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Live Timing and Scoring

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Saw the live timing this am, looks like many are taking it easy in CMC/CMC2, Dave Schotz came out blastin' though!

Looks like an hp track from the comparative lap times so far.

Its all about the infield!

My car will not turn with a dam!

John, this was posted over on the NASA forums



I know this is questionable posting this guy's business and contact info, but he's at the track and John had some tuning issues.

John ... also, contact Glenn and see if you can't get your turning issues sorted. We have gotten our cars pretty damned neutral and predictable.

I did get the motor tuned, it run's great!

Right now it won't turn, Jason S. @ UE has been working with me, and i think we found it. The upper GW a-arm is hitting the shock tower, so im installing stock uppers right now. Im getting crazy chattter on the front. I have to do an alignment right now.

Thank you so much Mitch, Glenn stop by to help, but he was dressed so nice and they just popped to keg og of shinner bock.

I found the smoking gun. With the aero load, John was bottoming the GW upper arm on the shock tower. HARD. Spring rate --> infinity spring can't damp, rebounds uncontrolled, car loads, spring rate --> intinity repeat

So the shudder should be gone now that John has the stock upper A arms back on the car.

Jason S.

I knew you were having last minute issues with the motor. Glad you got it sorted.

Dressed nice? We're talking Glenn Landrum, right? Short guy, dark hair, wears glasses, platform shoes ...

Glad John/Jason found the issue - let's just say it makes a difference to not have the arm hitting - LOL. I just went through the sorting same issue.

Good luck out there !

Go John! A little birdie told me that T1 is flat!

Rock N roll guys (and ladies)!

Too bad you're not at Mid O this year, I miss seeing everyone already!!!

Looking at the schedule the Championship race for Group B (CMC/CMC2/FFR) is Saturday, AI/AIX on Sunday.

It looks like that was only a partial cure. I've spoken to Mitch and Alan and all three of us are a bit on the stumped side so any other ideas would be helpful.

These are the parts that have been changed and the mid corner chatter persisted. Primarily in the slower / tighter radius corners:

K member
Upper arms
Rack
Tie rods
wheels / tires


These parts have been checked and are in good shape:

Hubs
Lower ball joints
inner lower A arm bushings


Contact has been checked for contact:

swaybar - tie rods
Upper arms - shock towers
swayber - sub frame

Tire pressures are 26 cold, and ~33 hot. Temps are within 10 deg across the face [275 RA1]

Front shocks were refreshed in March. Shock/spring/bar combo has been in place for ~3 years.


Unknowns (to me):

UMI K members -- Are they stiff enough??
Front sub frame starting to crack -- Alan Blane's Idea
Try higher front tire pressures -- Mitch's Idea

Sooo Any thoughts? TIA,

Jason S

How much castor is in the car? If it's running a "bunch" and picking up the contact patches due to excessive camber gain at the extremes of steering travel, that will do it. I've seen it in autocross a bunch and have to remember to unwind the wheel to get the tires back on the ground and working. Does less steering help get it hooked up and turning?

What's the toe setting?

I'm with Alan, subframe cracked/bent good thing to check. I'd check the rear end too to see how much play in the axles, is it making any noise?

Hey Kevin,

I knew I was forgetting something.

Original alignment:

-2.5 camber, 7.5 caster

I was thinking exactly what you were, but we reset alignment to -2.5 camber, 5.0 caster and nothing changed....

Julie, Alan and I both looked over the frame and its fine. :-|

The thing that has eliminated MOST of the rest of it was Mitch's pressure idea. Going out 28 psi cold removed most of the shudder. John is going to try 30 psi front 25 psi rear this afternoon. Seems crazy high as far as RA1 cold pressures go. The other AI 4th gen there (Tommy Schlender) with significant DF is running almost exactly the same settings that John Started with, and has never seen sudder much like the rest of us.

I still don't consider this one solved, but I am completely out of ideas....

Jason S.

When tire pressures get that far out of whack, its indicative of something hardware wise not working together.

Something to consider is the 35mm Strano bar might be too much of a mis-match with the 21 rear.

