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I seem to recall instances accounted here, where the subframe bolts became loose, or where the holes in the subframe for the bolts became enlarged. For those who have experienced this problem, I would like to know what preventative measures are recommended.

I've been using a Givi top case since I got the bike a few months ago, and want to make sure that when I start touring long distances with top case and saddlebags, or with my wife riding pillion, that the subframe mounts won't fail.
 

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No idea, they put helicoils (or something like that) in my screwed up holes. not preventative.

My prevention is a touring diet. More miles, less luggage. No more topcase, instead a tailbag, and only woman under 70kg on my rear seat :)
Replacing the givi side cases with smaller lighter SW Motech Aero bags too.
 

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I would say the best preventative measures would be no top cases and keep the bolts tight. Next time I'm working in that area I plan to retorque / reinstall with some of that gooey red loctite.
 

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You can only torque it so tight because the bolts screw into the aluminium frame. Mine came loose with a lowside that pulled the tail box off it's mount. I got longer steel screws, tightened them to the allowable torque, then added steel nuts, lock washers & washers to the exposed ends (inside the frame). I was then able to torque up the nuts to slightly compress the frame and pan together. I've had this set up for 2 years now with no further problems, even running 2-up & with the tail box.
 

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I've been running a Givi case on the Givi rack with laptop, lunch, shoes, etc. in it for 25,000 miles and haven't seen any signs of weakness in the subframe. I've also done some light touring with soft side bags and a duffle secured to the topcase rack. Unless you plan on packing it full of beer on a regular basis, it's plenty strong.
 

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I've been running a Givi case on the Givi rack with laptop, lunch, shoes, etc. in it for 25,000 miles and haven't seen any signs of weakness in the subframe. I've also done some light touring with soft side bags and a duffle secured to the topcase rack. Unless you plan on packing it full of beer on a regular basis, it's plenty strong.
My subframe got wasted with the topcase alone, after one year, which I never overloaded. No side panniers, no passengers ...
Just riding like I always would (I always rode with the topcase), which is pretty hard for the bike, but not that you'd expect the subframe to suddenly being able to move 3cm up & down.
 

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I bet, with the leverage involved, a top case that hangs way back there puts more stress on it than a passenger???? Especially loaded up with touring gear. I think my wife carries Acme Anvils in her purse, and thats where it usually end sup.

No lie, last ride I had to split the load of that purse between two bags as I could feel it pulling me left when it was in the left bag.
 

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I bet, with the leverage involved, a top case that hangs way back there puts more stress on it than a passenger???? Especially loaded up with touring gear. I think my wife carries Acme Anvils in her purse, and thats where it usually end sup.

No lie, last ride I had to split the load of that purse between two bags as I could feel it pulling me left when it was in the left bag.
I don't know the physics but that seems unlikely to me.
The full freame + full load + top case weights 15kg. its 40cm further the a passenger ... which could weigh up to 100kgs for kawasaki specs.
But lets even say she only weighted 60 kg.
400% more force on the subframe for 40cm further weight ... that seems very unlikely for me.
 

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Which bolts are we talking about exactly; can someone post a picture? Interesting, a quick Google found discussions of the same issue on other Japanese bikes. I tried forum search and couldn't find more about this issue here; except the one where the bolts were stripped during a top case installation; maybe other discussion is buried in one of the luggage threads. I use the Ventura soft luggage system. Works well for my needs, and it's light.
 

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Exp, the chart here might give us an accurate measurement if we knew the distance, and exact weight involved.

Simple Lever Calculator Case #1 - Engineers Edge Engineering Calculators
Without doing the math (which gives me a headache), I'd have to agree with Exp. My guess is you'd have to way overload luggage to equal the stress of even a 125 lbs passenger on the subframe.

It's tough to say for sure but my guess would be that either the OEM subframe bolts have come loose undetected leading to damage or there is a design flaw that is remedied by using a longer bolt with a locknut on the other side.
 

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It's hard for me to imagine the bolt and nut fix offers anything more than additional clamping force.

I know that sounds overly simplistic, but it would seem either the factory bolts are not tight enough and not offering enough clamping force, or they are coming loose.

