aaarrrrggghhhh crap ( all fixed now)A WARNING TO YOU ALL BE AWARE
22-06-2009, 10:30 AM
#81
when a bolt is hardened or zinc plated you can get what is called hydrogen embrittlement,i am an elctroplater and do zinc plating and have come accross this once or twice,this is why seat belt bolts are not plated here is a link to it if you want a read
http://corrosion-doctors.org/Forms-H...rittlement.htm
cheeRS gary
AKA shrek
http://corrosion-doctors.org/Forms-H...rittlement.htm
cheeRS gary
AKA shrek
gary thanks for the link some interesting info in that black bolts all the way for me now
Last edited by andy escos; 22-06-2009 at 10:39 AM.
22-06-2009, 10:34 AM
#82
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when a bolt is hardened or zinc plated you can get what is called hydrogen embrittlement,i am an elctroplater and do zinc plating and have come accross this once or twice,this is why seat belt bolts are not plated here is a link to it if you want a read
http://corrosion-doctors.org/Forms-H...rittlement.htm
cheeRS gary
AKA shrek
http://corrosion-doctors.org/Forms-H...rittlement.htm
cheeRS gary
AKA shrek
22-06-2009, 11:33 AM
#85
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It is the acid clean before plating that causes the problem, the hydrogen needs to be removed otherwise it is 'traped' in by the plating causing the brittleness (even more so on chrome rather than zinc) - the baking removes the hydrogen (which I think comes from the sulphuic acid - H2S04 ?)
22-06-2009, 11:35 AM
#86
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Good point and worth checking but I 'think' the black is only external and a by product of the heat treatment process - the bolt will still be silver under the coating.
22-06-2009, 01:16 PM
#88
Advanced PassionFord User
Andy,
Do you have a pic of the other end of the bolt furthest away from the head and where it failed? straight on pic of the end of the bolt if you have one....
Do you have a pic of the other end of the bolt furthest away from the head and where it failed? straight on pic of the end of the bolt if you have one....
22-06-2009, 01:40 PM
#89
What i cannot understand is why they never had a torque setting?
As we all know you can just wang a bolt up
found this it could be some use
http://www.rpmmech.com/docs/tightening_torque.pdf
Paul
22-06-2009, 01:49 PM
#90
...............
TBH, they look very under-engineered at that end? Think of the size of nut on the end of an ARB that normally locates in the TCA. Using a bolt that size is asking for trouble.
Is it possible that articulated end locks up in certain positions putting more strain on the bolt?
Is it possible that articulated end locks up in certain positions putting more strain on the bolt?
22-06-2009, 04:48 PM
#91
ive been to my local machine shop today & he said he is happy with the amount of thread in the brkt & there is no point in reengineering the brkt to get more material to thread the bolt into but said it is a good idea to machine said brkt to take m12 socket cap bolts but use 8.8 rather than 12.9 as in this application they are to hard ,so i pick up my retapped brkt,s tomorrowps id recommend any body else with these comp struts to do the same .andy
22-06-2009, 04:58 PM
#94
Did you contact them today Andy ?
I have been away all weekend so only just seen this.
Looks like a simple bolt failure to me, but im sure as a testomony they will be delighted to hear that none of the parts they actually manufacture have failed.
I have been away all weekend so only just seen this.
Looks like a simple bolt failure to me, but im sure as a testomony they will be delighted to hear that none of the parts they actually manufacture have failed.
22-06-2009, 04:59 PM
#95
22-06-2009, 05:13 PM
#96
yes it is a bolt failure but why did both bolts fail when i was only getting my car out the garage at a very low speed i.e slip clutch coss its a awkward bugger to get in & out & why are my bolts 12.9 plated & every body i spoke to have got 10.9 black bolts unless it was a dodgy batch of bolts
22-06-2009, 05:15 PM
#97
The only issues I have ever heard of are arms bending and the shear bolt in the bracket breaking but thats what they are designed to do to when a car takes a heavy knock rather than twist the chassis.
There was a thread on here about 12 months ago showing the arm bend after a whack with a deep pot hole or something.
Items often have weak links designed into them, but that bolt is not classed as a weak link.
There was a thread on here about 12 months ago showing the arm bend after a whack with a deep pot hole or something.
Items often have weak links designed into them, but that bolt is not classed as a weak link.
