PSA Triumph front sprocket

[Yakoo752]

We have 2 Scramblers, 3 Bonnevilles, 1 tiger 800, 1 tiger 1050, and an Explorer. The explorer has 600 miles it was the only one not loose. Me late ranged from ok 12000 to 32000.
It is a flaw with the washer it is NOT a precision fit and begins working from day one.

I really don't know - All I speak with is from personal experience on the matter and the conversations I had with Triumph regarding the replacement of my countershaft...

I can tell you from the video you posted, the washer is bent incorrectly. You should bend completely parallel to the angle of the nut's edge (whatever you want to call the side face of the nut - simply bending it in the middle as shown, allows it to rock)

After my conversation with Triumph, I now replace every time I replace the sprocket AND I bend BOTH opposites of the bolt face (ie north an south or east and west but 2 opposing sides of the nut)

 

[Tri750]

No matter if it's a Triumph or a Kawasaki or whatever, that tab washer is meant to be replaced each time it's removed. The BMW's use a type of locknut as well that is replaced each time the dreaded dealer removes it.
I used to stock half a dozen of each.
When installed, as previously mentioned, the tab washer is to be bent over two opposing flats fully across and "pinched" tight using Channel locks or peened over using a small drift and hammer. The one in the video is an accident waiting to happen.
If it's an epidemic or a known problem it's the owners not being aware of the need of replacement or the reluctance to spend the money.
If a dealer doesn't have the tab washer, maybe it's a lame dealer or they are just out. Sales history is tracked on the computer and will answer that.
I keep a couple in my tool box for the old Z1.

 

[ThumperX]

Then what is happening is that these tab washers are being installed incorrectly at the factory.
None of our bikes have had the chain or sprockets replaced all are dealer serviced.

 

[ilikefood]

No matter if it's a Triumph or a Kawasaki or whatever, that tab washer is meant to be replaced each time it's removed. The BMW's use a type of locknut as well that is replaced each time the dreaded dealer removes it.
I used to stock half a dozen of each.
When installed, as previously mentioned, the tab washer is to be bent over two opposing flats fully across and "pinched" tight using Channel locks or peened over using a small drift and hammer. The one in the video is an accident waiting to happen.
If it's an epidemic or a known problem it's the owners not being aware of the need of replacement or the reluctance to spend the money.
If a dealer doesn't have the tab washer, maybe it's a lame dealer or they are just out. Sales history is tracked on the computer and will answer that.
I keep a couple in my tool box for the old Z1.

This problem isn't caused by the washer being bent improperly. As you can see in the video, the nut didn't rotate at all. It's not the nut rotating that's causing it to become loose, it's a minute amount of play between the countershaft splines and the sprocket, which eventually shortens the bushing under the sprocket. No matter how well you bend the lock washer, that won't eliminate the play, because the washer itself has more play than the sprocket. The DRZ has exactly the same problem, and the solution is loctite on the countershaft splines.

 

[Yakoo752]

This problem isn't caused by the washer being bent improperly. As you can see in the video, the nut didn't rotate at all.

what? Yes it is, in the video OP posted, you can clearly tell the nut is moving on the countershaft - the locking washer is designed to prevent the nut from spinning on the countershaft. If there is no opportunity to spin because it's being held captive, it doesn't spin.

it doesn't have to rotate xxx*, it just has to move

it just has to remove sufficient pressure off the washer to allow the washer to walk off the splines - it's not much of a lip

it also indicates that installation security is not as much torque setting but washer bending - the above video, the washer is installed WRONG

 

[Yakoo752]

None of our bikes have had the chain or sprockets replaced all are dealer serviced.

mileage?

when you bought them BRAND NEW from the dealer - who installed the front sprocket, washer, and countershaft nut?



FWIW - I'm not saying it was installed correctly at the factory, I'm saying the blame may be on a dealer and not the manufacturer.

 

[ThumperX]

The bikes range in miles from 8000 to 17,000 the Scrambler that lost the chain had around 15k.
The video posted is not our Scrambler it is one of many posted on you tube.

It is my understanding that the splined washer is generic to all the bikes and is not a precision fit to the shaft splines. Overtime it works allowing the nut to eventually back off.

