Xpert 4000 Series "Super Torque" Metal Gear Waterproof Digital Brushless Servo

Xpert 4000 Series "Super Torque" Metal Gear Waterproof Digital Brushless Servo
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This is the Xpert 4000 Series "Super Torque" Waterproof All Aluminum Case Metal Gear Brushless Servo. This servo is identical to the standard SM-4401 servo, but is waterproof for improved reliability in harsh conditions. Xpert servos feature brushless motors, combined with metal gears, 4096 resolution and a unique SIC (Single Integrated Circuit) to deliver incredible performance and durability. The design features a machined aluminum upper and lower case for incredible durability, with an aluminum middle case that provides optimized thermal dissipation. Additionally, over current protection, over temperature protection and a built in fail safe delivers reliability that make this servo a great choice for a variety of applications.

For more Xpert Servo specifications and recommended applications, click here.


  • Waterproof!
  • Brushless motor design provides extremely high speed, incredible efficiency, and low power consumption.
  • 4096 resolution and SIC (Single Integrated Circuit) for the highest performance and durability.
  • Light weight design
  • Aluminum middle case for optimized thermal dissipation.
  • Strong Metal Gear
  • Glitch-free
  • Sophisticated error correction
  • High-Speed, High-precision 12-bit AD converter and CPU calculation
  • Fail safe
  • Over current protection
  • Over temperature protection
  • Start tone


  • Speed:
    • @4.8V: .106 sec/60
    • @6.0V: .085 sec/60
  • Torque:
    • @4.8V: 14.72 kg-cm (204.31 oz-in)
    • @6.0V: 18.40 kg-cm (255.39 oz-in)
  • Input Voltage: 4.8 - 6.0V
  • Dimensions: 40x37.8x20mm
  • Weight: 73.6 g
  • Frequency: 50-400Hz

This product was added to our catalog on November 10, 2014

Verified Owner
Tuesday, Nov 3 2015 (about 4 years ago)
Xpert 4000 Series "Super Torque" Metal Gear Waterproof Digital Brushless Servo
You're out of luck.
I used this servo on my xray xb9 for one season (about 12 competitions and 30 days of practice) and have no any problems. Month ago I bought a new xb8 and put this servo there. Everything is good. This servo is cheaper than savox, there is no need in bec, and it is waterproof.
P.S. 04.03.2016. Now it is one year of using this servo. Everything is good. I use it in different conditions: sand, mud, water, in summer and winter... In september I bought a new xb8 and put this servo on it from my previous xb9. You can watch some fotographs of my xb8:
Verified Owner
Saturday, Oct 3 2015 (about 5 years ago)
Xpert 4000 Series "Super Torque" Metal Gear Waterproof Digital Brushless Servo
This servo seized up on me. I opened it and that potentiometer shaft had seized. Upon re-assembly the servo is really stiff. When I powered it up, it works, but you can tell the servo is fighting in it's neutral position. This servo is only about 2 months old, and has only had a few hours on the track. I'm sending it out for service. Considering my other Xpert servo is also seizing up on me, don't risk your dollars, buy another brand.

*below is Xpert USA's official response:

In response to the low ratings and comment posted previously by a customer we thought it was important to note the following information. If would be very rare for a potentiometer to go bad, and would need specialized equipment to verify that. Its a rare claim to be made - only 2 units we ever received with that claim worked with no issues found. Also to have 2 different units with the same exact failure would be rare. We even gave the customer new units as a show of good faith, even though no issues were found. We just wanted to make sure customers were not mislead without all the information. Xpert servos have industry leading protection built into the units with both over current and thermal protection built into the software. Its possible that some may see these protections as a glitch or issue that is actually protecting the servo from the root cause of a different issue.
I would like to add that their warrenty service was very good and they did stand behind their products. I'm not out for blood, I'm only being objective and critical. I bought two servos, both failed in the same manor. Based on that experience, how can one give a positive review, you can't. But I do thank you for standing behind your product.