Torque specs for Caliper halves bolts
 

I’ve researched everywhere on this site, the fsm and even g37 and it seems nobody knows the oem torque spec for the 4 17mm and 4 14mm bolts that hold the front and rear calipers together. So my question is for those of you that have rebuilt the calipers before what did you torque it too so it wouldn’t leak?

If you know the size (you already have that) and grade of the bolts, you can look it up in torque charts on the 'Net.

I looked up how to tell the bolt grade and it doesn’t have any marking on the top so I assume it’s a grade 2? But when I went to look up the torque specs for a 17mm grade 2 bolt I was very confused which one to look at to say the least lol

I'd try taking one of the bolts to a hardware store or machine shop to get it IDed.

Edit: My guess is that it is Grade 5. But I'm no expert. If it's zinc-plated, it's probably Grade 2.

Edit: Discovered that metric bolts use a different rating system that I am not familiar with. You need to get help from someone else.

The specs are not in the manual anywhere. What I did was to measure the diameter of the bolt shaft. Not what wrench will fit the head.

Here's a list of metric bolt torques and how to find out which grade. Nissan doesn't always mark their bolt head as for grade.

https://www.swtc.edu/Ag_Power/diesel...e%20values.pdf

This is information is not hard to find, as posted in response to your OP. It has been also been discussed on this forum before...

http://www.the370z.com/brakes-suspen...per-bolts.html

So I measured the bolt the front are M12 and the rear are M10 I can’t measure the pitch cause I don’t have the tool or know how too lol just used a YouTube video to figure out how to get the diameter lmao. I have no idea how to tell the grade though, based on the link you gave which grade would the bolt fall into? I’m a novice at this but I’m trying to learn as much as I can.

Yeah I saw that, but Idk the grade of the bolt and since rusty said that Nissan sometimes doesn’t put the markings for the grade I’ll never be able to guess it lol. Plus the link he sent and that thread and the one on this one give different torque numbers. Rusty since you’ve done it before do you remember how much torque you put on them ?

Found my notes. The 10mm was 40 ftlbs, and the 12 was 70 ftlbs. The heads have no markings on them to tell what they are. So I went with a spec in the middle. When you reassemble the halves. Take a honing stone with oil and stone the mating surfaces of each half. This will remove any high spots. The o-ring in between the halves. Make sure you put brake assemble lube or brake fluid on it before bolting the halves together.

I wish I could give you endless rep !! Thank you so so much rusty! Alright I’ll look up how to do all that and go buy the stone, I read on another thread that you said to use some blue liquid, I’ll find it again and use that to see the high and low spots.

The liquid is Hi-Spot Paste. Put a little bit on a folded paper towel and spread on one half. You need a very fine film on it. Bolt the halves together and torque to spec. Un bolt and look at the half that you didn't coat. You should see the transfer of the paste. 100% is great. But don't think you will get that. Long as you have full transfer around the o-ring. You will be good.

If you get the paste on your fingers. GOOD LUCK on getting it off. :rofl2:

The stone to get is one of those knife sharping stones that is about 2" wide and about 6" long. Spray it and the half with WD40. And work back and forth. Keeping everything wet. Any high spots in the metal will look like bright shiny areas. If you have any. Keep stoning. But be careful on the edges. You don't want to round off the edges. Keep the stone flat at all times. It's an art.

https://www.mscdirect.com/product/details/00264101

Man I’m a terrible artist but good thing there’s YouTube nowadays 😂. Okay I get what you mean, I’m confident in doing it myself now with all the information you’ve given! If I have any problems I’ll shoot you a dm if you don’t mind haha. Thanks again for all the info and help ! :tiphat:

You may have to stone, clean, bolt together, stone, clean, bolt together a couple of times. On mine, I got about 75% contact all over. Around the o-ring hole, It was 100%.

If you don't like the idea of using a whet rock, get a large, flat plate (metal works best) and lay some wet/dry sandpaper on it. Place caliper half on sandpaper and go to town. Use plenty of water/oil/etc.

Use a very fine sandpaper. Start off with 800 grit. Glass plate is the best.

Funny thing, i was wondering the same, but decided to just take a torque wrench and measure the torque.


The rear calipers are 32 ft-lbs.
I was going to measure the front calipers tomorrow.

How did you measure the torque?

Since there are 4 bolts per caliper, i just picked a starting point and increased the torque value until the bolt started turning and i took the last value (32 ft-lbs) and checked it on the remaining bolts and then incremented it to 33 ft-lbs and checked to make sure they turned a little before clicking.
They all clicked at 32 ft-lbs and turned at 33 ft-lbs so the rear bolts are 32 ft-lbs.


You could also buy a digital torque reader or analog torque wrench to measure it, but i wasn't going to spend that money.

That's in the ballpark of what I had posted of 40 lbs. On the chart I linked. 32 ftlbs is for a lubed torque spec, and 40 ftlbs is for a dry torque spec for the same bolt. The factory uses a wet spec because of them using a thread locker of some kind.

The bolts are a 8.8, or a 9.8 class.

There's no marking to determine the grade of the fastener.

