Generator Bolt Size

[Miker]

I was tooling around in the area of the generator and noticed both the bolts securing the generator to the bone are gone. Could someone please provide the bolt size and dimensions?  Thanks!

[aviationfred]

I don't know what the actual size and thread pitch are. I do know that they are available new from Yamaha. Randy at RPM should be able to get a set for you. The P/N is 95027-08030-00




Fred

[Miker]

I don't know what the actual size and thread pitch are. I do know that they are available new from Yamaha. Randy at RPM should be able to get a set for you. The P/N is 95027-08030-00




Fred

Thanks, but I prefer to replace important bolts immediately and for a reasonable cost. The Ace by me carries literally every size bolt.

[roverfj1200]

I don't know what the actual size and thread pitch are. I do know that they are available new from Yamaha. Randy at RPM should be able to get a set for you. The P/N is 95027-08030-00




Fred

Thanks, but I prefer to replace important bolts immediately and for a reasonable cost. The Ace by me carries literally every size bolt.

There are 3 bolts the same size . Remove the other and just match up.

[ryanschoebel]

I will pull a bolt and check this afternoon. Ace does have them, as Ive had to replace them in the past.

[red]

Miker,

Bolts may be available in the same size and pitch, but in various grades, for various loads.  I would caution against using match-um-up common hardware, unless you can match the intended bolt grade as well as size and pitch.  Common hardware will be better than nothing, while you get the correct parts, but maybe not for the long term. 

You did not say what year FJ you have there.  The Part Number may be different there, for the various years of the FJ.  If you provide your year of FJ, the correct P/N could verified.  Happy to help, if needed.

My US$.02 worth.
.

[Miker]

I will pull a bolt and check this afternoon. Ace does have them, as Ive had to replace them in the past.

Thanks very much Ryan for pulling the bolt and providing the answer to the question.  I really appreciate it. 

roverfj1200 - there are three bolts for the generator cover, but only two to hold the entire generator assembly in place on the '85 FJ1100: p/n 95027-08030-00 https://www.yamahapartshouse.com/oemparts/a/yam/5004259ff8700209bc788299/generator

red - I should have mentioned I have an '85 FJ1100.  I have replaced a bunch of the butter soft bolts on the bike with grade 12.9 socket heads, which is more than sufficient strength wise and an upgrade from the original equipment.  Ryan measured the bolts at M8 x 30mm.  I am willing to bet the standard 1.25 thread pitch will work.  If not, I'll spend another $.60 for a couple fine thread.  Beats ordering online and paying an exorbitant amount of money in overall cost for a couple bolts and waiting days on end for them to arrive. 

[RPM - Robert]

Miker, Rover was referring to the later model alternators. They used a three bolt design because almost every two bolt alternator snapped the bolts off.

On another note. The higher the grade bolt the more brittle they become; which may cause premature failure from the high vibration frequencies of the bike. I don't know that it matters all too much as the two bolt design just didn't have sufficient strength to begin with, hence the later 3 bolt design. But you may want to keep a close watch on them. Just something to consider.

Also, don't forget a couple of washers to spread the load. The original bolts are flanged.

[racerrad8]

FYI, the bottom one is definitely broken off in the hole by looking at the picture.

I can't tell if the top is broken off, but you have a 50/50 chance...

Now the question one must ask...

Are the broken bolts Yamaha or off the shelf hardware store bolts?

The things that make you go.... Hmmm

Randy - RPM

[FJ_Hooligan]

snip   p/n 95027-08030-00

snip  Ryan measured the bolts at M8 x 30mm. 

Look at that part number then look at that bolt size.  See any correlation?

[Miker]

Thank Randy and Robert. I'm surprised you were able to see that broken bolt. It was a pain to get out. Yup I included washers and thread locker. 

Very cool David. Thanks for pointing that out.

Vibration frequency vs bolts is an interesting topic Robert. I don't know anything about it. All I know is 12.9 (or anything grade 8 and above) is as strong as it gets and what is recommended among auto builders. I guess you'd need all the facts to make an argument, including whether or not the Japanese forged the FJ bolts with an alloy and tempered them to withstand the specific frequency of the FJ. I found this article though - not on bikes, but on vehicles that rattle quite a bit: http://www.superchevy.com/how-to/additional-tech/1705-automobile-fasteners-street-rod-project

[Miker]

FYI, the bottom one is definitely broken off in the hole by looking at the picture.

I can't tell if the top is broken off, but you have a 50/50 chance...

Now the question one must ask...

Are the broken bolts Yamaha or off the shelf hardware store bolts?

The things that make you go.... Hmmm

Randy - RPM

That's one bolt I didn't shear off when tightening. I suppose the previous owner did that. I've sheared off four valve cover bolts , a pickup coil bolt, a center stand bolt, and stripped most of the carb bolts. Those were all Yamaha.

[oldktmdude]

   The easiest method that I've found to remove broken alternator bolts is using a 6.5mm left hand twist drill bit. Easy as.
I am yet, undecided whether to use Lactate on these bolts. On one hand , if you use Loctite and you break a bolt, it is a lot more difficult to remove. On the other hand, if you don't use it, it is more likely to loosen and possibly break. Six of one and a half dozen of the other. Your choice. At the moment, I don't use it and check tightness when I do oil changes. So far, so good.
   Regards, Pete.

[Motofun]

Ha HA..."lactate"...you trying to milk this job?   

[ribbert]

  ..... undecided whether to use Lactate on these bolts......

Well Pete, in all my years I haven't tried that one  

I have a bottle of blue loctite that must be 40 years old and I've worked on more vehicles that Pat's had hot dinners. Unless someone stuffs up, thread depths, widths, pitch and torque are designed to stay tight in the application they are designed for.
I honestly can't remember the last time I used loctite unless it was specified, and even then not always. Seriously, hundreds and hundreds of all sorts of engines and no loctite nor do I have any recollection of finding things loose.

The last time I can remember this not being the case was back in the 70's when VW cylinders would come loose over time, the factory fix was new cylinder studs with a different thread pitch, that was it, problem solved. They did not suggest a loctite type product.

The only thing a mechanic hates more than a broken off stud brought to him is one that has been loctited in!!!

Correction, what they hate most is an easy-out and sometimes a drill bit as well broken off in what remains of the bolt.

Sure, there is a time and place for loctite but generally automotive engines aren't one of them.

Pat, perhaps you could have the final word on this for us.

Noel