^good info

 

A friend of mine has a set of longacre scales for $600 with case and laser level. I have no part in the sale but if anyone is interested PM me and I can give you the guys email.

 

Now you speak up..... At 850, its not worth it. At 600, it is.

 

Buy scales, you won't regret it if you think auto racing is lifetime hobby for you.

 

I always start with a $20...but that doesn't get me anywhere at the Porsche shop.

 

I buy the guy **** mexican food at the place next door, and he pretty much lets me do it.

 

hmmmm scales or HANS? hmmm???

 

Lol why a hans, you don't even wear a ******* driving suit.

 

Huh? Two completely different modes of protection.

 

Is it required in your class or sanction? I'm not up on the SCCA/NASA track rules.

If its not, a good neck brace should keep your cervical vertebrae inline while the harness keeps you locked into the seat. Just make sure your harness is installed correctly so it doesn't do more harm then good if the time were to arise that you actually needed it.

 

Just because it isn't required, doesn't mean your melon isn't worth the extra money spent on safety. Well we are talking about hustler here though....

 

scales

 

I still don't know when to adjust spring pre-load vs. ride height.

Right now I have steady-state understeer (I think its worse on left turns). I don't know if I should crank valving, increase rear preload to raise rear spring rate, or something I don't currently understand.

 

Did you try tweaking the tire pressures?

 

I didn't want to screw temps becuase they were as good as they were going to get.

 

Jump onto M.net and PM Perryrace. He's one of the guys I've been going to for all my newb questions..... Which appear to be the same ones you have. They are the same questions I had walking into my high performance steering and suspension class years ago..... which taught me NOTHING.

 

As far as pre-load vs ride height-

If you have the option to adjust them independently, you want the optimum up/down travel you can get being set with pre-load, then the bottom adjusters to fine tune the ride height. PLEASE scold me if I'm wrong, as that is the only way it makes sense to me currently. Without testing and playing with the car on the scales, this is all just speculation on my end

While your PM'ing him, can you ask him about adjusting the valving on the shocks? What symptoms to look for to determine that you have them too soft where its not controlling the spring at all or too stiff where its dampening too much? That was the other big question I had in that class, that yet again got me no where.

 

if it's understeering, soften the frt. shocks a couple clicks, take a few laps see what it feels like. the softest setting that still controls the spring motion is always gonna give the most mechanical grip.

 

But inside the car, how do you monitor the spring control?

 

Right now I have steady-state understeer (I think its worse on left turns). I don't know if I should crank valving, increase rear preload to raise rear spring rate, or something I don't currently understand.[/QUOTE]
I assume you already corner balanced? You may have a bit of "wedge"(>50% weight on the LR and RF corners). It may be a simple issue that you need more -camber on the front end.

There is a shitload of variables, so I have some questions:

• Have you verified your tire temps as measured outside/middle/inside immediately after hot lapping? You want to see slightly higher temps on the inside of the tires(especially on the fronts).
• Do you have adjustable sway bars?
• What shocks and spring rates are you running?

I am NO suspension guru, but I have picked a lot of minds over the years, so here are my thoughts on the subject:

If you increase the preload it will make the car sit higher and increase shock travel while static. To compensate for a higher sitting car you should then shorten the shock body(if you have adjustable body length shocks).

Preloading the springs is HUGE in the offroad and rally car world, but I am not sure how many road racers or autoxers do it. I have not experimented with it yet, but the optimal goal for every vehicle is to maximize traction, so it makes a lot of sense that the off road cars that catch a lot of air and hit tons of dips and bumps would want to use spring preloading coupled with SOFT springs to optimize the traction.

That said, people that are running FM's AFCO suspension seem to be putting down some pretty good lap times, so maybe there is something to be said for running softer springs, but having shocks with TONS of travel(coupled with spring preload to keep the static ride height).

I like the suspensions that use helper springs of decent stiffness) - this makes preloading the shocks irrelevant(unless the helper springs are not stiff enough, like under 100ft/lbs).

The results to spring preload is:
1. Less preload your suspension will have less droop and down travel.
2. More preload will add more droop and suspension down travel.

The compression/rebound damping of the shocks have TONS to do with how well they react over big bumps/dips, so spring rate + shock damping need to be taken into consideration if you are contemplating adding preload to the springs.

I played with some shocks years ago that did not have adjustable body length, but they did have adjustable ride height via spring preload. The spring rates were quite low so in order to get a decent ride height I had to add a **** TON of preload(like 15 full turns on each collar) which ended up causing the springs to coil bind under hard compression. It sucked.

On a track or autox miata I would NEVER go below 375/250 front/rear spring rates, unless you have fairly stiff helper springs on the coilovers.

[QUOTE=hustler;594160]I still don't know when to adjust spring pre-load vs. ride height.