dgdoc

Hey guys.

Many of you who know me know that I've been struggling with one thing after another for about 2 years since my last PR (11.45).

My car had not been cooperating, with a variety of ailments from CV joints to most recently, a defective Clutch Master Cylinder that was restricting fluid flow and slowing clutch engagement. While all this was going, my driving actually got worse from being too aggressive and fighting a sluggish clutch pedal.

Last fall I had my clutch problem corrected by Tony's Corvette and then spent the long winter waiting for an opportunity to get back out to the track. (Studying log files from previous passes was getting really old!).

Last week, I got back out to MIR and finally knocked out a few decent runs. The weather was in the high 50's, partly cloudy, with a DA of around 600'.

On my first pass, ran 11.43, followed by an 11.429 a couple minutes later. Let the car cool and ran an 11.431.

Obviously, there is still some rustiness/sloppiness (1-2 shift - yikes), but was nice to get the rhythm back. Seems that being more relaxed and a little less aggressive on the launch - and having confidence that the car was finally right, all contributed to breaking out of the slump.

Although it felt great to finally be back at it, from looking at my times, wondering if there is a new problem: Too much consistency?
Never thought that would ever be a problem. But, think the more experienced racers here might agree there is some benefit in "going for it" once in a while. Otherwise, I might be locked in at the current levels forever.

Anyway, wanted to say thanks again to Ranger and my other friends here on CF forum for all the support and encouragement during this long ordeal.

Phil

Timeslips:





Click here for high-definition version

[Thanks to Ranger and Chris for the video]

glass slipper

Congratulations, I know it's nice to see results after a long battle.

smallblk400

very nice launches!!! Good solid #'s for bone stock

'06 Quicksilver Z06

Nice going dgdoc. Glad to see that things are falling into place for you.

Madsen

Congts.

I know how it is to want to run fast and not get what you want. Your runs look great keep it up......

Dr.Ron

Nicely done Phil, ESPECIALLY after your issues & lay offs!!
I have a question, what was that hiccup/glitch at the end of the 1-2 shift on your 1st pass on the video?? Was It sounded like you hit the limiter AS the tires were chirping or something....

Nice launches as well! What RPM's were they at?

Ron

obzidian

Nice launch!! And congrats on new p.b.! I would also like to know your rpm at launch and looking at your video, how soon after the car moves forward is the clutch fully engaged?

A.

dgdoc

Thanks glass slipper, smallblk400, Quicksilver and Madsen.

I very much appreciate the kind words and all the support. After a long struggle, it really helps to restore a bit of confidence.

IQ AUTO VETTE

Great runs, good to see stock vettes running unreal #s, keep up the good work.

dgdoc

Thanks Ron!

Its been a long time and felt like I was coming out of retirement. Its been fun, but hard watching you and the other guys having a great time at the track. I mean, there is only so much excitement one can get from sitting in front of a computer screen analyzing data logs.

The first run on video was my first run in almost a year and clearly showed signs of rust. Yes, your ears are correct. The 1-2 shift was very sloppy and I did clip the rev-limiter while the clutch was coming out entering 2nd. I recall seeing a 1.8x 60' flash up on the board and lost focus. First time I saw this in the video and in the logs was a "YIKES/WTH" moment - Perfectly captured on video for all to see! Would have conveniently "lost" the video had it not been a new PR.

The launches were at 3600-3700 RPM, soft release, and managed to keep the RPM's above 2200. The traction was very good most of the day.

On the last pass with the 1.85 60', the car slowed down after the 330' as the DA went up, otherwise would have been a better time (and not .002 slower than the previous run).

Thanks obzidian -- I'll have to look at the logs and verify when the clutch was fully locked up.

I recall that the low point for RPM's was around 2200. If that's correct, it meant the car was going about 18.8 MPH when clutch lockup occurred.

Make sense?

GARY2004Z06

Congrats Phil. Very nice 60's. Very consistent ETs. Ron would be jealous. He could use those at the CC.

dgdoc

OK - Checked the logs from my first pass.

