rear drive torque arm

[richard100t]

I was riding today & downshifted when something godawful happened. The front bolt nearest the tranny sheared off on the torque arm. The really bad part of it was the nut end was still in there & the pork chop was/is keeping me from getting it out without a hacksaw blade. After a $75 tow bill the bike is safely home hopefully without damage to the rear drive. At first I thought it was the transmission & I kept thinking of the single plate clutch & a thousand dollars dissapearing from my checking account. Fortunately its a $2 bolt & nut & probably a new torque bar from RossoPuro. I've heard of the bushings going south in these things but never heard of the bolt shearing off. Any thoughts on this little problem? Of course I want a better bolt than the last one but until I get the torque arm out & have a look at it I wont know just why the part failed.

[Guest ratchethack]

Egad, Richard! My sympathies, but sounds like you made out OK -- relatively speaking. I'd be sure to give the rear UJ a good once-over for excessive play as a result of being pushed far past its operating angle limit.

 

I think this may be a first, but it's the kinda thing that compels me to dash out for an inspection.

 

The bolt in question is fully supported at both ends by ears welded to the crossmember! All I can imagine is a defect in the bolt or an over-torque by Luigi.

 

I don't know why you'd need a new torque arm, unless it got loose and wreaked havoc on itself? In order for the arm to have come out of there, the remaining part of the bolt with the nut on it should simply pop out with very little persuasion.

 

I reckon the bolt in question must have no hardness designator on it, or it wouldn't o' let go. In this case, you'll want to consider Metric Class 8.8 or even 10.9 with a replacement. This'll provide 93,000 or 136,000 psi yield strength, respectively. Either one o' these are overkill, but a pretty good guarantee against a repeat performance.

 

Let us know how it goes & good luck.

[richard100t]

Egad, Richard! My sympathies, but sounds like you made out OK -- relatively speaking. I'd be sure to give the rear UJ a good once-over for excessive play as a result of being pushed far past its operating angle limit.

 

I think this may be a first, but it's the kinda thing that compels me to dash out for an inspection.

 

The bolt in question is fully supported at both ends by ears welded to the crossmember! All I can imagine is a defect in the bolt or an over-torque by Luigi.

 

I don't know why you'd need a new torque arm. In order for the arm to come out of there, the remaining part of the bolt with the nut on it should simply pop out with very little persuasion.

 

I reckon the bolt in question has no hardness designator on it. In this case, you'll want to go Metric Class 8.8 or even 10.9 with a replacement.

 

Let us know how it goes & good luck.

I'm not sure if I'll need a new torque arm until I get it out & have a good look at it tomorrow.The remaining part of the bolt with the nut on it is facing the backside of the porkchop & cant be pulled out that way. The other problem with that is I cant loosen the nut off the bolt threads because I have nothing to hold the bolt still while I try to loosen the nut. Of course if the nut end had sheared off this would save me some time with the hacksaw & even that will probably not work as it will just spin as I try to cut it off. The whole thing should be resolved just in time for the recent warm weather to pass into brutal cold winter where the bike will just sit for a few months anyway Oh well its been a very enjoyable long riding season this year & I still love the bike after 16k miles. Although something with a more relaxed riding position & a large fairing would be good for longer trips.

[richard100t]

Well I got the torque arm out today & it looks completely undamaged. The total cost of repairs so far is 63 cents. After I put in a new nut bolt & washer I took it up the street & it seems ok. Its dark now so I'll have to wait until tomorrow to closely inspect the ujoints & shaft.

[Guest Mattress]

I'd replace it with a grade 12.9. The difference in price is insignificant.

[jrt]

I imagine you had a defective bolt. Glad you are OK.

[richard100t]

I'd replace it with a grade 12.9. The difference in price is insignificant.

Yes I agree, tomorrow I'll have more time off work to go to a proper bolt shop to get the right hardware.

[Guest Mattress]

Hi. I don't mean to insult you, but be sure you get a matching grade nut to go with the bolt.

[docc]

I've gotten vague on those metric hardness grades: 8.8, 10.9, . . . is it?

 

I was thinking 8.8 is equivalent to grade 5, 10.9 is grade 8?

[Guest Mattress]

Ooohhh, good question. I'm not at work right now otherwise I'd look in my specs for a cross reference. The grade 12.9 is highest quality we use in diesels (head bolts I think). The grade 10.8 seems fine for almost everything else on an engine, but since he is only buying one bolt I'd go for tops.

 

Also, I read on a webring site of one instance of this bolt falling out, on a Daytona. Might be worth a touch of Loktite or safety wire.

 

Any bolt that could fail and cause you to have an accident needs special attention IMO.

[docc]

Possible, perhaps, that the bolt loosened up and the constant fore and aft stress on the bolt finally broke it?

[Guest Mattress]

Possible, perhaps, that the bolt loosened up and the constant fore and aft stress on the bolt finally broke it?

 

Nice thought, thou guess we will never know. Part of winter plans includes checking bolts for retained torque. I posted a torque chart here some months ago from the V11 manual. Search for Torque chart.

[dlaing]

I've gotten vague on those metric hardness grades: 8.8, 10.9, . . . is it?

 

I was thinking 8.8 is equivalent to grade 5, 10.9 is grade 8?

From what I gathered here:

http://www.labsafety.com/refinfo/ezfacts/ezf269.htm

Class 8.8 seems to be about equal to a Grade 5.2

Grade 8 and 8.1 are about equal to Class 10.9

[richard100t]

Well I've replaced the bolt as I've said. Now I've test ridden it down the street & it makes a noise when I get on or off the throttle. Its hard to tell just what it is because of the engine noise, but its in the driveshaft area. The white lines still are aligned & the ujoint bolts are tight & I regreased the shaft & rear joint. Any ideas what the new problem may be?

[richard100t]

Ok I tried tightening the rear wheel because the caliper holder wiggled slightly. I had been leaving the wheel at the level of tightness instead of overtightening it. Well for whatever reason that noise I described in my last post has stopped. Could the rear wheel not being tight enough have caused the front bolt nearest the tranny to snap? I would have thought the one on the rear drive would go but maybe it was the leverage that caused it to snap? Btw the rear wheel was not overly loose either but I did turn the nut around about twice before the caliper holder got snug. Something to think about I guess.