A 50 Ounce Roadside Jack for the Tesla Model 3

The Tesla Model 3 is one of the increasing group of modern cars that includes not one item for attending to a failed tire. No spare, no inflator, no tire sealant and no jack. Tesla’s assumption is probably that a user with a tire problem will not address the problem themselves, but summon assistance, either via Tesla’s app-based Roadside Assistance or via a third-party solution.

Even if the user is determined to use a portable inflator and tire sealant to get their vehicle back on the road for a more permanent solution, the Model 3 presents a tire-repair “gotcha” - its tires are lined with acoustical foam to dampen so-called “cavity noise” - resonance created in the volume of compressed air inside a tire from impacts with road features.

The acoustic resonance dampener in the Model 3 tires is a polyurethane foam strip (judging from diagrams this strip appears to be perhaps 1” to 1.5” thick, and the width of the tread area) lining the inside circumference of the tire. Tesla is not the first or only manufacturer to utilize the technology, but must have reasoned that it was a worthwhile strategy to reduce unwanted sounds that would otherwise be masked out in internal-combustion engined vehicles.

Tesla’s online store currently lists a “Model S/X/3 Tire Repair Kit” - which appears to be an existing 3rd-party retail product, similar to the integral inflator/sealant “mobility kits” supplied with other modern cars lacking spare tires. But reports on Model 3 forums support the obvious conundrum regarding the self-sealing tire goops, which all work by stacking up bundles of tiny fibers in punctures to provide a structure onto which the sealant finds purchase as it cures. Even if the acoustic foam were porous - which it probably isn’t - the sealant would probably block the foam passages before it ever reached the puncture. So I have no confidence that a liquid tire sealant will work.

About to embark on a transcontinental trek in our Model 3, I was determined to pack contingency solutions for likely mishaps. (As I write this, we are still waiting for two coolant lines which were punctured by an errant truck tire tread fragment which flipped out from under a car ahead of us as we were passing an 18-wheeler at 70 mph. We had to continue our trip in a rental car, and will be retrieving the Tesla soon. But that’s another story.)

I settled on these items for my emergency tire kit:

This set of items can only address a limited set of puncture parameters: a puncture in the tread area; and holes of less than 1/4” in diameter. That said, the majority of road-hazard tire violations I’ve repaired were of this nature, typically caused by screws, bolts or nails. I’ve installed many tire plugs with the wheel still on the vehicle, but the low stance of the Model 3 and closely-contoured fenders severely limits access to the tread surfaces, so getting a wheel and tire off to be able to install a patch in the field would be of tremendous benefit. I’m still uncertain whether I could successfully install a plug with the acoustic foam without unmounting the tire from the wheel, but I’ll have to find that out if and when it happens.

(November 2019 Update: I recently had a slow leak, which our regular tire shop found was caused by a nail fragment and patched for free, working around the acoustic foam. A year ago when we took delivery of our Model 3, there were many questions in online forums as to whether tire service organizations would know how to deal with the foam, and I read accounts of tire shops unmounting punctured tires, cutting out a block of foam to access the inside of the tread for applying a repair, and then gluing the removed foam back in place. With nearly 400,000 Model 3s delivered in a little over a year and a half, service organizations must now have had a fair amount of experience. I’ve also had to replace an entire wheel and tire for a pothole incident, and in early 2019 our Continental Procontact RX RX 235/40R19 tires with Conti Silent foam were not readily available in tire stores - I ended up buying a replacement from Tesla. When I was at the tire shop last week before they had evaluated the tire, they said it would take a half day to acquire a replacement, if it came to that.)

Getting a tire plug kit was easy. I’ve owned many, and I know what I like. Big T-shaped handles on the hole reamer and the plug insertion tool are a must for the difficult task, although you can still end up with cheesy Chinese-made stuff (of course, the better stuff is also made in China). I ended up buying an AAA Auto Club branded inflator. It looked cheap, but it had a digital PSI preset function, a good buyer rating from thousands of reviews on Amazon, and I figured AAA had a reputation to uphold. I bought an inexpensive telescoping lug wrench which included among its four socket sizes the 21mm (I think) that the Model 3 requires.

But what would I use for a jack?

I read forum threads about people comparing “lightweight” floor jacks, but those present a number of challenges. The lightest aluminum floor jacks capable of safely lifting a ton (the Model 3 is impressively stiff - getting a rear tire off the ground by lifting at a rear side jacking point almost unweights the front tire, which means lifting half of the 2-ton car) still weigh 30-40 pounds (half the weight of their steel counterparts); they are bulky to pack in the car; and most important of all, may not fit under the very low jacking points of the car. For something you really hope you’ll never use, it’s a lot to ask, especially when you pack as much as we did for our cross-country trip.

I ran across this Tesla Motors Club forum post, “The perfect Model 3 emergency jack?” in which the original poster elaborates on his personal jack solution: an incredibly elegant Porsche scissor jack included with 911 variants, Boxsters and 944s, among other models. Many examples can be found on eBay - many new - for around $100. Most astonishing, this aluminum jack - rated at 1,000 kilogram working load (2,205 pounds), itself weighs only 40 ounces (1.14 kg)! It’s separate aluminum handle weighs only 5.1 oz (143 grams).

