noodels

3mm is not enough 6-9mm is required for 11kgs on my type of R&T DFV
check with your vendor

ThreeD

Just checked. On the SBG FPSport kit the recommended preload is 2mm. Probably is less than w standard DFV kit due to using a custom shorter shock cup which allows running lower heights while keeping shock travel. I believe the actual damper they are using is slightly different than the regular S2000 DFV kit as well.

DanielB

When I bought this kit SBG said they had the shocks revalved to their own custom specs. Pasted from my conversation with them:

These are actually geared toward street use, while being good on track... basically a better balance. What we've done is make the valving curve more compliant by slightly reducing compression damping while increasing spring rate.

Anyway the sport kit had a few goals:
-The first was increase spring rate to reduce body roll as the stock Ohlins spring rates leave a lot to be desired. At the same time we geared the valving curve to reduce compression damping (in relation to rebound damping) slightly to make the suspension more compliant/supple instead of a high compression rate meant to squeeze every 1/10th of a second out of lap times with the penalty being street comfort and ride quality. So these are more comfortable even though these are a higher spring rate. Win win.
-The second was to increase the amount of compression and rebound travel with the standard shock length (non-long-stroke) as higher rate springs need less compression travel which can then be used for rebound. Basically it gives you more rebound while keeping you away from the bump stop (win win)
-The third was to set it up for stock cars with a wheel stagger, or square tire setup with a front bar (we recommend a 32mm front bar for square tire setups and offer our own bar which is coming out next month, or there are also lots of other bars which fit the bill made by other companies).

noodels

Maybe worth a measure to see if you have correct clearance <to illuminate bump stop issues effecting your problems>anyway due to a fitment error.

ckowalc

I'm guessing this was at a TNIA event? Not sure if I talked to you I have a black AP2 with roll bar and bride seats. It's hard to see your steering wheel inputs and turn in point from the video since its from the following car but I'd adjust your driving line for that corner as djsilverjohnson was saying. Some of the rear end instability probably has to do with the extra lift from having the top down (can't blame you though I usually go top down). I have done a good amount of laps at AMP and T16 is one you have to warm up to but you should be to go flat out fairly comfortably with 200 TW tires especially now that they have added asphalt run off (just don't turn in too early). I've done it with stock suspension and with the Ohlins DFV (10k/8k) I have now. Randy Pobst is at most of the TNIA events at AMP so if you see him I'd ask if he is available to drive your car and ask for tips around the track.

I won't change the car right now, it seems you have a pretty good setup just adjust your driving style a little bit and learn the track a little bit more but it seems like your a moving at a pretty good pace. My car oversteers at AMP more than any other track mostly because of all the cresting corners. BTW, make sure you've always got 1/2 a tank of fuel on track otherwise you'll start to starve mid-corner in T16 because of the long left hand sweeper before. That is when the real butt clinching happens.

Here are a couple my videos as reference. The one with just me is on stock suspension and the one with Randy is on Ohlins. The car is setup pretty oversteery in these videos.

ThreeD

Good to get the feedback especially on people who have driven AMP in these cars. I also deal with a good amount of oversteer at all the cresting corners as the rear end gets unloaded. Either way sounds like some butt clenching is expected on 16 and maybe some line adjustments may help with it. I still think of front sway bar might help balance out the suspension though. Will check out those videos when I get a chance.

thomsbrain

The S2000 body has rear end aero lift. If the car is balanced at lower speeds but gets loose around 100 MPH, the issue is probably aerodynamic. Any suspension change you make to change handling at high speeds will compromise lower speed handling. It's your choice about what you can live with, or you can just add some sort of rear downforce to maintain balanced handling across speeds.

Dezoris

Its very hard to to make general recommendations on setup. I run the DFV on 12/10 swifts on stock valving. On 255 RS4s I have to run at 2 clicks from full stiff. I have virtually no issues with bumpsteer. Only problem is aero. I also dont run crazy low because then you can get into travel issues and need to deal with geometry correction. If you are on stock valving go way stiffer with less variation between front and rear stiffness. I found in many cars going softer or too soft in rear shock settings makes it far more loose.

robrob

I know this is basic but just because you're losing the rear end on bumps doesn't mean it's being caused by bump-steer.

ThreeD

I took your feedback and did some shock tuning tonight on the 11k/11k SBG Ohlins. They are not stock valving but in prior testing I had noted that going softer on the rear shocks made it even more loose than it currently is; I just hadn't tried any stiffer yet. Have a loop near my house that has a couple 80mph mid-corner bumps that used to upset the chassis on the prior setup. Started at my usual 10F/7R and settled on 6F/3R. Tested it all the way up to 2 clicks from full stiff in the front and full stiff in the rear; incrementally one axle at a time. Took a good amount of time. I will probably end up going to about 4F/3R as the transitional response at 6 in the front still leaves some to be desired.

It used to be all "loosey-goosey" over those bumps and is now MUCH more planted now over high speed (80+mph) mid-corner bumps. Steering response and transitional response was the notable improvement with changing the front damping. Car seems to be more stable under hard braking, though I will need more track time to get a better evaluation of that. No problems with corner exit traction as I had previously feared.

Happy to say the car feels much better than before and now feels "as it should". Direct, planted, and pretty much the same ride quality as the prior settings in the majority of situations.

Appreciate the input, all!