Tighten steering stem locknut

So I've repacked the bearings in the steering stem of my 1978 KZ650 D1 and installed the stem. How does one measure the torque for tightening such a nut? I was able to use the tool from the toolkit to remove it but I'm at a loss for how to torque it to the proper setting without making a special socket to use with my torque wrench!

Any help is gratefully appreciated.

There are several ways to do it; here's what I found to be accurate regarding the torque level; this is for the KZ650-C1. (Sorry about this being so lengthy.)

I adapted the steering stem lock nut spanner wrench so I could torque the nut to specs. I started by drilling and tapping 2 holes in a flat bar and drilling 2 holes in the spanner to match. I bolted the spanner to the flat bar and center punched a spot 7" from the center of the spanner lug (where it would center on the steering stem locknut). I drilled a hole there and filed it square to match my 3/8" torque wrench drive. The added length adds leverage so you MUST calculate the appropriate torque wrench setting to achieve the correct torque on the steering stem locknut. Here's the formula from the CDI torque wrench site:

(TA x L) / (L + A) = TW


L = Effective length of the wrench as described below.

Dial Wrenches = The measured distance from the center of the square drive to the center ring or notch on the handle.

Micrometer Wrenches = The measured length from the center of the square drive to the center of the handle, with the wrench set at the desired torque reading

A = The measured length from the center of the adapter drive to the center of the wrench square drive.
TA = (Desired Torque) The torque value designated for the fastener with or without an adapter.
TW = (New Setting) The torque setting on the wrench allowing for the added length of the adapter. This reading will be lower than the desired torque.

According to the Kawasaki Service Manual the steering stem locknut should be torqued to 19.5 - 24 foot pounds which equals 234 - 288 inch pounds. As a first try I decided to use a Desired Torque (TA) value of 250 inch pounds, so in the formula TA=250.

I set my torque wrench at 250 inch pounds and measured the distance between the center of the 3/8” square drive and the center of the knurled handle (see pic) to determine the torque wrench effective length (L). This distance was 8.21 inches, so in the formula L=8.21.



I knew the effective length of the spanner/adapter (A) was 7" because I cut the center of the 3/8" square hole 7" from the center of the spanner lug (where it would center on the steering stem locknut -see pic), so in the formula A=7.



So plugging those numbers into this formula:

(TA x L) / (L + A) = TW

(250 x 8.21) / (8.21 + 7) = TW



Doing the math gave me this:

(250 x 8.21) / (8.21 + 7) = 135

So, I set my torque wrench at 135 inch pounds to apply 250 inch pounds of torque on the steering stem locknut. YOUR NUMBERS WILL BE DIFFERENT! They will vary from mine depending on the effective length of your torque wrench, the combined effective length of your spanner and adapter, and the amount of torque you desire. I made a table for my use (see pic) that made it easier for me to adjust the steering stem torque to different values as needed. You may want to do that using the lengths for your spanner/adapter and torque wrench lengths; your table will be different than mine.



Don't forget, when using the adapter be sure to reset your torque wrench to the number (TW) derived from the formula. This number MUST be considerably lower than the desired torque of the fastener or something is wrong. Also, when using an adapter it is important that you keep the spanner, adapter, and torque wrench oriented in a straight line (see pic).



I HIGHLY recommend you take a look at the CDI Torque Wrench site. They give a detailed description of the use of torque adapters - which is what the spanner actually is. Go to

www.cditorque.com/

click on "TORQUE FACTS" then select "USE OF ADAPTERS."

If you do use this method be sure when you are done to check the steering to ensure the handlebars still move side to side freely so you know the nut is not too tight and check the forks for fore & aft play to make sure the nut is not too loose. Ed

Thats probably way mor accurate than my answer. I say tighten tight enough the balls dont fall out.

fully seated as the say lol

In the Scheduled Maintenance chapter of the Kawasaki service manual for the 81 KZ650, there is a note - I don't know if it is applicable to the earlier models.

NOTE: 1. If a suitable torque wrench is not available, tighten the steering stem locknut lighly (until it just becomes hard to turn), and then continue for another 1/16 turn (about 20^o ) from that point.

NOTE: 1. If a suitable torque wrench is not available, tighten the steering stem locknut lighly (until it just becomes hard to turn), and then continue for another 1/16 turn (about 20o) from that point.

That's the way I did it but also fine tuned it by "feel". I had the front wheel up so I could turn the forks and get the feel of them.

Same here. The manual's way is handy as a starting point, since the 1/16 turn & 20^o stuff isn't exactly precise when you're eyeballing it. One of these days I'm going to make a lock nut socket from a large socket... the pawn shops around here don't have a junk tool bin any more, otherwise I would've had one made already... or at least tried. hee.

martin_csr wrote: In the Scheduled Maintenance chapter of the Kawasaki service manual for the 81 KZ650, there is a note - I don't know if it is applicable to the earlier models.

NOTE: 1. If a suitable torque wrench is not available, tighten the steering stem locknut lighly (until it just becomes hard to turn), and then continue for another 1/16 turn (about 20^o ) from that point.

That's whe way I do it also

When you install new bearings, you should tighten the preload down, while turning the forks, to seat them. Then back off the preload nut and tighten until the forks do not flop from side to side. A smooth movement from center to the stop is ok.

Also, this should be done with the top clamp loose. When you set the preload nut, tap the top clamp down with a rubber mallet, tighten the center bolt, THEN tighten the fork tube pinch bolts. This locks down the adjuster and doesn't put stress on the top clamp.