Preferred wheel size at Willow Springs?

[DaveR]

I'm building a car that I plan to run at Willow. What's the best wheel diameter: 15", 16", or 17"? Is wider always better?

[DaveR]

Another related question: Do I need 13" rotors with 4 piston calipers on front? What brakes do the guys with 15" wheels use?

[marty]

I run 15's and Dunlops. If you really want to learn to drive and aren't concerned about being passed by half the field, stick with 15's (not much tire choice, but the wheel size looks better to me). If on the other hand you want to go "fast" and drive on the street on the same set of wheels and tires, go to 17's as you will then have an abundance of tire choices, good to great!

[Horse]

I would say that you should use the wheels that your manufacturer recommends-
Wilwoods fit under 15's and they were good enough back then and are good enough now to scare me- When I went for a lap with DAve Dralle in Thomas Kirkhams car - I had blisters on my hands from holding on - so I guess 15/s would work out just fine!


ps never had I loved a blister before....

[coyled]

Dave, the 17's have a wide selection of dual purpose, track and street tires. The 17's will give you more ultimate grip than a 15 but will have a knifeier edge. When they start to go, you spin. I run 15's with bfg ta's on the street. They are landscapers tires at best but on the street ,How hard should you push it anyway? I have run the 15 inch hoossier dot bias plys and now run the goodyear bias ply slicks in 15 inch. They hunt when cold but once they warm up, stick like snot. Also, because they are bias ply, the cobra will slide pretty far before they completely go away. If somebody is faster with 17's its mostly because of the driver, the 15's work well. Good luck.

[DaveR]

Scott,

Thanks for the tire advice. What kind of differential is preferred at Willow? Are most people running clutch type rear ends? I'm thinking about buying a Truetrac which is a gear type limited slip discussed on this forum. Bill Thomas in San Bernardino tried to convince me that a Detroit "soft" locker would work well at Willow. Any thoughts? Dave

[Ant]

Coyled,

Reading your post on Goodyear 15" race tires, I guess what you are saying there is not much advantage in going 16" or 17" race tires slicks!

I am about to order my Trigos and will have one set for road, and as there is a poor range of tires in NZ relating to muscle car 15" sizing I am uncertain whether to get another set made by Trigo, or leave my options open in a larger size rim!
From what I can gather a lot of racers are using Roger Krause Tires, so the 15" Goodyears, Hoosiers and Dunlops must be very good? I dont mind importing some to here if they provide good results and the car will still look good on original looking wheels.

DaveR,
What about Eatons new carbon fibre clutch LSD, they seem to be popular with some racers, some of the locker types are better in 4WD and offroad vehicles.
In fact quite a few people use the normal Ford LSD if setup properly last for a while. I have used Detroit Lockers over the years can be a bit scary if the car isn't the best handling. One of the easiest cars I drove was my 650hp last Cobra I owned it had a locked 9" IRS but it killed parts like axles etc

[RaceDeck]

Big Bob Evans had a big thread going about this a while back and I think that by the end of the many pages of the thread, the consensus was that the faster lap times at Willow were being had on 15". I have driven both and I personally like the "feel" of the 15"'s...they give you a sense of where you are as to the tire limits...with the 17"s I felt as though they hoked up great in a turn but when you reached teh limit there was no warning...and off you went back end first...

[DaveR]

Ant,

I decided against the Locker when I read a post on the other board where someone said "can you imagine racing autocross with a Locker?" The Eaton seems to be the LSD of choice, but I thought I would try some thing different, so I bought a Truetrac gear drive. I don't have it on the street yet, so the jury is still out.

[Ant]

DaveR,

Good luck with your Truetrac differential, I guess if you set up your car to handle and drive it accordingly it doesn't matter as long as its driveable.

LSD and other designs have come a long way, all that was available years ago was either Detroit lockers and some poor LSD units, I suppose thats why locked diffs are popular and work well on the track, but must cost some horsepower dragging one wheel at times.