Race Duetto coming together, have questions...

Nader · #1 (**permalink**) 08-21-2009, 11:55 AM

I'm piecing together my race car, finally.

1. What do we like for treaded racing tires in 205/14?
2. Source for front sway bar? I've heard an S3 Spider unit may work.

Bear with me in the coming months, I'll have more questions for sure.

**genericwood** · #2 (**permalink**) 08-22-2009, 08:01 AM

Nader, are you limited to a 60-series tire? If not, you might want to consider a 225/50-14. If you can't go lower than 60's, a 205 is the right tire. In the Midwest, a lot of us are still running Hoosier Street TD bias ply tires. I have never felt I was at a disadvantage based on tires. I'm sure others will chime in with recommendations for radials, if that is your choice. I know there have been issues with some of the better tires being discontinued in 14" sizes.

As for the sway bar, you should probably let us know more about your overall suspension set up. I'm guessing you could use a late model spider bar, but you may want something stiffer.

Erik

**conedriver** · #3 (**permalink**) 08-22-2009, 08:16 PM

This may be a redundant question, but is very important: what sanctioning body will you be racing with, and what allowances / restrictions are applicable to your car and class?

Quote:

Originally Posted by Nader

I'm piecing together my race car, finally.

1. What do we like for treaded racing tires in 205/14?
2. Source for front sway bar? I've heard an S3 Spider unit may work.

Bear with me in the coming months, I'll have more questions for sure.

Nader · #4 (**permalink**) 08-22-2009, 08:25 PM

Building the car to run with the stringent SOVREN rules, but also SCCA. So I'm running a partial interior, and all the usual suspension upgrades with springs, Konis, bushings, etc. No Watt's or Panhard in the rear. I suppose I shouldn't consider an S3 sway bar, either.

I'm limited to 60 series tires, so 205 is the widest I could go. 185-195 would do if it was sticky.

**conedriver** · #5 (**permalink**) 08-23-2009, 07:53 AM

Why not?... if the rules allow something, and it is beneficial to your car, use it!

(assuming the part/modification fits within your budget "Speed costs money, how fast can you afford to go?")

Quote:

Originally Posted by Nader

Building the car to run with the stringent SOVREN rules, but also SCCA...No Watt's or Panhard in the rear. I suppose I shouldn't consider an S3 sway bar, either....

Nader · #6 (**permalink**) 08-23-2009, 01:30 PM

SOVREN is our race organization up here, and they're supposedly strict. But I don't suspect a late model sway bar will raise hackles as long as nothing exotic is going on with the rest of the suspension.

Sooo, is the S3 front swaybar the way to go for this old Roundtail? Does it bolt right up without mods?

I'm thinking of getting Falken Azenis in 195/60-14 for trackday/practice/rain purposes.

**msiert** · #7 (**permalink**) 08-23-2009, 02:53 PM

You can get a 29 mm front sway bar from Alfaholic's. That's the largest I know of that will fit in the stock location for a late model Spider. The stock S-4 front sway bar is 24 mm.

Classic Alfa Romeo cars

barbone105 · #8 (**permalink**) 09-01-2009, 03:45 PM

all the 105/115 production front bars are the same - 24 mm.
the only exception i know of is the GTA bar, is 20mm.
andy

Nader · #9 (**permalink**) 09-01-2009, 06:04 PM

So if the GTA bar is thinner, then do I want a softer suspension setup for the front? Granted, I won't be running a sliding block rear suspension. I keep hearing that the front should be stiff, and the rear soft, at least for Spiders. This is confusing.

barbone105 · #10 (**permalink**) 09-01-2009, 07:02 PM

no, i think the lighter spring and bar specs for the GTA are because they are so light.
this was the street bar. have no idea what folks ran on the track, but i'd guess heavier.
andy

**genericwood** · #11 (**permalink**) 09-02-2009, 06:36 PM

Quote:

Originally Posted by Nader

So if the GTA bar is thinner, then do I want a softer suspension setup for the front? Granted, I won't be running a sliding block rear suspension. I keep hearing that the front should be stiff, and the rear soft, at least for Spiders. This is confusing.

Alleggerita · #12 (**permalink**) 09-24-2009, 04:29 PM

With very stiff front springs the stock 24mm may be enough, but likely you'll prefer more front bar.

GTAjuniors had an optional 26mm bar. Shankle blade style bar is 1 1/16 or 27mm. Alfaholics is available either in original style or late Spider style - 29mm. GTAm often used 28mm and 30mm.

A set-up from a known source, as discussed above is a good idea.

If you got the stomach to modify - $$$ - drop spindles or other ways to prevent the front roll center from going subterranean when the car is lowered, will make a difference.

sputbasty · #13 (**permalink**) 10-04-2009, 09:32 PM

Very much appreciate your help.

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**msiert** · #14 (**permalink**) 10-05-2009, 02:58 PM

Get a Panhard Rod !!!

As Erik (Genericwood) once said to me, this will be the signal best thing you can do to lower your lap times.

Orion Motor Sports

Nader · #15 (**permalink**) 10-05-2009, 06:40 PM

Thanks for the input. Like I said in post #4 above, no modifications to the suspension's geometry is allowed. No Watt's or Panhard.

I'm pretty sure there is no absolute recipe to an ideal suspension since this is no spec racer like the Spec Miata I once had. Every car is different; total weight, weight distribution, center of gravity, tire compounds, driving style, etc... The differences may be even more pronounced when comparing Spiders to GTVs. What works for an X pound GTV may not be so great in a Y pound Spider. So I'm just going to experiment from my current starting point, once the car is done (hopefully by Spring).