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

[stewteral]

Hey 914ers:

If you have been following my posts on 914 chassis settings, here is one that applies to ALL 914's.

To start, per my posts:

-I Squared the chassis with paralleled strings to measure and set the toe, front and rear. (Front = 0 to -1/16 toe, rear = 0 to -1/8" toe)
=Results: steering a bit "nervous", but all else stable.

-Camber: For Street cars, Standard front with -1 to -1.5 degrees rear.
=Results: nothing noticeable.

-I bumpsteered the front suspensions to within 0.008" from prefect at 2" compression.
=Results: nothing I could feel driving the car on the street. TBD on-track.

-CORNER WEIGHT BALANCED THE CHASSIS: With the car weighted for the driver weight, I adjusted the rear spring ht. and the front torsion bar ride height. For the rear, large diameter washers can be added to make adjustments, while the front is too easy with an 11 mm wrench.
=Results: WONDERFUL!! With all the previous chassis settings done, the car still wanted to pull to the right as though I were on a highly crowned road. After the balancing the corner weights, side-to-side, the car now runs STRAIGHT and TRUE right down the road. The sense through the steering is now light, equal and very linear as to where I want to aim the car.

Conclusion: Take the time to either build wt check lever, as per my photo or find a very strong STEEL ladder and wing it. Regardless, the benefit from the effort is completely WORTH IT!!!

If you have any questions, please let me know!

Terry
stewteral@verizon.net

[neilca]

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)

[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