08 XC90 Brake caliper torx bolts

dnwong · Post by **dnwong** » 10 Aug 2014, 12:51

I accidentally loosened the torx bolts holding the two halfs of the front caliper. Its a big torx T55? Anyone know the torque spec to re tighten.

gntl2000 · Post by **gntl2000** » 11 Aug 2014, 05:54

I have an '09 but the year should not matter. Those aren't Torx bolts. A 7mm Allen (aka Hex) socket is what you need torqued to 30Nm.

arfstrom · Post by **arfstrom** » 06 Jun 2016, 21:20

My O5 XC90 uses Torx 55. I would have appreciated it if had been allen (hex), it would have saved me a trip to the Menards.Then after that trip, It wasnt' the bolts that I needed to take off. There was a 14mm that was what I needed.

(more for the random googler, like me, that was looking for this information prior to running to Menards.)

amadeov · Post by **amadeov** » 21 Oct 2016, 13:40

Both bolts are present on all 2003-2012 XC90 front brakes. There are two 7 mm Allen/Hex bolts (which are also the caliper pins) that are located underneath the plastic protective coverings toward the upper center of each front caliper. There are also four T55 Torx bolts that hold the front half and the back half of the caliper together.

Guess who has been working on his front brakes and suspension on his 2007 XC90 V8.

Post by **pgill** » 07 Jul 2019, 12:33

My Audi uses ATE calipers and I removed the T55 so that I could upgrade to the larger S4 rotors.

At the time my research indicated that I should use about 60 ft*lbs.

So that is what I did.

However I checked the T55 bolts based on your question and I discovered the following

M12 x 1.75 grade 10.9

The 10.9 is a higher grade steel that can handle more torque

My original research was appropriate for a grade 8.8 bolt

For the 10.9 the torque rating is much higher about 97 ft*lbs for a zinc plated bolt

https://www.imperialsupplies.com/pdf/A_ ... Charts.pdf

I’m going to check my T55 bolts and if they are loose I will post again

I am going to increase the torque to 70 ft*lbs

Good luck

Paul

Post by **pgill** » 07 Jul 2019, 14:34

Follow up

Everything was still tight

I set the torque wrench to 40 ft*lbs and it clicked without moving the bolt

Raised the torque to 70 ft*lbs and the bolt did rotate but only a few degrees

I’m happy with 70

Take care

Paul

Post by **SuperHerman** » 07 Jul 2019, 16:19

I am going to throw a word of caution out there. Strongly suggest one sticks with the specs.

Torque by bolt hardness ignores the other half. The bolt can tear the threads out - just something to be cognizant of, especially with Aluminum. Rotors are pretty robust.

Post by **pgill** » 07 Jul 2019, 16:34

SuperHerman,

You are 100% correct

Thanks for pointing that out

The 12 mm T55 steel bolts mount the aluminum half of the caliper to the cast iron part of the caliper

The Aluminum is not threaded it is held in compression by the 12 mm bolt

The female threads are in the cast iron part of the caliper

The correct torque should be due to the cast Iron

Maybe 60 ft*lbs is a good torque

Good discussion

Thanks for your input

Paul

Post by **pgill** » 07 Jul 2019, 20:26

Hopefully a picture will help

Red side of caliper in the picture is Aluminum

Dark brown side is cast Iron

Four T55 M12 bolts hold the two sides together

One of the bolts is visible in the picture

Thanks

Paul

Post by **pgill** » 08 Jul 2019, 08:39

All,

I found another link with a recommendation for a M12 Bolt going into cast Iron

Note: if you look at the chart the recommendation for Aluminum is significantly lower which is consistent with what SuperHerman pointed out

https://www.allpar.com/fix/body/fasteners.html

: bolt.jpg (53.01 KiB) Viewed 5787 times

Based on this I am comfortable with 70 Ft*Lbs

Take care

Paul