Be an interesting change if they milled a ridge into the sub frame and frame where they met. Where a top ridge on the sub frame was bearing down on the bottom ridge of the frame.

Only seems to happen to people who carry passengers a lot, or carry a top box a lot. Seems the OEM did not get all a calculations correct on this particular part as it works in the real world.

Seems like anyone who is experiencing any problems in this area, for now, would be best off using the prescribed longer bolt and nut arrangement which offers far greater clamping force than the OEM set up.
 

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Without doing the math (which gives me a headache), I'd have to agree with Exp. My guess is you'd have to way overload luggage to equal the stress of even a 125 lbs passenger on the subframe.

It's tough to say for sure but my guess would be that either the OEM subframe bolts have come loose undetected leading to damage or there is a design flaw that is remedied by using a longer bolt with a locknut on the other side.
Heres what I'm thinking....its that pivot point. Sort of the way you can use a see saw with your fat friend. As soon as you move her fat butt close to the centerline of the see-saw, you can balance as your lighter weight moves away from center.

So yes, the passenger weighs more, but is closer to the pivot point. Its similar to picking up a 25lb weight. Super easy to do as long as its near your body. Extend your arm out, grab it, then feel it pull your shoulder.

On the offroad bikes, subframes are very lightweight. I just had the one off my yz 250 and its under 3lbs, made of boxed aluminum. It all works fineas logng as the bolts are tight. Let them loosen, and its over.
 

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A bolt and nut WITH WASHERS will help provide the necessary tension IF the bore size is oversize and the bolt head can't provide the correct tension. I have no idea if that is the case here. If the bolts can maintain their torque over time, you shouldn't have any elongation problems.
 

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Heres what I'm thinking....its that pivot point. Sort of the way you can use a see saw with your fat friend. As soon as you move her fat butt close to the centerline of the see-saw, you can balance as your lighter weight moves away from center.

So yes, the passenger weighs more, but is closer to the pivot point. Its similar to picking up a 25lb weight. Super easy to do as long as its near your body. Extend your arm out, grab it, then feel it pull your shoulder.

On the offroad bikes, subframes are very lightweight. I just had the one off my yz 250 and its under 3lbs, made of boxed aluminum. It all works fineas logng as the bolts are tight. Let them loosen, and its over.
I totally get you. I think what we're saying is we don't think that 50 lbs of luggage being 8 inches further down the lever is going to cause more stress than a 150 lbs passenger.

A bolt and nut WITH WASHERS will help provide the necessary tension IF the bore size is oversize and the bolt head can't provide the correct tension. I have no idea if that is the case here. If the bolts can maintain their torque over time, you shouldn't have any elongation problems.
I agree.
 

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This is what i am thinking, either the stock bolts are simply not tight enough to eliminate sub frame to frame sheer, or they are coming loose over time.

I am leaning towards the first as the people who report the problem have more weight on the subframe than those who dont.
 

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The N1K is my 2 up/touring bike and I have a sh!tload of miles with 60 lbs of luggage and/or a passenger on some seriously bad roads and after 35,000 miles I have not seen this problem (yet). (knocking on wood)
 

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Have you checked the bolts yet? Can you just to see? Do you have a torque wrench? Can you check the bolts for proper torque?

The most difficult part of a problem like this is weeding out the personalities and odd information, and trying to just limit it to the metal bits and what actually happens with them.
 

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Have you checked the bolts yet? Can you just to see? Do you have a torque wrench? Can you check the bolts for proper torque?

The most difficult part of a problem like this is weeding out the personalities and odd information, and trying to just limit it to the metal bits and what actually happens with them.
I thought you knew me a little better than that. Per this and all the other great discussions we have on this forum, I always send myself a reminder to check said topic when I get home to see if my bike might have the same issue. The last time I checked it for this they were tight with no signs of play. I will check it again when I get home in a couple of hours and yes, I have all the torque specs and own four torque wrenches.
 

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Sorry Boss I was not trying to upset you or question you. I just trust your input so wanted to know your findings.

I am trying to find the source of the problem.
 
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