DRZ400 Engine Sprocket Nut Torque Confusion

[Throttlejockey650]

Hey all,

I have a 2012 DRZ400S and I have been following the threads regarding the preventative maintenance fixes especially the "loctite" fix for the engine sprocket.

There does not seem to be a consensus among forum members as to the correct torque value for this nut because I have read that it should be 79.5lb-ft and also 101.5lb-ft on various posts.

I am not sure where everyone is getting this information, but I just purchased the 2012 Factory Suzuki Service Manual for the DRZ400S/SM P/N: 99500-43092-03E and the torque spec. stated for the engine nut is 105lb-ft. This value is stated in at least two sections of the manual 3-9 and 8-24 torque table.

It seems to me that Suzuki is aware of the problem of this nut backing off and has taken steps to correct the problem, the most visible of which is to increase the torque value on the nut by a pretty large margin of 24% thus increasing the clampup force that restricts the countershaft sprocket from rotating relative to the countershaft.

I am not sure if the countershaft and associated external threads or the nut has been redesigned to handle the greater torque values, or if there was just such a large margin of safety available with the initial torque spec that they could just increase it without detrimental effects. Point being....if these parts on my bike are identical to previous years then we should all be torquing to the higher value as this in an of itself could eliminate the problem all together possibly without the loctite.

That being said...I did remove the nut on my bike and locktite the threads of the nut only...NOT the splines common to the sprocket. The reason for this is that assuming the nut doesn't back off any due to the threadlocker being applied...then there should be no way for the countershaft sprocket to rotate at all relative to the shaft assuming the clampup force applied to the sprocket is greater than the rotational force of the sprocket to the shaft.

This also makes me wonder if any of the other problem areas have been addressed by Suzuki for 12'.

Comments, thoughts, suggestions are welcome and encouraged!

Regards,

Shawn

Edited June 4, 2012 by shawplat

[Erik Marquez]

1: 80 FTLB is fine when done with the loctite fix.
From what you posted, you are not understanding the fix, it has nothing really to do with the threads on the nut or CS.

Yes, the sprocket on the splined shaft does move, in rotates, slightly under load and that is what causes the issue.. it's NOT the nut coming loose, it;s parts wearing and lessening the clamp ;load provided by that nut.

Been tested many times at higher TQ values, all the way to failure of the nut threads.. no clamp load capable of those parts will stop the rotation of the splined sprocket on the splined shaft...if there was a much tighter spec on the splines, or an interference fit, we would not be here.. but for production and repair/replacement needs, that splined fit is very lose (by general fitment standards).. stopping the movement is the key.

2: Please scan that section of the manual and post or email to me, Id be grateful. If Mother Suzuki has done this, it will be the first time they have EVER done anything to address the issue, I would like to read through the entire section to see if anything else has been changed...

I ran part numbers this morning, they have not introduced any new parts (same PN, no superseded PN).. not the counter shaft, seal, second gear bushing, the seal spacer, nor CS nut.. so the parts are the same for all years.

Bottom line, regardless of the CS nut TQ you used, if you did not do the loctite fix as described, you still have the same issue you started with.

[Noble]

Shawplat - Thanks for posting this question. As you may know there was a post a few weeks ago that raised this question about 105 ft lb vs the old standard 80 ft lb. I have followed this question for many years and was one of the original investigators on loose sprockets. The previous post about 105 ft lb was the first I had heard of it and I was skeptical at first but the poster confirmed that the new manual did say 105 and the units were ft lb. So I believed it but is is good to have a follow up confirmation since I have not personally seen the new service manual.

I'm good with using 105 ft lb and have adopted it for my own. 80 ft lb has proven itself over many years and I have no problem with continuing to use, but I'm going with 105 from now on.

There are several other important torque number that have (or may have) changed. Would you please post the FT LB torque spec from the new Suzuki service manual for:

Cylinder head bolt 10M.........

Balancer shaft nut.................

Primary drive gear nut...........

Generator rotor nut...............

Clutch sleeve hub nut....................

Engine sprocket nut..............

