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Message started by KenGLong on 07/12/09 at 15:14:22

Title: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/12/09 at 15:14:22

I was reinstalling the clutch today and got all the way up to the part where I'm supposed to torque the clutch spring bolts to 8-10 ft-lbs. I set my torque wrench to the specified torque value, tested it in my vise to be sure it would click with very little pull then proceeded to do the clutch spring bolts. I had already tightened them down snug with a socket using a criss-cross pattern. I went about a quarter turn on each then moved to the next one in the pattern. I kept going around like this thinking they weren't tightening up like they should when one suddenly got real easy to turn. Another quarter turn on it and the head snapped clean off. I removed the other three and they were all stressed beyond usability and there were bits of aluminum in the threads.

I've got four more bolts on order as well as a new pressure plate (about $41 total from Ron Ayers) but I'm wondering what I did wrong here? Could the parts have already been stressed so that they were unable to take any torque? Maybe I didn't do something right? Maybe my torque wrench lied to me? I just don't know.

All thoughts welcome.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by PTRider on 07/13/09 at 07:13:57

Thoughts---

---The torque spec was for dry threads and these were lubed.
---The bolts were already fatigued from use.
---The torque wrench was out of calibration.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by justin_o_guy2 on 07/13/09 at 08:27:21

4E4956050 wrote:

Thoughts---

---The torque spec was for dry threads and these were lubed.
---The bolts were already fatigued from use.
---The torque wrench was out of calibration.

---the old "nuts happens" happened.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/13/09 at 09:21:50

Yeah, stuff happens. But, all four bolts felt about the same as I was trying to torque them down. The one that snapped was just the first in my opinion. I'm sure all four would have snapped had I kept going.

I have new parts on the way but I would really like to understand what happened before I destroy another $40 worth of parts.

I'm going to get a 1/4" drive torque wrench so I can be a little less muscley even though my 1/2 drive torque wrench has been working fine for several years. (It matches my 1/2" drive beam-type wrench within 5 lbs or so at the mid-range.)

Title: Re: Torquing the clutch spring bolts = "snap"
Post by Balderdash on 07/13/09 at 09:31:13

717F747D7675747D1A0 wrote:

It sounds like you did each bolt more than once? If so, why? Was the wrench not indicating the proper level was reached? Does it have a meter or an arm or does it just click loose when the setting is reached?

I'm thinking your wrench didn't work right, and you shouldn't have to do each nut more than once, IMO.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by Boule’tard on 07/13/09 at 09:32:46

717F747D7675747D1A0 wrote:

(It matches my 1/2" drive beam-type wrench within 5 lbs or so at the mid-range.)

Ah, there's a good clue right there. A lot of torque wrenches are very accurate in the middle of their range, but not accurate at all in the top or bottom 20%. Your 1/2" drive torque wrench probably goes to what, 200 ft-lbs? It sounds like you are on the right track buying a smaller torque wrench for low torques.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by justin_o_guy2 on 07/13/09 at 09:42:56

Yea, theres the problem. I would just use my "best Guess" before Id use a 1/2" torque wrench at 10 pounds. They arent usable at that setting, IMO.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/13/09 at 11:47:34

252B2029222120294E0 wrote:

I'm going to get a 1/4" drive torque wrench so I can be a little less muscley even though my 1/2 drive torque wrench has been working fine for several years. (It matches my 1/2" drive beam-type wrench within 5 lbs or so at the mid-range.)

My bad, I was using a 3/8" clicker to torque the clutch spring bolts. Still, 8-10 ft-lbs is at the very bottom of it's scale. Funny, I had just used it to do the head cover bolts and it worked just fine for those. Only difference was the orientation of the wrench. It was horizontal for the head cover bolts and vertical for the clutch bolts.

Bummer, Harbor Freight is all out of 1/4" drive torque wrenches. Won't have any more for a couple weeks.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by justin_o_guy2 on 07/14/09 at 01:12:00

So, since its vertical, you could hang a 5 pound weight on a 2 foot long tool, or 10 pounds on a 1 footer & get on the road. Or, just use your torque elbow & take a run at it.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by LANCER on 07/14/09 at 02:30:17

I use my calibrated hand from all but the most critical of bolts.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by Toymaker on 07/14/09 at 04:20:47

me too. Our bikes have such low torques that other than head bolts, I use my calirated hand for most jobs. 10 ft-lbs ain't much :)

Title: Re: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/14/09 at 05:48:21

The SSM calls for a specific torque value on these bolts. I figure it's to ensure all four are tightened down about the same to prevent warping the pressure plate.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by justin_o_guy2 on 07/14/09 at 08:46:57

Then, summon all your knowledge & prepare all 4 the same & carefully work them down.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/14/09 at 14:27:32

4E5157504D4A7B4B7B43515D16240 wrote:

Then, summon all your knowledge & prepare all 4 the same & carefully work them down.

[grin] That's what I did!

Title: Re: Torquing the clutch spring bolts = "snap"
Post by KenGLong on 07/22/09 at 17:09:10

The new parts arrived today and I did a test assembly on the bench to practice. The four new bolts went down just fine and compressed the springs down until the bolts bottomed out in the studs just like they are supposed to.

I can only assume that the old bolts were stressed and combined with a torque wrench that was too big for the job, gave way. As soon as my 1/4" torque wrench gets here, I'll finally have this bike back on the road.

Title: Re: Torquing the clutch spring bolts = "snap"
Post by justin_o_guy2 on 07/22/09 at 19:45:01

Id bet a dollar the bolts were fine & that it was the torque wrench not "Clicking" at the low torque.