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Caliper bracket bolt size?

31K views 14 replies 7 participants last post by  Big Blue 
#1 ·
Curious, does anyone know the size of the bolts that hold on the front caliper brackets? I'm asking because I plan to remove the rotors and replace, but when I went to tackle it last time I didn't have a socket big enough and don't feel like running out to get the size....
 
#3 ·
Thats the bolt for the caliper to hold it to the bracket.

I think the OP is talking about the actual bracket that wraps around the rotor, the pads mount in it and the caliper bolts to it.

If I remember correctly it was a 19mm bolt head, but its been a while, I have sockets this size so it didn't stand out to me, it might be even larger than that.

19mm is the same size for the lug nuts, so you could always pull out the lug wrench that is in the back with the tire jack and use it to remove the bolts, at least check to see if it fits.
 
#5 ·
Ahhhh, OK, the link comes up to a diagram that seems to show the bolts for the caliper to the adapter.

So, this may or may NOT work, but the lug wrench that is in the back with the scissors jack should fit a 19mm bolt head. Of course its a compact wrench, might NOT be enough leverage, but worth a shot if you're trying to do this on the cheap, at least you definitely confirm what size socket you'll need to get.
 
#13 ·
Bumping this as I lost the right front lower bolt on my way home from work after pulling out of gas station.

Had a rattle and put it off thinking it was the top strut nut.

Top bolt was loose too so I removed it and put on the bottom and tightened best I could. Lasted 5mi till I had to tighten it again. Another 5mi and made it home.

Nice adventure on new years eve.
Home depot had the bolt size mentioned above in stock.
 
#7 ·
21mm socket with 95 ft-lbs (actually greater, maybe a lot more, for a bolt that has been torqued down that long)?

nserafini you might want to consider picking up a 2' breaker bar with the socket. If I remember correctly, I had to break those bolts free with my 2' breaker bar, the 8" socket wrench wasn't enough leverage for those big bolts.
 
#8 ·
Thanks kids. I've been putting it off because the last two times I went to remove a wheel, I've rounded the acorn nut ( I have a 4-way wrench and even though the size should be exact for the nut, it seems that my gorilla hands can round it ).... Perhaps if the weather is nice this weekend I'll go pickup new nuts, a 21mm, breaker bar and plan to curse the gods trying to get them off.. Or I'll take it to a shop and see what they will charge to do the work :)
 
#9 · (Edited)
After you get the caliper off there is a rubber o ring that holds that rotor on.
It is on the hub or unit bearing.
That is if it is still the stock rotor.
Most people leave it off after they put new rotors on.
I think it is there more for assy. at the factory.
Make sure you torque the caliper bracket back on to factory specs! It may see excessive but I have seen them come loose before.
 
#12 ·
Yea, my grandfather gave me a 4-way lug wrench, it still sits on the shelf and I never use it.

I use a breaker bar with a deep well socket the proper size for the lug nuts, then torque wrench set to 100 ft-lbs to tighten them in a star pattern with the same deep well socket. I've never rounded a lug nut, but I did ruin a set of studs on a mini-van years ago, using excessive oil/anti-seize everytime I rotated the tires on the mini-van. The torques are dry torques, NOT wet torques, and even a 100 ft-lbs on "some" studs while very wet, multiple times, can ruin them.

NOT saying to never lube your wheel studs, but do it sparingly and NOT every time, just when needed, remember the torques are dry torques. Since then, only when rust shows up on the studs do I lube them and then just a tiny smear of anti-seize or a drop of oil, I haven't ruined the threads on studs yet using that rule.

I suspect Commanders come with higher quality studs than '91 Mini-Vans, so even a person using excessive lube all the time might NOT recreate what happened on my mini-van, but the principle still applies.

As far as Rotors seizing to hubs, and aluminum wheels seizing to rotors. A little anti-seize every once in a while (NOT every time) goes a long way in preventing that.

NOTE, the FSM for many modern vehicles state NOT to use anti-seize or greas between the rotor and hub. That is because the run-out spec for many modern brakes is less than the width of a human hair, so the fear is using excessive anti-seize or grease will trap a human hair or other debri that will throw the rotor out of run out specs. What I do, I apply the anti-seize and then wipe it off, in fact buff it into the rotor surface on each side just a bit, just to leave behind a slight residue burnished into the surface of anti-seize, nothing sticky. Sure enough that is all that is needed, after that treatment, there is nothing getting trapped in the anti-seize to throw off the run-out, and years later I can pull aluminum wheels off the rotor or the rotor off the hub without a hammer.
 
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