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Old 21st December 2015, 16:41   #31
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Default Re: PCD Variation Bolts (aka Wobble Bolts) - Myth versus Reality

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Originally Posted by PatchyBoy View Post
No. I want to know why people consider these bolts to be unsafe. I beg to disagree with the bold part. I am convinced that done right, this setup is only as dangerous as the OE setup, unless someone provides me with scientific evidence proving otherwise. After all TUV certification does not happen that easily.

Stress cracks and bolt loosening will happen if the bolts are not tightened to manufacturer specified torque, both with these bolts as well as with OE bolts. The bolts can only fail if the shear forces overcome the clamping forces and that is impossible, if the bolts are torque correctly.
Its not possible to "convince" anyone on topics like this. Everyone have their beliefs and are entitled to. We just need to be sure we don't risk our and others lives on the road.

However, after going through this thread and having worked for some time analyzing metal failures during early part of my career (yes I am a mechanical engineer) I do feel that the stock setup is the best setup.

Why do I feel so? Here's why:
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Originally Posted by PatchyBoy View Post
Stress cracks and bolt loosening will happen if the bolts are not tightened to manufacturer specified torque, both with these bolts as well as with OE bolts. The bolts can only fail if the shear forces overcome the clamping forces and that is impossible, if the bolts are torque correctly.
OE Manufacturer specified torque is applicable to OE manufacturer supplied parts.

You change something in the chain and you need to go back to your drawing board and calculators. How can I guarantee that the replacements are good enough to take the specified torque? I have no knowledge of where these parts are made, I have no idea who designed them, I have no proof of tests made on them to validate their use on automobiles - Anything thats not OE - there is no governing body like ARAI to certify the parts for safety and functionality.

The material selection (type and grade of steel, properties influencing strength) the manufacturing processes, heat treatment, surface finish, quality control, all contribute to the fitness of the end product. I trust OE suppliers to take care of these factors as they do have the engineering depth and experience built up over the decades.

A shiny top class chrome surface is useless if the material can not take the load. What if they are harder / tougher than the mating parts? They can eat deform mating parts and induce failure elsewhere.

So, will wobbly bolts work: Yes they do

Will I have them on my car? NO.

I simply don't have enough knowledge and information on and about the part and manufacturer and this stops me from trying these things on my car.

In case I have an issue with the OE part I know whom to approach for a redressal - in aftermarket non-OE replacement - we have to fend for ourselves.
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Old 21st December 2015, 18:43   #32
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Default Re: PCD Variation Bolts (aka Wobble Bolts) - Myth versus Reality

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Originally Posted by autocrat View Post
Its not possible to "convince" anyone on topics like this.
I was not trying to convince anyone. I was only looking for some solid inputs about the potential problems with these bolts.

Quote:
How can I guarantee that the replacements are good enough to take the specified torque?
Thanks a lot. It was this kind of specifics I was looking for, from a forum as reputed as TBHP. Much appreciated. I just did not want to be ignorant and then have this nagging feeling in the corner of my mind. Thanks again.

Last edited by PatchyBoy : 21st December 2015 at 18:49.
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