On October 13, 2021, Zero Motorcycles issued a recall for some 2020 Zero SR/F motorcycles due to the risk of insufficiently torqued rear rotor bolts that may come loose. If these bolts loosen during normal operation of the bike, they could cause damage to the bike or even result in reduced braking capability. This could, in turn, cause an increased chance of crashing.  

Affected bikes consist of all 2020 SR/F models manufactured prior to December 19, 2019. The final five digits of the VIN numbers on affected bikes will be 13511 or lower. Affected VINs range from 538ZFAZ79LCK11526 to 538ZFAZ76LCK13511 and are non-sequential. A total of 411 motorcycles are believed to be affected by this recall, per Zero. 

If you own a 2020 Zero SR/F, warning signs of this problem include what Zero terms “an objectionable noise” if the bolts have started to back themselves out of the rear rotor. Additionally, scratch damage from the loose bolts may be evident on either the caliper arm or swingarm of affected bikes. The noise is reportedly high-pitched and obnoxious.  

Zero began investigating this issue after receiving reports of three demonstrator vehicles in Europe showing damage caused by the rotor bolts backing themselves out. At the time, Zero factory instructions stipulated that Loctite be used (though the notice doesn’t specify which formulation), and that rear rotor bolts be tightened to a torque of 10 foot-pounds. Zero noted that all affected bolts reported met those installation requirements. So, it re-examined its existing processes and determined a new tightening torque specification of 26 foot-pounds would be safer. 

As of January 20, 2020, Zero began a service campaign, and notified both dealers and owners of this tightening torque change. However, in the event that any SR/F riders missed this campaign, Zero is now voluntarily issuing a safety recall to address this issue. The company is unaware of any injuries or crashes resulting from this issue as of October 13, 2021. 

Zero Motorcycles dealers will re-torque rear rotor bolts on affected bikes to the new, higher specification of 26 foot-pounds. Dealers will also inspect the bolts for damage at that time. If they are not damaged, then they will not be replaced. However, if damage is observed, they will be replaced and torqued appropriately, free of charge to owners. Zero also advises that owners should check the torque of the rear rotor bolts every 4,000 miles or six months, as the maintenance schedule spells out. 

Dealer notifications will be issued between October 18, 2021 and October 25, 2021. Owners will be notified between October 25, 2021 and November 8, 2021. Zero’s number for this recall is SV-ZMC-020-417. Owners may contact Zero customer service at 1-888-841-8085. The NHTSA campaign number for this recall is 21V-795. Owners may also contact the National Highway Traffic Safety Administration Vehicle Safety Hotline at 1-888-327-4236 (TTY 1-800-424-9153) or go to www.nhtsa.gov. 

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