Shift times:
1-2: 0.39 (YIKES!)
2-3 0.28
3-4: 0.28

Launch:
Launch RPM: 3600-3800
Clutch Pedal out: 3300 RPM, 10 MPH.
Clutch Lock-up: 2695 RPM, 20 MPH.

Peak TM Intervention
(Timing Retard): 9.6 Degrees
RPM: 3000 RPM
Speed: 25 MPH

Hope that helps.

Let me know if you have any questions.

Dr.Ron

So could YOU!!!

I'd say that is a "fast release" of the clutch on the launch Phil...Nice going.

And I agree, that was a "focus lost" 1-2 shift...

Ron

WeaponsGradeTorque

walterm32

Its about damn time you got out there doc. I wasn't around this weekend to see your thread any earlier. Back to the #7 spot I see!!Congrats on the new PR and doing it in +600 DA should make you feel real good about the fall weather and what your going to see then. I see your 60' got better and will continue to do so now that your back in the game, have a proper working clutch and can get out there and get some reps. Sorry I missed it.

dgdoc

Thanks Gary, but don't think Ron would be jealous of anything I do behind the wheel - especially with consistent 11.43's. However, behind a computer screen might be a different story.


"Clutch Out" is simply the point that the position sensor reported the pedal was out. The switch is not calibrated to the exact position that the clutch is fully engaged, and varies from car to car depending on clutch wear, self-adjustment, etc. So should assume that the clutch is still slipping somewhat at this point.

But this sensor is as good an indicator as we've got, so I find it very useful for comparing runs. Really nice of GM put one of these on the clutch pedal in the C6 -- and you can be absolutely sure they didn't intend it for what I'm using it for.

"Clutch Lock-up" - Represents the low point in RPM's after the clutch is out. What happens in between Clutch Out and Clutch Lock-up is either wheelspin or additional clutch slip. Easy to tell from listening to the videos or looking at the MPH graph.

In the example I referenced above (Pass 1), it was all clutch slip and no wheelspin.

dgdoc

Mike - You're spot on. It is about damn time.

It's been fun watching you and others knocking out ever improving times, but after almost 2 years of BS and one thing after another, it felt good to finally get back in the game again.

As you know, the 60's are a matter of technique and practice. I was too anxious/aggressive before trying to overcome issues with the car. Just relaxing and visualizing the launch helped out quite a bit.

Still don't know why I had all the wheelspin last year (evident on the videos you took). I've still got the same, almost 4 year old Goodyear EMT's, but now they are hooking up OK. Might be due to a better, more precise burnout, staying in the groove, better track prep, or some other factor that I haven't identified.

Whatever it is, I'm very pleased to be back and looking forward to some runs with negative DA's. Hopefully if things go well, will see some 11.3x's later this year.

Thanks again,

Phil

Red Rochester

walterm32

Your crazy if you think your only good for 11.30's this fall. You'll be in the teens at very least if you get some good practice in before then. Mark my words. With the mid 1.8 60's you had last week alone you'd be in the 11.20's in the cold weather. Your too humble sometimes and I think you already know you'll do much better than the 11.30's. I'm willing to bet your clutch was F'd up for longer than you think and was causing the string of launching issues and wheelspin issues you were having.
About the "fast release" of the clutch you guys talk about. I just wanted to point out how much I've found the clutch can be slipped in the z06. IMO as long as the rpms aren't rising as its being slipped there is no problem as long as the clutch isn't already hot and the fluid is very clean. Listen to the launch on this video of me on March 23rd. I was experimenting some that day and trying to push it a bit on slipping the clutch and raising my rpms. I launched right at 4000 on this pass and you can really hear how much I've started to slip it now days. I think this was a 1.77 or a 1.79 60'.
http://www.youtube.com/watch?v=7X0rQGWYoqI
Just to state it again for all you MUST have pristine clutch fluid and a cooled clutch to slip it this much or it WILL sink to the floor on you. Trust me. Back to back passes are all the clutch can handle being slipped like that in very cool weather. In warm /hot weather I think 1 pass is all its good for before it needs to be cooled down again.