Porsche Cayenne Project: Installing An Engine Skid Plate From Eurowise

2022-05-21 03:30:43 By : Mr. Grace Cheng

Porsche built the original Cayenne with incredible driving dynamics, both on the tarmac and off-road, but the factory underbody panels need some help.

When I bought a 2006 Porsche Cayenne Turbo last year, the combination of spectacular driving dynamics paired with relatively impressive off-roading ability drew me to the model. Porsche built the first-generation Cayenne, known by the internal designation code 955, with an optional air-lift suspension system, adjustable shocks, and a true low-range transfer case equipped with a locking center differential. Throw in 450 horsepower from a twin-turbo 4.0-liter V8 and the combo remains unique to this day other than the next face-lifted generation, the 957.

But a few little modifications can go a long way towards increasing the 955's off-roading potential, without sacrificing much of the on-road characteristics that made the 955 the world's first super-SUV. I began by sourcing a set of knobby Open Country A/TIII tires from Toyo for better traction in sand and snow without adding too much road noise or crushing my miles per gallon. The new rubber added another dimension to my off-roading plans but all along, I knew that the Cayenne's dry-sump V8, Aisin six-speed automatic, and transfer case needed a bit more protection than the flimsy plastic underbody panels installed from the factory.

After a fair amount of research and some inspiration from Harrison Schoen, aka 957Adventure, I landed on a beefy steel skid plate from Eurowise, in North Carolina, to armor the underside against the big bumps. Luckily, installing the engine skid plate proved surprisingly easy, requiring only a special rivet-nutter in addition to a standard set of average tools. Eurowise published a video on YouTube showing how to install the skid plate, but out in the desert without cell phone reception, I wished for a written-out DIY guide with photos—now, I'm writing one.

To start installing the stronger skid plate, begin by removing the plastic trays underneath the engine and transmission. A bunch of 10-millimeter screws and four Phillips-heads hold the two pieces together and secured to the truck. Whether you want to keep the original pieces or toss them affects how quickly you can finish this step—I decided to keep them for comparison (and in the spirit of Porsche originality).

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I grew up with the mantra "measure twice, cut once" drilled into my skull from a young age, so before I began playing with the fasteners that Eurowise ships along with the skid plate, I first used a safety stand to hold the heavy piece of steel up against the subframe mounting points. This allowed me to verify that the holes matched up without any clearance issues or rubbing of the engine and trans surfaces. Just by eyeball, the rivnet holes looked aligned and the clearance looked fine. Plus, I now knew exactly where to install the six rivnuts, since the kit came with no extras.

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Learning How To Use A Rivet-Nutter

Eurowise offers an add-on rivet-nutter tool with all their skid plates. Having never used one before, I took the time to lay out all the various pieces and read the included instructions. Eurowise's video gave a hint about how to use the tool but skipped over what prep might be required. I fiddled with the various heads and installed the M12 fitting, after screwing it into a rivnut as a test. Don't forget to tighten the correct-size lock washer on top after replacing the tip! And always make sure to keep a little gap between the rivnut itself and the tool's pressing edge to avoid stripping threads or crushing prematurely. This definitely qualifies as one of those tools where everything makes sense only after you've used it once.

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My first try at rivnutting involved a bit of trepidation. I wanted to avoid stripping any threads, worried about crushing the metal too hard, but also needed to make sure the grip lines kept the nut completely fastened. My recommendations include prepping with enough travel length by turning the center dial back a bit, but also starting with the handles at an acute angle. This allows for a bit more leverage at the beginning of the squeeze, after which the process gets easier.

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After the first rivnut, I felt more confident and moved quickly. I installed the smaller four first, not realizing that the larger rivnuts still used the same M12 threads—the order doesn't really matter as long as the larger rivnuts go into the larger holes, so maybe starting with the bigger two makes a bit more sense to avoid a mistake. Regardless, pay attention to the gaps between holes on the skid plate itself!

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Again, because of my amateur rivnutter status, I hand-tested each one by screwing a bolt in halfway and wiggling it, just to make sure I applied the right amount of pressure. They all seemed tight enough to hold up the skid, plus I figured that torquing down the bolts with the skid plate installed would further increase pressure on the rivnuts.

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Next, I slid the skid plate back up on the safety jack, with a block to hold steady and maintain pressure on the bottom as I screwed the bolts in hand tight. After a lot of experience dealing with the finicky skid plate hardware on my 1998 Mitsubishi Montero, the Eurowise design seemed incredibly easy, with more space for wiggling the bolts in and avoiding stripping threads. Plus, the larger bolt's head gets some protection from the metal shim rings, in case of a rock collision (the entire point here, after all).

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Eurowise specifies torquing down the bolts to between 40 and 50 lb-ft, which seemed a little low to me since they measure almost a half-inch thick. Plus, the bolt heads work with 3/4-inch or 19-millimeter sockets, just like lug nuts that typically torque to more like 80 to 100 lb-ft. But the limiting factor here seems like the rivnuts themselves, and torquing to 45 lb-ft felt tight enough after I stopped thinking so hard and just did it.

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This skid plate from Eurowise, which weighs around 70 pounds, truly impressed me in terms of fit and finish. The metalwork itself looked substantial enough to take a beating, while the hardware lined up much more precisely than just about any other piece of aftermarket equipment I've ever bought. Suffice to say, I plan to purchase the matching transfer case, rear differential, fuel tank, and air suspension skids as soon as my budget allows—each piece costs a pretty penny, but much less than tearing up and needing to replace a critical Porsche part!

The only question that arose during this job involved the two plastic pieces on each side, seen above, that screw onto the original engine trays. I decided to tuck them behind the skid plate rather than trimming, just in case I ever reinstall the originals. If they make a racket on rough roads, a quick chop should solve the problem.

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The engine skid alone makes me confident enough to test the Porsche and those Toyos once more on a nearby tough trail up Paiute Ridge, on the Mojave Road. I've previously driven this climb multiple times in a Jeep Gladiator Rubicon and my Montero, so even though the trail always changes a little due to weather and traffic, I should learn just how well the Cayenne's low-range and center diff function. Hopefully, the truck shows up for the challenge and justifies my installation of such a beefy skid plate—not to mention the financial hit. In the meantime, the rough roads of West Los Angeles won't know what hit them when this Cayenne comes rolling through.

Sources: eurowise.com, instagram.com, and youtube.com.

Michael Van Runkle grew up surrounded by Los Angeles car culture, going to small enthusiast meets and enormous industry shows. He learned to drive stick shift in a 1948 Chevy pickup with no first gear and currently dailies his 1998 Mitsubishi Montero while daydreaming about one day finishing up that Porsche 914 project. He's written in various media since graduating from UC Berkeley in 2010 and started at HotCars in February 2018.