Hi spec brakes
16-01-2008, 11:43 AM
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Re: Hi spec brakes
Originally Posted by cameron2
Where can i get some of the allen bolts from? The ones that hold the bell to the rotor? 
Hispec supplied 8.8 grade but I have 12.9 grade waiting to go in - any nut and bolt supplier should be able to help
I dont know what quality / grade the Hispec nuts are so I will be using K nuts on the back - not cheap though
16-01-2008, 11:57 AM
#5
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Re: Hi spec brakes
Originally Posted by WD Pro
Hispec supplied 8.8 grade but I have 12.9 grade waiting to go in
I dont know what quality / grade the Hispec nuts are so I will be using K nuts on the back - not cheap though
I dont know what quality / grade the Hispec nuts are so I will be using K nuts on the back - not cheap though
also what are K nuts Cheers
16-01-2008, 12:08 PM
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8.8 & 12.9 = the bolt grade or strength, the higher the number the better. Will be stamped into the head.
8.8 is the start of high tensile stuff (normally hex head), 10.9 grade (eg ford prop shaft bolts) is actually quite rare and 12.9 is probably the best / most easily available stuff 'off the shelf' (normally socket cap heads).
Thats why you just cant replace stuff with stainless as its a 'little' weaker than 8.8
Lots of other fancy / military / aerospace grades but maybe limited sizes or bespoke applications etc.
K nuts are redily available 'aerospace' type nuts that are very strong light and self locking. They come in self colour but silver plated ones can be had if your a bufty. I think the CVH rockers are held on with a K 'type' of nut.
As a rule of thumb only ever 'upgrade' from what the OE supplies as they will give you the very cheapest that will 'just' do the job.
WD
8.8 is the start of high tensile stuff (normally hex head), 10.9 grade (eg ford prop shaft bolts) is actually quite rare and 12.9 is probably the best / most easily available stuff 'off the shelf' (normally socket cap heads).
Thats why you just cant replace stuff with stainless as its a 'little' weaker than 8.8
Lots of other fancy / military / aerospace grades but maybe limited sizes or bespoke applications etc.
K nuts are redily available 'aerospace' type nuts that are very strong light and self locking. They come in self colour but silver plated ones can be had if your a bufty. I think the CVH rockers are held on with a K 'type' of nut.
As a rule of thumb only ever 'upgrade' from what the OE supplies as they will give you the very cheapest that will 'just' do the job.
WD
16-01-2008, 12:36 PM
#7
20K+ Super Poster.
Stainless is way stronger than 8.8, but has no DUCTILITY, so is unsuitable for some uses.
A bit like the ones you are fitting are not the best as they have little Ductility, also, and where heat and contraction/expansion is an issue, careful thought needs to applied.
tabetha
A bit like the ones you are fitting are not the best as they have little Ductility, also, and where heat and contraction/expansion is an issue, careful thought needs to applied.
tabetha
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16-01-2008, 12:50 PM
#8
PassionFord Post Troll
Originally Posted by WD Pro
8.8 & 12.9 = the bolt grade or strength, the higher the number the better. Will be stamped into the head.
8.8 is the start of high tensile stuff (normally hex head), 10.9 grade (eg ford prop shaft bolts) is actually quite rare and 12.9 is probably the best / most easily available stuff 'off the shelf' (normally socket cap heads).
Thats why you just cant replace stuff with stainless as its a 'little' weaker than 8.8
Lots of other fancy / military / aerospace grades but maybe limited sizes or bespoke applications etc.
K nuts are redily available 'aerospace' type nuts that are very strong light and self locking. They come in self colour but silver plated ones can be had if your a bufty. I think the CVH rockers are held on with a K 'type' of nut.
As a rule of thumb only ever 'upgrade' from what the OE supplies as they will give you the very cheapest that will 'just' do the job.
WD
8.8 is the start of high tensile stuff (normally hex head), 10.9 grade (eg ford prop shaft bolts) is actually quite rare and 12.9 is probably the best / most easily available stuff 'off the shelf' (normally socket cap heads).
Thats why you just cant replace stuff with stainless as its a 'little' weaker than 8.8
Lots of other fancy / military / aerospace grades but maybe limited sizes or bespoke applications etc.
K nuts are redily available 'aerospace' type nuts that are very strong light and self locking. They come in self colour but silver plated ones can be had if your a bufty. I think the CVH rockers are held on with a K 'type' of nut.
