aaarrrrggghhhh crap ( all fixed now)A WARNING TO YOU ALL BE AWARE
20-06-2009, 11:46 PM
#41
I don't understand the failure mechanism there? 
... The bolts are under no load, as the vertical load is being transmitted through the two large plates/stepped washers either side of the TCA, via the stepped hole in the TCA. The horizontal /car moving forwards directional loading is pushing the compression strut into the car, so the bolt is under no real axial load!! The only time I can see the bolts being directly stressed is if the car is going backwards, where the bolt will be holding the strut together against the front washer/plate in the TCA.
Did they fail as the car being driven/towed backwards?
The only other thing I can think of is were the bolts actually home and tight, or had they bottomed out allowing a gap between the head and the large washer/plate? If there was a gap it would allow the comp strut to move back and forth in the TCA and hit the head of the bolt, eventually knocking it off as your pics show..... Also, was there a small washer fitted under the head?
Might be worth contacting Compbrake as I am sure they would appreciate the heads up, and Tony will be more than helpful I am sure in resolving this.
... The bolts are under no load, as the vertical load is being transmitted through the two large plates/stepped washers either side of the TCA, via the stepped hole in the TCA. The horizontal /car moving forwards directional loading is pushing the compression strut into the car, so the bolt is under no real axial load!! The only time I can see the bolts being directly stressed is if the car is going backwards, where the bolt will be holding the strut together against the front washer/plate in the TCA. Did they fail as the car being driven/towed backwards?
The only other thing I can think of is were the bolts actually home and tight, or had they bottomed out allowing a gap between the head and the large washer/plate? If there was a gap it would allow the comp strut to move back and forth in the TCA and hit the head of the bolt, eventually knocking it off as your pics show..... Also, was there a small washer fitted under the head?
Might be worth contacting Compbrake as I am sure they would appreciate the heads up, and Tony will be more than helpful I am sure in resolving this.
the bolt is like 20mm max long, and the thickness of the end plate is about 5mm, then you have the gap of the tca bit where the old bushes would go,, so all in all there is only about 10mm of the thread going in to the strut. imo i would like more lol
21-06-2009, 08:44 AM
#44
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21-06-2009, 05:51 PM
#51
PassionFord Post Troll
suprised they are 12.9 and zinc coated? that usally takes the strenght out them,,i always use uncoated 12.9's
Last edited by andrewg; 21-06-2009 at 05:57 PM.
21-06-2009, 05:54 PM
#54
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Aircraft are built with them, so can't be that bad?
21-06-2009, 05:59 PM
#60
PassionFord Post Troll
dono thats what my bolt supplier told me when i asked for 12.9 plated,,
21-06-2009, 06:17 PM
#62
if there is nothing connecting the other side to that, then why would it brake at exactly the same place and at the same time if it wasn't doing a wildcat non union approved walk out?
perhaps there was an issue with the bolt heads from before that caused the snapping or perhaps it was the long down time?
perhaps there was an issue with the bolt heads from before that caused the snapping or perhaps it was the long down time?
21-06-2009, 06:22 PM
#64
if its 4x4, or 6x4 or 8x8, the compression strut is still the component that holds the wheel in the arch, when you brake it will still pull on the bolts if your going backwards because the wheels will want to go forward, which they did when the bolts broke
i would also drop the struts to make sure the tops havent been damaged when they were pushed forward
i would also drop the struts to make sure the tops havent been damaged when they were pushed forward
Last edited by JTECH James; 21-06-2009 at 06:27 PM.
21-06-2009, 06:41 PM
#65
if its 4x4, or 6x4 or 8x8, the compression strut is still the component that holds the wheel in the arch, when you brake it will still pull on the bolts if your going backwards because the wheels will want to go forward, which they did when the bolts broke
i would also drop the struts to make sure the tops havent been damaged when they were pushed forward
i would also drop the struts to make sure the tops havent been damaged when they were pushed forward
21-06-2009, 06:42 PM
#66
This thread should be read by all who fit shiney stainless bolts to there cars suspension
If a high tensile bolt can fail like this then a stainless item which is more brittle has no hope
Glad it happened like that Andy and not at speed
Paul
If a high tensile bolt can fail like this then a stainless item which is more brittle has no hope
Glad it happened like that Andy and not at speed
Paul
22-06-2009, 08:58 AM
#76
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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, 09:01 AM
#77
Team HOTHOT!
I'd be more concerned about the bolts being fully threaded aswell - for the load and type of application they are in you need partially threaded bolts with the unthreaded/shoulder part being the load bearing piece to avoid this sort of thing happening!
22-06-2009, 09:05 AM
#79
Team HOTHOT!
Andy - if you want me to, I can get you some 12.9 black M12 socket caps (what's the pitch? standard 1.75, 1.5 fine or 1.25 fine?) in the length you require and whatever "unthreaded" length needed aswell (at a guess, 5mm unthreaded in this case) for pennies - let me know via PM if you need them as I can have them to you on Weds if you need?
Last edited by Graceland; 22-06-2009 at 09:07 AM.
22-06-2009, 10:24 AM
#80
Andy - if you want me to, I can get you some 12.9 black M12 socket caps (what's the pitch? standard 1.75, 1.5 fine or 1.25 fine?) in the length you require and whatever "unthreaded" length needed aswell (at a guess, 5mm unthreaded in this case) for pennies - let me know via PM if you need them as I can have them to you on Weds if you need?
graceland thanks for your kind offer but i got some new black m12 12.9 socket cap bolts this morning & im going to drill & tap the bracket out to suit should,nt break then ,just makes me feel happier knowing there m12 & not m10 .