The short answer
Some Model S and Model X of 2014 to 2020 with a front motor shake under hard acceleration when the suspension is raised, and the front halfshafts are the cause. Tesla's bulletin SB-21-39-001 says it is a vibration only, with no effect on steering, braking or acceleration. If the owner complains and the shaking is there, Tesla fits both updated front halfshafts. It is a repair bulletin, so nothing is done until the problem shows.
The bulletin at a glance
| Bulletin | SB-21-39-001 R3, 19 January 2024 |
|---|---|
| Type | Repair bulletin: done when the problem shows |
| Cars | Model S and Model X of model years 2014 to 2020 with a front motor |
| Labor time | Small front drive unit, built up to 24 April 2019: 2.35 hours, or 3.75 with the clevis Raven front drive unit, built from 25 April 2019: 1.80 hours, or 1.90 with the clevis moved |
| Parts | Both front halfshafts, updated, and on the small drive unit an axle seal |
| Mobile service | No, it needs a service center |
Which cars it covers
Model S and Model X of model years 2014 to 2020 with a front motor, since the halfshafts belong to the front drive unit. Tesla says the years are a general approximation. Which halfshafts and how long depend on the front drive unit: the small one on cars built up to 24 April 2019, the Raven one on cars built from 25 April 2019.
What to ask the seller
Whether the car shakes under hard acceleration, and if it had the repair, the invoice. The latest revision of the bulletin points Tesla's technicians to billing the owner for it, so it may not be free.
Common questions
Why does a dual motor Model S or Model X shake when accelerating hard?
Tesla's bulletin SB-21-39-001 blames some versions of the front halfshafts, with the suspension raised. It says the vibration has no effect on steering, braking or acceleration.
How long does Tesla take to replace the front halfshafts?
Tesla's labor time is 1.80 to 3.75 hours, depending on the front drive unit and on whether the clevis is moved or replaced too.