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Please see pic attached. The left part is the reflection from the shiny rotor. I circled what seems to be the pad itself (due to camera angle, the reflection seems to show better than the real thing)
. Do I have this right? It seems quite thin.
Brake pads typically are recommended to be replaced at 3mm thickness (about 3 dimes) I cannot determine much from your photo. Try more photos from different angles.
It's hard to see the pad in your photo. The best way to determine pad thickness is to use a brake pad wear gauge. It's difficult to judge pad thickness by "eye balling" if you are not experienced at it. I've been carrying measuring calipers in my pocket for over 40 years and I know what a millimeter looks like.
The minimum brake pad thickness for the gen 3 RX and all other vehicles made by Toyota that I've looked up is only 1 mm. You'll find it in the specifications section of your owners manual.
I don't know at what pad thickness you'll hear the brake wear indicators start screeching but I would assume it would be at or just above 1 mm since that's when the electronic wear indicators on the LS cause a low brake pad warning messages to be displayed in the instrument cluster.
If you don't have a brake wear gauge and don't want to buy one, the tip of a straightened wire coat hanger works fairly well. Most wire coat hangers are 2 mm thick. If the tip of a wire coat hanger barely fits in the space between the brake disc and the brake pad backing plate (i.e. the non-wear portion of the brake pad) then you know you'll need pad replacement relatively soon. Depending on how you drive, it can take up to 10,000 miles of driving to eat through 1 mm of front brake pad on a gen 3 RX or the several other models that use the same braking system.
Most people replace brake pads when there is still a lot of life in them. I once had a Lexus dealer service writer tell me that brake pads on an LS were worn to the point that they were going to cause me to crash when there was over 25,000 miles of pad life left - maybe she was trying to reach her sales quota. Early brake pad replacement is one of the most common scams in the car repair business. Service writers can be under immense pressure to sell unneeded services like premature brake jobs. Just smile and decline - they're only doing their jobs.
For people who check their brake pad thickness only every 25,000 miles, maybe they should change the pads when they are worn to 3 or 4 mm. Those who check brake pad thickness every 5,000 miles when they rotate their tires can let their brake pads wear down to or near the minimum specification and reduce maintenance costs by replacing brake pads as few times as possible.
I wish Toyota would put electronic brake pad sensors on its less expensive models like the RX. I always waited until I saw the warning message in the dashboard displays of my Lexus LS and Mercedes sedans before I bothered to have the brake pads changed.
if your having a hard time differentiating the rotor from the pad.... chances are your pads are low.... very low.. There should be considerable amount of pad to see visually.
If you look at a new [OEM] pad, there is a slot in the middle and a scalloped leading edge.
To examine the pads on vehicle, you have to take the wheel off and look at the sandwich from the gap in the caliper assembly. If the pads are worn to the point that you can not see the slot then the pads need to be replaced. Similarly if the pads are worn to the point that the front scallop has vanished then once again you should replace the pads. To confirm you can do the actual measurement.
There are other indicators too ..
I have notice that the OEM pads start shedding excessive amount of pad dust as the near end of life.
If you do not regularly top off the brake fluid and you notice significant drop in the master cylinder then again examine the brake pads.
so does this mean I have no way to examining my pads without taking the wheels off?
There are gauges that are designed to check the thickness of the brake pads without removing the wheels but you have to know the backing plate thickness to use them and they aren't seen as being as accurate as checking the pads directly. You might be able to check the pad thickness without removing the wheel if you can get under your vehicle enough. But if you are going to jack up the vehicle and put it on jack stands to check pad thickness, you might as well remove the wheel and make it easy.
It's a hassle to remove the wheels just to check pad thickness which is why it is usually done every 5,000 miles when the tires are rotated. Are you rotating your tires per the maintenance schedule?
I've mostly retired from doing car maintenance so I let dealership service departments measure pad thickness when the tires are rotated at 5,000 mile intervals. They know that if they tell me my pads need to be replaced that I'm going to measure them myself to verify that they really do. I actually had a greenhorn service writer tell me recently that one of our vehicles needed a brake pad replacement. He totally backed off when I told him that I knew that the minimum pad thickness was 1 mm, that I had recently checked the pad thickness myself, that I wanted the old pads back and that I wasn't going to pay for the pad replacement if my measuring showed that the old pads were still good.
