running 19mm torsion bars with a smart racing bar, with the smallest diameter bar they offered. Had under-steer until I went to the lightest smart racing bar. Front shocks are Koni's set to almost total soft. Rear springs are 240# if I remember correctly. They might be #225, but will check.

With Avon's no under-steer at autox's or hilllclimbs. I'm 100# ligher than you.

Are you going to Dot-radials to make a class?

I am currently running in PCA class M01 and SCCA FP, I am looking to move away from the Canti's due to the limited availability. Cant find soft compounds.
Going to either Radial slicks or Dot-R autox tires. I found this chart listing the front torsion bar spring rate

SIZE ( mm) SPRING RATE ( Lb/in)
18.8 110
21 173
22 210
23 250
24 296
25 350

I believe I have 330lbs / springs on the front which by the chart would be the equivalent to 24.5mm bar, which seems stiffer than those listed in this thread from 19mm to 21mm.

There are some mine fields with a suspension set up like I related..

A stiff shassis is needed to *make the suspension do its work*......I'm talkin' bridge stiff. A stock chassis will flex all over hell and make handling inconsistent.

To help the suspension do its work, low friction bushings....not cheep derlin/poly whatever, are needed.

Over 200 lb rear springs can/will cause cracking aound the un-reinforced rear towers long term.....the rougher the venue, the quicker this happens.

Enjoy (IMG:style_emoticons/default/biggrin.gif)

J P

I should have given more details of the 914's current setup, In addition to the front and rear coil-overs on Bilsteins, the front struts have raised spindles. front and rear Elephant racing polybronze bearings, Reinforced rear trailing arms and lower console, full 8 point cage. no reinforcement on front and rear shock towers. Front sway bar (Weltmeister) and no rear bar.

From the setup's listed everyone is softer in front between 125lbs to 175lbs and stiffer in the back 225 to 275. (IMG:style_emoticons/default/confused24.gif)

[Randal]

Right, no soft compounds with Canti's.

Before you go to radials check out the soft compound Avons. They are expensive, but they work. Also believe the real soft Avon's have more tread on them to start out.

[nolift914]

Right, no soft compounds with Canti's.

Before you go to radials check out the soft compound Avons. They are expensive, but they work. Also believe the real soft Avon's have more tread on them to start out.

I took a look, what compound do you run A11 or A24

[Randal]

Right, no soft compounds with Canti's.

Before you go to radials check out the soft compound Avons. They are expensive, but they work. Also believe the real soft Avon's have more tread on them to start out.

I took a look, what compound do you run A11 or A24

I'm running A45 for both autox and hillclimbs. Magic actually. Perfect for light weight 914's.

Good idea to decide on front tire size you want (narrow or wide) then ratio your weight balance to the rear tire. In effect you end up with every inch of tire with the same weight, i.e., just like F1. Smaller in front is better.

You're concerned about getting heat into tires, so run narrower tires in the front.