Countershaft loctite fix - comment

[Noble]

Sometimes entertaining, sometimes educational.  The sprocket shows quite a bit of wear but is still serviceable.  Video looks fine, good to.  Original torque on the nut was 80 ft lb. That was upgraded by Suzuki to 100 ft lb.

[michaelks]

What I still don't understand is why should the gear bushing be the sole culprit. That would mean that up to the bearing inner race all parts are solidary and the sprocket/spline play is entirely delivered to the bushing, causing it to wear off. The bearing being beyond suspicion, there also could be some rubbing between the sprocket and the spacer that follows it, so both these parts could wear as well.

[Erik Marquez]

What I still don't understand is why should the gear bushing be the sole culprit. That would mean that up to the bearing inner race all parts are solidary and the sprocket/spline play is entirely delivered to the bushing, causing it to wear off. The bearing being beyond suspicion, there also could be some rubbing between the sprocket and the spacer that follows it, so both these parts could wear as well.

Second gear bushing is softer then the spacer or gear it rides against.. So as the sprocket rocks on the splines it wears the bushing... and somewhat flares the edge...

Once you re tighten the nut, the bushing binds against the shaft and gear.

[michaelks]

There are a few parts together on this shaft, between the shaft nut and the 2nd gear. Not to forget that this gear, as well as the sprocket, ride on splines, so both will have play on said splines. However hard the torque, eventually this combined play from acceleration/deceleration will have to somehow bear on the interfaces between the nut-washer-spacer-bearing-gear bushing-gear-washer. Any of these interfaces, or all of them together, will be wearing against one another and so the torque that binds them together will eventually diminish, but then there will be progressively less wear too.

 

Well but - If one applies Loctite to the sprocket-spacer interface, one is merely transferring the wear to the remaining interfaces, since that one will be locked. Unless one can trust that the upgraded torque (from 80 -> 100 lbf.ft) will not allow any twisting. It seems that some kind of Loctite was previously applied here :

 

 

My old Honda XR250 didn't have a nut on the sprocket at all, which was held in place by a bracket that allowed some axial play. Maybe it would be best in our case to not torque at all, securing the sprocket with something similar, so then there would be no wear to worry about.

 

 

[Erik Marquez]

There are a few parts together on this shaft, between the shaft nut and the 2nd gear. Not to forget that this gear, as well as the sprocket, ride on splines, so both will have play on said splines. However hard the torque, eventually this combined play from acceleration/deceleration will have to somehow bear on the interfaces between the nut-washer-spacer-bearing-gear bushing-gear-washer. Any of these interfaces, or all of them together, will be wearing against one another and so the torque that binds them together will eventually diminish, but then there will be progressively less wear too.

 

Well but - If one applies Loctite to the sprocket-spacer interface, one is merely transferring the wear to the remaining interfaces, since that one will be locked. Unless one can trust that the upgraded torque (from 80 -> 100 lbf.ft) will not allow any twisting. It seems that some kind of Loctite was previously applied here :

 

 

My old Honda XR250 didn't have a nut on the sprocket at all, which was held in place by a bracket that allowed some axial play. Maybe it would be best in our case to not torque at all, securing the sprocket with something similar, so then there would be no wear to worry about.

 Replaced several XR series counter shafts because of the sprocket retention design.. Google "welded front sprocket" what you will find is cir clip or retainer plate designs welded up because the splines wore. 

 

It's not a better or worse design, just different with it's own inherent issues to be dealt with. 

 

To the rest... you have never had a DRZ transmission apart have you? You sound well reasoned in your post.. Im sure if you have had one or a dozen apart you would understand why your theory is off.

 

Bottom line...

 

The fitment of second gear to the countershaft splines is a much tighter fit then even the best made countershaft sprocket.  

[cal_tony]

@ Marquez

 

Well!...  after  hearing all about the DRZ primary sprocket loctite fix and doing it for so long now I know why I was doing it.

 

I had always thought it was to avoid the 600R 650L problem of worn splines. Even I had even seen a 600 R tac welded job. My comment "Gotta use loctite".

 

So, now it makes me wonder.............. should all primary sprockets be loctited?