Several people on this thread shared their modifications to utilize the Porsche jack. I purchased a jack and handle on eBay, along with the molded foam holder designed to fit within the cavity of a spare Porsche wheel. I determined that I would modify the jack in a way similar to some examples found in these forums, but with a male “spud” designed to fit in the Model 3’s jacking point receivers. Having a jack accidentally intrude into the battery pack assembly is a distressing concept, and I thought Tesla’s own solution for avoiding this was worth leveraging.

While the forum poster who originally mentioned using a Porsche jack chose to jack under the Model 3’s suspension arms - which circumvents the issues of suspension droop when jacking on the chassis - I am a bit squeamish about experimenting with putting jacking loads into unfamiliar suspension elements of a Version 1 automobile. So I was committed to using Tesla’s jacking points.

I measured the dimensions of one of the Model 3’s jack point receiver openings (and eventually measured the dimensions of an aluminum third-party jack adapter I purchased for use with car lifts and floor jacks). Here are the approximate measurements:

Experimenting with objects from my garage, I found that a 16 mm impact socket with an O.D. (outside diameter) of 0.945” was a slightly loose fit in the right rear jacking receiver.

When the Porsche jack arrived, I measured its vertical dimensions and range of motion.

Using the 5.1+” height I’d measured from the ground to the bottoms of the receivers on inflated tires (keeping in mind that those tires would likely NOT be inflated when the jack was utilized - but if necessary, the car could be driven onto an object to raise it for jack clearance), I calculated these possible lift yields with the Porsche jack:

So as long as the suspension droop of the Model 3 didn’t exceed 5.4” (or almost 7” if I placed a 1.5” spacer under the jack for maximum lift delta), the Porsche jack should work for removing tires from the Model 3.

I had two modification/fabrication tasks: 1) remove the low, oblong Porsche locating spud from the jack; and 2) in its place, mount something as close as possible to the dimensions of the Model 3 jacking adapter’s spud.

In photos I found of one of the many aluminum aftermarket Model 3 jack adapters (see the red anodized adapters I ended up buying in photos below), I saw that the reverse side of the spud had a large Allen-bolt. In a perfect world, removing this bolt might allow the spud to be removed, and thus mounted using its threaded hole with a shorter bolt. But when I experimented with one of the jack adapters I purchased, I couldn’t establish whether the spud could be separated from the puck. Maybe if I’d really put some effort into it, it would have separated, but I decided to seek another path. In retrospect, it might have been worth chopping up a $20 adapter to have a nice, tapered spud. But my eventual solution worked just fine.

That solution was my initial fall-back plan for a spud: a socket for a ratchet. I measured sockets in a hardware store with a micrometer until I found something close to the 0.95” O.D. of the spud of one of my new Model 3 jacking adapters. A Crescent-brand 18mm 12-point socket measured 0.96” O.D., and cost about three dollars.

The height of the aftermarket jacking adapter spud was 0.66”. The height of the Crescent socket was 1.10”. So I sawed off the top of the socket to something close to the target height, and ground the sharp edges off the end.

I’d looked closely at photos of other mods of the Porsche jack, and could see that after those modders had removed the oblong Porsche locating spud, it revealed an oblong slot. When I inspected my newly-acquired jack, I saw that the spud was anchored in the top weight-supporting “deck” of the jack by simply having its short, slotted peg spread apart to mechanically retain the spud. Because the jack is assembled with pressed and peened parts and no removable fasteners, it wasn’t practical to disassemble any part of the jack to access the peg to grind off the splayed “wings.” So I drilled through the top side of the spud with successively larger bits until I could punch and grind the peg away and remove the Porsche spud.

I’d picked up a dome-headed carriage bolt to anchor the socket-spud. In a perfect world, the square key under the bolt head would have engaged into the socket’s 3/8” opening, and helped to prevent the bolt from turning when I tightened the nut. But it didn’t. An internally-tabbed star washer worked to fill in the gap between the bolt head’s square section and the socket enough so that the bolt didn’t spin relative to the socket.

The 3/8” diameter bolt was a loose fit in the oblong hole left in the jack deck after drilling out the Porsche spud.

I fabricated a washer/spacer out of a scrap of metal to center the bolt in the oblong hole.

The whole assembly is very tidy.

To somewhat inhibit the sharp edges of the Porsche jack’s top surface from creasing the bottom of the Tesla (I’m assuming that the steel around the jacking points is heavier than that, but it’s still as much as a ton bearing on a square inch or two of surface), I picked up a large, 1/8” thick neoprene fender washer to slightly distribute the pressure.

The final modified jack with new socket/spud still fits in the Porsche foam holder. For now, I carry the whole Porsche intra-wheel foam carrier in the compartment under the Model 3 trunk floor, along with the collapsible lug wrench, AAA inflator and jacking pad adapters.

The final test: clearing the front and rear tires from the ground at full suspension droop, with some jack range to spare. When jacking a front tire, I trust Tesla’s rear axle parking brake mechanism to safely prevent the vehicle from rolling (they do). But when jacking a rear corner, there is the potential to unweight the opposite rear tire enough to allow the vehicle to move fore-and-aft on its non-braked front wheels, which could result in falling off the jack. To be most secure, chocking one or more wheels furthest from the jacking corner would be advisable.

I hope we NEVER have to use this jack, but I’m glad to have something in the car which serves the purpose with a minimum weight and volume penalty.

All content ©2019 Ellsworth Chou - no reuse of copy or artwork without permission of the author.