2018 DRZ 400 SM, how to remove rear sprocket bolts

[Fred Covely]

Ok, so wanted to do the rear sprocket change for highway gearing on a new from the factory 2018 DRZ 400 SM.  Reading here I was forewarned the bolts were tight.  Here is what I tried:

- new 12 point box wrench on the 12mm nut..... stripped

- heated sprocket around one bolt with a torch and then tried ryobi cordless (300 ft/lb) impact wrench.  No dice.  (in retrospect this is obvious as the sprocket itself has no threads, so this had zero impact)

- Heat sprocket around another bolt and retried the new 12 point no dice.

- then I went back and watched some video's and one guy who was obviously a welder or metal worker was explaining that you have to heat the nut, not the bolt.  That made sense to so I went back and was able to get off the first I tried by heating the bolt for about 90 seconds, then hitting it with the ryobi impact wrench, came right off.  However the next 3 I tried did not work that way!  I ended up trying both the hex screw and the nut itself and  no dice on 3 straight. 

I took another break and read some more about how long you should heat the nut, and decided I had probably overheated the area a bit.

Here is the process I came up with and was able to quickly remove the remaining 5 bolts.

1) use a cheap  torch.

2) it works best with the tire standing up.

3) point the flame directly at one SIDE of the NUT!  (so you have to kind of squeeze in from the side), and give it a 30 second count right on one side of the nut without moving it, just straight on flame

3) rotate the rim 180 on the vertical go to the other SIDE of the NUT and do the same for another 30 seconds

4) quickly attach a box wrench to the nut (I used a 12 pt but think a 6 would be even better).  Give a couple of swift whacks with a mallet to the wrench and it should break free.  This was the step I think I was missing.  For whatever reason just trying to wrench it off at that point just strips it, but a hard fast blow breaks it free.

Whats happening:  The direct heat is causing the nut to expand and also if there is loctite on it (I could not see any once they were off but I don't know that much about loctite) it will melt it or at least soften it.  heating both sides for about 30 seconds each I think is enough to loosen it up but not so much that the bolt itself starts expanding.  The swift whack with the mallet gives it enough of a shock to break it loose.

I used the same procedure but used vice grips rather than a wrench for the one I had stripped.

Putting these back on, I'm inclined to go red Loctite but think I'm going to live with blue as I will be in the middle of nowhere a lot and will not have access to a torch.  Once I'm back in civilized parts, I'll go red.

Per one thread, I did try reasoning with both the nut and the bolt, but they were antisocial about it and I ended up consigning the nut to hell fire, and screwing the bolt entirely.

 

 

Edited May 1, 2018 by Fred Covely

[Noble]

6 point wrench is definitely better.  Also a quality wrench that fits the nut well is desirable. Are you sure you were using a 12mm wrench on a 12mm hex nut?  They don't really strip that easily.  Personally I don't see the need for thread locker adhesive on sprocket bolts when tightened securely.

 

[Rhinoracer]

I've never needed a torch to loosen the sprocket bolts.

I don't use loctite on them either. 

[Fred Covely]

Rhino.. curious what year is your drz? 

[Rhinoracer]

'01 S wheels, I also have an 09 SM wheel set.

My torque wrench doesn't fit so I just hand tighten with a 6pt box wrench, as tight as possible w/o using extensions to avoid overtightening.

[ptgarcia]

Had you removed the bolts before or was this the first time they've been off?

Sprocket bolts usually come with some thread locker pre-applied (at least all that I've seen) so I would not add any more to that, not even the medium strength stuff. 

[Fred Covely]

This is a brand new DRZ, so never removed.  I went to the dealer today and picked up a set of new nuts and bolts which as you say is pre-applied on the bolts from the dealer.  I had a guy at the dealership look at one of the bolts off the factory bike and he agreed, you cannot see any obvious signs of red loctite, but the metal has a slight blue hue to it.   I feel like from the factory they are just torqued on very tight.  I'm having a hard time finding 6 point wrenches at HD/Lowes/Autozone, etc.  I think they have them at Harbor Freight but am wary of the brand but could be wrong on that.  Because I really don't want to have to to change this with a torch, I'm probably taking off the red loctite and going with blue.

[ptgarcia]

16 minutes ago, Fred Covely said:

This is a brand new DRZ, so never removed.  I went to the dealer today and picked up a set of new nuts and bolts which as you say is pre-applied on the bolts from the dealer.  I had a guy at the dealership look at one of the bolts off the factory bike and he agreed, you cannot see any obvious signs of red loctite, but the metal has a slight blue hue to it.   I feel like from the factory they are just torqued on very tight.  I'm having a hard time finding 6 point wrenches at HD/Lowes/Autozone, etc.  I think they have them at Harbor Freight but am wary of the brand but could be wrong on that.  Because I really don't want to have to to change this with a torch, I'm probably taking off the red loctite and going with blue.

