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Krt9r
Posted on Monday, July 03, 2006 - 03:57 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hi there,

Was rebuilding my bike yesterday after I dropped it on the left side.
Everything went well (I am really amazed how easy working on this bike is!) until I screwed the clutch cable back into the brand new primary casing. I could feel the nut starting to contact the casing, turned a bit more (without much effort) and the resistance disappeared.
Now the inner thread of the casing is gone, and I can't believe I overtorqued it!!! It really looks like either the thread was not properly machined, or the quality of the casing material is not what it should be.

Has anyone ever had such thing happen on him?! I have not gone to the dealer yet to complain but once the thing is damaged it is difficult to prove that it was not right from the start...


Cheers,


Olivier
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Nd_xb
Posted on Monday, July 03, 2006 - 05:44 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

I'm pretty sure it has happend many times before. The casing is aluminum (?) and overtightening can and will strip threads. I had it happen on my primary adjuster bolt. The usual solution is the heli coil , or time-sert method of drilling - tapping - rethreading or inserting the time-sert, then being very careful while screwing the cable in the next time around.
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Krt9r
Posted on Monday, July 03, 2006 - 06:26 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The thing is I had no time to actually apply much torque before the thread got stripped. I also think it is aluminium (or magnesium?) and I know you have to be carefull with alu threads... I don't think I applied more than about 5Nm (sorry I am lost with lb.ft unit), in any case it was not a sufficient torque to properly tighten the cable, but still I destroyed the thread...

Thanks for the solutions, in this case I could also just put a nut from the inside of the casing to secure the cable...


Cheers,


Olivier
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Jackbequick
Posted on Monday, July 03, 2006 - 07:59 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

The service manual calls for a 3-5 foot pounds torque spec on that clutch cable shank. Which is pretty stupid because no one has a torque wrench with 3-5 ft/lbs as a mid range value. 36-60 in/lbs maybe but not 3-5 ft/lbs.

5Nm is equal to 3.7 ft/lbs so you were "in the ballpark" when that stripped. The clutch cable end is aluminum and many people have broken them off in overtightening them. I read about it before I messed with one and when I put mine back (noting that the primary seal on it comes from an O-ring) I tightened very lightly, only enough the deform the O-ring a little.

An associated problem is the granular nature of the aluminum investment castings like that primary cover. They just don't have much density or strength.

At least you found a solution. If it leaks, I would put some pipe thread sealant on the shank.

Check out this link for what is one of the world's best free softwares - the "Convert" utility by Josh Madison.

http://joshmadison.net/software/convert/

That will let you do Nm to ft/lb calcs quickly. It's a stand alone app, just dump it into a folder and run it.

Jack
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Kurosawa
Posted on Monday, July 03, 2006 - 08:31 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thanks Jack! Been looking for something like that.

PS, I hand-tightened the clutch cable housing to the primary cover. Just seemed like the thing to do, didn't think it over.

(Message edited by kurosawa on July 03, 2006)
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Krt9r
Posted on Monday, July 03, 2006 - 03:08 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Thanks Jack for the link!

But as you say I must have been in the ballpark so why did the thread strip?!?
Also the oil plug is given at 14-30ft-lbs, which is a lot more than what I put on the clutch cable shank (I agree the thread is bigger, but still...).

You're very right when you say that the structure of the casing is not very strong, and I wonder if in my case it is not locally even weaker than that because of some manufacturing issue...
That's why I was asking if anybody had similar problems.


Cheers,


Olivier
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Jackbequick
Posted on Monday, July 03, 2006 - 10:54 pm:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Olivier,

Take your choice, bad luck, dirty thread on the cable, poor casting, weak thread in the casting, wrench out of whack, or you underestimating your strength. It's really hard to say.

I try not to use any torque wrench around bottom or top of it's range if I can avoid it. So for something calling 3-5 ft/lbs I would use my smaller torque wrench at 36-60 in/lbs.

On the metric scales, for 3.7Nm I'd be looking for a smaller torque wrench to get more feel.

And if I'm tightening something and get that nervous feeling that it might be too much, I'll settle for the low end of the range or even a lower reading.

But the clutch cables on the Buells are know to be fragile. Like Kurt says, hand tight is good enough there if the O-ring seals and does not leak.

Jack
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Krt9r
Posted on Tuesday, July 04, 2006 - 07:22 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

OK I'll know for next time... Though I hope I won't ever drop the bike again! (now where's the fingers crossed smiley?!)

Anyone has the precise thread description so I can get the right HeliCoil?

Cheers,

Olivier
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Jackbequick
Posted on Tuesday, July 04, 2006 - 09:52 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Here is a better choice than a helicoil for a "wet" location. I've not used these but someone pointed them out here recently.

http://www.timesert.com/

If the TIME-SERT were installed with red LocTite it would make a permanent and leakproof repair with a sealing surface for the O-ring.

Are you a machinist or have access to one? The cost of the tooling and install on a TIME-SERT might be pushing the cost of used or maybe even new primary covers.

I don't have cable to measure the thread on any more. It went away with my M2. :>(

Jack
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Krt9r
Posted on Thursday, July 06, 2006 - 07:20 am:   Edit Post Delete Post View Post/Check IP Print Post    Move Post (Custodian/Admin Only)

Hi Jack,

Thanks again. Well I am no machinist and getting things for american sized threads is not very easy around here in Europe...

Maybe I will stick with the option of putting a nut from the inside of the casing. Downside is that I need to remove the cover before I can remove the clutch cable, but then I don't think this happens too often...

Looking forward to riding again!


Cheers,


Olivier
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