Rennkafer

iTrader: (3)

Find a local race prep shop and get them to test your springs... most decent prep shops will have a spring rate tester similar to this http://www.longacreracing.com/catalo...id=575&catid=5. You'll have to remove the springs from the coilovers but that job isn't too tough.

hustler

iTrader: (6)

Its become clear to me that I'm going to have to buy this **** myself because Dallas doesn't have much of a track scene in terms of people like you and I, rather than Ferrari and Porsche clubs.

chpmnsws6

iTrader: (12)

The redneck in me would use a scale pad on my press and build a fixture for it. You can then measure the first 2-3 inches of spring compression with it.

Rennkafer

iTrader: (3)

The problem is to get accurate results you have to compress the spring at least 1/2", preferably an inch. So on a 300lb spring, you'd need a scale with at least a 600lb rating, which you're not going to find at Walmart... What you could possibly do with a larger press is make up something like a "Ruggles Scale" (basically a cantilever arm) with a 3 or 4:1 ratio.

Simplest is take off your springs and find a prep shop to measure them. Any prep shop (road race OR nascar) should have a spring tester.

chpmnsws6

iTrader: (12)

Scale pads read 1200+ pounds (typically 1500+ per pad) so you can get at least 2-2.5 inches of compression out of it which will give you a reliable reading.

hustler

iTrader: (6)

How much of an increase in dynamic camber will I see going from 949's recommended 3.5-5*? Rob Fuller / Robispec told me, "3-rules of suspension tuning: her **** can't be too big, her *** can't be too small, and you can never have enough caster."

I'm currently not using the inside of the tire, evident from tire temp and looking at wear at 2.75* front camber and 3.5* caster. Considering the SM guys run 3.5* camber and 5* caster...is that a bad idea for me to run the same? 5* of caster sounds like too much, but my tires are asking for more.

Also, I wonder if I could increase braking grip if I ran less camber in the front, and more caster?

Rennkafer

iTrader: (3)

Sorry, I misread your last post... I was thinking cheap scales not corner weight scales.

The type you're talking about would do up to about a 600lb/in spring, fine for rear springs, big enough for some but not all fronts (and that's at 1/2" preload on the springs, the minimum you should use)

Rennkafer

iTrader: (3)

I've never seen the numbers run on a Miata front suspension to give you an exact amount. If anyone has run it through WinGeo or a comparable program that would be interesting to see.

I will say that if you're running a depowered rack, you will notice the difference in steering effort at lower speeds. My car, because of the offset bushings, will only go as low as 5.3* caster at my current camber setting. More static camber would allow me to get less caster, but I didn't want to run more than the -2.3* front camber I have on a mostly street driven car.

hustler

iTrader: (6)

So do i want to raise the car up from 4"/4.25" at the pinch welds and soften rebound on the shocks or just stuff in a bigger rear swaybar? I have to pay about $300 for an alignment so I'd rather not try this multiple times. I'm at max camber in the rear current at 2.6* in the rear and don't want to lessen that...thoughts?

webby459

iTrader: (8)

Of course you will increase braking grip if you run less front camber. But, you can also increase braking grip by reducing camber gain by adding a stiffer front spring...

On the SM camber, are guys REALLY getting -3.5* without offsets or anything? Yikes, they are either really low, or cheating with parts, or a little of both.

The benefit of more caster for you would be more camber gain and a little added wedge that the caster will give you, which will also help you dial out some mid corner understeer.

If you are reppin' 300 AND are not unloading the inside rear tire exiting, why not max out caster, it's win-win.

The mantra I've been hearing a lot lately is to work on the end you are having trouble with. So, if you are pushing mid, just band-aiding it with a larger rear bar would go against that ethos. Maybe you can find a little bit lighter spring or bar for the front to try out?

Also, are the track guys in agreement with those huge camber numbers? Granted, I'm an autocrosser, but ~-2.6 or 2.7* front with max caster and around -2.0 rear works out with pretty good temps and excellent grip. In the rear I am close to having to put in offset bushing to get some camber OUT, I would need to if I wanted to go much lower.

hustler

iTrader: (6)

I'd run more camber if I could, my outside edge is hotter and more worn than the inside of the tire. All the Cali track crew run those numbers or more camber...tire temps don't lie.

