Different calipers with smaller bolt, can't find info

In the process of changing front brakes. New calipers are different than the front, just by the bolt that holds calipers. Mine are 19mm. Replacements are 17mm. Everything that I find at the auto store show small hole 17mm. There is a before and after date of 6/15. What am I missing. Can’t find any information.

 

I am bored. are you sure new calipers direct replacement of original. what are you ordered and from what supplier. you should be able to re-use original bolts. why are you changing calipers. do you know how to bleed brakes on 4Runner. if you having troubles already - don't do it.

 

my thought exactly. Why are you replacing the calipers? Calipers very seldom fail. VERY SELDOM. in my 30+ years of working on cars, ive replaced calipers maybe 5 times.

 

Exactly this.

Don’t be a parts swapper and diagnose the issue properly. Auto part stores don’t always give you the correct parts. Their catalog may have incorrect information and can cross reference the wrong part. Always double check your part at the store, or bring the old part with you.

 

It's not just about the caliper "failing" that you have to replace the calipers. If you've ever lived in a harsh environment, pistons FREEZE into the calipers...corrosion basically welds them to the bore of the caliper. Then they don't move and they can destroy the disk because they won't retract. If you can't free the pistons conventionally, you'll destroy the bore most likely trying non-conventional ways to break them free. I've rebuilt many calipers in my day, as well as replaced them.

The 4runner we just got had this issue. Frozen pistons in 3 of the 4 calipers (both rears and driver side fronts). I could not pop any of the frozen pistons free and I tried all the tricks I've used of the years. None would budge. When I had these apart, I looked at the seals and noticed that these OEM seals were some of the flimsiest I've seen. The "snap ring" that holds the seals in place in the front could easily bend and then you're letting in moisture. So it was time to replace the calipers at this point. I was able to find 2 new OEM fronts and 2 OEM remans. Don't mess with aftermarket remans ever.

To the OP, your question/post doesn't really make sense. The bolt diameter for the fronts is 14mm...so not sure what you're measuring. If you're using the head socket size, that's not correct and this can vary between bolt diameter. But the fronts OEM bolt is 14mm. I've read floating around there's a 12mm bolted version too, but I can't verify that. Maybe that's the 2WD version? Either way, the majority of the front bolts and receiving holes will be for a 14mm bolt

 

Frozen pistons was a big problem with the 4th gen.

 

This 2016 is the first 4runner I've worked on since I personally owned a 99 Tacoma back in the day.

 

I have a 2017 in upstate NY and it is a rust-bucket. All calipers are frozen. I replaced the rear, but the fronts have 19mm caliper
mounting bolts and everything I find has either 14mm or 17mm. So Markhole3 is correct. The auto parts stores keep giving me the
wrong calipers. Now I bring a mounting bolt with me to try fitting in the hole. No luck so far.

 

I believe the changeover from 17mm to 19mm front caliper mounting bolts occurred in 2015, but not positive on the year.

 

Yea the change was in mid-year 2015. I’m going through it now. Went to parts store gave me calipers with 12mm bolt holes. Mine has 14mm bolt mounting holes. So going back to Toyota Monday and but the proper ones. I’ve heard part stores are junk for Toyota parts but I was just hoping to get it done today to get me by for a bit until I could get up to Toyota where I used to work. They treat me good there