Wet torque bolts vs dry torque with torque wrench - Kawasaki KLR 650 Forum
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post #1 of 14 Old 10-21-2019, 03:38 PM Thread Starter
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Wet torque bolts vs dry torque with torque wrench

Hallo everyone,
i m a 1991 Tengai 650 owner.
I just did the doohickey upgrade with eagle mike lever and spring and put a new rotor bolt.
Before tightening bolts with torque wrench i usually grease threads, and so i did with rotor bolt before finally tightening it as prescribed to 175 N-m.
Then i had a doubt and after surfing on internet about greasing bolts before tightening i realise that this is a mistake and the result of greasing bolts is that with the same torque they are screwed about 30% tighter than dry bolts.
I also read in kawasaki 1989 Tengai workshop manual (that i own) rotor bolt (always put a new one) should finally be tightened to 195 N m unless after intermediate tightening to 120 you realise there is oil on the thread, in that case tighten to 175 N m, so i can assume this case is similar if not equal to thread greasing as i usually do.
I also read in a post on a forum that tightening a bolt in further steps (first to 120, then 160 then 175) like i did is not so effective as tightening all in once, and the final tightening is not really a 175 but less.
Can anyone suggest me what to do, shall i stay with my bolt or replace it with a dry one and tighten it as well to 175?
Sorry if i cant be more clear and thanks to anyone that could help me

Fabio

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post #2 of 14 Old 10-21-2019, 06:32 PM
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motofcalco,
I had read 10% difference between dry & lubed threads, but what ever.

I always use Anti-Seize grease on the threads & under the head of the flywheel rotor bolt.
I loosen the rotor bolt after the first 15 - 20 ft lbs, but I DO NOT remove it and dry it!
Then I torque in it a couple of steps up to 130 ft lbs (175N-m), because I need a better grip usually. I even re-use my own personal rotor bolt.

The 2008 & up Gen 2 units suggested 144 ft lbs (195N-m) dry threads (for no explainable reason). The original KL600-A1 suggested only 90 ft lbs. All of the models use the same part number rotor bolt as your bike.
I've removed factory assembled rotor bolts that probably did NOT even have 40 ft lbs applied by the assembly line! I've had other Gen 2 units which almost destroyed my puller bolt, I had to quickly heat the steel center hub to remove rotor. (Some people have destroyed the rotor threads because they did not use heat.)

The original KL650-A1 oem service manual had a really Big ERROR, it called for 195 Foot Pounds (235N-m) which was hopefully corrected with a Service Bulletin before anyone needed to use the 1st Edition oem service manual.

In my opinion your bike will be perfectly fine.

pdwestman
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post #3 of 14 Old 10-21-2019, 06:43 PM
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Buongiorno, Fabio. Welcome to the forum.

You have over-torqued the bolt.

The torque value for that bolt does specify a dry installation, but the torque spec has varied quite a bit. The following is some stuff I have written in the past on the topic and I have simply cut and pasted it here. This is simply background information.

"I'd have to check manuals, too, but I believe it was in the KLR600 manual where it was called a replacement item. The funny thing about that is that the torque requirement (which has varied quite a bit) was lower in that usage. edit: For those not familiar with the early KHI manual system, the KLR600 was the base manual so any requirements in it, unless superseded in a later supplement, carried through to 2007. Thus the bolt replacement may have carried through to 2007; dunno if it was ever superseded in a Gen1 supplement.

This is one of those things were, when asked what is needed, I suggest a replacement bolt because it's never a bad idea to replace the bolt, it isn't that expensive in the grand scheme of things, and I don't want to take any liability or have a guilty conscience should something go wrong with the bolt replacement. If a replacement bolt is used then the original bolt should be cleaned with acetone and used for the initial torquing, then the new bolt is installed.

Some history: The bolt has not changed over the entire run of KLR650s. The torque was, at first, 118N-m (or 156N-m, depending on which page of the '84 manual you happened to be reading). Then it was raised to 176N-m, and finally to 195N-m. As far as I know, the crank has undergone at least four iterations. First the '84 KLR600 crank, then it was lengthened by a halfish inch for the '85 and '86 600s, then the '87 crank came along only to be replaced in 1988. It changed again in the big '96 redesign and again with the Gen 2 introduction in 2008.

