Cal Club Autocross Forums

We wouldn't if we were running at El Toro. The car was great at Nationals and El Toro, but on the less grippy surface at CA Spdwy it's pushy. Note Brian's PAX results from the last event. Brian raised the rear of the Vette a bit after Sat's practice to try to get it looser. For Karen and my benefit he didn't want to make it too loose ... but it wasn't enough for him on Sunday.

Brian wants me to do the "O"ring test on the front shocks to see if we're on the bump stops and thus pushing. But if that's an issue, it would have been at least as much of an issue at El Toro/Lincoln.

Don't know what the title is really about but this thread sounds as bad as the spec civic thread on the sccaforums

I've come to realize that changing a car is beneficial only if it's going to make it more confidence inspiring for you as the driver to drive.

Jeff Wong wrote:Don't know what the title is really about but this thread sounds as bad as the spec civic thread on the sccaforums

I've come to realize that changing a car is beneficial only if it's going to make it more confidence inspiring for you as the driver to drive.

Mako Koiwai wrote:We wouldn't if we were running at El Toro. The car was great at Nationals and El Toro, but on the less grippy surface at CA Spdwy it's pushy. Note Brian's PAX results from the last event. Brian raised the rear of the Vette a bit after Sat's practice to try to get it looser. For Karen and my benefit he didn't want to make it too loose ... but it wasn't enough for him on Sunday.

A good setup is a good setup, site specific changes required should be minor.. but it's stock so there are usually so many compromises who knows. I'm with those that say, if the car is already setup well enough to be in the top 10 in pax then just drive it until you can get it there consistently. At that point you can at least see if the changes you're making are making it feel faster or are actually faster.. though without data aq I doubt even that.

I can say that once we had Max's and Toby's cars dialed in, minor tire pressure changes for surface variation were all that were required.

Mako Koiwai wrote: Brian wants me to do the "O"ring test on the front shocks to see if we're on the bump stops and thus pushing. But if that's an issue, it would have been at least as much of an issue at El Toro/Lincoln.

ET and Lincoln are no where near as bumpy as Cal Speedway.

Mako Koiwai wrote:The car was great at Nationals and El Toro, but on the less grippy surface at CA Spdwy it's pushy. Note Brian's PAX results from the last event. Brian raised the rear of the Vette a bit after Sat's practice to try to get it looser. For Karen and my benefit he didn't want to make it too loose ... but it wasn't enough for him on Sunday.

ignore the results from the last event. it was way too hot, all cars were likely fighting push at some point (unless you're a porsche, in which case it was probably crazy loose). If it was a big time event, like nationals or a tour, etc, then yes chase the setup to make the car balanced. but it wasn't so just ignore it, the car will work better when it's cooler.

the o-ring test is going to tell you that you were hitting the bump stops at some point, guaranteed. it's way too bumpy out there. it won't tell you if you were riding the bump stops though, and therefor i wouldn't change anything based on what it tells you.

Yah ... we should really do a Skid Pad O ring test ... or have to tip toe through the bumps at CA Spdwy.

Interesting, Brian doesn't really believe in Corner Balancing his cars ... saying that there are a lot of other areas that are more important. More on that later.

The set-up will likely change anyway because we'll be going to 710's once these Hoosiers wear out, ie. our front tire will go from a 295/35 to a 295/40 = 4/5th inch (!) taller tire. Or we give up width and go to the 275/40 710, same heights, but narrower. I believe the narrower tire is suppose to give great turn in.

What Would You Do ?

Since we'll mainly be running at bumpy CA Spdwy ... will it be better to run the taller tire?

The taller tire won't change your suspension geometry unless you change your ride height, so ignore the question of sidewall height.

And my apologies to Marshall, but I have to respectfully disagree. If you're on the bumpstops, you *may* want to increase your ride height if you're getting non-linear suspension responses from the end on the bumpstops. My rear suspension has the zip ties juuuuust touching the bump stops. They're not jammed into the stop material though.

The zip ties are in the same position as before I raised the rear, yet the improvement is huge. Before raising the ride height 1/8", the car was hopping off the bumps. After? It's no problem controlling the car through the bumps, even at full throttle.

Mike

Mike Simanyi wrote: The zip ties are in the same position as before I raised the rear, yet the improvement is huge. Before raising the ride height 1/8", the car was hopping off the bumps. After? It's no problem controlling the car through the bumps, even at full throttle.

Mike

But what if you were just hitting the bump stop once and making the change would compromise your handling everywhere you weren't... I think all Marshall is saying is that the O-ring by itself just tells you the peak tavel, not how often or how much. Makes it hard to make decisions that would involve a tradeoff.

