Dear Tesla community : Making the Small Drive Unit immortal wasn’t easy – but it also wasn’t impossible. Simply buying existing repair kits is not enough because milling or clicking noise was still there.
The clicking noise and axle vibrations we noticed on an SDU we received over two years ago seemed like an isolated case at first, most likely caused by the half-shafts. But in the past two years we received around 20 similar inquiries, and we weren’t fully certain about the root cause, so we didn’t act prematurely.
After 5 months of dedicated work, we finally identified the real issue, sourced suppliers, and solved the last missing piece: the output differential gear. The repair process itself demands precision and attention to detail – inspection of the gear seat radius and bearing surface, machining or polishing when required (in this case polishing was sufficient), production of hardened shims to fine-tune gear backlash, and the use of new shafts heat-treated to 61 ± 2 HRC and precision ground to the required tolerance. Pin holes are drilled with carbide tools, side faces milled for oil relief, while the hardened gears themselves usually remain intact, with wear limited mainly to the shims. In this work, even a deviation of 0.01 mm can make a crucial difference.
Soon we’ll release a full video and a new repair kit, complete with an exchange program for refurbished differentials (“old for new”), as well as reconditioned motors available for other workshops and franchises.
We also discovered why Model S and X often destroy brand-new half-shafts in a short period of time. The cause is not only wheel suspension or motor mounts – but also a worn differential inside the e-motor. Excessive wear and internal play within the planetary gear set cause the axle to shift off-center under load, ultimately destroying the CV joint.
It’s also important to note that not every clicking or knocking sound automatically means the drive unit or differential is defective. The motor is the cause only if the half-shaft has noticeable vertical play inside the motor housing. In other words, not every forward or backward knock is a legitimate differential failure – misdiagnosis can easily lead to unnecessary motor replacements.
This issue can appear after around 300,000 km, but we have also seen units running smoothly up to 600,000 km without any differential problems. Driving style plays a decisive role – aggressive launches and drifting significantly accelerate wear, while smoother driving habits can extend the life of the drive unit far beyond average expectations.
OEM Price: 3800€ + Tax
OEM Labor Rear : Front : 800€ : 1200€
EVC Reman : 2000 + Tax
EVC Labor Rear / Front : 400€ : 800€
EVC Diff: 580€ + Tax
Part numbers: 1035000-00-F, 1037000-00-F,