The threaded section for the rotor bolt, though, has never changed."


So, let's say that you have, by tightening it wet to 175 actually torqued it to 225. That's pretty tight, being 30% over the specification. Even though the original recommendation to replace the bolt was back in the KLR600 manual and is no longer in the current manual even with a torque spec that is 65% greater than the original specification, I would begin to worry a bit about that bolt.

As big a pain in the butt as it might be, I would err on the side of caution and replace the bolt and torque it, dry, to 175.

As to the torquing in stages, the current instruction is to tighten it a bit, back it off, then torque it all in one motion. Even though the earlier manuals did not call for that, I think it is good practice. By doing so you can see if the rotor is on correctly, if the starter ring gear is binding, etc. But note that the bolt is backed off and torqued all at once. As mentioned above, I think that the initial torque should be done, dry with the old bolt after cleaning it, then the final torquing done all at once with a new bolt.

Tom [email protected]

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Last edited by Tom Schmitz; 10-21-2019 at 06:48 PM.
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post #4 of 14 Old 10-21-2019, 07:01 PM
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Two men, two opinions.

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post #5 of 14 Old 10-21-2019, 07:39 PM
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Fabio,

Yes, two men, two opinions.

You should be aware that if there is one person whose opinion I would defer to, it would be Paul's. Paul has vastly more experience than I do; knowing that I tend to be conservative. And anal-retentive. And obsessive-compulsive.

And for the geeks, this difference in wet vs dry torque is called the "K Factor". It varies slightly depending on what the wet component is, but is generally accepted as 10-15% (just like Paul said ;^)).

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

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post #6 of 14 Old 10-22-2019, 08:53 PM
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I saw that you got the same sort of conflicting answers over on the klr650dark.net site, Fabio.

Your engine will be fine.

pdwestman
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post #7 of 14 Old 10-22-2019, 09:17 PM
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As well as misinformation. ¯\_(ツ)_/¯

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem
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post #8 of 14 Old 10-23-2019, 04:07 AM Thread Starter
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Thank you to every contribution, now i can have a better picture about
the topic.
I posted the same question in klr650.net forum and i realise also through the years Kawasaki has changed a few times torque value and procedure.
Also i m not a professional mechanic and never tightened a bolt to such a high torque, no confidence through doing the same job several times and i was concerned about thread damaging, or bolt cracks in case of too much torque, also in case of redoing the job you can replace the bolt but not the crankcase, the parts are critical, the rotor spins often at hight turns even if the bolt is not axially stressed, also is difficult to really quantify the K factor.
Anyway i m not in a hurry and have enough time to think about what to do.
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post #9 of 14 Old 10-23-2019, 11:12 AM
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So reading the tea leaves in both conversations;

- specs vary by year and by source. It seems that most sources indicate 130 ft lbs wet or 144 ft lbs dry (a difference of 11% which is consistent with Paul's suggestion).
- Since you torqued it to 130 ft lbs wet, you would seem to be spot on for at least some sources and since the bolt has never changed....

If it was my bike, I'd call it good and go riding.

Cheers,
Dave
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post #10 of 14 Old 10-23-2019, 07:48 PM
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Not to be argumentative, as I don't have all of the service manuals, but where is the reference to "130 ft-lbs wet"? The KLR600 manual lists torque values for bolts not otherwise specified and states "All of the values are for use with dry solvent-cleaned threads". I would think that also applies to the fasteners, like the rotor bolt, that do have a specified torque. Ref pages 14-3 and 14-10 of the KLR600 manual (each of which lists a different torque value).

It has always been my understanding that torque values are dry unless it is specifically stated that lube is to be used, e.g. the cylinder head bolts (moly-disulfide in the Gen 2 manual, "grease" in the KLR600).

Tom [email protected]

“Some days I feel like playing it smooth. Some days I feel like playing it like a waffle iron.” -Philip Marlowe

“'Why' and 'How' are words so important they cannot be too often used.” -Napoleon Bonaparte

Sting like a butterfly.
Noli Timere Messorem

Last edited by Tom Schmitz; 10-23-2019 at 07:51 PM.
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