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reed12b

Front Sprocket Removal Questions

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I need/want to replace my chain and sprockets. On another site (ZX6R) I hang out there are a lot of comments about how hard it is to remove the nut on the front sprocket. Since I have never done this, couple of questions.  Do you guys recommend using an air impact wrench to remove the nut? if not, how can one person do it by themselves? I don't want to put the transmission in gear and hope to break it loose that way.  The model year of my bike is known for having a weak transmission and I don't want to put that much stress on it.  One approach was suggested to put a 2x4 between the wheel and swingarm, but is that a risk to the wheel?

 

Any recommendations or suggestions?

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With 2 ZX6Rs I am extremely familiar with the front sprocket nut that was installed by a gorilla at the factory. Although both of mine have had the nuts removed several times now (only the first time breaking them loose is the bear) I think my new DeWalt impact wrench might be able to remove those nuts initially. At the time I removed them I only had a nice Ingersol air impact and it wouldn't budge them. I ended up using a cargo strap around the rear wheel with a board attached to it, and a long breaker bar with a length of PVC over that and then a larger diameter piece of PVC about 6 feet long over that. I stood on the pegs and the brake as hard as I could along with the strap on the wheel I was able to break it loose using all my might on the 6 foot length of PVC. I would love the chance to try my DeWalt impact on that nut however. Just make sure it's in neutral so the impact doesn't hammer on the transmission.

 

P.S. How many miles are on that bike? You think the original chain and sprockets are on it? If not it shouldn't be as hard to remove it.

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Just did my chain and sprockets with Terry's help and he had an electric impact that did it in like 2 seconds. 

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Impacts definitely help but I know a lot of manufacturers suggest not using them. Apparently there are cases of damage done by the impact on the transmission. 

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Ive used my electric impact without an issue. Just make sure the trans is in neutral before pulling the trigger. I notice that with electric(Snap-on Lithium Ion 700+ ft lbs in reverse) the hammer blows are of a much higher frequency than the hammer blows in my Ingersoll air impacts. You dont even feel the impacts of the electric impact hammer.

 Besides the removal in neutral deal, to me the main thing is properly torquing the sprocket retaining nut during sprocket installation.

Again in neutral, I either place a 2" X 4" wood block through the rear wheel to lock it against the swingarm, or have someone stand on the rear brake to prevent rotation during torquing.

  Years ago one of our own who shall remain nameless didnt get the nut torqued. The nut decided it wanted out, and it appeared upon its exit it damaged the transmission's countershaft threads. By using a metric thread file I was able to clean remnants of the nut from the shaft  threads, the shaft threads being harder than the nut. New nut and tangwasher, all was good.

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Thanks for the replys guys, good info to know.  The bike has about 18,000 miles, the last 3 years mostly track only duty. Going to try the 1 down in front and 2 up in rear to see how I like that.  Per the ZX6R guys that is the sweet setup for better acceleration and not making it too prone to do wheelies.  I put the 2 up sprocket on it and every gear change it was popping up the front.  Want to calm down that behavior. 

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What do you have against wheelies? :) If 0/+2 is too wheelie prone for you then -1/+2 will be even worse. That would be the equivalent of about 0/+4.

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5 hours ago, crash said:

What do you have against wheelies? :) If 0/+2 is too wheelie prone for you then -1/+2 will be even worse. That would be the equivalent of about 0/+5.5.

I guess I am confused, I thought it would be different.  I am going to the Gearing Comander site, (I think that is the name, I found it last year) and look at what the gear ratios will be with the various combinations.  

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Adding teeth to the rear will reduce your top speed. Removing teeth from the front will also reduce your top speed (and reduce the top speed of each individual gear). Say you have a 43 tooth sprocket on the rear and you add 2 teeth. You're changing the ratio by around .04% (2/45). By taking a tooth off the front you will be changing the ratio by around .07%. (1/15). If you do both of those things you will be changing the ratio by around .11%. I ran -1/+2 on my ZX6Rs which ends up with 15 teeth on the front and 45 on the rear, or 1:3 final drive ratio. The speedometer was around 10% high with stock gearing. With -1/+2 they are about 20% off. If the speedometer reads 100 I am really only going 80 (verified by GPS). Now, there are reasons for running a specific gear ratio and I sometimes changed gear ratios based on tracks I run but I found -1/+2 to work fairly well at all of them. I would change if I was between gears at a critical point which would cause me to lose time. Yes, when you gear it down like that the front will come up easier in the lower gears, but you control that twisty thing on the right so it really shouldn't be a big deal. Now, with -1/+2 by bike would top out at around 152MPH on the GPS (would have been more like 180 on the speedometer which is wrong) if I recall, and I would never reach the limiter in 6th in high gear on any of the tracks we run so you should be fine running that combo.