 

Tony

[Noble]

It would not be a bad idea to Loctite all countershaft sprockets that are clamped to the shaft with a nut.  It would be pointless to Loctite a "floating sprocket" design.  The Loctite would pound out very quickly.

 

As one of the original instigators of "Loctite the sprocket" I recognize it is not the ultimate answer.  It is simple, inexpensive and reasonably effective. It has worked for a lot of people for a lot of years.  The Loctite can fail over time.  Worth while to check the sprocket routinely.  I think the 100 foot pound nut torque helps.

 

Running a DRZ400 as a "floating sprocket" also works.  The hazard is, when the nut is loose and only retained by the bent tab (lock) washer, it will eventually fall off.  So if you do that, a spare nut and washer needs to be in the tool kit and both items need to be checked regularly and changed occasionally.  And spline wear can also occur.  It is an alternate to splitting the cases when tightening the nut binds the transmission.  Call it a stop gap measure.

[highmarker]

Since loctite only cures in the absence of air (threaded fasteners) I have trouble seeing it do anything at the sprocket spline interface but squash out?  If the sprocket is loose fitting you might try some other brands? my old XR the only tight fitting sprocket was oem, the aftermarket's weren't good.

[Erik Marquez]

Since loctite only cures in the absence of air (threaded fasteners) I have trouble seeing it do anything at the sprocket spline interface but squash out?  If the sprocket is loose fitting you might try some other brands? my old XR the only tight fitting sprocket was oem, the aftermarket's weren't good.

Anaerobic thread lock works when in contact with metal and in the absence of air.. But it does not need to be in a vacuum to cure.

"Threadlockers are a single component anaerobic adhesive comprised of unique liquid resins that harden (or cure) to a durable solid when exposed to metal ions in the absence of air."

 

The lack of open air contact crated between the nut/washer and the spacer behind the sprocket does just fine.

as anyone that has ever removed a DRZ front sprocket following this procedure will attest.  

 

It's not really a guess, or new news. 

But if you feel the need to prove or disprove this your self,, try it, let us know your results. 

[michaelks]

It seems to me that the loctite fix is merely making a single part out of the sprocket-washer-spacer assembly. They are now welded together. So what happens to the sprocket play on the shaft splines? It moves on inside. Where will it be at its worst, whether at spacer - inner bearing race or at same race - gear bushing or further down the line, who knows. Hopefully the better machined parts will slip more easily and also wear less for the same reason.

 

I think there is no wear to speak of inside the engine, compared to the wear at the sprocket. That's why the loctite fix works. There's no oil at the sprocket, parts are rubbing dry against each other, and so the nut gets loose. I was surprised to see my nut so far out at sea. That's because the wear went on even after it was loose, it was almost one turn away from the sprocket. So the wear is at the sprocket and nowhere else.

 

I would suggest it's pointless to torque the nut too much after the loctite has been applied. Torque won't stop the twist, and so tightening up will only make trouble for that bushing. Just enough to make sure the bearing is spinning, no more. Parts will be moving against each other just the same, but lasting much longer because of much less wear.

[ohgood]

Since loctite only cures in the absence of air (threaded fasteners) I have trouble seeing it do anything at the sprocket spline interface but squash out?  If the sprocket is loose fitting you might try some other brands? my old XR the only tight fitting sprocket was oem, the aftermarket's weren't good.

 

 

i can assure you it cures, completely, in a nice form filling (firm) way between the splines of the sprocket and the shaft. at each sprocket change (sometimes weekly, sometimes monthly) i pick out the old slabs of loctite from the splines before installing the new sprocket, with loctite. i have very little wear at all on the shaft splines, but every new sprocket can be rocked forward/rearward rotation enough to be felt by hand. if this was left unchecked (without loctite) i'm certain it would start hammering away on the shaft splines, and the pieces down line from it. 

 

overtorquing things usually means a trip to a machine shop, for things that hold other things together in an important way. or it should. 