The only time I check pad thickness myself is spring and late fall when I switch between summer and winter wheels/tires. I have a high lift floor jack, jack stands and wheel chocks to make it easy and safe. It takes about one hour per vehicle to do the winter/summer wheel switch including TLMS reprogramming and checking the brake pads. I don't find it necessary to use a brake pad gauge until the pads are quite low. It's obvious to me when there is plenty of pad left by doing a visual check but I've owned cars with disc brakes since the mid-1960's.
Jim in his 2 posts has explained the stuff fairly well.
There is estimation and measurement. You can measure with difficulty the outboard pad [depends upon the wheel spoke pattern and using the depth measurement part of the calipers (the measuring tool). For precise measurement you have to take the pads off and use a mircrometer or calipers.
I just estimate and purchase the parts and at first convenience replace the pads. I have never actually measured the pads or tried to keep using the pads to the min spec.
The following website shows the kind of brake pad gauge that can be used to measure pad thickness without knowing the backing plate thickness and usually without removing the wheels: https://www.lasertools.co.uk/product/6678
Even if a gauge like that is used, it still may be necessary to lift the vehicle in order to measure the inboard pads.
I try to make brake pads last as long as possible both to be frugal and to minimize the potential of vehicle damage. I used to replace brake pads myself but I stopped doing it after getting less than perfect results. I don't have the equipment to machine/resurface brake discs and I've found that it costs substantially less to have brake discs resurfaced by a shop that has the right equipment than it is to replace brake discs. With currently available equipment, brake discs can even be resurfaced without removing them although not always.
We don't currently have an RX but our 2014 Sienna Limited uses all the same front and rear brake components as the gen 3 RX and gen 3 Highlander. It's currently at 80,000 miles and, at the current wear rate, both front and rear brake pads will requirement replacement for the first time at about 110,000 miles. I'm the sole driver of the Sienna and sometimes drive it like it was stolen. That said, I would think that brake pads on the somewhat lower weight gen 3 RX could last at least as long as the brake pads on our Sienna - to or beyond 110,000 miles. A person can buy a lot of other nice $#!+ by avoiding unnecessary brake jobs!
Last edited by Kansas; 05-03-19 at 09:36 AM.
Reason: bad schpeling
I tip my hat to anyone getting 100,000 miles on a set of brake pads on ANY vehicle, even with mostly highway miles. I have been driving for nearly 50 years and the best I have ever been able to do is about 65,000 miles. My 1974 Datsun 260Z would run through brake pads about every 18,000 miles. I was barely out of college and drove that Z like a Formula One car, though.
I tip my hat to anyone getting 100,000 miles on a set of brake pads on ANY vehicle, even with mostly highway miles. I have been driving for nearly 50 years and the best I have ever been able to do is about 65,000 miles. My 1974 Datsun 260Z would run through brake pads about every 18,000 miles. I was barely out of college and drove that Z like a Formula One car, though.
The first Datsun sports car I drove (test drove it, didn't buy it) was a new 1966 Datsun 1600 roadster which made my 1964 Triumph Spitfire seem like a complete P.O.S. I don't think the Spitfire's front brake pads lasted even 5,000 miles and its rear brakes were drum.
The original front brake pads on my wife's 1998 Camry V6 were less than half worn when the car went to a nephew at 125,000 miles in 2012. I used to kid my wife that she must drag her feet to stop the car. Front brake pads on my Lexus LS sedans always lasted until about 75,000 miles when the low pad warning happened and I sometimes drove those cars REALLY hard. Rear brake pads on the LS sedans were good for 130,000 to 150,000 miles.
How long brake pads last apparently largely depend on pad composition. I used only OEM brake pads on my Mercedes sedans and the front pads lasted between only 20,000 and 25,000 miles before the low pad warning in the instrument cluster came on. At least the electronic pad wear sensors were very inexpensive which was good since they had to be replaced at each pad change. At one time, Mercedes used extremely soft brake pads which was probably why there was so much obvious brake dust on the wheels. Aftermarket shields were available that were supposed to reduce brake dust buildup but some thought they interfered with brake cooling.
I do or have all the required maintenance done on our vehicles but I try to be frugal about it. That way my (retired) CPA wife lets me buy more toys!
05-01-19, 10:55 AM
How to examine brake pads
