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Saab 9-5 Caliper Bracket Bolts #4585186
11/26/17 06:39 AM
11/26/17 06:39 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
Joined: Oct 2008
Posts: 1,350
MD
I had to take a rotor off of my 05 Saab 9-5 yesterday and got into a confusing situation with the bracket bolts going back on. Torque spec is 103 ft. lbs plus 45 degrees. I took the bolt to 100 (limit) with my clicker torque wrench and then went over to my beam wrench. Torque climbed to about 120 and then leveled off. I was able to get about 20-25 degrees of the 45 (car was on jack stands). I ended up doing all this twice because I didn't like how the quarter turn was going.

I'm wonder if I'm okay with where I left things. I'm short of where the specs are, but I'm a little concerned about the flattening of the torque as I was attempting the quarter turn. Was the bolt stretching or a washer flattening? I haven't seen anywhere where it says that these bolts are single use, but am wondering.

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585196
11/26/17 06:54 AM
11/26/17 06:54 AM
Joined: Oct 2012
Posts: 4,825
Taiwan
Ducked Offline
Ducked  Offline
Joined: Oct 2012
Posts: 4,825
Taiwan
If I don't like the way something like that is feeling I stop. Last time I remember doing so was with caliper bolts. I'd rather they be under-torque than broken.

I don't use a torque wrench very often and regard the specs as rather rough guidelines, given all the uncertanties re thread lubing and condition. Brakes seem OK.

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585211
11/26/17 07:24 AM
11/26/17 07:24 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
Joined: Oct 2008
Posts: 1,350
MD
If I didn't break them, they won't snap by themselves, will they?

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585301
11/26/17 08:53 AM
11/26/17 08:53 AM
Joined: Sep 2015
Posts: 1,598
USA
mk378 Offline
mk378  Offline
Joined: Sep 2015
Posts: 1,598
USA
45 degrees is 1/8 turn not 1/4. It would be like the hour hand going from 3:00 to 4:30 on a clock dial.

Last edited by mk378; 11/26/17 08:59 AM.
Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585328
11/26/17 09:28 AM
11/26/17 09:28 AM
Joined: Dec 2014
Posts: 1,684
'murica
Ethan1 Offline
Ethan1  Offline
Joined: Dec 2014
Posts: 1,684
'murica
Originally Posted By: ET16
If I didn't break them, they won't snap by themselves, will they?


A stretched caliper bolt absolutely can break while you're driving. It's there for a reason: it gets loaded every time you brake. And if something is tightened to a torque-angle, it's likely to be one-time-use!

Re: Saab 9-5 Caliper Bracket Bolts [Re: mk378] #4585366
11/26/17 10:05 AM
11/26/17 10:05 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
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Posts: 1,350
MD
Originally Posted By: mk378
45 degrees is 1/8 turn not 1/4. It would be like the hour hand going from 3:00 to 4:30 on a clock dial.


yes, my mistake. That's about what I did.

Last edited by ET16; 11/26/17 10:10 AM.
Re: Saab 9-5 Caliper Bracket Bolts [Re: Ethan1] #4585367
11/26/17 10:06 AM
11/26/17 10:06 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
Joined: Oct 2008
Posts: 1,350
MD
Originally Posted By: Ethan1
Originally Posted By: ET16
If I didn't break them, they won't snap by themselves, will they?


A stretched caliper bolt absolutely can break while you're driving. It's there for a reason: it gets loaded every time you brake. And if something is tightened to a torque-angle, it's likely to be one-time-use!


I thought that this might be the case, but I find no mention of it.

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585368
11/26/17 10:07 AM
11/26/17 10:07 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
Joined: Oct 2008
Posts: 1,350
MD
I'll order new bolts. Should I retorque to a lower value in the meantime?

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4585564
11/26/17 12:44 PM
11/26/17 12:44 PM
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
Johnny2Bad Offline
Johnny2Bad  Offline
Joined: May 2013
Posts: 2,160
Saskatchewan, Canada
Leave them as is; playing with the bolt stresses it further, and either it's OK at the current value or it isn't. Regardless, it won't be stronger if you go back in there. Replacing them as is your plan will be fine when you get the parts.*

All bolts stretch and all bolts are weakened from the first installation to be weaker on the second (or subsequent) stretches. It's got nothing to do with "Stretch To Yield" except insofar as they are designed to survive only the first stretch, while with other fasteners it's dependent on the actual use at what torque / stretch in what location how closely the fastener is to replacement.

I know that re-using bolts is a time-honoured shadetree tradition, but those who don't mind spending a bit more to be sure of a repair will always replace stressed fasteners in critical locations with new.

* I'm so thankful for the Bolt Supply House here in my city, they have everything .... and I mean everything ... available in stock, just drive and pick them up. There are fasteners purchased from there flying on the Space Shuttle as we speak. Plus prices are better than OEM almost all of the time.


'57 FL Straight 50 wt
'90 Miata 1.8L w/Rotrex Supercharger [Mobil1 0W-40]
'96 Ram 1500 [3.7L Mobil1 0W-20 / 1L 15W-50]
'01 PT Cruiser [Mobil1 0W-40]
Re: Saab 9-5 Caliper Bracket Bolts [Re: Johnny2Bad] #4585999
11/26/17 06:51 PM
11/26/17 06:51 PM
Joined: Oct 2012
Posts: 4,825
Taiwan
Ducked Offline
Ducked  Offline
Joined: Oct 2012
Posts: 4,825
Taiwan
Originally Posted By: Johnny2Bad


There are fasteners purchased from there flying on the Space Shuttle as we speak.


Think its retired. Probably too late to ask for your bolts back though.

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4586418
11/27/17 09:25 AM
11/27/17 09:25 AM
Joined: Oct 2008
Posts: 1,350
MD
ET16 Offline OP
ET16  Offline OP
Joined: Oct 2008
Posts: 1,350
MD
Folks at Saabcentral say that the bolts are reusable, nothing in the manual about single use.

Before I read the last messages, I went back in and examined the bolts, cleaned them and retorqued to 100 lbs with loctite blue. I have new bolts on order just to be extra safe.

Re: Saab 9-5 Caliper Bracket Bolts [Re: ET16] #4586539
11/27/17 12:07 PM
11/27/17 12:07 PM
Joined: Jan 2007
Posts: 17,501
Clovis, CA
Merkava_4 Offline
Merkava_4  Offline
Joined: Jan 2007
Posts: 17,501
Clovis, CA
The problem with using a torque wrench on everything is you never develop a feel for what tight is.

I use torque wrenches primarily on applications that involve gaskets.


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