[ACTman]

_{I thought I would add that pvertightening the nut will result in crushing the forth gear bushing major transmission damage.}

_{Just as E.Marquez has said, it is the slight lash in the splines of the shaft to the sprocket that causes the sprocket to not remain tight. For years dirt bikes have had sprockets that don't tighten down at all and just run with the sprocket being able to "rattle" on the splined shaft. The torsional vibrations of the engein are going to always put a beating on the parts so you can't fix it with higher torque. I am sure the DRZ being used for street, supermoto, etc, will eventually wear on the shaft, necessitating replacement. Taking up some of the lash with locktite, seems like the most practical quick-fix but don't be too concerned when the sprocket is able to move after a short period of time.}

[thumpty dumpty]

_{I thought I would add that pvertightening the nut will result in crushing the forth gear bushing major transmission damage.}

_{Just as E.Marquez has said, it is the slight lash in the splines of the shaft to the sprocket that causes the sprocket to not remain tight. For years dirt bikes have had sprockets that don't tighten down at all and just run with the sprocket being able to "rattle" on the splined shaft. The torsional vibrations of the engein are going to always put a beating on the parts so you can't fix it with higher torque. I am sure the DRZ being used for street, supermoto, etc, will eventually wear on the shaft, necessitating replacement. Taking up some of the lash with locktite, seems like the most practical quick-fix but don't be too concerned when the sprocket is able to move after a short period of time.}

So, what are you saying here? Everyone figured a work-around for this except on one bike?

[Throttlejockey650]

Hey guys,

Thanks for the responses. I have a hard time believing that that Suzuki mucked up the simple calculations needed to design the shaft, nut, and sprocket assy. to resist rotational slippage under full clampup. It's not that difficult to determine the max torque applied to the driveline and design a shaft and nut with frictional clampup needed to react this torque. I suspect that under full clampup the sprocket is not rotating relative to the shaft, but rather after multiple load cycles it starts to loosen the nut ever so slightly which eventually does allow it to start rotating and wearing down the splines which then just progresses to the failure point. Anyhow here are the requested scanned copies from the 2012 Factory Service Manual.

Regards,

Shawn

[ACTman]

So, what are you saying here? Everyone figured a work-around for this except on one bike?

I am not sure where you get that impression. I will take another crack at it. What I am saying is that a lot of other bikes I am familiar with don't use a nut at all. Instead, the sprocket has a clip or retainer to prevent it from falling off, but otherwise it is able to rattle on the splined shaft. The DRZ uses a nut to retain the transmission shaft, but it is important not to overtighten the nut in an attempt to prevent the sprocket from coming loose. You will not be able to torque the nut enough to prevent movement. When (not if) the sprocket moves (takes up lash in the splines) it causes wear. Although the nut hasn't turned, as the parts wear from the movement of the sprocket, this causes the sprocket (and nut) become loose. The locktite fix is basically applying material to fill the space causing the backlash in the splines and prevent it from moving.

[Noble]

Torque table - very interesting. Only the countershaft nut torque was changed.

Here on TT, 10M head bolt is 43 ft lb and Primary nut torque is 100 ft lb. I though maybe Suzuki would change those too.

[RedRider3141]

I don't get it. I just regeared my DRZS from a 13T to a 15T for an upcoming DS ride and had to use a gear puller since I had done the loc-tite fix 4 years ago. Oh C!@# that was on solid. Anyways, I've owned a multitude of Honda's and each one had the same simple CS retainer. A small plate and two M6 bolts. Once installed and tightened to 11-15 ft-lbs (hand tight) the sprocket wiggled like crazy but never failed. Why is it such a problem if the DRZ sprocket comes loose? How does Honda do it?

All the following bikes I've owned or worked on have been like that: CT90, XR100, XL175, XL250s, XL250R, XR250L, XR250R, XR400, FT500, XR650R. It's so easy to change that some guys gear up to ride to the trails then stop for 10 minutes to gear down for the trails.

[Noble]

There is no argument that there are 2 common ways to secure the sprocket - Nut clamp and retainer. Both work, both have advantages and disadvantages. Nut clamp often works loose. I have found it on every nut clamp style I have ever worked on. Usually not a problem. DRZ it can signal possible wear in the transmission or not. Retainer style just get looser and looser. If you don't own the motorcycle long enough, it is not a problem. XR Hondas will eventually need a replacement countershaft. My 02 200 EXC needs a new counter shaft right now. See those streaks on the sprocket? That is fretting corrosion, metal being warn off under load. Ever see that on your trailer lug nuts, the nuts are loose.

[Erik Marquez]

Ive replaced more then one XR countershaft over the years due to worn splines.. ask any good tech he'll tell you the same.. Google imiages "welded sprocket"

This is a common find

The method works for sure, but has it's own down sides.

[Wayward Son]

yep,"floating sprocket" is french for "needs a counter shaft".

