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Discussion Starter · #1 ·
So, riding the rocky washes and trails outside Vegas yesterday and on my way out I noticed an odd sound and the bike didn't quite feel right. After a little bit of thinking this, I got off the bike and did a quick walk around and noticed a bolt missing (imagine that). Thankfully, I always keep a spare bolts container on my bike and was able to pop a temporary bolt in there.

Anyone have thoughts/recommendations on where I can get a decent replacement and one that is strong? I assume it just shook loose (since the KLR is such a SMOOTH rider) and didn't break 'cause I wasn't hauling any weight but my fat butt. I figure if I am getting a replacement, might as well make it a stronger one and make sure I'm using Locktite.

Also, (sorry for the long post) I did a brief look around, but are there spot I should check for the frame cracking when this bolt goes missing and is ridden for a short while?
 

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Eagle Mike sells a kit with replacement grade 8 bolts for the subframe mounts. Also sells a kit to do the up mount drill through / replacement.

If you only ride street and weigh less that 180, may not be worth it. But for serious play -definitely worth your time and money.
 

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As previously mentioned, Eagle Mike sells a socket-head cap screw kit for strategic connections on a Gen II KLR.

A socket head cap screw is way stronger than grade 8 screws and gobs stronger than the OEM fastener.

With proper torgue you shouldn't need Locktite.

Jason
 

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Just once, I would like to have someone explain why and how the drill-through mod is better than having a pair of screws on either side, perhaps upgraded in diameter and grade as in the Gen 2. How is it that drilling completely through a necked-down section of frame member, especially with the possibility of drill wandering, a good idea?

The website provides no justification beyond "Eliminates the weaker 2 bolt setup in favor of one bolt all the way through for the upper subframe attach point. No more worry about keeping the bolts tight, or the original bolts breaking." How is the two-bolt setup weaker?

I'm known to carry some heavy loads on my subframe, as well as being a big fella in my own right. I run a filled Chase Alaska bag or my home-made Super SE540 top case, plus panniers. Frankly, I'm way over the weight limit that KHI specifies quite often. Hell, my pannier racks and the Seahorse stuff exceeds the weight before I have even loaded the stuff up! My Gen 2 subframe screws are installed with blue LoctTite and properly torqued. I have never lost a subframe bolt nor have I found one to be loose on a pre-ride inspection.

I am serious; I'd really like to see an engineering justification for drilling through the frame and installing a single bolt in the place of two screws.
 
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All transparency, I do not have EM's bolt upgrades, but will chime in on Tom's comments. If one long drilled through bolt is the same diameter, hardness, grade, etc than two. I am not sure how it is better than the two. Especially, if their respective fitment would be arguably better from the factory than a ham fisted beer drinker like me shoving a drill bit on my old craftsman through some KHI frame assembly?

Now, if the longer bolt provides additional support somehow, or an extension of a key bearing surface. then there may be something. but left side bolted snug, right side bolted snug, sounds a bit better than outer left side bolted, outer right side bolted, nothing in between. Is the point that the large bolt is higher grade? Again I have no intimate knowledge of the functionality of this mod, but someone teach me and maybe we will all improve understanding.

sweaty in Minnesota, line6
 

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Well, I did the drill through on my 2001. For the record, I don't think it's necessary except on a Gen1, running 2 up or heavily loaded offroad....and even then, necessary isn't the right word. On my 2000 (realizing I don't ride 2 up or have any panniers/top boxes), I skipped the drill through and went with some upgraded bolts. On a Gen2 with the larger bolts, it's all less important IMO.

I do think the drill through is stronger as you aren't relying on the tightness of the individual bolt threads, even if the nut on the end comes off, assuming the bolt stays in place, it isn't going to fail. Not having threads at the shear point is the biggest difference from where I sit.......do you need it? probably not....is it stronger? I believe it is.


Dave
 

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Just once, I would like to have someone explain why and how the drill-through mod is better than having a pair of screws on either side, perhaps upgraded in diameter and grade as in the Gen 2.
Two connections = two opportunities for loss of pre-load and either fastener failure or the fastener backing out. One connection = only one opportunity to do the same. Also, one longer fastener will provide more stretch than two shorter fasteners, which will be more fatigue resistant.

Jason
 

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I want to mention that a similar bolt on the other side wanted to come loose on my bike as well. Since the KLR shakes so much I figured I should be on the lookout for this sort of thing, so I got a whiteout pen (you know, a pen that you can use to white over characters you accidentally type with your typewriter) and marked the positions of all the bolts. I check 'em as part of my pre-check, so I know when one starts to move. Especially for those foot peg bolts, I don't ever worry about 'em now. That one is the only one I've ever found creeping out, and after I tightened it again, it hasn't budged since.
 

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Discussion Starter · #10 ·
so I got a whiteout pen (you know, a pen that you can use to white over characters you accidentally type with your typewriter) and marked the positions of all the bolts.
This is a great idea and will definitely have to do! Thanks!
 