Regardless of whether the washer appears properly installed or not this is a real issue and not something that just happens after a chain replacement.

This thread is posted in hopes that every single member of this board who owns a Triumph checks their countershaft sprocket before their next ride.

 

[corndog67]

Loctite could work as a fix, but on the shaft splines, not on the threads. It looks like exactly the same problem that DRZs have (I posted about this a little earlier).

Loctite is made to hold screw threads together, not fill gaps in loose splines. Wrong application .

A quick search of triumphrat found this: http://www.triumphrat.net/twins-technical-talk/220557-front-sprocket-nut-was-loose.html

Wonder if its simply insufficient torque at the factory or sprocket & shaft metal annealing with repeated heating & cooling cycles, making the sprocket slide in on the shaft.

Annealing high carbon steel is between 1400 and 1500 degrees F. Low carbon is 1650 degrees F. How hot do you think your countershaft and sprockets get? Hint: your orings and seals would melt before 300 degrees.

If you care to check, different manufacturers of sprockets have differing amounts of clearance on the countershaft . I've found my factory KTM sprockets are tighter than any of the aftermarket ones I've tried.

I think part of the solution would be to check the countershaft nut every time you change your oil, replace the washer and possibly the nut every time you change your sprockets. If you've got slop in the splines, not much you can do, besides changing the countershaft itself. I'd sell the bike before I did that. You aren't going to be able to fix loose splines.

 

[ThumperX]

Loctite is made to hold screw threads together, not fill gaps in loose splines. Wrong application .



Annealing high carbon steel is between 1400 and 1500 degrees F. Low carbon is 1650 degrees F. How hot do you think your countershaft and sprockets get? Hint: your orings and seals would melt before 300 degrees.

If you care to check, different manufacturers of sprockets have differing amounts of clearance on the countershaft . I've found my factory KTM sprockets are tighter than any of the aftermarket ones I've tried.

I think part of the solution would be to check the countershaft nut every time you change your oil, replace the washer and possibly the nut every time you change your sprockets. If you've got slop in the splines, not much you can do, besides changing the countershaft itself. I'd sell the bike before I did that. You aren't going to be able to fix loose splines.

This!!!
This is the solution!

 

[ilikefood]

what? Yes it is, in the video OP posted, you can clearly tell the nut is moving on the countershaft - the locking washer is designed to prevent the nut from spinning on the countershaft. If there is no opportunity to spin because it's being held captive, it doesn't spin.

it doesn't have to rotate xxx*, it just has to move

it just has to remove sufficient pressure off the washer to allow the washer to walk off the splines - it's not much of a lip

it also indicates that installation security is not as much torque setting but washer bending - the above video, the washer is installed WRONG

This is a bit long and detailed, but I think it explains exactly what's happening. This was investigated in painful detail by DRZ owners who have been dealing with exactly the same problem (and found a solution):

In the video, the nut moves just a tiny bit and then the washer stops it. The washer is still on the splines and the nut doesn't rotate nearly enough to loosen itself. This problem is NOT caused by the nut rotating on the countershaft threads and loosening itself. The nut is still in the same position it was when it was tightened, and the washer is still doing the job it's supposed to do - it stops the nut from rotating. This may seem counter-intuitive - how can a nut become loose if it doesn't rotate on the threads? Here is explanation of how this happens:

The problem starts because there is a tiny amount of play between the sprocket and the countershaft splines. The chain puts huge forces on the sprocket, and because the tolerances aren't tight enough, the sprocket can move a tiny bit back on acceleration and forward on deceleration. And the sprocket is being pushed into the bushing behind it with a lot of force by the torqued nut, so you have metal grinding against metal under a lot of pressure. Eventually the bushing behind the sprocket wears away (or thickens and mushrooms) enough that the sprocket becomes loose. The nut still hasn't moved at all, but the length of the pieces the nut is holding together has become shorter. And torquing the nut tighter than spec actually makes the problem worse, because there is more force grinding the sprocket into the bushing behind it.

