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Caliper Stretch Bolts?


Smiler

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Looking for some information please.

I have just been arranging for a new set of tyres for my 8th gen. While shopping around some people have told me that the caliper bolts are stretch bolts and need to be replaced when they are dropped to get the wheels out while others have not mentioned it at all.

Has anyone else had the same mixed message? 

 

Thanks all

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This comes up every now and then.....

 

 

 

IMHO you only change them if they started to look grotty.  Other than that use a torque wrench as not to overload them.

 

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Pro-Bolt do a set of titanium bolts that look really good and don't need replacing at the OEM torque 

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Stretch Bolts!! Be the last thing in the world I'd want is to have my Caliper Bolts stretch!!! Not a term I've heard of. Just to back up Dutchy, have always used the original bolts provided they are in good condition, never had any issue at all and have always done my own brake servicing.

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Stretch bolt is a term used to describe bolts that are torqued beyond the point of plastic deformation, otherwise know as torque-to-yield.  Modern VW owners are intimately familiar; seems like I throw away at least $50 worth of fasteners for any remotely major maintenance task.

 

Some manufacturers, like M-B, give a total fastener length at which point the fastener must be replaced. 
 

I usually re-use the caliper bolts 3x and replace.  Strange that when you go to the dealer, they never have any in stock...

 

 

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26 minutes ago, MadScientist said:

Stretch bolt is a term used to describe bolts that are torqued beyond the point of plastic deformation, otherwise know as torque-to-yield.  Modern VW owners are intimately familiar; seems like I throw away at least $50 worth of fasteners for any remotely major maintenance task.

 

Some manufacturers, like M-B, give a total fastener length at which point the fastener must be replaced. 
 

I usually re-use the caliper bolts 3x and replace.  Strange that when you go to the dealer, they never have any in stock...

 

 

Thanks for the insight MS. Won't be buying a VW in the future!!

Cheers.

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With "stretch bolts" you generally tighten the bolt to a prescribed torque setting. Then you tighten the bolt

a certain amount more, usually by measuring the head of the bolt for movement. Some call for marking the

bolt head and stopping when you reach a certain degree of movement, i.e. 20 degrees or some such.

 

These are more common with very tight bolts like high performance head bolts. I would imagine the reason

Honda recommends replacing the bolts is to get fresh thread locking compound into the bolt holes. That's my

thought and I'm sticking to it. :beer:

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15 hours ago, FJ12Ryder said:

These are more common with very tight bolts like high performance head bolts. I would imagine the reason

Honda recommends replacing the bolts is to get fresh thread locking compound into the bolt holes. That's my

thought and I'm sticking to it. :beer:

 

That is a good theory, but it doesn't explain why Honda didn't just use this kind of instruction (copied from the front of a Honda Workshop Manual):

 

5ad09f62b7c16_HondaLockingAgentSymbol.thumb.jpg.8d2cf1529967bf88c53648d63241c86a.jpg

 

Rather than this one:

 

5ad0a1322ba24_HondaNewPartSymbol.thumb.jpg.0303fbcf0e32ba4ddf9491546e0be463.jpg

 

Perhaps they wanted dry thread lock to be used, rather than wet thread lock (which could throw off the torque reading)?   Or perhaps there was some other reason (e.g., fastener deformation)?  I generally just use titanium these days...

 

Ciao,

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Dutchy’s Post was spot on for the real world. Madscienist and FJ12 are also right though. 

 

Bolts can generally be reused but can become deformed if they’ve been in service a long time or some gorilla insists on overtightening them. 

 

I generally use Titanium (6AL4V) like JZH. It has a lovely springy quality and unlike steel always reverts back to its original shape when released.

 

FWIW, I never use Loctite on brake components. Copper slip every time. I know most people will strongly disagree with this (and even consider it unsafe) but I’ve never lost a brake component on road or track in 20 years. I do, however, regularly check the bolts for tightness. 

 

YMMV. 

 

Stray 

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