Topic: Spoke torque specs - CB750

[markb]

I just relaced my spokes and had searched the posts for a torque spec with no luck but saw that several people were looking for it too.  I've got several shop manuals and found a spec in a Clymer manual for 1969-77 CB750 that may be helpful.  It listed a torque of 1.9-2.2 ft.-lb. for the front and 1.5-1.9 ft.-lb.for the rear.  I didn't want to spend over $100 on a spoke torque wrench so I used my spoke wrench which is about 6" long and a spring scale to measure the torque on a spoke.  The 6" (1/2 foot) wrench made the math easy, I just measured double the force (for example 3.8-4.4 lbs. on the front and 3.0-3.8 lbs. on the rear) on the scale.  Then I got a feel for how tight to make them and the tone they make when you tap on them.  Then it was an easy matter of going around and making them all the same.  Hope this helps someone.
Mark

[MCRider]

I just relaced my spokes and had searched the posts for a torque spec with no luck but saw that several people were looking for it too.  I've got several shop manuals and found a spec in a Clymer manual for 1969-77 CB750 that may be helpful.  It listed a torque of 1.9-2.2 ft.-lb. for the front and 1.5-1.9 ft.-lb.for the rear.  I didn't want to spend over $100 on a spoke torque wrench so I used my spoke wrench which is about 6" long and a spring scale to measure the torque on a spoke.  The 6" (1/2 foot) wrench made the math easy, I just measured double the force (for example 3.8-4.4 lbs. on the front and 3.0-3.8 lbs. on the rear) on the scale.  Then I got a feel for how tight to make them and the tone they make when you tap on them.  Then it was an easy matter of going around and making them all the same.  Hope this helps someone.
Mark

Yes it does thanks! I've often wondered.

Also, one should put a little assembly lube on the threads and on the nipple to rim interface so that your torque reading is actually accurate and not just overcoming friction.

[Duke McDukiedook]

Yeah, and then after you tighten them up you have to make sure the wheel is still true and not out of round... doh! Hope it still is after all that work.

[markb]

Good point on the lube, I did that.  I also made myself a fixture for tightening the spokes.  I took a piece of old countertop so I had a good flat working surface and drilled a hole to locate the axle in the hub.  Then with the spokes still loose I carefully measured the rim to the hub to get it centered and drilled three 1/2" holes, 120 degrees apart outside the rim to put 1/2" wooden dowels to locate the rim.  Unfortunately (maybe fortunately) it was a little loose so I wedged cardboard between the dowels and the rim to tweak it around and get it tight and perfectly centered.  I put spacers under the rim to center it on the hub axially.  Then I went around and tightened each spoke so it just barely bottomed out and then worked my way around a half a turn at a time until they were all tight.  On the front wheel the "hop" dialed in at 1mm and the "wobble" at 1.5mm.  I tweaked it a bit but I could have just as well left it.  I haven't checked the rear one yet.  I got the idea for this after touring a Harley-Davidson plant and we timed a woman lacing a wheel in less than 3 minutes on a special fixture that located the hub and rim and was able to spin around like a lazy susan.  This included putting on the hub and rim and all the spokes and tightening all the spoke nuts so it was ready to check for trueing and sometimes they didn't even need it.  She had a special tool that dispenced and tightened the spoke nuts.  Amazing!

[rhinoracer]

Thanks for sharing. I've always wondered what a 'ding' sounds like and after tightening 40 spokes all sorts of dings start sounding the same.

[ev0lve]

Is 1.5mm in any direction acceptable? I had it in my head it should be less than one (and fubared my rear rim trying to make it happen). I'll see if I can find where I read that. Finally let a pro do it and haven't checked it cause I'm not sure I want to know at this point 

There it was:

http://forums.sohc4.net/index.php?topic=368.msg205745#msg205745

Specs all over the place -
No spec is given in the Honda CB750 Shop manual, but another text gave a general "rough" rule of 1mm, so we have some work to do.

I was shooting for 0.5mm or less as another publication gave this is the general rule for wheels to be run over 90 MPH.

The Honda spec being 2mm max:


Seems I need to work on my OCD and truing a rim is taylor made for obsessive tweaking.

[MCRider]

Is 1.5mm in any direction acceptable? I had it in my head it should be less than one (and fubared my rear rim trying to make it happen). I'll see if I can find where I read that. Finally let a pro do it and haven't checked it cause I'm not sure I want to know at this point 

There it was:

http://forums.sohc4.net/index.php?topic=368.msg205745#msg205745

No spec is given in the Honda CB750 Shop manual, but another text gave a general "rough" rule of 1mm, so we have some work to do.

Seems I need to work on my OCD and truing a rim is taylor made for obsessive tweaking.

In the body of that thread, the writer mentions less than .5mm for wheels destined for 90mph+.

Mine are always sub .25mm radially and axially. They come together pretty quickly, but I've done a few over the years. Aluminum are easier than steel, more compliant. You can actually see them move as you work them.

[ev0lve]

Sub .25... Trying to get below 2 I overtightened mine and cracked one of the holes the spokes fit into (eventually, it didn't pop while I was working).

I bow to your mastery of the black art of truing  Tips? While I hijack the thread...

[markb]

My Honda shop manual says 2mm and one of my Clymer manuals says 2mm.  The other Clymer manual says a new wheel should be within 1mm on both hop and wobble but also says it should be serviced if the wobble is greater than 3mm or the hop is greater than 2mm.  Not arguing, just another source.  I will probably have the tire guy check mine before he mounts the tires too.

[ev0lve]

Given that I rode mine with a broken spoke for a couple weeks before I started tearing it down and didn't notice anything out on the highway as far as wobble or hop I'm thinking the spec is mighty loose and anything below 2 is probably acceptable unless you're taking it to the salt flats or something.

Still, .25. Having a tiny bit of experience ruining my rim that's impressive.

[MCRider]

Given that I rode mine with a broken spoke for a couple weeks before I started tearing it down and didn't notice anything out on the highway as far as wobble or hop I'm thinking the spec is mighty loose and anything below 2 is probably acceptable unless you're taking it to the salt flats or something.

Still, .25. Having a tiny bit of experience ruining my rim that's impressive.

its like so many things in life, what's necessary, what's acceptable, and what's possible. 2mm could be fine, if all the spokes are tight.

I'd say if you got a wheel from Buchanons and chucked it up in a stand, it would be dead on. Cool...but so what?

[ev0lve]

Noob obsessiveness mostly. I've calmed down a bit in the last 7 months