Corner Weight Balancing of 914s, The benefits of equalizing the side-to-side corner wts. Options

[stewteral]

Test day results,

The weather was absolutely perfect 69 degrees no wind and sunshine. I was in a goup with a bunch of Spec Miata's. Did two sessions and the car performed flawlessly. This thing just stuck like glue, I couldn't get to slide even when I goofed up. First lap was a 2:04 the best lap was 1:54 lots of 1:56's in between. One comment about the SM guys, they are some really good drivers and despite their reputation very courtious. They don't give you a lot of room but enough room.

Now for numbers,

First the ride height was not a problem. The car didn't scrape or bottom anywhere. I did have tie wraps on the shock shafts to measure shock travel but I have not measured it yet.

The toe out in the front was very noticable, ie scary as hell, on the first lap. The car was wandering all over the place. Then a Miata passed me and like in the movie "Up" I said "squirrel" and the wandering was completely forgotten and the chase was on. I didn't notice the wandering again.

I had on Goodyear 430's all the way around the tire temps were

First session
LF 118,137,143 PSI 18-25
LR 132,143,146 PSI 20-24
RF 138, 136 130 PSI 18-18 this tire has a bit of a leak
RR 140, 140, 135 PSI 20-24

Second session
LF 128, 140, 149 PSI 18-23
LR 129, 143, 147 PSI 20-23
RF 141, 136, 131 PSI 18-23 Leak appears to have stopped
RR 148, 143, 140 PSI 20-23

Based on these numbers I believe the LF could stand about 1/2 degree less camber. But that is the only change I would make at this time. (IMG:style_emoticons/default/smile.gif)

Hey Neilca,

Glad you had a great time! Your tire temp numbers look pretty even, but as you noted the LF could use less camber.....and what do you think about the LR?

I don't know the Goodyear 430 compound, what temp does Goodyear recommend as optimal for the tire? I ask because I had a chat with Hoosier and found that even though my temps across the tires looks good, ALL my temps were BELOW where the tires generate max GRIP!

So I have a couple choices: 1) with the balance finally coming right, I have to GET UP ON THE WHEEL and driver FASTER & HARDER.....or 2) buy a whole new set of SMALLER width tires that will run hotter by themselves.

.....Can you guess my choice? (IMG:style_emoticons/default/smile.gif)

Enjoy those track days!!

Terry

[neilca]

Terry,

Yeah the left rear could use a bit less camber. The Goodyear 430's are a medium compound. The temperatures are below what Goodyear would like to see, but it was only 69 degrees that day. My events in May and July will be about 25 derees higher in air and track temperature. To generate more heat I could go with the 240's, which is a softer compound and more grip too.

This was my first time at speed in 14 years so I expect I will be generating more heat with more seat time. It was a gas, next event is Time Trials at RA in May.

[ChrisFoley]

Just a point of reference - I think the current FProd lap record is a 1:38 or 1:39, set a couple years ago in late March. My best during the National in 2005 (my first time at RA) was about 1:46 with 140hp, a poorly adjusted Rennshift and no practice/qualifying.
I was slow through the esses, not knowing just how much speed could be carried down into the valley.

The softer tires aren't going to generate any more heat, they will just grip better at lower temps. The way to get the tires hotter is to carry more speed throught the turns. If you didn't feel the tires slipping against the pavement you don't need a softer compound to go faster.