Prius pulling to right under regen braking

Problem is likely in the right side half-shaft axle.

 

I had a brake fluid change once that left one rear (drum) brake inoperative. Just for giggles: jack up the rear, spin a rear wheel then have an assistant push down the brake pedal, see if it stops the wheel. Try this on both sides.

Symptoms I noticed: seemed to take longer coming to a stop, ABS was going off a lot, and there was an odd side-to-side rocking, just before full stop.

 

did it do it before they were replaced?

 

I wish I could guide you further- just offering support in the logic department. Regenerative braking and engine braking both depend on the torque coming back through the driveshafts to the differential. The diff combines the force and delivers it up to the trans.

If a wheel bearing is worn, a CV joint binding too tightly…? I’m really not sure where to look. Might help to take temperature measurements of the bearing hubs at the bottom of a hill immediately after descent.

 

I wouldn't presume to know when it's regen braking vs friction braking (or both?). Again I would recommend to raise the rear and verify you have braking on both sides.

One other question: is braking distance the same as usual, does it seem to take longer to stop? Or no?

 

it's always regen with foot off both pedals?

 

Yeah must be.

 

Note that regen and B are just 2-wheel (front) braking, while normal friction braking (when in Neutral) is 4-wheel. A problem at one wheel position will be more noticeable when braking with just 2 wheels, and somewhat masked in 4 wheel mode.

 

These guys?