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Change bolts/nuts?


Turbobrick
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Are essential nuts and bolts on suspension, brakes, engine require changing to new ones everytime they are removed?

 

I'm reading through my Haynes manual and they recommend changing the bolts and nuts of items like brake caliper, suspension arms, engine mountings, etc.

 

Necessary or just anal? [crazy]

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I'd say necessary. The Bentley manual that I bought for VW Jetta/Golf/GTI also says that all the bolts and nuts in the front and rear suspensions must always be replaced when reassembling.

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Necessary? But why? Could it be the bolts are tensioned/stressed when tied the first time and loosening it will cause it to loose it's tension and rigidity? [:/]

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Contamination by grease and grit shouldn't be a big deal as when U tie the bolts, the grease will be forced out of the threads through the nut. Also cleaning the bolts will do but they specifically asked to change to NEW ones...... [crazy]

 

I'll check around, will post new findings when I come across any.

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Neutral Newbie

Just a guess, its been a long time...

 

For max strength, you want to torque it to just below the elastic limit (or is it the plastic limit). So it means that the bolts are "stretched" (technical layman term :-P ) and the strength is not what it is supposed to be. This setting is supposed to minimise the "relaxation" effects assuming no lock nuts. Like I said, its been a long time since i last studied this, so I may well be talking cxxk!

 

grease not the problem here, only affects the torque setting (wet vs dry). grit, depending on the type, could affect the threads (unlikely but possible).

 

I'd be anal retentive and change 'em. cheap insurance vs consequences.

 

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Contamination by grease and grit shouldn't be a big deal as when U tie the bolts, the grease will be forced out of the threads through the nut. Also cleaning the bolts will do but they specifically asked to change to NEW ones...... [crazy]

 

I'll check around, will post new findings when I come across any.

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Agreed, the tensile limit of the bolt may be stretched to it's maximum for extra strength so removing it will "relax" the bolt and the original strength cannot be retained.

 

On the other hand, my mech just air wrench the bolt it and if it does not break so be it [:p]

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Neutral Newbie

But if the tensile limit is already exceeded, air wrenching it is not a solution, but could lead to other nice, interesting situations.

 

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Agreed, the tensile limit of the bolt may be stretched to it's maximum for extra strength so removing it will "relax" the bolt and the original strength cannot be retained.

 

On the other hand, my mech just air wrench the bolt it and if it does not break so be it [:p]

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I get a "sick" feeling everytime I see an air wrench put into use on my brick, it always seems to be a overkill on the tightening of the nuts and bolts......are there air wrenches with built in specific torque settings? [angelic]

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Ha ha! I can imagine you hovering anxiously around the brick with torque wrench in hand ready to hand it to the mechanic everytime he reaches for the air wrench. You'll have to take leave everytime the car goes into the workshop. [laugh]

 

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I get a "sick" feeling everytime I see an air wrench put into use on my brick, it always seems to be a overkill on the tightening of the nuts and bolts......are there air wrenches with built in specific torque settings? [angelic]
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You ah, sometimes can make me ROTFL one. [laugh]

 

Makes me wonder: Are there ANY workshops in SG that are anally retentive when it comes to doing things properly, e.g., observing manufacturer-specified torques. Are agent workshops any better than independents?

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Even agents don't follow the recommended torque specs or tuning specs so wat do U think about independent workshops? If U wanna get the job done, do it yourself! [;)]

 

Those Americans get all the fun, some even have a hydraulic lift for their cars in the home garage!

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