3 quick questions - audible/felt thunk with regen brakes, and 2 more

MileHighMotoring said:

Two quick questions from a new Roadster owner.

1) There's a pretty strong thump when you take your foot off the accelerator pedal, when I assume it's switching to regen braking. Going very slowly, under 10 mph, if I pull my foot it's really noticeable. I can hear it and feel it too. I've got lots of experience with regen braking (hybrids, and this is my 3rd BEV) but this is not what I've heard or felt before.

2) I have clear round stickers on the inside the arms that hold the side mirrors. Just wondering what these would be doing there? The car has the factory pait protection film, but it's hard to imagine a rock hitting the rear-facing side of the side mirror arms...

3) On the little display screen, when driving the top right always says N/A. What am I missing there?

Click to expand...

#1) It sounds like a worn rear tie rod. You shouldn't have any noise when you take your foot off the pedal. It could something else, but you should get it inspected, as the tie rods can be a serious issue.

#2) The stickers are actually body colored and cover the bolt holes that attach the mirror to the base.

#3) The top right displays altitude and direction, and gets info from the GPS antenna located next to the left headlight, under the bumper cover. It is probably bad or disconnected.

#1 could also be normal CV axle slop (where it connects to the gearbox), I've always had it since 3k and yes you can feel it under 10mph. I've learned to lightly let off the accelerator and lightly press on it so its a smooth transition. You can make it happen like I said after its thumped upon a quick low speed regen and then again when you make a quick tap of the accelerator. Also could be coming from inside the gearbox, such as the diff. I have around 56k, the noise hasn't gotten any louder. So with mine it appears more of a design feature.

Below isn't a pic from the Roadster, but its the same part/area I feel the noise is possibly coming from. My best guess is that there's some play with the component the CV slides into, the part the black boot wraps around. If its not there, its coming from inside as I mentioned (possibly the diff). Also double check your rear-tie rod as well, that could cause a noise like that as MAUTO indicated. You should be able to narrow down if its coming from the outside area by the wheels or more inward like the gearbox:

I have the same sound when stepping on and off the accelerator pedal. It's more of a "clank" sound and feels like slop in a CV or gearbox as Wiztecy points out.
It's been there since 3k miles (have 13k now) and I had it checked out by Tesla at 8k miles. They said all cars had it but some 2.0s don't seem to have the sound.

After months of debugging I'm pretty sure it's the gearbox engaging. I could not narrow it down - it's really hard - you would need to raise the car.

As for #3, it'll show "N/A" when you're in park, but direction and altitude while the car is in gear so, depending on when you looked at it, you might not have a problem. If it shows N/A all the time then I agree with MLAUTO; you've probably got a bad GPS antenna.

If the sound is from the front left it's probably the CV. There is no drive in front.

MileHighMotoring said:

The regen thunk sounds like it's coming from the left front tire area, like it's really close to my left foot.

When you say left headlight (for the GPS antenna) is that driver's side or passenger side? Any way to see it without major surgery?

Thanks everyone.

Click to expand...

Left is drivers side. You will need to remove the headlight to reach it. Not that hard-only three bolts once you remove the wheel well liner. The connector is a 6 pin white rectangular one. It should be visible underneath without removing the headlight.

The clunk from the left front sounds like something loose. If it is right by your feet it is probably something with the steering rack-either it is loose or a bad tie rod. Jack up the wheel and see if you can get a clunk by forcing it in different directions. There shouldn't be any play. If you get the wheel well liner off, you can check to see if anything else is loose. About the only thing heavy enough to cause a load clunk is the brake vacuum pump in front of the tire.

MileHighMotoring said:

The car had it's annual physical a few months before I bought it and wasn't driven at all in that time since. I'm sort of shocked that something like this wouldn't have been caught by a Tesla service tech's test drive, inspection, and annual service.

Click to expand...

Typically they don't road test the cars during servicing unless you pointed out something where they'd need to look further and investigate by driving and reproducing. Its typical of most service centers. I personally don't want them driving my vehicle unless I ask them to.

wiztecy said:

Typically they don't road test the cars during servicing unless you pointed out something where they'd need to look further and investigate by driving and reproducing. Its typical of most service centers. I personally don't want them driving my vehicle unless I ask them to.

Click to expand...

They road test mine every time. I know this because I get the toll road bill (Don't drive them, so it's a separate bill each time).

jerry33 said:

They road test mine every time. I know this because I get the toll road bill (Don't drive them, so it's a separate bill each time).

Click to expand...

LOL they drive mine, too! Before I had my EZ Pass transponder I got a ticket in the mail along with a nice little photo "portrait" of my car driving through! Actually the most recent service they didn't drive it. I monitored everything with OVMS, which was kind of fun. Thankfully they plugged it back in when they were done with the port!

edit: Tesla apologized and immediately paid the ticket. They also always got permission to test-drive before hand.

By the sound of the tickets I think those Roadster's were chosen cars to do their lunch runs

I know they take mine for a test-drive, when needed. When I had the car in to service the PEM (because of overheating), they took it for a test drive.

How do I know? Because when I drove over there to pick it up, I ended up behind it on the roads around the service center.

I had to take a picture of it...mainly because the guy who does the Roadster service (who is a great, great guy) doesn't really fit into the Roadsters very well!

MileHighMotoring said:

And on the GPS antenna, I paid $150 in diagnosis for them to tell me it's faulty and will be another $600 to replace it. I declined that for now. Any reason I need this? I don't like seeing "N/A" on the display, but $600 to tell me what direction I'm traveling is a bit rich. Apparently the GSM connectivity is switched off because of this. Not sure if this is important to have functioning in a Roadster.

Click to expand...

I had my GPS module replaced under CPO warranty about 2 years ago. I think the part itself is only about $90. Considering the Tesla up charge for the part + labor, $600 might be about right. It does take some digging around - I think jacking one side up, removing a tire, then some wheel well panels, and maybe a headlight, finding the old module, and the tracking the wire back to wherever it goes. An audio shop might be able to replace it for you for less.

As far as the functionality and cost-benefit of repair, I guess if you want to know your direction and elevation, it might be worth it. I think OVMS uses it for car location, too. $600 does seem steep for that, but knowing myself, it would drive me crazy enough that I'd probably pay to get it fixed. I just want things fully functioning, especially in a car at this price point. On the other hand, I can certainly understand your decision to decline the repair.

See this thread, it's only $65. Takes less than an hour to replace.

Roadster data/GPS module, need help