 

If you just torque them down un- gorilla-like there's no need to remove the pre-applied thread locker.

Here's a nice 6-pt ratcheting wrench. Not cheap, but excellent quality. https://www.amazon.com/SK-Hand-Tool-80005-Ratcheting/dp/B00SQ4G7VI, but if you get a quality wrench a 12-pt will be fine.

[Fred Covely]

I appreciate that link and will grab one.  On the loctite... my understanding is that the red loctite is permanent without heat even if you don't torque down the bolt? 

[Noble]

Loctite is a some times mis-understood product. Loctite is a brand name.  Loctite makes a lot of different products including anaerobic thread locking adhesives, the item generally refereed to here on TT simply as Loctite.  Loctite makes dozens of thread and press fit anaerobic compounds. The 3 we are most familiar with are low strength purple, mid strength blue and high strength red sold in auto parts stores.  Red permanent is not really all that permanent. There are a lot of factors that affect the strength of the bond. Size of the fastener, gap to be filled, surface cleaning, surface condition, material.... The idea of "permanent" is to use it where the fastener will not generally be removed very often. The purpose of Loctite is to reduce loosening of the fastener due to vibration and often to seal the thread.  Loctite is never a substitute for proper tightening of the fastener. The purpose of a bolt is to clamp something together. Loctite without the clamp defeats the purpose of the bolt.  For example if Loctite is used on the nuts of the sprocket bolts but the bolts are only finger tight, the nuts might stay on but the bolts would eventually shear off due to repeated hammering in the bolt holes.  When tight the drive force is not taken directly by the bolts.  The force is transferred to the hub flange by the clamp load.  Loctite or no Loctite, the best way to prevent a fastener from loosening is proper tensioning of the fastener.

Your question - is red Loctite permanent even if the bolt is not tightened?  Yes under the right conditions the bond of the bolt to the nut can exceed the torsional strength of the bolt. Normally not but yes it is possible.  An example is the counter shaft retaining bolt of a modern KTM motorcycle. KTM uses a high strength pre-applied thread locking compound on the bolt. When the bolt is tightened, the locking compound cures and the bolt is near really permanent. (which is odd since the bolt is intended to be removed) Without heat to soften the bond there is about a 20% chance the bond is stronger than the bolt and attempts at removal will break the bolt before the bolt turns in the threads. Never actually seen this happen with common red Loctite.  There is a super strength green that is the real thing when it comes to being permanent.

Also keep in mind there are more Loctite anaerobic compounds than there are colors.  Not all reds are the same, not all greens are the same, etc.  You have to go by the product number not the color to know what you are getting.

[Fred Covely]

This is good input on the loctite and I appreciate your time on the reply.  I checked with a buddy of mine who was a dirt bike mechanic for a lot of years. His take was that if you go with anything but red, thats ok, but you have to make sure you check those bolts on a regular basis.  My journey will take me mostly on good roads through the US and a lot of Europe so I switched out to better road gearing on the back sprocket.  However, when I hit Novosibirsk Russian, I'm going to go back to the factory sprocket and maybe even a bigger sprocket for the dirt and mud which will ensue in both Mongolia and Northeast Siberia (Road of Bones).  So when I am in Novosibirsk I'm going to take a couple days to convert the bike.  On balance I'm going with the red and a really good box wrench per ptgarcia above as I think it should be trivial to pick up a cheap torch in Novosibirsk, maybe even have a bike shop do that along with some other changes.  I again, appreciate the info.  You can see my trip here at covely.com where I'll be post regular videos and pics.

[Erik Marquez]

The fasteners come thread locked from the factory, using a high strength anaerobic thread lock. It is technically heated to 250c to soften, but will be soften sufficiently to allow removal with hand tools at about 200c.
Softening the thread lock is a key to not destroying the factory sprocket fasteners. 
A quality tool on the nuts is another, 6 point is better that 12 point for this task... But a 12 pint wrench designed to attack the flats of the nut like Snap Ons flank drive works well also.

Heat the nut to 200~250c (use a temp gun, your likely guessing really low) hold the hex side of the fastener with a well fitting hex key, turn the nut with the wrench or socket... if doing this with hand tools, use of a dead blow soft faced hammer on the wrench end will likely improve the odds of cracking the nut loose.

[Fred Covely]

Erik, that agrees completely with what I saw on the new bike.  Suzuki is probably using a clear thread lock and so its not visible, but the bolt sure acts that way.  By heating the nut for 30 seconds on two opposing faces its probably getting to your 200-250c temp (I would have no way of knowing how to measure the temp on a heated nut).  Hopefully this thread will help other newbies like me get the job done.

 

Edited May 2, 2018 by Fred Covely