Inside the cabin, we’re adding a bunch of devices:

• Android tablet for the rally software
• Rabbit Pro box for GPS and wheel speed sensors
• Dashcam
• helmet intercom
• Rallysafe tracker
• A smartphone for the driver’s display

Naturally, there’s no universal standard for this stuff. We have two USB-C consumers, two 12V units, an ATM06-2S plug, and a plain-old USB-A. Oh! And the shielded three wire cables for the wheel speed sensors, plus the large gauge static drain wire.

Hope Renee wasn’t planning on putting anything else in the glove box. Here’s a little tray with supplies for four of the seven devices.

 

The Targa Newfoundland registration materials include an outright declaration that you shouldn’t run a tire aspect ratio less than 40. Lower aspect ratios are better for ultimate steering and cornering performance, but we won’t be on a race track. We’ll be on country roads, and in neighborhoods, and on moderate arterials within towns. There are potholes, broken pavement, frost heaves, nooks, crannies, cracks, rough patched places, the lot. Heck, that set of hazards also describes the 3500 miles of US roads between here and St. Johns.

So this project skews the tire-and-wheel formula away from circuits and toward “normal roads”; that is to say, “rally roads”.  We want more sidewall!

The Cayman, even with its large front brakes, can fit 18 inch wheels. Porsche even sells a factory accessory set of 18s, mounted with Pirelli snow tires. Having the specs of that accessory set, I duplicated the wheel widths and offsets onto a set of Made in Spain Braid Wheels. I paid the $376 customs duty with a smile; I’m sure the Spaniards will send me a check soon.

The tires are high-performance all seasons, in the identical sizes of the factory accessory set. The UTOG Treadwear rating is a 540; somehow I doubt we’re going to reach the mileage that that rating usually implies.

Here’s an 18″ front with the all season 45 aspect ratio versus the OE 20″ with a 35 aspect ratio tire.  Mr. Dunlop would be proud.

 

The Cayman’s engine is amidships, but its radiators are upfront. Porsche must think that these cars live on a racetrack, cause there’s really no grill over any of the three front radiators. But off courses, the roads are littered with rocks, and metal debris, and the odd low-flying bird, and the gaping maws of the radiator inlet started looking like intake scoops to me. I was concerned.

I got some nice metal honeycomb grill material and was going to fabricate my own protective grills.

But I soon realized the most effective way to do that would be to remove the front bumper. Then I didn’t wanna remove the front bumper 🙁

Aftermarket to the rescue. I’m not the only one that wants those grills. These came from England, in like four days…and they pretty much snapped in.  Maybe not immediately, but Josh methodically got to the right technique for it.

The installation also reminded me that my friends have higher standards for fit-and-finish than I do. I’m … more of a tractor mechanic than a supercar wrench. I take comfort in my continuing opportunities to improve. 

The Hall Effect sensors we’re using come from a rally savant in Spain. One nice touch that he includes is an indicator light—on the sensor itself—which tells you it’s working.

See, there are several ways to assemble this kind of system incorrectly. (I’ve tried most of the incorrect ways…)  Once you’ve done that to yourself, and skipped the testing because “I know it’s right”, only to find yourself at the rally without a odometer, you’ll never skip the testing again.

So when you’re mounting these sensors, putting the magnets in place, aligning the barrels of the sensors to the face-plane of the magnets, adjusting the gap distance, … your testing can take place under the car. All you need do is power the Rabbit box, spin the wheel (or brake disk, in this case), and watch for the lights.

This car company’s obsession with weight doesn’t end with that jack I described in the previous post.

A gram here and a gram there, and pretty soon you have … several grams.

Consider the lug bolts. The 996s had bolts with 19 mm heads, the 997’s were also 19 mm heads, but the heads were shorter by four or five mm, and this car now has 17 mm headed bolts — all these with the same thread size. A steady trimming away of what was not needed.  Because if you don’t need it, why are you carrying it around?

When you notice these things, you may start to develop a sympathetic obsession. You’ll notice if something that you’re adding to the car is made of heavier material than it needs to be. That sensibility can lead you to building things differently.

Here is a fabricated mount to hold the driver’s display for our rally computer. 

The fittings and vertical stalk are just nicely manufactured commercial products made for motorcycles. But that larger horizontal base is a small chunk of high performance aluminum tubing. 

OK to be honest, it’s a sawn-off end of a mountain bike handlebar that I’ve had my fabrication oddments bin for years. Using materials on-hand is a longstanding obsession for me. 😉  Here’s the matching piece from the other end of those handlebars (I trimmed the bars at some point to improve ergonomics).

 

Regardless of its history, that chunk of tubing is very light and very strong, and in my current weight-obsessed state, it seems the perfect thing to use.

A big reason that we’re taking our newest car to Targa is that there’s less chance of a worn out part failing on the long, long transit to the other side of the continent. Or on the long transit back, for that matter.

Lower chance of part failure means a lower need to carry spare parts. And it’s a good thing we don’t have to carry many spares for the Porsche, because there’s very little cargo room in the car.

Porsche does not include a spare tire, even an inflatable one, with this generation of Cayman. The car does come with a small air compressor and a canister of tire sealant, which could be used to seal a small puncture and get you off the side of the road. There’s also Porsche roadside assistance, which is what I think most people use.

Porsche roadside assistance isn’t going to be any help during the rally, there’s just no time to wait for them, nor are they likely to have a solution that would have you back in the event, ready to run the next stage. We will have to have spare tires and wheels readily available to us on The Rock. That’s the subject to a future post. 

There’s also no jack provided; but that’s an easy fix. The 996 generation of Porsches came with a tidy aluminum scissors jack (p/n 99672121100), and those jacks still work for our car. They’re so light!