Saab 9-5 Caliper Bracket Bolts

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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.
 
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.
 
If I didn't break them, they won't snap by themselves, will they?
 
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:
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!
 
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:
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.
 
I'll order new bolts. Should I retorque to a lower value in the meantime?
 
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.
 
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.
 
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.
 
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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