22-06-2009, 07:44 PM
#100
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Glad this happened at low speed, and shame it happened at all! 
When I was installing my roll cage I needed more bolts and my supplier recommended 8.8 as anything higher was too brittle in his opinion and may snap under load.
Hopefully you have it all sorted now
When I was installing my roll cage I needed more bolts and my supplier recommended 8.8 as anything higher was too brittle in his opinion and may snap under load.
Hopefully you have it all sorted now
22-06-2009, 08:02 PM
#101
the design in these comp struts is not unique to comp brake, i have used the same set of comp struts and bolts on my last rally car for nye on 10 years, and have never broken any of them, and that includes probably 100 or so miles in very rough forrest stages.
22-06-2009, 08:03 PM
#102
Too many posts.. I need a life!!
I was going to suggest that 12.9 are most likely too brittle. Failure looks like mainly fast fracture caused by an over load condition, but there may be some fatigue, its hard to tell from those images. Its likely that they were yeilded the last time you were out (and given it a beating) and began to yeild and elongate making the problem worse (like having a loose bolt).
JAmes.
JAmes.
22-06-2009, 10:15 PM
#109
And what it does (for those that don't know) or want to disect
Fits into this
Which screws into this
To create this
Which looks like this
There is no load on the bolt (weight) there is no tortional load on it (twist) and I suspect going from a M10 to M12 won't gain you any greater clamping force as the distance is set by the other components but lets see what the experts in the field say.
It the PF over engineered market needs it then we can get it done
Simple
22-06-2009, 10:55 PM
#112
But I have seen many things sheer from over tightening, watched a crew do it only yesterday and that was to an M12 wheel stud. Rattle them up with a gun then nip them up with a breaker bar. Eventually it cries enough and "snap" you have a broken bolt.
Done it myself with a head bolt, 11 set to manufacturers spec final one went "snap" before it got there.
Your caliper is generally held on with an M10 bolt and a wheel held on with a M12 if you think that small component needs an M12 then change it
but as markk commented there are literally hundreds and hundreds and hundreds out there all running fine at M10Im not sure how a bolt manufacturer would make a dodgy batch of bolts either as I guess the presses are churning them out literally in millions per shift 24/7. They don't just make 4 for these every time we sell a set.
As for the torque treat it like a caliper bolt and you will be fine
swing on it like your life depends on it (like the wheel stud and head bolt above) any you too may get grazed knuckles and swear words being emmitted uncontrollably from your mouth
Last edited by NUTS RuS; 22-06-2009 at 11:01 PM.
22-06-2009, 11:51 PM
#116
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Dont think it was crap bolts. Looks like it was overtightened to me, which caused stress cracks - then the moisture in the british air finished the job off. Soon as its corroded enough, 'roberts your fathers brother' - off comes the head.
High tensile bolts are useless if they are overtightened. I break em all the while at work. If what said above is true, (there is no weight load or twist load) then on your new bolts stick a bit of thread-lock on the thread, smear vaseline/grease on the head and dont go mad with the tightening. (And no jokes about vaseline on the head or whutever)
Stainless bolts are just as easy to break via overtightening, but provided they aren't overtightened they would be a better option as they stand up to the weather a fair bit better (i.e. they dont corrode). However they cost a bit more that zinc plated ones.
High tensile bolts are useless if they are overtightened. I break em all the while at work. If what said above is true, (there is no weight load or twist load) then on your new bolts stick a bit of thread-lock on the thread, smear vaseline/grease on the head and dont go mad with the tightening. (And no jokes about vaseline on the head or whutever)
Stainless bolts are just as easy to break via overtightening, but provided they aren't overtightened they would be a better option as they stand up to the weather a fair bit better (i.e. they dont corrode). However they cost a bit more that zinc plated ones.
23-06-2009, 11:19 AM
#118
so have we figured out what bolts to use and what torques to torque them up to yet or is it still open to debate?
only asking ebcause i've got a set as well and am not sure if several years of sitting about the place doing 5 miles a year has affected them a lot or not
only asking ebcause i've got a set as well and am not sure if several years of sitting about the place doing 5 miles a year has affected them a lot or not
23-06-2009, 01:05 PM
#119
Advanced PassionFord User
If these kits were fitted to a normal RWD escort wouldn't they only be under load "compression" under braking. But as yours is a 4x4 they would also be load under acceleration which is maybe not part of the design ?