Ride height, coil bind, shock travel etc. - going static in the front? Too soft a front spring?

I am going with ride height and soft spring rate.

What is the static ride height currently? Fender to ground?

If you are getting aero load and going to infinity then can't be that far off from infinity under braking, and under directional load.

(but take me with a grain of salt... no one likes what I have done with my suspension.)

Are the front shocks shortened?

How much suspension travel is available?

Its not spring rate ...

Full travel
1000lb spring rate
Shocks are UE Bilsteins matched to the springs.

This setup is on dozens of cars across the country.

The difference is the sway bars. Most who run the 35mm Strano front use the 25mm strano rear.

What do you mean by chatter? Come find me tomorrow and we'll do a run down. I'm crewing for Algozine and Erickson in GP Garage 11.

Thanks for all the additional thoughts. The 21 is on there because the car is over steering in some corners and under steering in others. It sounds like some others have had this issue with the 35mm bar up front. So that's certainly something to try.

Hey TJ it was great to meet both you and David today as it was to meet Glen, Jeff and to see Todd and Al again. I'm back in CA already so I'll say more on the whole nationals experience tomorrow.

Jason S.

22mm hollow strano rear. Sam doesn't do a 25 (and I don't think he likes them much either... ). A 21 solid or a 22 hollow are not too far apart in stiffness. I'm not thinking that's it.

What's the toe setting?

Try taking some rebound out of the front shocks...

Edit: I think this car has UE bilstiens, and they aren't adjustable.

Is this thing getting "hard" onto the bumpstops during body roll? That would spike the outside tire and can cause this same issue.

Here's a link to some pics http://www.chevyasylum.com/racing/racing20...13/Welcome.html

I know this guy from another site and he (Ray Buck is his name) lives and breathes to shoot auto racing/shows/exhibitions etc. So if you are looking for some pics of yourself or your competition, keep this link handy. I'm sure he'll have the action well covered and will be updating his page frequently.

Good luck and be safe.

Chris

Doh! ... I knew that ... not sure why I wrote 25. But it is good info about the 22/21. I thought there were some wider differences between the two.

John has 1000/400 spring rates. I doubt it ever sees the bump stops at Miller unless he's on the curbs. From what I'm gathering Miller is glass smooth.

That is true. We walked it Tuesday night and it was incredible.

No front bump stops and after we swapped the GW arms that were acting as bump stops back to the stock uppers, there are no ride height issues.

Toe is 1/16 out.

I'm not really sure I buy the bar, but I've had emails from others who have had that be their issue. With the RA1's even in the most severe under steer, I've never had them shudder. They just slide more and more. I've had race slicks that shudder, just not the RA1.

I don't think John has another bar with him, but perhaps testing with a 1LE bar would be a good data point.

Oh, I think Nick has a spare 1LE bar with him....
Jason S.

Speedcast TV

username is: thunder valley racing
Password is : racer1

Race time for CMC/CMC2/FFR is 3:20pm

Spec Pinata is rolling out now.

CMC in an hour ...

Unofficial results Dave Schotz wins CMC2 and Glenn Landrum CMC! Congrats guys!!!! Brown/Chicca blew up, appeared to finish under a meatball a few laps earlier, not sure if they will be docked from CMC2 second place. Looks like Kevin Margetta finished second in CMC, congrats buddy! It is an all Camaro sweep in first place!!!

Brown's car looked like a rear wheel seal, not a blown motor.

Very nicely done gentlemen!!! Nice job. Sorry I missed it this year...

Congrats to everyone

Does anyone know what happened to Tommy? Looked like he had the lead going into T1 on the start and then went to the back in a hurry.

During practice, he hopped a curb and did something that made the car not want to turn left.
They couldn't find out what it was before the green flag.

Watched the AI/AIX race today, congrats to John Wheeler for finishing the race in a very tough megabucks field! Was sorry to see the leader Dean Martin do a tank slapper (from what I could tell) and then hit the armco head on. Hope he is ok! Looked like a pretty good impact.

Oh man thats too bad. I was jumping for joy when the field went into T1 and then thought he hurt the motor or something the way he was slowing.