Keep snapping bolts

[markjenn]

Seriously though, if 50 pounds in a top box upsets the cg of a bike so much to be a problem, the bike has bigger problems than the top box.

This much weight this far aft takes the motorcycle completely outside of its design envelope and the bike will handle like crap. It has nothing to do with the S10 - no bike tolerates this well and no bike mfg allows this much weight in a top box. Choosing to ignore basic stuff like this and going so far outside the design envelope is asking for trouble.

- Mark

 

[markjenn]

Interesting. I did not know that the FJR came with the same warning. Must be exclusively a Yamaha thing. A buddy of mine bought a new GS last year with all the factory boxes. No such warning on it either.

Yes, it appears Yamaha is being more conservative and as someone has mentioned, it may just be that Yamaha's lawyers are louder. But there are aero considerations as well as weight. Yamaha may not want to spend the money to test for aero stability with all three boxes. Or they may not want to put a speed limitation on the bike with luggage which is one way around the aero stability issues. (BMW recommends a speed limit of 110-mph.) While the GS may not have any admonishment not to use a top box with the panniers, it probably has a very modest weight limit on both, typically limiting the payload in each individual pannier or top box to 20-lbs. BMWs do tend to have more generous weight limits than Japanese bikes all-around, gross weight, luggage weights, etc.

- Mark

 

[triman11427]

Re: Keep snapping bolts and Related subjects

If you haven't ridden with the top box off you have no idea how the ride is changed as compared to no top box. It makes a huge difference. I do not fill my top box with particularly heavyitems and he ride is definitely different. My earlier point was if the weight of the box is 90% of the racks capacity, then its a ridiculous engineering arrangement. The point of the additional storage is greater capacity for longer trips. Anyway, I've got to back out the severed bolt from the frame. So far the extractor isn't moving the bolt. Liquid wrench is next.

 

[Checkswrecks]

I totally understand the dynamics and why top boxes can potentially affect handling. I'm very aware of the Honda ST1300 handling problems, when handling was badly affected. Yes, the top box makes a difference, but less than a passenger. Handling issues good and bad are extremely model specific.


I have abused the top box limits horribly on this bike in both weight and speed - and never had an issue. My bike has carried a Givi 52 Liter Maxia box since new, run 115 mph across the desert with the top box packed solid, and it's been hammered down countless gravel roads. My top box is almost always on, because splitting traffic with side boxes is a really bad idea. Same with both of the FJRs I owned. I do check the mounting hardware each time the box comes off to wash the bike.

As for the breaking bolts, it is a place that manufacturers are notorious for saving money. I'm with Jaxxon in suggesting use of higher grade bolts and observing torque limits during installation. Torque too high can cause failure from overload and too loose can actually be worse because of fatigue loads on a loose bolt.

 

[snakebitten]

Loaded like a pack mule. And very non-aerodynamic.

85mph speed limits across West Texas.
2-up like this too, sometimes.

That little OEM top box wouldn't scare me much on this Beast.

 

[scott123007]

Yes, the top box makes a difference, but less than a passenger.

Uh, sort of, but not really...
Pound for pound that statement is totally false, but realistically you're not going to have 100 lbs in your top box. If you did, it would take about a 250 lb passenger to have the same effect.

 

[frez]

A 100 pound pillion would likely have more effect on the CG than a 50 pound top box based on my estimates above. The CG is moved by (mass x distance), and this could be somewhat offset by engine bars and a skid plate if you have them fitted.

The greater effect is on the moments of inertia (or the torque required to move about an axis) as this is calculated (mass x distance x distance), i.e. effecting leaning and suspension movement.

There is an aerodynamic effect of having a top box in place, especially with no pillion as it will cause turbulence and an area of low pressure behind the rider. IMO, this is most likely the cause of any high speed instability on certain bikes rather than changes to the CG or moments of inertia.

 

[Checkswrecks]

Uh, sort of, but not really...
Pound for pound that statement is totally false, but realistically you're not going to have 100 lbs in your top box. If you did, it would take about a 250 lb passenger to have the same effect.

In theoretical design terms, you are absolutely correct.
But then, I've not found too many <100 pound passengers.
::003::

 

[Dogdaze]

Sorry, but if you need to carry that much crap perhaps use a pickup? Look at the oem luggage rack it states max load at 14kg, that's for the weight, not just for the plastic rack limitations, surely a manufacturer knows exactly the tolerance levels of it's bikes, why oh why do we feel that we know better? When I travel long distances I travel light, bare essentials, not everything and the kitchen sink. Adding 20kg to the very rear of the bike and high up WILL affect the stability of the bike, the suspension has been set up for the type of bike it is, that being said an adventure bike, not a friggin U-Haul truck for house moving!!

 

[triman11427]

When I travel I bring along a small compressor and tire repair kit as well as a spare quart of oil and some bottled water.These 2,3 or 4 items alone, which I consider essential, bring me that much closer to the limits. I don't claim to know better than the manufacturers, I just would like a bit more leeway before exceeding their limits.

 

[triman11427]

Now the extractor snapped

So just to add to my frustration the extractor bolt snapped inside the hole as well ::010::This is beginning to get frustrating. My research tells me only a carbide tip will drill through the extractor bolt. Welding is not an option. Any suggestions?

