Friday, October 24th, 2014

I went down to Laguna Seca Raceway today to cheer on a few friends racing at the SCCA Runoffs, the national championships of amateur racing. Joe Harlan qualified his Nissan 200SX to race in GTL, and Phil Mendelovitz qualified his Datsun Roadster to race in EP. The #79 Phil is racing is a former Runoff winner in 1987 and last raced at the 1989 Runoffs with it’s previous owner Bob Studdard. Here they are pitted in the Nissan paddock.

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“I know there’s money in racing, I put it there!”

 

 

Here’s what happens when I tell my fabricator Paul Moore to just go for it, no instructions included. I asked him to make me some door panels for my Datsun 710 race car, and here’s what he created… All aluminum and a little black paint. My wife says it kind of looks like a Chanel handbag ;-) 710 door panels (Small)

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Great photo by Bob Pengraph of 710s dicing at the HMSA Portland Historics, July 2014.

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Admittedly an aluminum driveshaft isn’t at the top of the list of budget performance upgrades. The biggest bang-for-the-buck improvement is just more track time, period. Then there’s the basics of good tires, good set-up, and good maintenance. Once the basics are covered you can start working on upgraded suspension, brakes, gearbox and engine, and of course weight loss (both car and driver). But once all the low-hanging fruit is gone, you should start doing your cost vs performance calculations wisely when picking the next upgrade. Basic physics shows the greatest advantage in weight reduction comes from unsprung mass and from rotating mass, ie wheels and tires, brake components, crankshafts, and yes, driveshafts.

After a recent gearbox swap in the 710, I was needing a new driveshaft, so I figured it was an appropriate time to do an aluminum driveshaft upgrade. At the same time I increased the diameter of the driveshaft from 2.5″ to 3″. I found some engineering tables that show the dramatic strength increase realized by just small increases in a tube’s diameter, therefore helping reduce driveshaft whip at high speeds. And even with the increase in tube diameter, I dropped the weight substantially by switching from steel to aluminum, from 15 lbs to 11 lbs. Yes, it cost more at $450, but since I was needing to have one built anyways, I think it’s an upgrade worth the money. If you’ve really got some extra bucks to throw into the project, a carbon fiber driveshaft will increase strength and reduce weight even further. The guys at South Bay Driveline in San Jose, CA did a great job as usual, and they don’t make me feel stupid with all my dumb questions ;-)

Last week I raced the Crossle at Buttonwillow Raceway and the afternoon temps were over 100 degrees. Well I found out what those cool looking air ducts behind the radiators are for on other cars I’ve seen, to divert the radiator exhaust air away from the pedal box. My feet were on fire, I actually thought my left shoe was melting! So my crew mate Art whipped up a cardboard air dam to get me through the weekend, and it worked great. Who needs swoopy looking carbon fiber anyways ;-)

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Spent a little time in the garage today cleaning up the old 710 grill. Gave it a power wash, rubbed it down with a little fine sandpaper, then some acetone. Spray painted it with Krylon Fuzion plastic-adhering satin black, hand painted the perimeter with some metallic silver, cut and formed some 3/16″ stainless steel wire mesh for the headlight grills, and couldn’t resist installing a spare Datsun grill badge from the Wagon. Now it’s the best looking part of the car ;-)

Datsun 710 grill

The h165 axle on my Datsun 710 had 1/8″ toe-out and zero camber. It made the handling a bit twitchy and did not give ideal tire wear, so I took it to Paul Moore at The Moore Speed Co and had him fix it for me. After removal and measurement, he used the cut-and-weld method to alter the axle housing geometry to an ideal 1/16″ toe-in and 1/2 degree negative camber.

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710 axle toe adjustment