Ultegra fixing bolt torque?
 

I’m going to pick up a left crank power meter from a buddy for a killer price. I have the tool to remove to fixing bolt on the left crank arm, how tight should the bolt be when I reinstall? Does it require any type of loctite?

If you're talking about the plastic cap bolt - Shimano says .7-1.5 Nm. I just hand tighten with tool by feel, similar to how you'd tighten a headset cap. Take out the play and maybe a tighten a little more, as long as it doesn't bind.
The actual Crank arm fixing bolts are 12-14 Nm, which I believe is critical for accuracy if you are installing something like a Stages, 4iiii etc arm.

Use a little grease on cap and bolts but NO loctite!

Yes on the attachment bolts, I have a in/lb torque wrench so it should be right at 102-105in/lbs. Thanks on the grease, it looks like metal but I guess it’s plastic.https://cimg8.ibsrv.net/gimg/bikefor...7415507f5.jpeg

Yeah that's the one. On my 6800 I'm pretty sure that part is plastic maybe 8000 is alloy? Anyhoo, same principal tool looks like this or is sometimes attached to BB wrench, eg
Park Tool.

Just for clarity all this part does is pre-load the Bottom Bracket bearings; the two 5mm allen bolts are what actually hold crankarm to spindle.

https://cimg3.ibsrv.net/gimg/bikefor...ce525f9e61.jpg

The crank fixing bolt is just for preload-- some are metal, some are plastic, you can buy rainbow colored ones from China. The supplied tool from Shimano is made of plastic and you tighten it with your fingers. The torque spec I've always used is "snug."

The pinch bolts (as mentioned in post 2) are important and should be torqued to spec.

Thank you!

The Shimano Technical Documents website will have the torque spec for everything. All Shimano questions should start with this site.

https://si.shimano.com/


Page 19 of the FC-6800 dealer manual says the plastic cap is 0.7 to 1.5 N-m while the pinch bolts are 12 to 14 N-m.

https://cimg6.ibsrv.net/gimg/bikefor...385c88d0bc.jpg




-Tim-

Yep finger tight. If you remove your chain spin the cranks and pay attention to how freely it spins. Then pay attention to how tight it feels when you loosen the compression cap. When reassembling make sure both cranks are seated properly in the BB, go finger tight in the compression cap, torque the other bolts to spec (don’t torque one side and then the other...do a little on each side at a time until they both are to spec). Spin the crank to make sure it’s not binding and spins freely as before. Then your good.