I'd rather adjust set-up than buy stuff right now. I'm trying to not spend any more cash on parts. I'm going to see how much travel I have this weekend and what that means about bump-stops. I'll raise it up if I must.

Does anyone know if the valving rates are identical in the front and rear Tein Twin Flex? I've respected the logic of more rebound damp in the front (in terms of "number of clicks" from stiff) compared to rear. If less rebound damping means more grip, then I could potentially run 8-clicks from stiff in the front, 6-clicks from stiff in the rear. I've avoided this because its illogical if the valving is the same.

spoolin2bars

iTrader: (1)

omg..... forget illogical valving. it would mean more if it wasn't for the fact that your SPRINGS are different rates! testing, testing, testing. like i told you all year, you can get all the reccomendations you want, but it might not work the same on your car, with your parts, and your driving style. the only real way to find out is to try it! and yes, softer means more grip. the softest setting you can run that prevents excess movement in the suspension will offer the most grip. that being said, why are you so scared to turn the screws on your shocks?

hustler

iTrader: (6)

I don't think its reasonable to run more rebounding damping in the rear than the front...and not addressing the real problem. If the springs are softer in the rear, then I should have less damping in the rear.

Rennkafer

iTrader: (3)

^ This...

To give you an example, we have a pair of FIA 2 liter sports racers owned by different people that we run for them. Both cars are the same make/model, have similar engines (within 25hp or so) and both cars run the same wheels/tires/shocks. The spring rates/damping settings are a fair bit different between the two cars because of driving style differences, but both are fast in the hands of their respective owners. We restored one of the cars several years before the other and it took 4-5 races before we had the second one dialed in the way the driver wanted it, despite having started with the settings used on the first car done which we knew worked quite well.

Testing is the ONLY way to know what works the best for YOU... there is no magic bullet that anyone can tell you that works "best".

hustler

iTrader: (6)

I didn't think I was at that level where I should depart from advice and forge my own path. I'll check the ride height by measureing travel then get it balanced and alighned starting this weekend. The car became much faster when I dropped it down and I like the way it behaves (fancy that, a driver like a super stiff car) and play with the valves.

spoolin2bars

iTrader: (1)

what would it hurt to turn the ***** on the front shocks? if it's worse, turn them back! if it's better, your welcome! if that's forging your own path......wow

i can tell you the next step, but i don't wanna blow your mind. okay, i'll tell you anyway. there is no such thing as the correct setting! i write down the temp./track conditions and my shock settings/alignment settings (if they changed from the track before) and keep track of how my car handled, parts of the track to look out for, etc.. the track surface at tws, msr cresson, and harris hill road for example, are all so different, that they take different shock settings to even get close to the same frt. to rear balance that i like. i hope your not chasing your tail trying to fix something for one track, that won't be there at the next. i forgot about that and thought my car was at fault for the terrible understeer i was getting. next session i realized it was my driving! i had forgotten what a track was like in a couple corners and was driving the traditional line (which induces gobs of understeer) and when i tightened up my line lo and behold, the car was glued and i could floor it instead of feathering the throttle at corner exit. good luck

hustler

iTrader: (6)

I record most of my data at the track, but the reason I put so much emphasis on getting it set-up before the track is so the day is not a waste. My note-taking has not been good enough but I've learned a lot from this thread. Unfortunately I will not be able to get scales and I'm not paying $600+ to get it done locally, especially considering I have to pay another $300 to get it aligned. I have to keep guessing.

hustler

iTrader: (6)

OK, I'm confusing myself now. Considering I have Tein Flex and turning the **** clockwise reduces rebound damping only...If the car is under-steering on exit I should reduce damping (turn CW) on the rear shocks to increase the speed at which the spring unloads the weight from the rear. Right?

I'm going to put my shocks in the middle front and rear and start over on rebound-valving next time I hit the track. I'm still on the fence about buying another sway bar.


I really wish I could increase rear compression right now.

JasonC SBB

I wrote a spreadsheet which calculates how many turns on which corners to hit 50% crosswt and your desired ride heights:

http://forum.miata.net/vb/showthread.php?p=4980765

hustler

iTrader: (6)

Thanks, those numbers batch what GSS told me to do after I weighed.