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Post by taint on May 4, 2008 12:37:57 GMT
As part of my on-going overhaul of my D6, I'm fitting a hugger to protect the new shock. Going to fit the hugger at the same time as the rear brake overhaul, I've discovered that the original tension arm bolts (aside from looking like carp) are now too short; they go through and I can get the nut onto them, but the hole for the split pin is obscured. I wanted to know if an A2 stainless steel socket cap bolt and a nylock nut would be a suitable replacement?
Are the originals high tensile steel, or just standard mild steel? The part diagrams I have don't mention  I have something on hand that will fit; so I'm going to fit them, but as this is safety related, I figure a second opinion is worthwhile T. |
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Post by taint on May 5, 2008 13:41:19 GMT
*bump*
Anyone?
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Post by 5watt on May 5, 2008 14:08:58 GMT
What is the upper one made of?
I doubt it will be high tensile since that would be stronger than the arm itself! And more importantly to the accountants, dearer than mild steel too.
You only need too worry about the bolt coming out, so the stainless with nylock should be ok.
Fit it and check it regularly, that way you'll know if it needs to be changed.
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Post by amorti on May 5, 2008 14:50:04 GMT
Yes but the arm isn't subject to repeated shearing forces. I would stick with HT. Cue clichés along the lines of "it's your brakes, your safety, your life", et ceteraaaa
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Post by amorti on May 5, 2008 14:51:04 GMT
PS, this tip is brought to you by someone who has seen a front caliper retaining bolt shear in normal use. I wasn't impressed! Bet it wouldn't have got to ten years / 50k miles if it were stainless.
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Post by taint on May 5, 2008 15:07:17 GMT
Hmm, if it was the retaining bolt, I wouldn't be using anything other than High tensile or titanium. I just wasn't certain what the arm bolts would be made from.
I'll have a look at ordering replacements.
T.
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Post by General Gman on May 6, 2008 13:08:40 GMT
Is there nowt on the head of the bolt to indicate ?
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Post by taint on May 6, 2008 18:28:07 GMT
G-Man, there's a number 6 or a 9 on the head and that's it. I'm not certain how that relates to the size; as the Bolt is an M8. Any ideas?
If it is high tensile it seems to be relatively soft; as the flats of the head have gotten quite chewed up.
Cheers
T.
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Post by General Gman on May 6, 2008 19:52:01 GMT
It's not high tensile, then - it would have the grade marked on it ( 8.8 or 10.9, usually)
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Post by taint on May 6, 2008 22:08:05 GMT
Ok, so the stainless should be fine.
Thanks G-man
T.
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Post by CD on May 7, 2008 16:23:30 GMT
I would go a little longer and drill it for a split pin. Stainless does not "give" like carbon steel so nuts tend to loosen. I'm sure if it needed to be high tensile the surrounding metal would be a lot heavier and the ally caliper lug wont be HT either.
Bolts generally shear because they've been over tightened. When I used to be a power station engineer we initially had routine maintenance schedules that included tighteness checks on motor and pump feet bolts. After a while with vibration and regular check tightening many sheared off. After that the schedules were changed to tapping the bolts/nuts not be sure they were fixed but not pulled with a spanner.
BTW the sheared bolts were 1" BSF or bigger.
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Post by General Gman on May 8, 2008 13:07:13 GMT
I would go a little longer and drill it for a split pin. Stainless does not "give" like carbon steel so nuts tend to loosen. I'm sure if it needed to be high tensile the surrounding metal would be a lot heavier and the ally caliper lug wont be HT either. Bolts generally shear because they've been over tightened. When I used to be a power station engineer we initially had routine maintenance schedules that included tighteness checks on motor and pump feet bolts. After a while with vibration and regular check tightening many sheared off. After that the schedules were changed to tapping the bolts/nuts not be sure they were fixed but not pulled with a spanner. BTW the sheared bolts were 1" BSF or bigger. Aye.... I used to test pumps / filters / mixers for the petrochemical industry, and if you get a severely unbalanced impeller, the mounting bolts can go fairly quickly - even stuff like M40 duplex stainless items |
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