Startling Discovery

[TechJunkie]

A month ago I took my final drive off my FJR, removed the drive shaft and universal to lubricate and clean while a new set of PR4s were being installed for my trip to Eastern Canada. I reassembled everything and verified that all torque specs were followed during reassembly. I took a checkoff ride and everything seemed great. The trip to Eastern Canada was nine days and 4,500 miles. Today I decided to wash the FJR and it was just a mess from the roads. When washing the back of the bike I looked down and froze where I stood. I couldn't find any crown nuts on the bolts which hold the final drive to the swingarm. I reached down and felt the inner most bottom nut and it was still there. I am shocked and feel fortunate to have gone such a long way and still be here to tell about it. If that final nut had come off on the interstate, well, lets just not think about it.

I was certain I followed the proper toruqe specifications, however, I threw my checklist away since it was on the back of an envelope I had handy. I didn't find the torque specs for these nuts in the GenII Bin of Facts so I searched the net and found a blow up of the Yamaha service manual page which had it listed. (At least if my memory serves me right.) Would someone be willing to verify the torque spec with me to ensure I don't mess this up twice?


I am now looking for the nuts. It appears their are "Nut, Crown 90176-10075-00" at least this is the part on Boats.net, however, they list it as "Part Obsolete". I did find them on Partzilla.com in stock.

I think I am still in shock!

 

[odot]

Guten tyte.....german spec.

 

[RossKean]

30 ft-lb

Did you remember to use the lock washers under the nuts? I have never torqued these but I think I will go out and check them!

 

[TechJunkie]

30 ft-lb
Did you remember to use the lock washers under the nuts? I have never torqued these but I think I will go out and check them!

I put back the washers that came off when I took it apart. If memory serves me correct these are not lock washers. They are listed as Washer, Plate 92990-10600-00.

 

[HotRodZilla]

I wish some of you would put the dammed torque wrenches down and just learn how to tighten shit.

The only thing that would have happened is your final drive would have come loose and would have drug behind you. Glad that didn't happen.

 

[RossKean]

30 ft-lb

Did you remember to use the lock washers under the nuts? I have never torqued these but I think I will go out and check them!

I put back the washers that came off when I took it apart. If memory serves me correct these are not lock washers. They are listed as Washer, Plate 92990-10600-00.

You may be right about it not being a lock washer. I don't recall anything other than the fact that one went missing when I had it apart the last time. Found it rolled across the floor! I checked another parts place and did not see an "obsolete" designation on these parts. If you Google just the part number you will get hundreds of hits. Yamaha uses both of these parts on dozens of applications across their product lines.

 

[RossKean]

I wish some of you would put the dammed torque wrenches down and just learn how to tighten shit.
The only thing that would have happened is your final drive would have come loose and would have drug behind you. Glad that didn't happen.

Agree! My torque wrenches come out when working on the engine and the steering head. Usually for the axle nuts too because I don't have an adequately calibrated wrist for large fasteners at relatively high torque.

Surprised to hear about these coming loose - I have never heard of it happening.

 

[JamesK]

Blasphemy I know, but is it remotely possible that you forgot to torque down those nuts, this is something I always worry more about than fixating on a specific torque value unless its on a very specific/sensitive component.

Here is Japan, when a bike shop does any work on a bike the mechanic goes over every bolt/nut that he touched during the given job and marks it with a sharpie or a paint pen. This insures that he physically double checks all the fasteners have been tightened. I use a similar technique by physically touching every fastener related to the given job with my finger, to ensure I recall tightening it down.

 

[rushes]

Don't believe everything you read.

Tighten stuff up.

 

[Queensland Ken]

The 4 acorn nuts were very loose from factory when I checked them at 500 kms, when I stripped and lubed everything that Yamaha didn't.

 

[RaYzerman19]

This is a good application for Loctite........

 

[escapefjrtist]

Only other time I've heard of this happening is when the nuts weren't tightened...

Agree all that's there is the acorn nut and flat washer.

--G

 

[TechJunkie]

Blasphemy I know, but is it remotely possible that you forgot to torque down those nuts, this is something I always worry more about than fixating on a specific torque value unless its on a very specific/sensitive component.Here is Japan, when a bike shop does any work on a bike the mechanic goes over every bolt/nut that he touched during the given job and marks it with a sharpie or a paint pen. This insures that he physically double checks all the fasteners have been tightened. I use a similar technique by physically touching ever fastener related to the given job with my finger, to ensure I recall tightening it down.

I am certain I torqued them. I remember torquing them as I was careful they were all snug before I started to be sure it was seated. I also remember trying to be sure my torque wrench didn't scar the swing arm as I didn't have any painters tape. Like you, I also retrace every bolt and nut before I consider the job done.

I am beginning to believe I may have used the wrong torque setting. It is the only plausible explanation I can come up with and I was the mechanic, It is on me. Just scary to think what could have happened at speed or in a lean. Guardian Angel was working overtime holding onto that last nut.

My dad was a millwright and worked with German engineers on some large projects. I will have to remember the Guten Tyte comment above for the right moment. He would yell at me if he found out I ignored or miss used torque specifications. I think I will not bring this episode up at our next get together.

New hardware ordered to square it all back up. Thanks for the replies.

 

[SouthernCruizer]

Said it before and I'll say it again...the MOST DANGEROUS tool in your shop is a torque wrench. This tale just re-enforces my belief in this theory. That is all.

 

[timk]

It happened to me also, except I had only one holding the differential on. Went to Fastenall and got 3, started to torque and damn one broke at about 5-10 lbs. Been running on 3 for quite a while.

 

[RaYzerman19]

Now Jay.... might go 50-50 with you as I've seen plenty of stripped or broken fasteners in the hands of the ham-fisted. I'll agree misused, mal-calibrated torque wrenches are dangerous.

 

[lnewlf]

nothin' worse that having yer nutz fall off....

 

[08FJR4ME]

The only parts I torque on my bike are the axel nuts. Every other fastener is wrist calibrated to my standards.

Dave

 

[Spud]

With all the aluminum on the bike I like torquing most things to specs in the manual; overtightening and stripping something is my fear. I almost always find that just as I'm thinking "that feels about just right" the wrench clicks. I splurged a while ago and bought a $120 torque wrench that I trust is pretty accurate, and I'm very careful with it so it will stay that way.

I really find it hard to believe that those nuts were at 30 lbs with the lock washers and tightened evenly that they spun themselves off after 4500 miles. Something else is going on here.....