 

in a past life i made blower shafts with 50-60 splines on the ends, which turned in the -same-direction- for their entire life. they were shrunk in place (heat the impeller's coupler and bearing holder) or liquid nitrogen the shaft, then gently slide into position on the shaft. every single impeller that came back was from catastrophic stupidity (tossing a hammer in the impellers, or similar), bearing failure, or impeller damage. all the splines were loctited during assembly, or if they weren't, they would wear either the shaft's splines or the carriers. sometimes both. loctite prevented this 99% of the time. these blowers were driven by high power electric motors. very smooth, very constant speed motors. the impellers were balanced to a nats hair, bearings set and torqued, and the impellers were gear driven, no chains involved. this is a -very- reliable method of driving heavy machinery at high rpms. some were rated at 150hp motors for around 12,000 rpm or more, with around 1/2 a ton of mass spinning. some were bigger. 

 

now. 

 

even with all that very rigid structure, sometimes a competitors fan would come back to us. splines were shit. bearings were shit. shivs were shit from trying to start the fan with terribly worn bearings. what caused it ? usually a vibration was present at shipping, which lead to-

 

spline damage 

 

which exponentially increased bearing, spline, and out of balance wearing on the entire fan. 

 

when i read the FAQ about loctite fixes, it made sense the first time. 

[ohgood]

It seems to me that the loctite fix is merely making a single part out of the sprocket-washer-spacer assembly. They are now welded together. So what happens to the sprocket play on the shaft splines? It moves on inside. Where will it be at its worst, whether at spacer - inner bearing race or at same race - gear bushing or further down the line, who knows. Hopefully the better machined parts will slip more easily and also wear less for the same reason.

 

I think there is no wear to speak of inside the engine, compared to the wear at the sprocket. That's why the loctite fix works. There's no oil at the sprocket, parts are rubbing dry against each other, and so the nut gets loose. I was surprised to see my nut so far out at sea. That's because the wear went on even after it was loose, it was almost one turn away from the sprocket. So the wear is at the sprocket and nowhere else.

 

I would suggest it's pointless to torque the nut too much after the loctite has been applied. Torque won't stop the twist, and so tightening up will only make trouble for that bushing. Just enough to make sure the bearing is spinning, no more. Parts will be moving against each other just the same, but lasting much longer because of much less wear.

 

 

no, the nut will be locked against the sprocket, the sprocket on the splined shaft. there will not be movement. adding vibration to an assembly is never a good thing. 

[Erik Marquez]

It seems to me that the loctite fix is merely making a single part out of the sprocket-washer-spacer assembly. They are now welded together. So what happens to the sprocket play on the shaft splines? It moves on inside. Where will it be at its worst, whether at spacer - inner bearing race or at same race - gear bushing or further down the line, who knows. Hopefully the better machined parts will slip more easily and also wear less for the same reason.

 

I think there is no wear to speak of inside the engine, compared to the wear at the sprocket. That's why the loctite fix works. There's no oil at the sprocket, parts are rubbing dry against each other, and so the nut gets loose. I was surprised to see my nut so far out at sea. That's because the wear went on even after it was loose, it was almost one turn away from the sprocket. So the wear is at the sprocket and nowhere else.

 

I would suggest it's pointless to torque the nut too much after the loctite has been applied. Torque won't stop the twist, and so tightening up will only make trouble for that bushing. Just enough to make sure the bearing is spinning, no more. Parts will be moving against each other just the same, but lasting much longer because of much less wear.

 

1: The threads on the countershaft nut will fail before 2nd gear bushing or the spacer deforms,, ie there is nothing wrong with tightening that nut to the current OEM standard of 101 ftlb after doing the locktite procedure.

 

2: The second gear bushing wear is stopped because the locktite at the countershaft gear splines has stopped the sprocket from rocking on the shaft and wearing the bushing outer end.

 

3: Discussion is great,, and logical and critical thinking important. But lets not loose sight of.. theory's of what might happen, might wear more due to performing the locktite procedure are just that theory,, while in practical use of this solution ...,, no additional damage or failures have been accounted for.

 

IOW... known issue, known solution,  No known linked failure caused by the solution = Win

[michaelks]

1: The threads on the countershaft nut will fail before 2nd gear bushing or the spacer deforms,, ie there is nothing wrong with tightening that nut to the current OEM standard of 101 ftlb after doing the locktite procedure.

