2018 Prime - 30k miles - Shaking on Braking

i can't think of anything else, very odd

 

Perhaps one of the following?
- Loose front wheel. Check to see if all lug nuts are tight and not stripped.
- Bad alignment (front wheels). It's not uncommon after a curb impact or multiple pot-hole hits.
- Loose or damaged ball joint likely caused by mild impact.
- Damaged or bent wheel rim, or even defect/damage to the tire. Although it likely would be noticeable not just when braking.

I would feel tempted to jack the car up on each side then see if any of the wheels is loose when twisting each at 9-3 o'clock and 12-6 o'clock. This should reveal free play caused by any of the first three listed above. Then spin each wheel while feeling the outer edges and surface to test the fourth.

however tempting, I'm am hesitant to suggest worn CV joint or wheel bearings. Just not enough mileage for that.

Cheers

 

A defective part isn't an impossibility.

 

Tire shine sprayed on rotor?

Pls post back w results so we can learn

 

The most likely cause of brake judder is from excess heat. Very heavy & hot use of the brakes can cause the pad material to be deposited unevenly on the rotor which then causes a stick-slip-stick-slip judder that is felt as vibration. Also, the brakes can be very hot, then the car is stopped and the pads held against the rotors so the rotors & pads cool unevenly resulting in uneven deposits.

The fix for either is to clean the uneven pad deposit off the rotors. This can be done by sanding the rotors with emory cloth and wiping with brake clean solvent. A glazed surface on the pads may need to be sandpapered off. If necessary a new pad material with a higher temperature rating must be used. The uneven brake pad deposits will incorrectly be diagnosed as warped discs. Cast iron discs don't warp. Resurfacing the discs to remove the "warp" removes the uneven deposits as well as removing some iron, so the problem is fixed. So does new discs. If anyone says the discs are warped, ask them to measure the runout with a dial indicator. A few thousands of an inch of runout is common even with new discs, maybe .002" to .003", so they need to be measured as well to know the real story.

 

I've read you don't want to sand rotors with aluminum oxide, which most emery cloth and sandpapers have. It is a hard material that can be left embedded in the rotor surface. Being harder than the iron and pad material, these deposits with eventually stick up above the rotor surface, causing the problem again.

 

In the work order did they indicate they rotated the tires? Perhaps something went wrong--a balancing weight fell off, or wheel not secured correctly. Whenever something new pops up, look at the last thing that was done to the car.

 

An improperly mounted wheel could lead to a 'warped' rotor situation.

 

Could it be a frozen caliper? My Camry had a frozen slide on the right drivers side. Car would shudder and pull to the right.

 

Multiple causes presented, but we won't know more until the OP actually looks at the wheels and brakes, or have a shop do so.

 

Quite obvious they didnt even look.
Time to let the dealership (owner) know, and to not go back there again.
That is a very severe safety problem.

Of course they will give a different explanation due to liability reasons.

 

generally, dealers give it a cursory eyeball exam and mark something down. but it often turns out on the next inspection, you get a completely different report.

you probably had stuck slide pins due to road salt

 

Something in that caliper prevented the pad from retracting when you took your foot off the brake pedal. Salt corrosion is a likely candidate, but it could be something else. In any case you'll need a new caliper, full set of front pads, new disc.

 

30K is the first in-depth brake inspection interval, per Toyota USA.

Every 5K:



At 30K (and every 30K thereafter):




Arguably very vague, but I would suggest a full, pull-off-the-calipers inspection.

 

for a dealer, that means a peek through the wheel spokes

 

Shouldn't be. Even the 5K "visual" inspection is during tire rotation, with the wheels off. A full brake inspection, they'll take the caliper off the rotor, clean and lube the pins, clean and lube the pads/shims, clean and lube the caliper contact points, check the rotor runout and thickness. That last item is all that's spec'd in the shedule, which is remiss. A traditional brake job is all of that. And you don't leave it till the pads are in need of replacement. This is a regular thing, while the pads still have intermediate amount of thickness, might be 2 or 3 times during the pad lifespan.

And it's not free. This is where owners and dealerships can unscrupulously "enable" each other, exercising mutually agreed on neglect.

 

agreed, it shouldn't, but then, how to explain brake pad thickness increase from service to service

 

Yeah I've had that. Maybe due in part in dealerships using % to describe?

I'll just carrying on with DIY brake maintenance, costs virtually nothing, till pads need replacement. And front or rear, takes about an hour.