Author Topic: [0001] Changing Sprockets  (Read 5197 times)

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Offline Juvecu

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  • Bike: '11 Versys 650 & '05 TT-R250
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[0001] Changing Sprockets
« on: June 06, 2013, 22:14:21 »
Summary: a recount of experiences while changing sprockets.
The original post was made by Descolada and can be found here.


So, it's done at last.

Changing the front and rear sprockets without breaking the chain took longer than expected because I took  advantage of having the rear wheel out and took care of some rust.

This was the first time I had done something like this so I wanted to recount my experience in the hope that it might assist others should they try to do this on their own machine.

I began by collecting information from members' previous posts on the process, possible issues and most importantly discrepancies between the user manual torque settings and those recommend by the more experienced among you fine folks.

Removal of the front sprocket cover was fairly uneventful with the exception of finding that the lock washer was pretty much the  only thing stopping the front sprocket nut from undoing. There was evidence of Loctite, but it had long since lost it's potency and was all dried up.

As per a previous recommendation, from Strommer I think, I removed the clutch adjustment mechanism from its location over the front  sprocket, but left the cable connected and placed the assembly in a small plastic bag. I then cable tied the whole thing away from the area making doubly sure I was not kinking the clutch cable in the process.

I used the wooden plank method for securing the rear wheel, letting me remove the front sprocket nut without overstressing (or perhaps damaging) the gearbox.

Next I turned my attention to removing the rear wheel, but before starting on that I removed the chain guard and both rear pillion footrests.

As you may have seen, I mentioned in another post that removing the rear axle bolt turned out to be a little troublesome. Following a 25 minute struggle I eventually found that the bolt had seized due to rust and corrosion. I broke out my wire wheel and removed all signs of rust and corrosion from the axle bolt, spacers and adjuster plates.

With the axle bolt removed I was able to move the rear wheel forward enough to carefully detach the chain and wrap it up for protection before resting it over the near-side swingarm. I wanted to keep the chain on one piece having only just replaced it a week earlier.

With the rear wheel removed I supported the rear brake caliper, strung it up so as not to strain the brake pipe, and broke out the cleaning and degreasing kit. Once the clean up had been completed I got a clear idea of what needed to be done to repair some rust damage. That took a few days to complete and during that time I fitted the new front sprocket and replaced the rear sprocket. I replaced the front sprocket with a Renthal equivalent and the rear with a Sunstar.

I didn't torque the front sprocket at this stage, but used Loctite on the rear sprocket bolts before torquing them to 50Nm. I also spent some time washing and cleaning the rear brake caliper as well as checking the remaining rear brake pad depth. I found this was all much easier to do with the rear wheel removed.

Yesterday morning I got everything together and started the rebuild process. I should point out here that I am going to recall a couple of horrible 'newbie' mistakes I made during this process and anything I really struggled with. I hope that it will highlight the points during the rebuild process so that others will not make the same mistakes.

It should also provide you with a good laugh  lol lol lol

Here we go.

I was pretty much putting the rear wheel in by myself so gave this some thought before I removed the wheel. To help with wheel height and alignment I collected enough wood blocks to hold the wheel at the correct height for when the time came to put the wheel back in. This would save me from having to hold the wheel up as well as struggling to get the spacers and the rear brake caliper assembly in place. I greased everything up and started the process.

While feeding the axle bolt in I tried to hold both spacers in place while checking that the rear disc was properly aligned and inserted into the brake caliper. I took several attempts to get this right because, as I focused on the spacers, the caliper would slip out again. Eventually the axle bolt poked through the right-hand swingarm adjuster slot and I gave a rather loud sigh of relief.

Sitting back I inspected my work. The wheel spun freely, it moved easily within the adjusters and the rear brake assembly worked without binding. Great stuff!

It was at this point that I realised I had progressed to the state of 'complete idiot'. The chain was still sitting happily over the wrong side of the swingarm and was not running anywhere near the rear sprocket. I had rebuilt the entire assembly without including the chain.

At this point it would be best to recall Homer Simpson giving a loud and legendary "Doh!".

So, I got better acquainted with the process of stripping out and rebuilding the rear wheel, but this time I tried the novel approach of including the chain  :angry-tappingfoot: :angry-tappingfoot: :angry-tappingfoot:

With the rear wheel assembly in place I went back to the front sprocket in order to apply Loctite, torque down the sprocket nut and bend over the flat washer. I followed the advice of forum members and torqued the the nut to 115Nm, but it was then that I encountered what was (for me) the single most irritating part of the whole process: bending the lock washer back over.

