Question
Number 10 Hornet class
QUESTION: Hi Dan.
I race a 1/4 mile banked oval and this year my car is a Nissan 240SX. I am in a stock class with no aftermarket parts or non factory adjustments allowed. Within the grey areas of course there is a lot of leeway. I have one race under my belt and my car is very quick right out of the box. I am running the max allowed 1.5 degrees right side camber and about a degree positive on the left. I dropped the rear swaybar and lowered the left side tire pressures to about 18 pounds to help(maybe) a bit with grip and stagger. I am wondering what I should try next to get my times down a bit more. I need to drop about 4 tenths to really run with the fastest cars. (I am now the only rear wheel drive)
I should point out that I have completely gutted the car, and there is nothing left there. Oh, and about 1/16 inch toe. I figured being rwd, there was no benefit to more than that.Any thoughts? How can I add wedge to a macpherson strut car?
Thanks for the help!
ANSWER: Hi Martin:
Wedge: Try raising the LR a little with shims under the strut cartridge.
And I think I would try running about 1/8 to 3/16" of toe OUT - - -that should get you into the corner faster. Now if the car 'hunts' or wanders to badly down the straight, reduce the toe out a smidgen.
Take your front struts out, and elongate the holes in the strut towers so you can move the mounting rearward. This will increase your caster. "Caster is Faster" is the old saying. When the steering gets too stiff in the paddock you have enough caster. Caster improves "camber gain" in the turns. Both front tires benefit.
Get a tire pyrometer and check your tire temps. Use this info to adjust your tire pressures.
If a tire is hot in the middle , there's too much pressure in it. If it's cold in the middle, not enough.
You can pre-load the rear bar by lengthening the down link. This will work to stiffen tht corner. Try it on the right first. Take notes, then try it on the left.
With only one race behind you , you are not going to run with the big dogs. It simply won't happen. You will need to develop consistency, and work HARD on your lines through the turns. Following the FWD cars will only cause you heartache. You can turn in later and come out sooner than they can, and actually benefit from a little push. When they start to push, they have to lift, you don't !
For more weight reduction, you can cut holes in the rear crossmember and the lower control arms. Also grind excess metal off the rear-end housing, and the engine block.
Get the book, "How To Make Your Car Handle" by Fred Puhn, Book stores usually have it , or they can get you a copy. it's about $16.00 and worth it's weight in gold. That book is the best advice on this page. Do that first. and read it at least twice before you start changing things.
Finally subscribe to Circle Track magazine - - -Google it for contact info. It's a GREAT mag.for any track racer. I am strictly a road racer, and I find something in it nearly every month that helps me. Nearly all tech info. !!
Good luck
Dan Liddy
Sarasota, Florida
---------- FOLLOW-UP ----------
QUESTION: Hi Dan, and thanks for the quick response. I should point out that its not my first race, just the first outing for this car. For the record, my last car was a FWD. You have given me some things to play with at the next test session. A couple of things come to mind; I pulled the rear sway bar off, thinking it would just create oversteer. Do you suggest replacing it and playing with preload as well as working with the front swaybar? I had planned to play with that next. Also wondering about tire pressures. I kept dropping pressure on the left over the night to get some heat in them, but they were hardly warm all night. It seemed like as good a way as any to get weight off the right side of the car. Should I air them back up and go back to suspension settings? Or is there a downside to running minimal air pressure if the tire is hardly working? I am not sure even with your suggestions that I can really get any weight on the left side, since we are not allowed to add weight.
Thanks again.
AnswerYou can change the weight BIAS toward the LR by RAISING the LR, Same for the LF Usually though you want to get weight OFF the RF because it is typically the heaviest corner, usually by 100 Lbs. sometimes even more.
The rear bar CAN cause oversteer, but only if it's too stiff. What it does is take twisting forces off the car, and will allow you to adjust the front without affecting the back so much. Try getting the front to stick first, then tune on the back just til it starts to come around. Then go back one notch. And if you can make the inside tires work, the outsides will follow.
Don't mess with tire pressures until you have temps to refer to, and it would be better if you have the "How To- - -" book to guide you through. The downside to minimal pressure is having a tire roll off the rim. This can happen when you have to take sudden evsive action in the wrong direction. Not a good time to lose grip.
As far as the front bar goes, you can pre-load it too. Use that as a tool to increase or decrease the spring rate on the RF. A longer link is stiffer.
Keep working on it and do get that book !
Dan
