R1150 GS shock bolts.

[goanna_38]

I've recently changed the rear shock on my newly acquired R1150 GS and I'm a bit dubious about the tightening torque required for the bottom bolt. It's an M10 bolt going into what I assume is aluminium and the torque quoted in the book seems a bit excessive. The book states it should be tightened to 58 Nm (43 lb/ft) and have medium strength thread locker applied to the thread. The thread itself looks fine and I can run the bolt in by hand so the thread is almost certainly undamaged, but when I torqued it up (in stages) once it got to about 40 Nm it felt a bit wrong. Is 58 Nm correct? When I pulled the bottom bolt out I noticed 2 things. It wasn't very tight and it never had any loctite on it. I'm seriously considering leaving it at 40 Nm with thread locker on it and then marking everything with paint so I can see if it moves. Am I being unreasonably paranoid? I'm pretty sure if that thread gets stripped I'll be up for a new swingarm front. 

[dirtrider]

7 minutes ago, goanna_38 said:

I've recently changed the rear shock on my newly acquired R1150 GS and I'm a bit dubious about the tightening torque required for the bottom bolt. It's an M10 bolt going into what I assume is aluminium and the torque quoted in the book seems a bit excessive. The book states it should be tightened to 58 Nm (43 lb/ft) and have medium strength thread locker applied to the thread. The thread itself looks fine and I can run the bolt in by hand so the thread is almost certainly undamaged, but when I torqued it up (in stages) once it got to about 40 Nm it felt a bit wrong. Is 58 Nm correct? When I pulled the bottom bolt out I noticed 2 things. It wasn't very tight and it never had any loctite on it. I'm seriously considering leaving it at 40 Nm with thread locker on it and then marking everything with paint so I can see if it moves. Am I being unreasonably paranoid? I'm pretty sure if that thread gets stripped I'll be up for a new swingarm front. 

Evening goanna_38

 

That is a relatively long bolt so they do feel sort of spongy when torquing. 

 

Those lower bolts have been known to break so I usually replace if possible & convenient.    

 

Spring strut to rear frame ............................. 50 Nm

 

Spring strut to swinging arm (clean thread + Loctite 243).......................... 58 Nm

 

Hydraulic spring preload adjuster to footrest plate ........................................... 22 Nm

[goanna_38]

I found thread on here about an 1150RT and the accompanying pictures look like there's an insert where the thread is. This pic (not of my bike) is one of the pics. Is the thread in the swingarm actually aluminium or is it a steel insert that the bolt threads into?

[The Fabricator]

Threaded into aluminum.

Me - 2000 r1150gs

My bolt has bent in the past.

It has not loosened.

I would like to get a stronger bolt.

Is it already grade 8?

Where can I get a stronger bolt?

[dirtrider]

11 hours ago, goanna_38 said:

I found thread on here about an 1150RT and the accompanying pictures look like there's an insert where the thread is. This pic (not of my bike) is one of the pics. Is the thread in the swingarm actually aluminium or is it a steel insert that the bolt threads into?

Morning goanna_38

 

That ring that looks like an insert is the imprint from the shock (strut) bushing, the lower bolt actually threads directly into the alloy swing arm. 

 

 

[dirtrider]

13 hours ago, The Fabricator said:

Threaded into aluminum.

Me - 2000 r1150gs

My bolt has bent in the past.

It has not loosened.

I would like to get a stronger bolt.

Is it already grade 8?

Where can I get a stronger bolt?

Morning  Fabricator

 

The bolt should be a metric 10mm X 80mm grade 10.9, if your bolt is a grade 8 (grade 8 is an SAE standard)  then it is an incorrect bolt. You can try to find a 10mm X 80mm grade 12.9 as long as the bolt head clears the outer hole & the bolt coating (like ZNS3 or similar) prevents corrosion & prevents reaction with the alloy housing threads & strut bushing. 

 

You want a bolt that isn't threaded over it's full length (only threaded on the end a little farther than what enters the threaded swing arm casting). (a full threaded bolt is more apt to bend due the the reduced diameter at the thread base) 

[goanna_38]

Ok, I had a bit of a measure and as near as I can tell there’s about 28 mm of bolt threaded into the swingarm. I’m going to assume that the swingarm is made out of a fairly tough alloy and BMW certainly aren’t going to suggest a torque setting that’s almost, but not quite, tearing the thread out. What I could see of the thread looked fine and without the drag of the lower shock eye the bolt itself threads into the swingarm with just fingers.

Grit my teeth and go for it then.

I initially set the torque wrench at 40 Nm and tightened.

All good, so I set it to 58 Nm.

I ended up chickening out before it went “TINK” but when I backed the wrench off to see how much torque I’d actually applied it indicated that I’d managed to get about 54 Nm on it.

That and the fact that there’s enough blue threadlocker on it to sink the Tirpitz decided me, that’ll do.