This took ages, partly because the sprocket kept moving, I eventually got my better half to apply the rear brake to lock everything in place, but also because I couldn't get a chisel properly inserted between the new sprocket and the underside of the locking washer. Looking again at the old sprocket it may be that, as well as doing away with the rubber 'noise cancelling' ring, Renthal have also made  the top surface of the sprocket flatter. This makes it the devil's own job to get a chisel between these two surfaces without either chipping the new sprocket or creating a tear in the edge of the locking washer.

I think that Amazon are going to publish a compendium of the curses used during this part of the process.   

With this done (eventually), I moved to my next Homer Simpson moment.

I removed the clutch adjustment mechanism from it's protective bag and realised it was in a terrible condition so started to clean it up (remember that it was still attached to the clutch cable so movement was somewhat limited). You know what's coming next of course, there was a reason for keeping it safe, in a bag.

The mechanism fell apart.

OK, so I sort of expected this given previous warnings by forum members about this mechanism. I simply continued cleaning it up, greased the innards and put it back together before bolting it back onto the bike.

Finally I went through the whole chain adjustment process, reinstalled the chain guard and the pillion footrests. I left the front sprocket cover off for now, so I could start her up and see how she sounded with the chain rotating and the engine idling.

Started up first time (as always), pulled in the clutch, selected 1st and clunk, the bike stalled. Hmm, that hadn't happened before, so  I repeated the process. Clunk, and a stall. OK, something wasn't right and the most likely cause was the reassembled clutch adjustment  mechanism. I figured that, as I hadn't had to actually adjust anything in this area and the cable had remained bolted in place, it had to be the mechanism.

I did two things to try and figure out what I might have done wrong. Firstly, I reached for my mobile phone because I had photographed the front sprocket area as well as other 'likely screw up areas' before I lifted the first spanner. Next, I thought back to what I had learned about this mechanism when I was reassembling it.

The mechanism is a barrel with a coarse "cork screw" machined into it. The cork screw is embedded with ball bearings that make the motion of the centre shaft's travel smooth. At the end of the barrel (facing out towards the rider's foot) is a small adjuster bolt and a retaining nut. There is a metal tab protruding from this assembly. The barrel can basically go back in one of two ways, each position 180 degrees opposite to the other - I wondered if I had simply got this wrong.



This is where the sound of Homer Simpson going "Doh!" should be inserted... Again!

I checked my photo of this area and sure enough the tab was in the opposite position to where it had been before it fell apart. I unscrewed the barrel and reinserted so that the tab was now 180 degrees opposite to where it had been. Bolted the whole thing back onto the casing and tried the clutch again with the engine idling. Success, the engine didn't stall and gear selection was as it should be. Turned the engine off and  bolted the casing back in place.

Finally, I ran through the whole process in my head and made sure that I had tightened everything properly.

Time for a short road test.

When I replaced the chain recently I knew almost immediately that something wasn't right because a loud whine came from the front sprocket area. I posted this experience (along with pictures) and the good folks of this forum were quick to point out that the sprockets looked a little too worn. So I knew that the noise I had been hearing (after that chain replacement) would be pretty immediate if changing the sprockets had not cured the problem.

Jumped on my bike, rode away and... nothing. No horrible whining noise and the bike seemed smooth through the gears. I took a 20 minute ride on a mixture of country roads and a short dual carriageway. Everything was sweet and I was a very happy chappie.

So, this account has been somewhat 'wordier' than I had expected and I am sure that some of you will use it as a viable alternative to sedative drugs should you need some extra sleep. I wanted to record it for others who may be attempting the same task, or may be experiencing a similar problem.

Things I learnt?

* Always make sure to take pictures of your work area before you start ripping things apart.
* Always make sure you have the right tools to hand.
* Check the forums for threads relating to the process you are about to attempt.
* Check that the torque settings you may be about to use are considered 'sensible' and have not been corrected by experienced V-Strom owners.

Things I can do now that I couldn't before?

I can competently change the chain and both sprockets on my wee and will no longer flinch at the thought of removing the rear wheel on my bike.

My thanks to all who chipped in with advice that helped me complete this process.

Des
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