rear rack bolts - Kawasaki KLR 650 Forum
1987 to 2007 Wrenching & Mods For maintaining, repair or modifications of Generation 1 KLR's. 2007 and earlier.

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post #1 of 13 Old 12-07-2013, 05:01 PM Thread Starter
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rear rack bolts

Is there a name for the type of head on the 6 bolts that lock down the rack?

Part 92992

http://www.kawasakipartshouse.com/oe...3e479044d/seat


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post #2 of 13 Old 12-07-2013, 05:11 PM
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Don't see that part number on that picture. If you mean 92002 it's called a flanged bolt just like it says in the description.



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Last edited by klr4evr; 12-07-2013 at 06:52 PM.
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post #3 of 13 Old 12-07-2013, 05:33 PM Thread Starter
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Perfect, thanks.


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post #4 of 13 Old 12-07-2013, 06:54 PM
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Junk is what I refer to them as. I've broken them twice and drilled and tapped to 5/16"-18.

A KLR is not a motorcycle, it is a blank canvas with which to paint the rest of your life.
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post #5 of 13 Old 12-08-2013, 05:06 PM
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Too much tension will break fasteners. Under tightening where there are reciprocating loads (pulling and releasing) eventually causes fatigue and subsequent breakage.

If the fastener breaks despite being correctly tightened, a option is to replace with a higher strength one. Specialized, special configuration fasteners are difficult to assess in terms of the strength grade category in which they belong however one may be able to choose another fastener which will substitute with the addition of a washer, or change in other drive type (i.e. Allen versus hex head).

What typically happens is that someone grabs a substitute without consideration for the strength of the replacement. A frequent issue is the use of stainless fasteners which have acquired the mystique of superiority despite that they are never higher strength grade. Most are in the junk category in terms of strength.

If the fastener is breaking rather than the threads being pulled from the mounting, there is obviously room for a higher strength fastener.

A frequent issue in addition to the use of insufficient strength fasteners and under tightening, is the use of low grade washers. This is almost completely unappreciated in the repair field but if one considers subsituting a nylon washer under a connecting rod nut, one will immediately see that the nylon will sqeeze out under the clamping/tightening. What is generally unappreciated is that the squeezing out is a process. The washer will continue to yield over time such that the fastener will become loosened even if was sufficiently tightened initially.

Increasing the fastener diameter is another often ignored option. As 19willys51 mentioned, a small increase from 6 mm to 5/16" provides an exponential increase in fastener strength as well as increasing the anchor strength of the mounting threads.

I cannot recall the sizing of the rack holes sufficiently to know whether 8 mm might also fit but seem to recall that there may be a sizing issue so that 5/16" is the best choice? Perhaps someone whose memory works can comment?

If one has not done so, compare tightening torque for 5/16" Grade 5 inch capscrew with 6 mm Grade 8.8 ISO metric. Also compare 5/16" and 8 mm. An even better excercise is to calculate the cross sectional area of the fasteners. Simply comparing the torques will show clearly why 19willys51's selection of 5/16" is so much stronger than the 6 mm.

A caution: it is generally best practice to avoid mixing fastener thread types such as installing inch sized fasterners onto a metric application or vice versa as subsequent service may not recognize the substitute. I've seen many problems which arose from the use of some inch fasteners into a metric engine. The person doing the work grabbed the wrong fastener and cracked the case. I happens....

General Motors vehicle of years past were really "interesting" because they used both inch and metric. As an added bonus, instead of using standard metric they created their own metric by adapting sort of standard size inch fasteners by threading to a sort of metric thread. Really "interesting".

The rack is not likely to be so affected by mixing up of fasteners but as a general principle, professionals avoid the practice. If one does decide to resize to another thread type, it is best to do them all. Nothing worse than fasteners of similar size with a slightly different thread.

Rats are not the only creature so affected, IMO, 19willys51. LMAO There is a huge depth of wisdom in that signature line.
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post #6 of 13 Old 12-08-2013, 06:49 PM
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Quote:
Originally Posted by Crashoverride View Post
Is there a name for the type of head on the 6 bolts that lock down the rack?

Part 92992

http://www.kawasakipartshouse.com/oe...3e479044d/seat


Crash
Assuming you meant to type, "92002," I notice 92002A has a SUPERSEDED notation and new part number:

BOLT,FLANGED,6X32


92002-1989 92154-0238

("92002-1989" is crossed out in the text, "92154-0238" is printed in red.)

Perhaps Kawasaki discovered the deficiency in the original bolt and replaced it with a higher-grade (greater strength) bolt, part # 92154-0238. (I said, "perhaps," don't know that this is so.)
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post #7 of 13 Old 12-08-2013, 06:53 PM Thread Starter
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Finally found a place that sold the bolts I want in small packs at a reasonable price, now just need to wait 5 months till spring.


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post #8 of 13 Old 12-08-2013, 09:31 PM
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Finally found a place that sold the bolts I want in small packs at a reasonable price, now just need to wait 5 months till spring.

Just curious; what are the replacement bolt specifications?
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post #9 of 13 Old 12-08-2013, 09:40 PM
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Couldn't you find a quicker shipping option?





Quote:
Originally Posted by Crashoverride View Post
Finally found a place that sold the bolts I want in small packs at a reasonable price, now just need to wait 5 months till spring.


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post #10 of 13 Old 12-08-2013, 09:46 PM
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Normk, first of all, your assessment of stainless bolts is 100% correct, stainless only has to do with corrosion resistance. They are generally not higher tensile strength tha carbon or grade bolts. That's why they are so commonly used in marine applications.

I chose a 5/16-18 over an M8 for one very simple reason, I had the tap and bolts handy. A 13mm wrench will also work(though not ideal) on the 1/2" head. The original cause of failure for the bolts on the rack was that I had installed a trunk and the factory bolts were not long enough to reach. I replaced them with what I thought were long enough bolts but were actually too long. I used a socket cap with rubber coated washers. The bolts actually bottomed out against the subframe and "tightened" but actually stretched the bolt as it had nowhere else to go. The vibration of much off highway riding, combined with the over stressed bolt resulted in a fatigue fracture with ductile finishing of the bolt. I repaced them with Kawasaki bolts that were of appropriate length. These bolts suffered the same fate but not from bottoming out. They suffered a textbook fatigue fracture. I tapped the 5/16 and have had no further issues.As Norm has mentioned the larger diameter has much more resistance to cyclic overload.

I would never ever mix metric and sae fasteners on an engine! Ever! Fastener grades are easily checked with a simple google search. Sae use dash marks on the head to indicate grade or tensile strength(6 dashes is grade 8, 3 dashes grade 5) while metric use a number system( 12.9 is stronger than 10.4) Bolts and washers and nuts are much more complicated tham mostpeople realize but this thread "no pun here" has been hijacked!

On an engine I would never consider mixing metric and sae fasteners! \ver!

A KLR is not a motorcycle, it is a blank canvas with which to paint the rest of your life.
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