[RedRider3141]

I guess since I've never had any of my XL/XRs bikes for longer than 10,000 miles, I've yet to encounter this issue.

Sorry to the OP for hijacking your thread... when i torqued my '00 DRZ it was to 80ft-lbs listed in my service manual from 2000. The nut and sprocket were both good and tight when I changed it last week. However, the bike probably had less than 1,000 miles on it since I did the loc-tite fix.

Edited June 8, 2012 by RedRider3141

[Rob Bayless]

My XR-250 sprocket got changed so many times that I probably torq'd it 20 times per year, no joke. I used to run a 15 to ride to the trails, and then slapped a 13 on at the trail head, back to 15 at the end of day to get back home.

Man, that air cooled beast was one of the best bikes I ever owned, so easy to work on. Took alot of abuse.

Hoping my DRZ will be similar after some minor mods.

[Throttlejockey650]

Since I didn't originally loctite the splines on my countershaft only the nut...I am thinking about taking the sprocket back off and redoing the "fix" unless the experts think I should be ok to run it as is.

I am a little worried about getting the nut back off since I used high strength loctite on it. What is the best way to go about doing this without damaging anything?

Is it safe to use an impact wrench on this nut? Can I heat the nut up with a torch to soften the loctite without changing the temper of the materials? What is everyone on here doing to remove the nut after being loctited on?

Also, how do I clean the old, dried loctite from the threads after removal?

Edited June 10, 2012 by shawplat

[Noble]

I didn't originally Loctite the splines.-----I recommend you Loctite the splines

I am a little worried about getting the nut back off since I used high strength Loctite on it.-------Usually not really a problem.

Is it safe to use an impact wrench on this nut?------Yes, with the transmission in neutral.

Can I heat the nut up with a torch to soften the loctite without changing the temper of the materials?------Yes. 250-300 F is plenty of heat. But really I doubt you will need to heat it a all.

Also, how do I clean the old, dried loctite from the threads after removal? ------Scrape with a pointed tool like a dental pick.[/size]

Edited June 10, 2012 by Noble

[RedRider3141]

If the more DRZ experienced members think its worthwhile to add the loc-tite to the splines. I used a clamp to engage the rear brake while the bike was in 5th gear. Even with high strength loc-tite I was able to use my 18" breaker bar to remove the nut once the rear wheel was held tight.

However, I too am curious if it is safe to use a rattle gun on the nut. This would save me time when prepping the DRZ for a ride. Depending on where I ride I like to change gearing to suit the terrain.

Since I didn't originally loctite the splines on my countershaft only the nut...I am thinking about taking the sprocket back off and redoing the "fix" unless the experts think I should be ok to run it as is.

I am a little worried about getting the nut back off since I used high strength loctite on it. What is the best way to go about doing this without damaging anything?

Is it safe to use an impact wrench on this nut? Can I heat the nut up with a torch to soften the loctite without changing the temper of the materials? What is everyone on here doing to remove the nut after being loctited on?

Also, how do I clean the old, dried loctite from the threads after removal?

[Wayward Son]

as long as the trans is in nuetral a air or electric impact is fine.

[MSKLR6fiddy]

Bringing up the dead to input our experience with our '02 DRZ400S. @ 20k the threads in the sprocket nut were stripped out and the sprocket was loose on the CS. CS oil seal leaking like a sieve. Bought Suzuki parts( Nut, locking plate, CS seal and bushing) to replace failed parts. Used blue 243 Loctite on CS threads only, NONE on CS splines, torqued nut to 105 ft. lbs. 20k miles later, replacing front sprocket(we use only factory sprockets on our bikes because they're leaps and bounds superior to any aftermarket sprockets, IMHO) the nut is still tight, and the sprocket isn't rattling on the CS splines. We do around 60/40 road-gravel/trails, no racing, just spirited trail riding. Thought that might help.

 

BTW, what Ed says about the impact is true, never use impact with trans in gear, unless you like replacing busted tranny parts. I've had people bring bikes in with busted gears from them using impacts with the bike in gear. I always torque the CS nut with the bike in neutral, holding rear brake.

[kebrider]

BTW, what Ed says about the impact is true, never use impact with trans in gear, unless you like replacing busted tranny parts. I've had people bring bikes in with busted gears from them using impacts with the bike in gear. I always torque the CS nut with the bike in neutral, holding rear brake.

 

Bike in neutral holding the rear brake? I assume you mean you reinstall the nut by hand using a torque wrench with the bike in gear and holding the rear brake.

 

KEB