Again, the same problem has been affecting DRZs for a long time, and the one reliable solution to this is to put Loctite on the countershaft splines (NOT on the threads). This appears to be enough to eliminate the play between the sprocket and the countershaft splines, and the nut doesn't get loose.

 

[ilikefood]

Loctite is made to hold screw threads together, not fill gaps in loose splines. Wrong application.

Yes, it's a weird application of Loctite, but as I've been saying, the exact same problem has been affecting DRZs for many years, and DRZ owners on Thumpertalk have investigated it in painful detail for a long time. Putting Loctite on the splines works, and there are thousands and thousands of DRZs that are using this method to keep their countershaft sprockets from loosening. Just Google "drz sprocket loctite fix".

 

[corndog67]

Does the sprocket trap the bushing behind it? Does the bushing rotate with the shaft or is it stationary? If the bushing rotates, there is no reason for it to grind on the thrust faces, everything should rotate as a unit. Have you tried different brand sprockets? As I mentioned, the KTM Factory sprocket fit noticeably tighter than the aftermarket, same with the Ducati I had. A loose spline is only going to get worse, I've seen some XR600R that were unbelievably loose.

 

[Bay Arean]

I don't have a socket or fixed wrench that size. Can I meaningfully tighten this thing with whatever adjustable wrenches etc? You guys are freakin' me out....

 

[RightCoastBias]

I don't have a socket or fixed wrench that size. Can I meaningfully tighten this thing with whatever adjustable wrenches etc? You guys are freakin' me out....

Just go buy the socket, it's worth it's weight in gold when you actually need it.

Using an adjustable wrench will just result in busted knuckles.

 

[Bay Arean]

Okey dokley.

 

[ThumperX]

Let us know if the mitos smug or loose.

 

[corndog67]

I don't have a socket or fixed wrench that size. Can I meaningfully tighten this thing with whatever adjustable wrenches etc? You guys are freakin' me out....

I bought a socket from Harbor Freight, big ole black impact socket, I use a new washer everytime it comes off, I use red loctite, even though they suggest 242 blue, I have a Snap-on impact, I clean the shit out of everything with rubbing alcohol, to reove all grease and whatnot, I zing the sprocket off before I remove the chain, so I can stand on the rear brake (I knew there was a reason for the rear brake, besides turning around in the dirt) and have someone zing it off, and I do the opposite when putting it back together, put the chain on, stand on the brake, and hammer that sucker home. I know I should use a torque wrench, but. I dont have a big one. I havent had any issues yet. But I dont hammer it until I see the threads start peeling out of the nut, I watch when things start cinching up, and just do it a bit until, I'm satisfied that things are where I want them to be.

Oh yeah, one time, the thickness of an aftermarket sprocket was about .060 thinner than the stock Ducati one. Ducatis have a little keeper chinga that goes over the spline, then turn about 5 or 10 degrees in a groove, and is held to the sprocket with 2 6mm screws. The sprocket floats on the shaft a bit, but I didnt like that much slop in there, so I bought a new stock one ($75, vs $20 for the aftermarket). Another thing to keep an eye on. Another aftermarket sprocket I bought had about .060 of radial runout (up and down on the rear). Sent that one back also.

 

[ilikefood]

Does the sprocket trap the bushing behind it? Does the bushing rotate with the shaft or is it stationary? If the bushing rotates, there is no reason for it to grind on the thrust faces, everything should rotate as a unit.

It's all theoretically supposed to rotate as a unit, but because the sprocket can move a tiny amount on the splines, it doesn't rotate as a unit. When you accelerate, the countershaft is driven by the engine, but the sprocket is held back by the chain, so the sprocket rotates back slightly (because of the small amount of play between the sprocket and the splines). Then when you close the throttle, the chain drives the sprocket forward but the countershaft resists, so the sprocket is pushed forward. That's where the grinding comes from.

You guys are trying to re-invent the wheel. It's a well-known problem on DRZs, it's been figured out and solved years ago.

 

[Yakoo752]

I just replaced mine a few months back - something in this conversation wasn't sitting well with me

They've updated, at least the one I've got which I ordered from the EU, to a Belleville washer which can't be folded over.

I'll snap a picture when I get a second.

 

[Yakoo752]