Well, maybe all you need are new bushings for the cush drive in the rear wheel.
From the side, with a grip on-top of the wheel/tire, try wiggling the wheel back and forth, side to side. If your cush drive bushings are worn, you should be able to see movement apparent. This will work best with the wheel off the ground. Hopefully you have a centerstand, or a bikestand if your centerstand is missing.
This can also reveal worn wheel bearings. Of course, in a 'worst-case scenario,' where someone working-on the bike failed to properly torque the rear axle castellated nut, the wheel would also wobble. The presence or absence of that wobble allows you to rule-in/rule-out those possible causes of it.
I have a question for
Rempage R1: what was the source of your bent axle? What was the cause of it bending? I'm no mechanical engineer, but the size of the axle and its alloy, It would take a considerable blow to bend the axle.
From the O.P.'s description of the force of impact, it doesn't sound like the blow was substantial enough to bend an axle. I would expect that a wheel would be cracked or bent from a sufficient force which could cause an axle to be bent. He doesn't say if he was stationary and the car was moving. It sounds like both bike and car may-have been moving slowly (per his self-report of '15 MPH') and that the car grazed him with enough force to knock him to the ground. I'd expect that to be something like traffic coming to a light, and the car tries to squeeze-in next-to the bike, as they're about to come-to a rolling stop, and, the car impacts the bike with a glancing blow. In the absence of the O.P. providing us with particulars, it's all academic anyway.
A bent axle is very easy to ascertain. Rolling a clean axle on a piece of glass, with the hex head off the side, will quickly reveal any 'hop' in the axle.
One of the things that my friend does on the Hyabusas entering the shop for work, is to regularly-replace the cush drive components in the rear wheel hub. These are frequently-worn to where they need replacement. It's like replacing a chain and sprockets, replace the cush drive pieces too. Here's one of the bikes at my friend's shop typically getting work done, like that, among other things this is receiving a full titanium exhaust, $2,000 for that, before installation.
When you're building big-bore Hyabusas running on NOS, things like cush drives are 'expendables.' One of their recent Hyabusa builds sporting a huge turbo turned 585 RWHP on a Dynojet dynamometer they use at another shop.
That might-bend your axle! Just out-of-frame to the left of this view is the NOS licensed filling station.
