Toffee Apple bolts

[DirtyDawg]

Who has replaced their drive member (Drive Flange) Bolts and if so with wat?
I was re torquing mine after replacing a seal and got to 30lbs and the thing twisted in half (Ken was a witness)
they arent H/steel...

[BigJon]

We keep the genuine parts in stock...

[Ken]

Who has replaced their drive member (Drive Flange) Bolts and if so with wat?
I was re torquing mine after replacing a seal and got to 30lbs and the thing twisted in half (Ken was a witness)
they arent H/steel...

here here mr speaker :D

[rick130]

they arent H/steel...

they should be, you've scored a dud.

[Blknight.aus]

if ones been loose and hammering itself it will get that butteryfeel as all the little stress fractures wave hands and part company, I see maybe 1 a month like it and its usually only one or 2 bolts on a flange that do it. then its replace the lot after lots of swearing.

[justinc]

The OE bolts are supposed to be grade 10.9 High tensile. I have broken a few in my time, and the reason is fatigue. The tensile strength of these bolts is quite high, but if overtightened then they will stretch only a SMALL amount before breaking. I have replaced these with grade 8.8 in the past to test the theory that a slightly lesser tensility allows some degree of stretch and movement before plastic deformation and breakage occurs. The 'test' vehicle was a 130 Defender, its rear diff now resides under the back of my RR, Still with 8.8 bolts.


JC

[Bigbjorn]

Are they perhaps a one use only bolt? must be replaced every time they are undone.

[DEFENDERZOOK]

The OE bolts are supposed to be grade 10.9 High tensile. I have broken a few in my time, and the reason is fatigue. The tensile strength of these bolts is quite high, but if overtightened then they will stretch only a SMALL amount before breaking. I have replaced these with grade 8.8 in the past to test the theory that a slightly lesser tensility allows some degree of stretch and movement before plastic deformation and breakage occurs. The 'test' vehicle was a 130 Defender, its rear diff now resides under the back of my RR, Still with 8.8 bolts.


JC




so.....if i fit 8.8 grade bolts to the next 130 i see......




will i end up with its diff under lurch.........?

[Blknight.aus]

no, they're reusable so sayeth the emei...

I prefer the 8.8 grade with a lock washer under it tho, just seems right to me...

[rick130]

<snip>
with a lock washer under it tho, just seems right to me...

errr, I hate spring washers and the like.
A good tension wrench and the appropriate loctite is a mechanic's best friend :D

FWIW, i had an article years ago on rod bolt failures conducted by Ford Motorsport in the US.
The three areas tested were over tensioning (IIRC plastic deformation was just starting) and under tensioning vs correct tension (based on bolt stretch)
Interesting conclusion was that the worst thing you can do to a highly loaded high tensile bolt was under tension it.
Fatigue failure life was substantially shorter (IIRC less than 1/2) for the under tensioned bolts vs over tensioned, which was only a slightly shorter life compared to the correct tension.

[rick130]

and if anyone ever needs to use a 12.9 metric bolt, better off using an Unbrako or Holo Krome socket head cap screw (allen bolt) as their heat treatment and material is so far superior to most all industrial hex head bolts.

In critical situations needing a Grade 5 SAE/Imperial size, try and source an AN airframe bolt for the above reasons.

[DirtyDawg]

and if anyone ever needs to use a 12.9 metric bolt, better off using an Unbrako or Holo Krome socket head cap screw (allen bolt) as their heat treatment and material is so far superior to most all industrial hex head bolts.

In critical situations needing a Grade 5 SAE/Imperial size, try and source an AN airframe bolt for the above reasons.

Hard to torque without proper device though.. I might give the 8.8's a go all round

[rick130]

Hard to torque without proper device though..


??? just use a tension wrench ???