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Discussion Starter · #11 ·
Thanks, everyone, for the advice and help. I will get those Eagle Mike replacements. I have had the drill through kit for awhile, but never installed it since I didn't think I needed it (dont have a lot of weight on there very often) and was a bit hesitant on drilling through the frame. Does that kit come with replacements for those bolts (that I lost) as well?

I definitely Locktite any bolt i take off. After losing this bolt, my license plate (I bought locking nuts for that), the exhaust bolt behind the rear brake fluid reservoir, the speedometer cable attached to the front tire, and almost losing my front brake cable harness I figured it would be a great idea. It's really rocky here, on top of the bike shaking so much.
 

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Discussion Starter · #12 ·
As previously mentioned, Eagle Mike sells a socket-head cap screw kit for strategic connections on a Gen II KLR.

A socket head cap screw is way stronger than grade 8 screws and gobs stronger than the OEM fastener.
I'm not seeing this kit on Eagle Mike. Would you mind sharing the link? I'm just seeing the drill through bolt kit.
 

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I'm not seeing this kit on Eagle Mike. Would you mind sharing the link? I'm just seeing the drill through bolt kit.
The Eagle Mike drill-through kit includes socket head cap screws for the main frame and sub-frame. There are a total of three screws, which replace the OEM fasteners that have reportedly been known to fail, especially on the Gen I.

Jason
 

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Discussion Starter · #14 ·
I'm not seeing this kit on Eagle Mike. Would you mind sharing the link? I'm just seeing the drill through bolt kit.
The Eagle Mike drill-through kit includes socket head cap screws for the main frame and sub-frame. There are a total of three screws, which replace the OEM fasteners that have reportedly been known to fail, especially on the Gen I.

Jason
Awesome. Thank you, Jason!
 

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Two connections = two opportunities for loss of pre-load and either fastener failure or the fastener backing out. One connection = only one opportunity to do the same. Also, one longer fastener will provide more stretch than two shorter fasteners, which will be more fatigue resistant.

Jason
Perspective.

Two connections = two opportunities for no loss of pre-load.

One connection = only one opportunity to not lose preload. Stated differently, an opportunity for single-point failure.
 

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...I do think the drill through is stronger as you aren't relying on the tightness of the individual bolt threads, even if the nut on the end comes off, assuming the bolt stays in place, it isn't going to fail. Not having threads at the shear point is the biggest difference from where I sit.......do you need it? probably not....is it stronger? I believe it is.


Dave
I don't believe that one bolt is stronger than two. If the failure is in shear then it is as likely to happen to a single bolt as it is one of two bolts. I think that if you calculate the clamping force of a properly torqued 10mm bolt, and its shear strength, you'll find that the subframe will fail before the bolt does.

If that one bolt does fail, are you not well and truly ****ed? Now, instead of one side being loose, both sides are loose. If that one bolt did come out, comedy would ensue.

I'm going to let the cat out of the bag and you all will be shocked and surprised.

The first time I heard of the drill-through mod I thought it was an ill-advised brain fart that somebody had.
 

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Discussion Starter · #17 ·
I don't believe that one bolt is stronger than two. If the failure is in shear then it is as likely to happen to a single bolt as it is one of two bolts. I think that if you calculate the clamping force of a properly torqued 10mm bolt, and its shear strength, you'll find that the subframe will fail before the bolt does.

If that one bolt does fail, are you not well and truly ****ed? Now, instead of one side being loose, both sides are loose. If that one bolt did come out, comedy would ensue.

I'm going to let the cat out of the bag and you all will be shocked and surprised.

The first time I heard of the drill-through mod I thought it was an ill-advised brain fart that somebody had.
These were my thoughts, as well. Thanks for your input, Tom!
 

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It would have been far simpler, easier and more doable to the 'average KLRista', if EM had simply supplied a 10mm upgrade drill & tap for the 2 upper sub-frame bolts, way back when. Rather than the drill-thru upgrade, imo.

And I'll ask the OP if he had ever checked those sub-frame bolts before? Who did or didn't do a thorough Break-in Maintenance tightening of all mountings at the 500-1000 mile mark? It is in the owners handbook (Bolt & nut tightness-inspect). This goes for all bikes, atvs, side by sides, snowmobiles.
 
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Perspective.

Two connections = two opportunities for no loss of pre-load.

One connection = only one opportunity to not lose preload. Stated differently, an opportunity for single-point failure.
As designed, two bolts are not redundant support mechanisms; failure of one bolt is a failure of the structure.

Jason
 

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I don't believe that one bolt is stronger than two. If the failure is in shear then it is as likely to happen to a single bolt as it is one of two bolts.
A single bolt is loaded in double shear, whereas the two-bolt design is loaded in single shear. Given the same cross-sectional area a double shear scenario will resist a greater force than single shear.

But the biggest advantage to a single, longer bolt is its resistance to fatigue.

Jason

P.S. You asked for an "engineering opinion" now you have one. What's next?
 
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