A friendly heads up to check your undercarriage bolts

A friendly heads up to check your undercarriage bolts

Hey folks, just a friendly encouragement to check your under carriage bolts if you’ve had your model three for several months… nothing major about this, or dangerous, just a curiosity I discovered and was able to fix easy Peezy. I was under there cleaning something off my rear bumper and I noticed of the three bolts that hold the rear undercarriage panel, one bolt appeared missing. I reach my hand to where the bolt should be and confirmed there was indeed just a hole there. I double checked the other two bolts and sure enough they were all loose and so I finger tightened and then ratcheted them tight. I was able to find a bolt and washer in my junk drawer for the empty hole. That made me curious about the undercarriage front panel, and sure enough when I tapped that panel, it moved a little up and down, so I checked the bolts and the two large bolts needed finger tightening and ratcheting down but the smaller bolts were all tight. When I go in next month for my inspection, I’ve requested the tech to double check the tightness of all my undercarriage bolts.

Just thought I’d share this to save someone from losing a bolt.

Now back to more driving...

Wilber | 03. Mai 2019

M3phan: thanks for the heads up. but i am not that familar with all the body parts and i dont know what a "rear undercarriage panel" is or the front one either. Could you either describe in more detail or link to photos?

M3phan | 03. Mai 2019

Sure. I’ve got a description of how to check it, followed by a link to a YouTube video of an undercarriage inspection with time stamps to the relevant panels I’m referring to

For the rear: Lay down and look under your rear bumper just past it. You’ll see just past then underside of the rear bumper, between the rear wheels, a plastic panel under the back end of the car. It has three bolts along it that secure it to the car. Check those with your fingers.

For the front: lay down beside one of your front wheels and look under the front end from the side. Look at the area between the front wheels and you will see a sort of fuzzy composite panel that is bolted up between the front wheels; you might also want to check the plastic panel that is underneath the front bumper, it’s not attached by bolts but clips, so double check that the clips are secured. Back to that front end composite panel between the front wheels, there are a few smaller bolts spanning its width holding it to the underside of the front as well as two much larger bolts, one one each side of the panel. Easy to see and check the tightness with your fingers.

This video of an undercarriage inspection might help… The front undercarriage composite panel can be seen at the 45 second mark, and the rear undercarriage panel can be seen at the 1:40 mark.

82bert | 03. Mai 2019

So we have 2 Model 3s. One that’s roughly 6 months old and a newer one. Both have a missing middle bolt on the rear under carriage. Wondering if this is how they’re designed?? All other bolts in place and tight. Anyone else wanna take a look?

82bert | 03. Mai 2019

Maybe a stupid thought, but there was an issue with water getting logged in rear bumper/carriage. Is the middle hole an exit for water??

coleAK | 03. Mai 2019

Back in October within a month of taking delivery of our LR AWD I had it on the lift to swap to winter tires. We also had the home in the middle. There was a discussion about it last fall and the consensus was it was there to allow water to drain. The discussion found Some of the early RWD had a bolt there but I’m guessing Tesla removed it as an easy fix.

TickTock | 03. Mai 2019

I was missing one on the front panel and it appeared the bolt was never installed in the first place (threads are very clean and no compression marks on the under panel). They are easy enough to find at a hardware store: M6-1 X 25

stopnair | 03. Mai 2019

I think everyone has good points...just wondering if a service call or visit to Tesla SC would answer the question ...

Kary993 | 03. Mai 2019

@M3phan - thank you sharing this info. Will check under the car this weekend and report back.

ajgianoli | 03. Mai 2019

All my Jan ‘19 built bolts were tight. The middle hole in the back undercarriage cover is just that, a hole. There is no threaded hole beyond it. Must be for water to drain. Either that or a leftover design.

cjw888 | 03. Mai 2019

Thanks for bring up the issue. Our model 3 is ~8 month old, and we just noticed yesterday that there is a gap below driver door, between the painted frame and back undercorriage. wonder if it is caused by loosened bolt(s) like you described. We will take to SC to check out and report back.

joshuatshelly | 03. Mai 2019

There is a service bulletin on this. Same thing happened to me. Bolts backing out. I removed every one and applied threadlock. Had I known about the bulletin prior to discovering this, I would have contacted service. The bulletin states that there are upgraded panels to be installed if this happens. Those early panels are rubbish, hence the bulletin.

My advice: hit service up.

cjw888 | 03. Mai 2019

Thanks, M3phan and joshuashelly, we were not aware of the service bulletin.

Manjushr | 03. Mai 2019

Indeed, our "front Aero Shield Panel" just fell. Here is the link to the Service bulletin. Ranger coming to switch them out this week.

Manjushr | 03. Mai 2019

Indeed, our "front Aero Shield Panel" just fell. Here is the link to the Service bulletin. Ranger coming to switch them out this week.

OrangeinCO | 03. Mai 2019

I checked mine, they all seem tight but the middle was missing. Reading the comments, it must be intentional. I've driven through some torrential rains and haven't noticed any issues, so I'll leave it!

Bighorn | 03. Mai 2019

What size socket?

surfpearl | 03. Mai 2019

@Bighorn - The socket size is 10 mm.

billdragon | 03. Mai 2019

Mine was in the SC last month. Hope they checked. I can't "crawl under it" to check.

Bighorn | 03. Mai 2019


M3phan | 03. Mai 2019

@82bert, my middle hole has a bolt, it’s the left most hole that had the missing bolt.

