Swing Arm Pre-Load

[Crossrodes]

I'm in the process of checking my swing arm alignment and adjustment.  The alignment was good before I started the adjustment procedure and I'm maintaining it as I go through the procedures.  Now I'm following the bearing preload adjustment procedure out of my Clymer manual and I have a question:

How do you ensure that the preload torque on the pivot pin is maintained as you torque the lock-nut?

One more question...what is an acceptable tolerance in the gap between the frame and the swing-arm tube?  I am within in .3 mm and don't seem to be able to get it much closer.

[nhmaf]

The Original BMw toolkit had a hollow, open-backed wrench that one could use to tighten the nut while keeping an Allen wrench/key stuck into the end of the pivot pin to keep it from turning.   Unfortunately, this didn't allow one to actually use a torque wrench on the nut.

I generally get the pivot (allen key) tightened up to spec, or just under, and put a dab of whiteout or some sort of temporary paint on the top "flat".   I get the nut tightened up so that it is snug but not up to its spec'ed torque.  That way, if the allen-keyed pivot does turn while I am getting the nut tightened up the final bit I can visually tell that it has moved, and may have to loosen/re-tighten things.

I don't think that you have to be EXACTLY dead-on as far as torque tightness goes, but too loose is very bad, and very tight is also quite bad as it will prematurely
wear out your bearings and will mess with the handling.  There is a fairly reasonable "zone" of acceptability, I think.

[Crossrodes]

Thanks for the tip.  I torqued the cones up to spec and marked their position as you suggested.  Once I had the locknuts snugged up the cones did not move at all.  I torqued the locknuts up progressively until I got to 105 NM.

Mike

[Semper Gumby]

Believe it or not I use a 4mm allen to position the swing arm equally between each side of the frame.  I set the torque on the pivot pins (to the highest setting of the acceptable range) and then set the lock nut.  There is no special procedure published just the right torque.

As I'm torquing down the pivot pin I am using the allen by rocking it in the gap between the swing arm and the frame.  I work slowly and the the final torque i do on the side with the least amount of clearence so when I am done the swing arm is in the center of the frame.

[Rob Valdez 79 R65]

+1 to all of the above!

I never thought of the white paint.  Now I need a to see if I have a socket that will fit!


 (I have always used the BMW tool/rubber mallet...)