 

2: The second gear bushing wear is stopped because the locktite at the countershaft gear splines has stopped the sprocket from rocking on the shaft and wearing the bushing outer end.

 

3: Discussion is great,, and logical and critical thinking important. But lets not loose sight of.. theory's of what might happen, might wear more due to performing the locktite procedure are just that theory,, while in practical use of this solution ...,, no additional damage or failures have been accounted for.

 

IOW... known issue, known solution,  No known linked failure caused by the solution = Win

 

#2 is what still wasn't clear to me, so the loctite also eliminates the rocking. Well that's great then. I'm waiting for the new sprocket I ordered to do this job. I don't know what I'm going to do about the rear 44 sprocket however, since mine is the only S in this country and the E's have bigger sprockets.

 

Sorry for too much discussion, but I'm too old to ride much, so I guess i'm more of an armchair amateur mechanic ?

[Noble]

When the nut is tight with no Loctite to fill up the space on the splines the sprocket will still move in rotation slightly on the splines under high torque loads (accel and decell over rough ground).  This slight movement carries the spacer behind the sprocket with it, the spacer carries the bearing inner race, the inner race carries the second gear bushing, movement occurs between the bushing and the shoulder on the shaft supporting the nut compression load.  That is what you are ultimately trying to prevent with the Loctite.  This is not all conjecture.  Years ago there was some engineering and testing done.  Since then many many empirical observations support the original conclusions.   As I said earlier, I recognize Loctite is not the ultimate answer.  But it is simple, inexpensive and reasonably effective and has worked for a lot of people for a lot of years. 

 

What is "too old" to ride much?

[michaelks]

Oh, it's when you'd really rather just walk.

[Noble]

I guess I'm not too old then.

[highmarker]

Think I understand what your trying to do with this now. Question, when you remove the sprocket does it seem glued in place tight on the splines?  Segments of loctite intact or crumbled?  trying to think of another fix like maybe specing a sprocket with tighter fit or lock insert? 

[simplygo]

Is there a youtube video that shows a quick get it done process for doing the Loctite sprocket fix for a drz?

[michaelks]

Well, let me see if I got it. I thought from what I read that it was the gear bushing that was soft and that it would mushroom with the torque applied. That seeming to have been disproven, the cause would then be the rocking from the sprocket/spline to be carried over to said bushing and causing it to wear away.

 

I would suggest, as before, that it is rather the rocking at the sprocket against the washer/spacer that is the main cause of wear.

 

Whatever, the rocking can be stopped with loctite. Some posts away, Mr Marquez wrote that the fit of the second gear on the shaft splines is much better that that of the sprocket, which begs an obvious question, as Highmarker observed. In that sense it would anyway be better to always use a new sprocket, which is what I will be doing.

 

Which brings us to the actual procedure. I have a few questions about it :

 

 

1- Apply loctite only at the tip of the shaft so that when the sprocket is fitted it will smear the liquid down or spread it along the shaft before fitting the sprocket ?

 

2- Loctite in the grooves (blue) or on the splines (red) or both ?

 

3- Don't see the point of loctite on the thread (green), except to make it very hard to remove the sprocket later. Apart from the fact that only an oiled thread will give a correct torque reading (unless the loctite may act as a lubricant in this case).

 

4- How can only four drops be enough (from the red color everywhere it would seem the PO just splashed it on all over)?

 

5- Apply how, with a small painting brush ? Or should it be a thicker layer if it's supposed to fill in gaps ?

 

6- I still would let the loctite cure with the sprocket pulled back (refer to all that discussion). And, another reason for this would be that rather than filling in any voids, the loctite binds together whatever surfaces are tight against one another.

 

7- Not to make too fine a point, but If I am right that the main wear is at the sprocket-washer-spacer then it might be good to apply loctite there as well so any left over rocking gets carried over to the well oiled interfaces inside.

 

8- Finally, do I need to remove the bracket and the spacer or just let them be ?

Edited September 22, 2013 by michaelks