 

[scott123007]

Re: Now the extractor snapped

So just to add to my frustration the extractor bolt snapped inside the hole as well ::010::This is beginning to get frustrating. My research tells me only a carbide tip will drill through the extractor bolt. Welding is not an option. Any suggestions?

You've never posted any pictures, but from your original post, it sounds like the broken bolt is on your rack, not the bike? Time to take it to a machine shop, before you dig this hole any deeper. (no pun intended)

 

[triman11427]

No pictures but the bolt is broken in the hole in the bike sub frame where the rack attaches to the bike. The broken piece is below the top of the hole so I'll be trying a couple of more things. I'm stubborn like that ::002::

 

[BarkSlayer]

If you're snapping bolts on a regular basis, the fasteners you are using are either undersized, over torqued (or both) or something is badly misaligned. Try the titanium bolts suggested earlier and use some good quality fender washers to spread the load a bit more.

 

[EricV]

Re: Now the extractor snapped

So just to add to my frustration the extractor bolt snapped inside the hole as well ::010::This is beginning to get frustrating. My research tells me only a carbide tip will drill through the extractor bolt. Welding is not an option. Any suggestions?

There are some options. Yes, a carbide drill bit will drill thru the extractor bit. Don't be fooled by "Titainium Carbide" coated drill bits, they will not help you any. Cobalt drills, marked "CO" on the bit, are also harder, but depending on the style of extractor, may not be hard enough. Call a machine tool business and see if they have what you need. You might also consider picking up a diamond burr bit for a dremel tool and using that to grind a divit as close to on center as possible, this will help you drill on center. Slow rpm, and don't apply too much pressure, but you need as big a hole in the bolt as you safely can, even if you need to drill in stages, going up a size after getting a nice small hole in there. And don't whack the piss out of the extractor when you put it in, or it runs the risk of spreading the bolt remains in the hold, jamming it even tighter against the aluminum threads of the hole.

I just did this routine today on a pressure washer, but got lucky and the broken piece, snapped off just below the surface of the aluminum head, was loose and came out easily. That type of break is vibration related. And a real pain. I replaced the bolts with studs, where you have a short end and a long end, with a shoulder in between. The short end goes into the hole and bottoms against the shoulder. Depending on your rack, this may be an option for you, going to studs rather than replacing the bolts again.

If all that fails...

You may need to find someone with a EDM machine to burn it out. Essentially it arcs with a special electrode that is hollow with coolant running thru it and 'burns' the bolt out. Will go thru hardened taps too. You're going to need to remove the subframe from the bike for that, and find a machine shop that does that type of work. But, at that point, you could toss it on a mill and use a carbide center cut end mill and just machine most of the bolt out, then pick out the remaining pieces. It's time consuming and precise work. (I'm a machinist, btw, and have done this many times, as well as the EDM for broken taps.)

 

[triman11427]

Re: Now the extractor snapped

There are some options. Yes, a carbide drill bit will drill thru the extractor bit. Don't be fooled by "Titainium Carbide" coated drill bits, they will not help you any. Cobalt drills, marked "CO" on the bit, are also harder, but depending on the style of extractor, may not be hard enough. Call a machine tool business and see if they have what you need. You might also consider picking up a diamond burr bit for a dremel tool and using that to grind a divit as close to on center as possible, this will help you drill on center. Slow rpm, and don't apply too much pressure, but you need as big a hole in the bolt as you safely can, even if you need to drill in stages, going up a size after getting a nice small hole in there. And don't whack the piss out of the extractor when you put it in, or it runs the risk of spreading the bolt remains in the hold, jamming it even tighter against the aluminum threads of the hole.

I just did this routine today on a pressure washer, but got lucky and the broken piece, snapped off just below the surface of the aluminum head, was loose and came out easily. That type of break is vibration related. And a real pain. I replaced the bolts with studs, where you have a short end and a long end, with a shoulder in between. The short end goes into the hole and bottoms against the shoulder. Depending on your rack, this may be an option for you, going to studs rather than replacing the bolts again.

If all that fails...

You may need to find someone with a EDM machine to burn it out. Essentially it arcs with a special electrode that is hollow with coolant running thru it and 'burns' the bolt out. Will go thru hardened taps too. You're going to need to remove the subframe from the bike for that, and find a machine shop that does that type of work. But, at that point, you could toss it on a mill and use a carbide center cut end mill and just machine most of the bolt out, then pick out the remaining pieces. It's time consuming and precise work. (I'm a machinist, btw, and have done this many times, as well as the EDM for broken taps.)

Thanks Eric you've suggested some great options. I'll give it a try today. Report later.

 

[EricV]

Something I forgot to mention, carbide is very hard, but also more brittle. It's easier to break a carbide drill, especially smaller sizes. Buy 3 to 5 drills, not just one. Odds are you will need more than one, but try really, really hard not to break off the carbide drill in the hole! If you do, and can't knock the pieces out, you'll instantly be on to the EDM process, as only diamond will drill thru the carbide. Mark any left over carbide drills so you remember later what they are, and they will be there for special needs in the future.

Luck and good karma sent your way!

 

[triman11427]

Now you tell me . Snapped the small one in about 2 minutes ::010::. Didn't snap in the hole so all is well. This is a project which will test my patience and skill set. Nothing like learning by ones failures.