I Need Help With Wheel Alignment Numbers

[Spydermon]

Hello Seasoned 911 Racer,

For the past two races, the front end of my car doesn't feel planted. The steering feels tight... and it doesn't wander or pull to any side.

Does anyone have "proven perfect" alignment numbers I could use as reference?

About the car: It's a 1971 converted to a 73RS with 8/9x15 Fuchs and Kumho Ecsta V710 tires. I club race on the west coast at Willowsprings, Buttonwillow and Laguna Seca. My tire pressures are around 28lbs depending on how hot the day is.

I used to use Kumho VictorRacers and never had any problems. Thanks for any help.

Randy.

[Eagledriver]

Planted is a very subjective term. Tight steering and not wandering would imply a good feel for the front. Most of the racers I know like to run maximum caster which gives alot of force back through the wheel (tight steering). If you wanted lighter steering forces you could reduce the caster. I don't have caster numbers as I just use the maximum. I run just a touch of toe in (1/8 inch) and I have about 3 degrees of negative camber.

-Andy

[petevb]

I don't think you're asking a question with a "proven perfect" answer, hence the lack of replies...

What changed two races ago that coincided with the different feel?

V710s require less camber than most other R compounds- you're probably looking for ~1 degree front, ~1.5 rear camber, +/- .25 degrees. Caster is usually "lots" or max, but it will make the steering tighter. Toe depends on the person- I like a little toe out front, in rear.

Before you chase alignment, look for something else wrong- your steering should move freely with both front wheels off the ground. My friend recently chased a steering issue for some time before realizing his struts were not rotating properly.

-Pete

[Spydermon]

Pete, what changed was, I replaced my tires to V710 and had my wheels aligned - possibly by someone who didn't know how to align a race car. Now the steering feels way-too-light in the front.

It's a real a white knuckle ride on the front straights of Willowsprings and especially over the hill at the start/finish line at Luguna Seca -- where I used to run flat-out. The corning feels about the same as it always did.

The 710s seem to take a lot longer to heat up (two laps) than VictorRacers (half lap). But when they are hot hot hot, they seem to be a bit stickier.

Randy

[Dave at Pelican Parts]

Sounds like you need more caster. That will make the front less "light" up front, at the expense of the steering being a bit more "heavy" all the time--the wheel will simply want to turn to where the car is going (usually straight ahead).

You may also want to dial out any toe-out in the front. The car will not want to turn-in as well, but it will want to "wander" less on the straights.

--DD

[Spydermon]

Thanks!

I have another question... I'm not too happy with V710 tires. What is a good replacement for the VictorRacers. Are they still available?

[petevb]

Originally Posted by Spydermon

Thanks!

I have another question... I'm not too happy with V710 tires. What is a good replacement for the VictorRacers. Are they still available?

Do you mind listing your current alignment specs and tire pressures? Most people I've seen who don't like the V710s were running pressures and cambers better suited to other R compounds. You might look into that before you switch.

Victoracers are (were) one of the slower R compounds out there. Hoosiers, V710s, and BFG R1s are some of the fastest, but wear faster. Nitto NT01s, Toyo R888/ RA1s/ Yoko 048 are slightly slower in speed but with good wear, more similar to your VictorRacers. I do believe the Victoracers are being discontinued- you might still find some.

[Spydermon]

Thanks again for all this valuable information. I don't know the current alignment numbers but I'll have it check next week.

[racing97]

Before you go changing your alignment specs just bump the hot tire pressure up to 38psi and see if that helps. The stability of the DOT's depends on a firm side wall.

regards