Question on brake rotors

It is not required to do but since the brake pads on the Prius lasts over 100k miles, you wouldn't have to do it that many times. I would recommend doing it just because you want it to be perfect for the next 100k miles.

 

I just did a DIY replacement of the rear pads. I just removed the rotors and went over them with fine steel wool. I'd had some light scoring on the outer face of one rotor, and on both the inners had a rusty zone, for about the inner 50%. I'm thinking the latter was due to the piston's cross pattern shifting on the pad, causing uneven pressure. Long story short: ~500 km's later, everything looks fine, discs uniformly shiny, minimal drag, not running hot.

OTOH, I can see the dealership's rational. They likely want to avoid potential problems, so just machine them all. Not sure what to say..., it does seem a little dodgy that they're insisting on it, saying it's a necessity.

Rear Brake Concerns | PriusChat

 

listen to mendel, he is the brake MAN!

 

It's the same logic used for alignment recommendations when replacing four tires. You would want to ensure any irregularities are taken care of to extend the life of the replacement wear items as much as possible.

Not required, but purely prophylactic. Besides, as Mendel intimated, if they didn't machine the rotors and the new pads didn't last as long (or wear as evenly) as the old ones, you'd be in there hopping mad with the bespoke "Nobody told me..."

The dealership is requiring it as SOP because they don't want to deal with the fallout and subsequent crap from customers.

 

I used to replace my own brakes and rotors in my previous clunkers. Normally i'd just slap in the new pads or rotors and go. But when replacing only the pads, i'd see shallow circular groves on my rotors. Probably those rotor grooves and ridges would easily eat my pads faster than if the pads had a flat surface to hold on to.

Since I didn't have the proper tools and knew I can easily replace the cheap pads if it wore out sooner, i just ignored them. Tongue in cheek - I figured once those ridges and grooves shaped the surface of my pads i actually would get more surface contacts (lol). Or even if i ruined both my pad and rotors, a pair of cheap pads and rotors cost me less than $100 anyway. Then i got smarter and just replaced both pads and rotors at the same time regardless of condition.

If your dealer has the proper machine and for the price you pay, I'd go on with it. I imagine all used rotors have microscopic ridges and grooves no matter how smooth they look. That way, your pads would last longer.

 

After years of just replacing pads - I now replace rotors AND pads at the same time when needed. Up here in Minnesota, you would be surprised at how rusty wheel components can get. A lot of local brake shops will NOT turn rotors anymore.

 

The price of rotors have come down a lot, sometimes it's the same price as turning a rotor vs replacement. I would also change the rotors and pads at the same time. It takes more than 120k miles to wear them out on the Prius....just once is enough for me.

 

Not good advice, in my opinion.

The rotors on these small cars don't have a lot of spare thickness.
If and only IF the rotors are damaged, I recommend replacement.
If they do not have significant damage, they should be left ALONE.

Turning the rotors routinely is "required" only to increase the shop's income.

 

This is not a "routine" if done once every 100K+ miles. For me, it's once in a lifetime

Yes I do agree you should not mess with rotors unless they are damaged and scored.

 

Close but not really. You can SEE damage to rotors and measure the thickness.
You can almost never "see" an alignment problem without putting it on the machine.

If you have been paying attention to the wear on the old set of tires you are taking off and there has been no abnormal wear, the odds are good that an alignment really is not needed either.

 

Al, ask them how much it costs to machine them and how much more to replace them. If it is a matter of only around $30 difference, get them to replace it instead.

 

congrats al, and thanks for letting us know!

 

I'm not sure why it's required to change your pads so early. They last over 100k miles

 

. On my 2005, I could see no wear on either rotors or pads after over 100K miles, actual friction brakes are not supposed to work until 8 mph. I am in CA so my situation may be totally different weather wise. It is a good idea to use the brakes in neutral at a low speed from time to time just to take any slight rust coating off.

 

. On the Prius, I believe they last forever. I quit worrying about them.

 

At 48500 km on ours and had a look while swapping to snows, I didn't measure but the front pads were noticeably thinner than new, maybe 6mm remaining. Maybe 7mm. We're very easy on them.