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Is Loctite required for caliper bolts?

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Old 06-23-2007, 08:55 AM
  #16  
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Originally Posted by shoebox
Same here. If bolts are tightened to spec, they should not go anywhere.

I agree in principle with this statement to a point.


If the opti were better specd, then it should not fail from moisture while under the 36K warranty period. Mine did once.

If the opti again were better specd, then maybe the two small rotor screws would not back out under the 36 month period and cause opti expolosion, mine did once.

If the power window electrical spec were more spot on, then they should roll up with proper force and not drag. Three motors replaced when the high resistance wiring and switches were the problem.

If the GM 10 bolt were better spec for 275+ STOCK horse power high performance engines, then maybe bone stock V* f-bodies would not grenade the R&P as often as they do. This is a "Performance vehicle" after all.

If the cup holder in my 1995 Camaro were better specd, maybe it would actually hold a drink rather than just collect coins. Wont hold any drink for crap, I am sure most would agree.

My point here is just because the GM spec is the GM spec, in some rare cases even GM will get it wrong. I torqued those big bolts to GM spec and had one still back out causing the caliper to swing down at highway speed, man what a wracket that was.

I see the loctite as added insurance with absolutely zero, zilch nada negative side effects. Aint no damn way that bolt will loosen now. I don't always treat the GM spec as the absolute gospel, due to manufacturing costs, GM like all the others will just meet their spec but not exceed it even if it only meant spending a few more pennies per unit. That loctite is expensive stuff, my standard bottle was $20 I think.

Last edited by wrd1972; 06-23-2007 at 09:05 AM.
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Old 06-23-2007, 08:39 PM
  #17  
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Originally Posted by wrd1972
I am quite confident that the heat generated by a propane or acetylene torch is quite different than the heat generated by brake usage plus its the rotor and caliper that take the brunt there. The big bolts in question could not possibly be subjected to anything over 150F or so.

It takes several hundred degrees F to loosen the red loctite.
For a little perspective, on a warm day, underhood temperatures can get uncomfortably close to 150°F at low speeds even if you aren't using the A/C. So I think 150 is a rather low estimate of front brake system part temperatures, even those somewhat remote from the actual friction surfaces. An upper bound could possibly be at or above the wet boiling point of your brake fluid under severe and continuous usage (mountain driving, track day). That's at least 300°F for any decent fluid.

At any rate, we know that red comes apart readily at several hundred °F. I couldn't read any numbers on those little bottles, so I don't know how many hundred "several" really is. Anyway, we don't know how long the red stuff will withstand temperatures slightly/somewhat less than its "quickly comes apart temperature", or how many thermal cycles to whatever slightly lower temperature it will put up with.

Re-installing the bolts with clean, dry threads to the correct torque has never let me down. That only means I have to wash my hands a couple extra times and be a little careful handling the bolts. I do torque these bolts to the top of the given range. Did this job (new pads and rotors) on all four on our Maxima earlier today actually.

On edit, if you are using a 'click' type torque wrench, it might be worth getting it calibrated. It may have been telling you a fib. I've stuck to the old-fashioned beam type mostly because there's less that can go wrong with it.

Norm

Last edited by Norm Peterson; 06-23-2007 at 08:53 PM.
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Old 06-23-2007, 10:17 PM
  #18  
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Originally Posted by wrd1972

I agree in principle with this statement to a point.


If the opti were better specd, then it should not fail from moisture while under the 36K warranty period. Mine did once.

If the opti again were better specd, then maybe the two small rotor screws would not back out under the 36 month period and cause opti expolosion, mine did once.

If the power window electrical spec were more spot on, then they should roll up with proper force and not drag. Three motors replaced when the high resistance wiring and switches were the problem.

If the GM 10 bolt were better spec for 275+ STOCK horse power high performance engines, then maybe bone stock V* f-bodies would not grenade the R&P as often as they do. This is a "Performance vehicle" after all.

If the cup holder in my 1995 Camaro were better specd, maybe it would actually hold a drink rather than just collect coins. Wont hold any drink for crap, I am sure most would agree.

My point here is just because the GM spec is the GM spec, in some rare cases even GM will get it wrong. I torqued those big bolts to GM spec and had one still back out causing the caliper to swing down at highway speed, man what a wracket that was.

I see the loctite as added insurance with absolutely zero, zilch nada negative side effects. Aint no damn way that bolt will loosen now. I don't always treat the GM spec as the absolute gospel, due to manufacturing costs, GM like all the others will just meet their spec but not exceed it even if it only meant spending a few more pennies per unit. That loctite is expensive stuff, my standard bottle was $20 I think.
I really didn't need all that, but maybe it makes you feel better.

I've never had a brake bolt problem on any car I have worked on in the last 37 years. Hopefully I won't have to resort to Loctite to keep things together and won't have any mishaps.
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Old 06-24-2007, 07:25 AM
  #19  
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Originally Posted by shoebox
I really didn't need all that, but maybe it makes you feel better.

I've never had a brake bolt problem on any car I have worked on in the last 37 years. Hopefully I won't have to resort to Loctite to keep things together and won't have any mishaps.
Sorry shoe, I am not trying to be a jerk. I am only trying to defend my stance with examples on the subject of "specs". It is actually my job as an engineer to challenge and test the specs of products in early development where I work.

I just wanted to point out that just because its spec does not mean it should be treated as gospel in every situation. As metals and materials age and things wear in then the spec may need to be exceeded by the competent end user. I determined that tightening to 52lb ft. first pass then 90deg. second pass per GM spec with my calibrated $325.00 Snap-on clicker torque wrench and angle finder was not working for me. Without some kind of adjustment I was doomed to have iffy front brakes.

Maybe I could have said it in a different way.

Good discussion though.

Last edited by wrd1972; 06-24-2007 at 07:46 AM.
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