Torque setting query - 4.8 steel bolts into aluminium

Message

MartDude · #1 Post by **MartDude** » Sat Feb 18, 2012 5:36 pm

I've been helping a friend fit a Puig screen to his Dorsoduro 750 today.

This involved replacing the SS handlebar clamp bolts (M8 hex socket heads) with 4.8 grade M8 galvanised hex head bolts, to secure the screen brackets to the bar clamp

Both parts of the clamp are aluminium.

The workshop manual gives 25 Nm for the OEM stainless bolts.

Can anyone suggest what the setting for these 4.8 bolts should be?

I've only been able to find this table, which hasn't been much help, or tables giving settings for screwing into steel

Someone on AF1 suggested replacing the bolts with 8.8, & torquing to the OEM 25 Nm.

D-Rider · #2 Post by **D-Rider** » Sat Feb 18, 2012 5:59 pm

TBH Mart, they're the sort of bolts I'd tighten by feel - maybe with a drop of loctite to make sure they stay put

MartDude · #3 Post by **MartDude** » Sat Feb 18, 2012 6:14 pm

If it had been my bike, I'd have done that. However, as it's a friend's, and it's almost brand new, I felt it should be 'done right'. I wouldn't want to be responsible for the bars coming loose while he's on the move, or for stripping his threads.

Willopotomas · #4 Post by **Willopotomas** » Sat Feb 18, 2012 6:14 pm

D-Rider wrote:TBH Mart, they're the sort of bolts I'd tighten by feel - maybe with a drop of loctite to make sure they stay put

I'm with Mr Rider on this. It's not a structural part of the bike, so just doing them up 'tight' will be the way to go. And as Andy say's, a bit of thread lock for peace of mind.

Nooj · #5 Post by **Nooj** » Tue Mar 06, 2012 10:34 pm

Want some nice A4 grade stainless ones?

MartDude · #6 Post by **MartDude** » Tue Mar 06, 2012 10:47 pm

Nooj wrote:Want some nice A4 grade stainless ones?

Not my bike. These bolts came with some 'tasteful' black plastic covers for the heads