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what type of steel
david - 18/5/10 at 11:06 PM

would high tension bolts be ok for bolting the prop shaft to the sierra diff.david

Frosty - 18/5/10 at 11:12 PM

I'm almost certain that the 4 bolts that fix the prop to the diff and just plain old 8.8 tensile. I'll let someone else confirm though.

[Edited on 18/5/10 by Frosty]

alexg1965 - 19/5/10 at 05:22 AM

I've just looked at mine which were from a Cosworth LSD and they're 10.9s

blakep82 - 19/5/10 at 05:36 AM

10.9 off the capri diff too

flak monkey - 19/5/10 at 05:42 AM

10.9 normally....

But....

The torque that they are tightened to is also well within the spec for an 8.8 bolt which means you'll get the same clamping load which is what transmits the torque. The bolts themselves dont take any of the load - unless something happens and they come loose.

Theortically 8.8 are fine. And I ran my pinto on them without any problems for 6000+miles.

I changed to 12.9 cap heads when installing the duratec though just for piece of mind.

David

matt_gsxr - 19/5/10 at 06:30 AM

to pre-empt the next question.

M10 x 1

http://www.burtonpower.com/

under transmission & clutch, then go to propshaft
£1.09 each 10.9 spec.

Matt

iank - 19/5/10 at 06:37 AM

quote:
Originally posted by Frosty
I'm almost certain that the 4 bolts that fix the prop to the diff and just plain old 8.8 tensile. I'll let someone else confirm though.

[Edited on 18/5/10 by Frosty]


'Plain old' 8.8 are HT

mcerd1 - 19/5/10 at 07:11 AM

quote:
Originally posted by flak monkey
10.9 normally....

But....

The torque that they are tightened to is also well within the spec for an 8.8 bolt which means you'll get the same clamping load which is what transmits the torque. The bolts themselves dont take any of the load - unless something happens and they come loose.

Theortically 8.8 are fine. And I ran my pinto on them without any problems for 6000+miles.

I changed to 12.9 cap heads when installing the duratec though just for piece of mind.

David


^^ while that is true - the diff bolts take some of there load in shear
for shear loading all the clamping they need is stop them coming lose...
(I know they should use the clamping to generate friction between the two surfaces - but that doesn't mean the bolts don't need any shear strength)

the 8.8, 10.9 & 12.9 grades (all HT grades) may refer to there tensile capacity - but the shear capacity is directly related to the tensile capacity



btw - in steel construction we have 4.6, 8.8, 10.9 and 12.9 bolts - then we have the HSFG bolts (High Strenght Friction Grip) in a couple of grades all to themself


[Edited on 19/5/2010 by mcerd1]

Daddylonglegs - 19/5/10 at 08:05 AM

Apparently, from what I've read on the forum, the main thing is that the 2 faces of the prop flanges are clean, dry and give a good face-to-face friction, then the bolts just maintain that.

MikeRJ - 19/5/10 at 08:06 AM

quote:
Originally posted by mcerd1
(I know they should use the clamping to generate friction between the two surfaces - but that doesn't mean the bolts don't need any shear strength)


If the clamping load is adequate then it does.

mcerd1 - 19/5/10 at 09:12 AM

quote:
Originally posted by MikeRJ
quote:
Originally posted by mcerd1
(I know they should use the clamping to generate friction between the two surfaces - but that doesn't mean the bolts don't need any shear strength)


If the clamping load is adequate then it does.


yes - but you can design it to work either way

this all assumes that you mount them in a similar way to the sierra - the way they are mounted on the dax, the bolts are basicaly 100% in shear (with 12.9 bolts)

[Edited on 19/5/2010 by mcerd1]

flak monkey - 19/5/10 at 09:25 AM

I think there is some confusion.

We are talking about propshaft bolts.

They should never see any shear load, all the load is taken by the friction between the prop and diff flanges which is generated by the clamping load imparted by the prop bolts. As long as they are tightened to the required torque, then this clamping force will be achieved regardless of if they are 8.8, 10.9 or 12.9 bolts.

mcerd1 - 19/5/10 at 10:15 AM

^^^ trust me to get the wrong bolts - I should really pay more attention to what I'm reading....


in that case I think I've got a spare set of the ford ones somewhere if anyone wants them (M10x1.0 grade 10.9)


[Edited on 19/5/2010 by mcerd1]

david - 19/5/10 at 10:35 PM

tks. for all your help. the reason is i am fitting a electricgearbox and need slighter longer bolts for the gearsprocked.tks again all.

mcerd1 - 20/5/10 at 07:10 AM

socket cap heads (the allen key headed ones) are fairly easy to get and as a bonus most of them are 12.9 anyway

what length do you need ?

[Edited on 20/5/2010 by mcerd1]