Rear wheels lock up at high speeds

most wheel bearings are just snug tight so the wheel does not rock on the bearings. they have rollers that need to roll.

It sounds like it needs to be adjusted or something in the transmission stripped, have you checked the rear axle and bearings, if that is the issue i think yo can get a axle and bearings for$250-$275

i would return the mule to the dealer where you bought it,and let the warranty pay for the battery and testing,etc.

Hey Ryan,
Are we talking front wheels or rear wheels ..or both?? We need more info as to when they locked, what you were doing when they locked...etc.. DO NOT FORCE anything,,, please reply with more info... Rear wheels = Have you tried pulling the brake arm backwards,(after you loosen the brake adjustment).. to relieve any brake shoe tension and see if they turn them?..Is the engine in neutral?

Billy, probably burnt belt.Check the attached links,Manuals and guides, Good luck with your Bike
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if its sat a long while with the parking brake on it could be stuck also.

i would assume your rear final drives turned to a pile of scrap iron. you will only have front wheel drive and it will sound like a rock tumbler coming from the back when you take off. most likely $1000 - $1500 to repair. then tell the kids allowed to drive it to stop revving it up before they put into gear its cool but it breaks stuff lol hope this helps

sounds like bad ujoints in the rear drive shaft.

Check the CV axles for play or looseness.

What you are probably experiencing is the overspeed governor. The engine has a governor installed to prevent overevving the engine and to prolong engine life. If this is the case, you need to upgrade to something faster. Modifying the governor is possible, but it will dramatically shorten the engine life and for that reason I will not go into it here. You can Google it and get information though.