I was checking the torque on a few of the critical fasteners on my 2012 1200 Sportster Custom.

When I came to the Stabilizer link (upper front) engine bracket mounting screws the service manual recommends 55-65 ft-lbs of torque. (These are the bolts that screw into the cylinder head).

This seems like a lot of torque for bolts that are in aluminum. Is this a misprint in the manual or they really are torqued this much? Anyone have a second source of information besides the 2012 service manual?


Thanks

 

Bump it up

 

That's what my book says and what I use.

.

 

Hi all,

Really does not give you a 'good' feeling when you are torquing it down to that spec, soft Aluminum and all, yikes!

 

Torque specs are generally a function of fastener size, not material involved.

 

Thread engagement is the critical factor if you're worried about stripping threads. Normal rule of thumb is that the bolt/screw should engage with the tapped hole by a length of two and one-half times the bolt/screw diameter.

In other words, if the bolt THREAD diameter (not the hex head or the wrench size) is 3/8 inch then the length of the bolt that is within the tapped hole (NOT the total length of the threaded part of the bolt) should be at least 3/8 x 2.5 or 15/16 inch.

The assumption is that normally this will cause the bolt to shear off rather than strip the threads of the female (tapped) hole. Naturally this is subject to the hardness and tensile strength of the female threads. I'd trust the owner's/shop manual on this one IF you are using the original mounting bolts.

P.S. As always when threading into aluminum, use some form of anti-seize compound -

 

Ooops, when I did my coil relocation and bolted the bracket in, I used lock tight blue... it was just a few days ago... should I get that out of there or leave it forever?

 

My service manual for the 2007 Sportster Custom says the same thing. You would think that if it was a typo it would have been caught a long time before they 2012s came out.

 

Just a personal opinion but if it was me I wouldn't lose any sleep. Loctite, while not anything like anti-seize compound, is likely better than nothing. (I think the danger of seizing a fastener is mostly due to metal-to-metal contact in cast aluminum.)

 

+1 - Blue Loctite is the way to go there.