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QUOTE - "Yes, when you gear it down like that the front will come up easier in the lower gears, but you control that thing on the twisty thing on the right so it really shouldn't be a big deal."

 

LOL that is my issue I need to deal with! Never really been much of a fan of wheelies after watching too many videos of guys over rotating their bike and crashing.

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I wouldn't worry about it. You're not going to flip your bike over unless you are intentionally trying to wheelie and don't know what you are doing.

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Oh, and with a -1/+2 change I would expect the front to come up around 10% easier than with stock gears. Not that significant. The main reasons I can think of for changing gear ratios is:

 

1) You are topping out in 6th down the straight requiring you to increase the ratio

2) You never get out of 5th on the straights and by reducing the ratio you can keep it in the power for more amount of the track which ultimately reduces your lap times

3) You are between shifts at bad times (transitions from gas on to brake) and you can reduce those occurrences by increasing or decreasing your final drive ratio.

 

Now, at our level playing with final drive ratio (front and rear sprockets) is about all you have to do. At WSB and MotoGP they might change the ratio of individual gears, which require gear changes in the transmission itself. They would do this for each track to reduce those cases of being between gears at bad times.

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3 hours ago, crash said:

I wouldn't worry about it. You're not going to flip your bike over unless you are intentionally trying to wheelie and don't know what you are doing.

 

I never claimed to know what I was doing! I prove that all the time.

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Thanks Dave, that is more the final ratio I was shooting to obtain. I just mixed up the numbers, probably too many adult beverages one night.  

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Interesting his stock front is a 15. Pretty sure from 07 on up it's 16/43 stock. I agree that even though 0/+4 and -1/+2 are similar ratio I would rather not drop below 15 on the front.

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I just spotted this video and had to share it! This is exactly what I worry about if I do something stupid.  

 

 

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At least he was dressed for the occasion.....

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2 hours ago, reed12b said:

I just spotted this video and had to share it! This is exactly what I worry about if I do something stupid.  

 

 

 

So, by changing your sprocket you're afraid you'll have this uncontrollable urge to put your feet on the rear pegs and yank it up into a standup wheelie, all in nothing more than a t-shirt? :)

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LOL, Maybe a bit more than a teeshirt. 

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I think I'm going to go back to the stock gearing to keep revs down and increase top speed in the lower gears.  About 5%.  Has the added bonus of reducing speedo error to about 10%; easier to figure actual speed = X * .9 vs X *.85 ...

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I have a speedo tuner on my 600. Don't need it on the zx10 because speed is measured from the speed sensors on the wheels on those so changing final drive ratio doesn't affect speedometer error. On my 600 without the speedo tuner the speedo is off almost 10% with stock setup and with -1/+2 it ends up being almost 20% off. My zx10s are only off by a couple of mph when running at around 75. I also run a GPS on my bike and actually use the speedometer on it for my speed. That's the most accurate.

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previous owner went -1 front on my speed triple. 

I rode it like that quite a while without knowing. When Terry and I figured it out, it went back to stock. I'm not 100% sure the term but there's a chain roller pad on the swingarm. Going -1 changed the angle coming off the front sprocket and put significantly more wear on that part. And I liked how stock gearing felt. It seemed like I was riding the torque wave longer which I much preferred. The -1 just felt snappier when I got on it, but that wasn't necessarily a good thing.

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Yep, that's one of the reasons it's better to go up on the rear rather than down on the front if you can. Down on the front will also cause the front sprocket to wear a little faster and there are claims that the sharper angle is harder on the chain. I'm not sure if any loss in power transfer.

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