I measured the front bolts at 63 ft-lbs.

Didn't feel like there was thread locker, but if so then it would already be dry by now and the torque values would be wrong since those would now be considered the breakaway torque.

According to this video, there's no thread locker on the bolts. skip to 2:50.
https://www.youtube.com/watch?v=artb4VxLaig

front caliper bolts are 63 ft-lbs
rear caliper bolts are 32 ft-lbs

These are definitely not class 8.8 or 9.8 since the head size doesn't match.
The head size for a Class 8.8 M10 is 16 mm and M12 is 18 mm. My caliper bolts are 14mm and 17 mm so these are based off the old standard.

Also the chart you linked to doesn't apply since that chart is for hex head bolts, where as the caliper bolts are hex flange bolts. Hex flange bolts are torqued higher.
https://www.swtc.edu/Ag_Power/diesel...e%20values.pdf

I know there is no markings on the bolts for what grade they are. I don't think Nissan would use the lowest grade, or the high grade bolt for this application. So I picked one in the middle, which would be 8.8.

The torque reading you are getting fall in line. Remember that you are not dealing with everyday bolting. This is Nissan speced. So the head size may not be what you are expecting. Car companies do some strange stuff.

I've rebuilt 4 sets of calipers so far. Of that. 3 had some type of thread locker on the threads. Most likely a triple boiled linseed oil. When I worked for Elliott TurboMachinery. We used to use this stuff all the time. Great thread lube until it drys.

Since the chart I linked to doesn't work. What chart would you use? And what torque would you use?

I hate to tell you. Those calipers in the video. Already have been apart, and cleaned. Plus when he took them apart. Where's the brake fluid? They have new pistons and seals already in them. The threads on the bolts have been wired brushed. The guy just took one side apart as a show and tell. He already screwed up in that video. He didn't put any brake fluid on the o-ring that goes between the halves.

I just found the spec's I was looking for. :tup:

The torque chart with head sizes are in the GI section of the FSM

Here are the torque specification and bolt discrimination pages from the FSM.

Page 19.

That where I found everything last night.

There is 2 standards. The PREVIOUS STANDARD, and the new NEW STANDARD BASED ON ISO. The caliper bolts are under the previous standard. As "g96818" found out. The 10mm is 14 mm across the flats amd the 12mm is 17mm across the flats. Under the new standard. The 10mm is 16mm across the flats and 12mm is 18mm across the flats.

No markings or a 4 on the head of the bolt would be a 4T grade. If the head had a 7 or 2 dots, 180 degrees apart. The bolt grade is 7T. If the head has a 9 or 3 dots, 120 degrees apart. The grade would be 9T, the strongest.

On the 4 sets of calipers I have rebuilt. I've never seen a marking on the bolt heads. Has anyone else seen any markings? So, given this information. I would say the bolts are a 4T grade. So the torque would be for the 10mm hexagon flange bolt is 26 ftlbs. For the 12mm hexagon flange bolt would be depending on thread pitch 41 ftlbs for the 1.75 pitch, or 48 ftlbs for the 1.25 pitch. I don't know what the thread pitch is.

Anyone else think that is right or wrong. Post up.

The chart I posted earlier is close to the 7T grade torque spec's, 10mm 41ftlbs, and the 12mm at 74 ftlbs. The chart listed 40 and 70 ftlbs.

Confirmed just now that there are no markings on any of the bolts holding the front or rear Akebono caliper halves together on my 2011.

The only markings on the bolts are "L" and "S" and only on the front calipers, rear caliper bolts have no markings. I have no clue what that means. I'm going off a whim and saying the nissan torque specs don't apply, since these are built by akebono so we need to find akebono's torque chart. If I had the exact material compositions, then I could try to calculate the torque values.

But in the mean time............what spec's? The 4T or the 7T?

That's the million dollar question that i do not know the answer to. If anything, I would assume 4T since there are no markings, which was why decided to just measure the torques. Like i said, these probably don't follow the nissan chart since theses are akebono calipers and nissan buys them already assembled.


I emailed powerstop tech support to see if they can give me the spec since they "reman" these calipers, even though they supply you with brand new calipers without the akabono tag.


I'll post back if they are nice enough to give me the spec, if not then I'm planning on going with what i measured and tossing some blue loctite on the bolts.

This may or may not help in your research but bolt torque is an indirect measure of bolt stretch.

When I worked at Elliott TurboMinchinery. On some applications, we measured bolt/stud stretch. On others. We installed the nuts hand tight. Then heated up the bolt/stud up. Then turned the nut so many flats to set the torque. We also used a HydroTorque wrench. Which is a hydraulic wrench. You set the torque by how much hydraulic pressure you have at the head.

Hope they do. Told them i was planning on powder coating their uncoated caliper and need to disassemble the calipers so we'll see.

I know this thread is really old, but I have the definitive torques straight from Akebono USA.


Front Caliper 17mm bolts: 69.2 - 93.6 Newton meters (51 - 69 ft-lbs)
Rear Caliper 14mm bolts: 32.0 - 43.3 Newton meters (24 - 32 ft-lbs)


This falls in-line with what I previously measured.