Good Luck to the Z Racers at the Solo Nationals!

[jmortensen]

Can anyone better at math and physics than me work backwards off of the wind tunnel data and figure out what the downforce would be at lower speeds? I'm sure that it is possible...

[tube80z]

Can anyone better at math and physics than me work backwards off of the wind tunnel data and figure out what the downforce would be at lower speeds? I'm sure that it is possible...

Force@lowspeed = Force@highspeed x (lowspeed^2 / highspeed ^2)

So for 55 MPH I get ~32 lbs. So Tom's measurement is pretty close. That said I can measure this on a stopwatch and so can a number of CSP miatas I run against (Jim Daniels/Ron Bauer).

Cary

[tholt29]

...but my spoiler has roughly 2X the area of the wind tunnel test unit. I wonder if spoiler area has a linear relationship here.

The wind tunnel test showed about 22 lbs downforce with the MSA spoiler, 50 lbs with the 5.25" spoiler... or 77 and 105 lbs total change. Also keep in mind my measurements were at the rear of the hatch versus at the road.

We will probably never know the real answer, but thats the nature of bench racing!

Tom

[260DET]

My first run on Thursday:

http://www.vimeo.com/1803106

.........................................................................................

-Rick

Love that HD video, the picture quality makes incar much more interesting.

[preith]

Love that HD video, the picture quality makes incar much more interesting.

Agreed, one of the higher quality ones I've seen lately. What was it taken with?

Also, Rick what broke on the car?

On a side note I must to say the first thing I immediately notice with many vid's is the bare skin. I wasn't too keen on the fire suit when I first started but feel naked without it now.

[fp280z]

Agreed, one of the higher quality ones I've seen lately. What was it taken with?

Also, Rick what broke on the car?

On a side note I must to say the first thing I immediately notice with many vid's is the bare skin. I wasn't too keen on the fire suit when I first started but feel naked without it now.

Thanks. The video was taken with just my point-and-shoot Canon PowerShot SD450 on a rollbar mount.

As for what broke, something wanted out of the tranny bellhousing and made its way out. My theory is that my clutch was not adjusted properly and the throwout bearing was dragging, finally giving up on my second run. With the stock hydraulics and stiff pressure plate it takes some time to get it adjusted just right. I adjusted it before Nats and still had plenty of freeplay at the actuator arm but I guess I was a little off and it started "pumping up", eventually enough to take up the slack I had adjusted in.

Just a theory, I haven't pulled the trans yet.

-Rick

[fp280z]

Looks like my throwout bearing theory was incorrect. My best guess is that the rivet on the pressure plate spring failed and vibrated everything else loose, eventually throwing two of the clutch cover bolts and two of the dowel pins out of the tranny.

http://www.typeischeap.com/clutch2008.html

-Rick

[preith]

Looks like my throwout bearing theory was incorrect. My best guess is that the rivet on the pressure plate spring failed and vibrated everything else loose, eventually throwing two of the clutch cover bolts and two of the dowel pins out of the tranny.

http://www.typeischeap.com/clutch2008.html

-Rick

Thanks for the pics. It's a shame but perhaps you can still save the flywheel. Why not abandon the old mounting holes, rotate the pressure plate, drill and tap new ones?

EDIT: One more thing to add. My coworker had ring gear issues with his Fidanza flywheel (DSM app) and sent it back to them. For $50 they rotated and tapped new ring gear mounting points, installed a new ring gear, and replaced the friction surface for free! Email their tech department: tech@fidanza.com. Their turn around is a bit slow, but they will respond eventually.

Edited December 4, 2008 by preith

[jmark]

JT, Rick and Tom you headed back to the SCCA Nationals this year?

[tholt29]

Of course! Wouldn't miss it! If I don't let John beat me at least once a year I start going through withdrawals!:classic:

It should be a good year. We're back on concrete. The class has 18 registered and we have a few new cars amongst the regulars. 6 different Z's, an M3, an Evo, a 911, a 914-6, an S2000 and a Mini Cooper S. The BMW and Evo should both be major threats.

Run order has just been posted and we are in the first heat on Tuesday and Wednesday... I just hope the weather cooperates.

Tom

[John Coffey]

Go Toby! Sorry guys, Toby's one of my best customers.

[fp280z]

I'll be there too of course! As Tom said, on paper it's looking like a great year for FP. +1 on the weather cooperating!!! (Although my only National trophy in FP was helped out by first day drying conditions in 2007. Hmm.)

Hey John, I may not be your best customer but I will be running the hood I bought from you this year!

-Rick