Which is why one should do this test on a skid pad ...

Mike Simanyi wrote: And my apologies to Marshall, but I have to respectfully disagree. If you're on the bumpstops, you *may* want to increase your ride height if you're getting non-linear suspension responses from the end on the bumpstops. My rear suspension has the zip ties juuuuust touching the bump stops. They're not jammed into the stop material though.
Mike

HOW DARE YOU DISAGREE WITH ME...wait, you have bumpstops? maybe that's your problem. take those things off and you'd have another inch of suspension travel you could lower your car back down that .125 inches. }:)

and yes, my point was you can hit a bump when going straight and not have a problem even though it will push the orings down. There needs to be a better test before you make a change.

Mako Koiwai wrote:Which is why one should do this test on a skid pad ...

a slalom would be better.

Mike Simanyi wrote:The taller tire won't change your suspension geometry unless you change your ride height, so ignore the question of sidewall height.
Mike

and I will respectfully disagree here as well. a taller tire could roll over more, have different transient response, change roll center height, thus a different setup is somewhat likely.

Good stuff ... you realize this thread is also for "yours" and our entertainment!

Mako Koiwai wrote:Good stuff ... you realize this thread is also for "yours" and our entertainment!

I still wouldn't change the car though.

put some sort of time limit on it. Like say a year, where you are only allowed to take notes and adjust tire pressures.

Marshall Grice wrote:

Mike Simanyi wrote:The taller tire won't change your suspension geometry unless you change your ride height, so ignore the question of sidewall height.
Mike

and I will respectfully disagree here as well. a taller tire could roll over more, have different transient response, change roll center height, thus a different setup is somewhat likely.

<nitpick>

Agreed. But none of that would matter until they actually change the suspension geometry, right? (I could be wrong. I frequently am... but that's why I like the "experiment!" m.o.)

</nitpick>

(Note that I'm expressly avoiding the <listen_mutha> </listen_mutha> html tag. What, you haven't heard of that yet? )

I'll definitely back up the "don't change nuthin' " comment though. And when you do, don't get too caught up in skidpad performance. It's only one metric, and can easily mislead you to a setup that doesn't work on real courses.

Mike

Man, I feel like I have to defend myself here.

The front of the car spends a lot of time on the bumpstops, I am certain of this. While obviously not optimal, the benefits of keeping the car low have outweighed the negatives on nearly all the lots/courses I've run on this year. The front shocks do a lot of the roll control and it's been yet another compromise of managing transitional feel vs. shock jacking (Guy's revalve went a long way to help this).

At most sites I've been able to tune the overall balance pretty effectively through tire pressure and rake, however the heat and bumps at the last event proved too much for the already taxed front tires.

I agree with several of you that until the car becomes the limiting factor, they should focus first on just driving. That said, if *I* were going to continue running the car at Fontana, I'd be starting with some ride height changes. Mako just needs to make sure he understands how each change is going to affect the overall system (I'm going to need some time to write up a reply to your last email .

While it's a great car, I'm really not going to miss the web of stock-class compromises.

Oh and I agree with Marshall: Mike, a proper suspension shouldn't need any bumpstops.

and ... what I'll be doing instead of playing with the new garage toy. So little driving time ... so much garage time in an AX'ers life ...

Mako Koiwai wrote: and ... what I'll be doing instead of playing with the new garage toy. So little driving time ... so much garage time in an AX'ers life ...

buy something other then stock and you won't be so happy with how much time you spend in the garage.

Brian Peters wrote: Oh and I agree with Marshall: Mike, a proper suspension shouldn't need any bumpstops.

I agree with him too.

I only have them on the new rear shocks until I have time to dial them out. I just have to make sure I can't bottom out the shocks without the bump stops in place...

I didn't run them on the old shocks at all.

Mike

Marshall Grice wrote:

Mako Koiwai wrote:Which is why one should do this test on a skid pad ...

a slalom would be better.

Linear pots hooked to the data logger would be even better

Will Kalman wrote:

Marshall Grice wrote:

Mako Koiwai wrote:Which is why one should do this test on a skid pad ...

a slalom would be better.

Linear pots hooked to the data logger would be even better

or put a camera on it.

I wish we could see more video of shocks/sway bars and HELMET cams!

Kristoffer Gjevre wrote:or put a camera on it.

Too slow unless you put Pete's 300fps camera on it. Even then, the motion blur would probably make it useless. Unless you hooked up 1000W of light on it or a crazy awesome strobe that can fire continuously at 300Hz! I'll stick to reading the data in graphical form

I thought we're looking at Low Speed absorption