As a rule of thumb only ever 'upgrade' from what the OE supplies as they will give you the very cheapest that will 'just' do the job.
WD
16-01-2008, 12:53 PM
#9
PassionFord Post Troll
Originally Posted by tabetha
Stainless is way stronger than 8.8, but has no DUCTILITY, so is unsuitable for some uses.
A bit like the ones you are fitting are not the best as they have little Ductility, also, and where heat and contraction/expansion is an issue, careful thought needs to applied.
tabetha
A bit like the ones you are fitting are not the best as they have little Ductility, also, and where heat and contraction/expansion is an issue, careful thought needs to applied.
tabetha
16-01-2008, 12:59 PM
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stocked
16-01-2008, 03:56 PM
#14
20K+ Super Poster.
Tensile strength is NOT the issue, if you are going to try and be smart do it properly.
DUCTILITY IS THE ISSUE.
The stronger the less appropriate it is, as it needs to have FATIGUE RESISTANCE, ie be part alloy mix, MUCH better AND stronger as it will not BREAK as easily as one which does not readily stretch.
Now smarty person ask yourself ONE of the reasons bells are made of alloy ?
tabetha
DUCTILITY IS THE ISSUE.
The stronger the less appropriate it is, as it needs to have FATIGUE RESISTANCE, ie be part alloy mix, MUCH better AND stronger as it will not BREAK as easily as one which does not readily stretch.
Now smarty person ask yourself ONE of the reasons bells are made of alloy ?
tabetha
16-01-2008, 05:09 PM
#15
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Originally Posted by cameron2
'K' nuts?
What are they? Pics?
What are they? Pics?
the above was taken from http://www.merlinmotorsport.co.uk/FA...duct_info.html
16-01-2008, 09:46 PM
#19
Originally Posted by HBS
Tensile strength:
Grade 8.8 = 800 N/mm2
Grade 12.9 = 1200N/mm2
Stainless A2 - 70 = 700 N/mm2
Stainless A2 - 80 = 800 N/mm2
Hope this is useful.
Grade 8.8 = 800 N/mm2
Grade 12.9 = 1200N/mm2
Stainless A2 - 70 = 700 N/mm2
Stainless A2 - 80 = 800 N/mm2
Hope this is useful.
ARP bolts tend to be 190 000 psi which is a term I can understand.
Mark
17-01-2008, 11:34 AM
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Originally Posted by NUTS RuS
Originally Posted by cameron2
How much then?
Cheers,
WD
17-01-2008, 11:42 AM
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Originally Posted by tabetha
Tensile strength is NOT the issue, if you are going to try and be smart do it properly.
DUCTILITY IS THE ISSUE.
The stronger the less appropriate it is, as it needs to have FATIGUE RESISTANCE, ie be part alloy mix, MUCH better AND stronger as it will not BREAK as easily as one which does not readily stretch.
Now smarty person ask yourself ONE of the reasons bells are made of alloy ?
tabetha
DUCTILITY IS THE ISSUE.
The stronger the less appropriate it is, as it needs to have FATIGUE RESISTANCE, ie be part alloy mix, MUCH better AND stronger as it will not BREAK as easily as one which does not readily stretch.
Now smarty person ask yourself ONE of the reasons bells are made of alloy ?
tabetha
I appreciate you are a very knowledgeable / respected guy and don’t want to knock your intelligence, however the comments you made further up the thread about stainless being stronger than steel is just not true in the context of easily available of the shelf bolts, i.e. the nature of this topic.
I didn’t tell the guy what to do, just what I was doing, after some questions I then provided some further info and a link
As for being “smarty” my guidance comes from some books on race car preparation written by a guy that made his living from building and setting up cars for top level Motorsport (i.e. far more knowledgeable than myself). As the bolts are loaded in single shear his recommendation is to bin the supplied items and use the highest spec bolts possible (he uses bolts rated at a higher tensile strength than a 12.9), to check torque frequently and to replace them every time they are removed. He claims to have seen inferior bolts sheer and to have witnessed the bolts actually pulling themselves out of a badly designed ally bell
The K nuts may well be over specced for the torque of the application but they have the advantage of being reusable, shake proof and more importantly having a wide flange to stabilize / support the assembly.
As I won’t be drawn into a argument over the net (and don’t get a lot of time to spend on it
) this will be my last post on this topic Cheers,
WD
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