M3phan | 03. Mai 2019

And I have an older M3, vin 26,xxx

M3phan | 03. Mai 2019

@ajgianoli, yeah but my middle hole has a bolt in it. Might have been dropped for manufacturing efficiency, I guess?? But many of the other bolts were finger loose. So there’s that.

Wilber | 03. Mai 2019

m3phan - thanks for the good details and the video. I'll check mine out sometime in next few days and report back.

huntermunk | 03. Mai 2019

m3phan I agree totally. Definitely check the bolts!

I took delivery about 2.5 weeks ago. Great experience until I got on the interstate after leaving the SC. The undercarriage fell away from the front end and started to scrape the pavement at 70 mph. The next exit wasn’t for 4 miles. Immediately went back to the SC and they replaced the undercarriage and had new bolts in 10 minutes. The technician said they only found 1 bolt remaining before the fix. Great service recovery by the SC afterwards but there was a slight dip in the overall experience for me. In other words check those bolts!!!

lilbean | 03. Mai 2019

Thanks so much for the heads up! And thanks for the socket info @surf. Two out of three were tight.

lilbean | 03. Mai 2019

Actually two out of three were loose and one was not tight. I went ahead and tightened the bolts on the bottom sides of the rear bumper as well, 10mm.

ajgianoli | 03. Mai 2019

M3phan, as my back undercarriage cover had three bolt holes - including the washer indents - and no center bolt, because there is no place for a bolt to go into the frame underneath, seems there was a design change. There was a concern about trapped water. Maybe this was the fix.

billlake2000 | 03. Mai 2019

lilbean, you did that? Way cool!

lilbean | 03. Mai 2019

Oh yeah baby! Love it!!!

lilbean | 03. Mai 2019

Thanks, @billlake2000! :o)

lilbean | 03. Mai 2019

Just did the X and I’m missing one out of four. Ugh!

RES IPSA | 03. Mai 2019

I have a LR RWD built in July 2018... VIN 52XXX

All three bolts under the back bumper were super tight and in place... All ten bolts under the front bumper were tight and in place. All I can say is that I have never driven the vehicle in bad weather or wet conditions (not very tough to do here in San Diego).

jjgunn | 03. Mai 2019

Hella nice find. I'll check out both cars in the morning.

The M3 only has 650 miles on it. They better all be tight.

The MX though....22,500 - need to check that out.

lilbean | 03. Mai 2019

The 3 has 10,000 miles on it and the X has 12,000.

roaddevil | 03. Mai 2019

Mine was built in early 2018, must be inspected by EM himself. I checked the undercarriage and did not find any missing or loose bolts, nor did I see any hole.

Sherry | 04. Mai 2019

Thanks for the "heads up". I checked mine, 4/18 purchase 12xxx VIN, 15k miles. The rear has NO screws in it and the front are all there and tight.

M3phan | 04. Mai 2019

@Sherry, you have three holes in the rear? No bolts? Yikes.

texxx | 04. Mai 2019

Checked mine this morning too. Oct '18 build with about 3900 miles on it. All bolts there, but not what I would call tight. Took a couple of minutes to snug them up. Long arms help if you can't get the car in the air. :)

Mikael13 | 04. Mai 2019

Just washed my car earlier and I remembered this thread. So, I checked and all bolts secure. One is missing in the middle at back but that’s where the water drained out after the wash. Dec 2018 build.

However, I noticed my left rocker panels were not clipped on!! So I just popped them back up. Never hit anything previously. No scratches down there. Weird.

Thanks for the heads up! If it wasn’t for this thread, I would have never bothered to look and I would have completely missed the loose rocker panel.

lilbean | 04. Mai 2019

+1 Mikael13 Yes. Very good, useful thread.

Bighorn | 04. Mai 2019

3 tight in the rear. August P.

M3phan | 04. Mai 2019

; )

M3phan | 04. Mai 2019

.,,ugh, Lord I apologize for that joke right there, and bless all the starving pygmies in New Guinea...

Bighorn | 04. Mai 2019

Left a perv trap;)

stopnair | 04. Mai 2019

Mar 2019 built - All 3 front bolts looks good. In the rear the middle one has no bolt but the other 2 are tight... The center hole in the rear seems intentional to not carry water but allow it to flow out...

JMobs | 09. Mai 2019

I can personally attest to check these bolts. Picked up my 2019 Model 3 LR AWD on Saturday 4 May. On 7 May, noticed a loud rubbing sound on the highway. Pulled over, the rear panel had come undone. Three bolts missing from the front. Replaced and GTG now. Noticed the mid front and rear panels are missing. Does anyone know if Tesla stopped putting these on the cars? My car is a Jan 2019 build.

M3phan | 09. Mai 2019

@JMobs, not sure. Someone here might know, but I’m sure the SC will.

httran26 | 09. Mai 2019

Ah nuts! I checked mine and not bolts in the three rear. Just empty holes.
Anybody know the bolt size?

beaver | 09. Mai 2019

I can’t tell if my rear bottom panel has the bolts. There is nothing over the plastic just a hole with a threaded metal piece recessed inside. Should there be a bolt with a head in each hole? It feels fairly secure but does flex. I have 28k miles with no issues. Mobile ranger is coming tomorrow to rotate my tires so I will ask him/her to take a look.

M3phan | 10. Mai 2019

Bolt size mentioned as 10mm