sprocket replacement

[twangin4u]

Someone told me I should replaced sprockets when I replace chain. Is that always the case? Are their measurements or tolerances that can be measured to see if I should replace mine when I install new chain?

[mz_rider]

Someone told me I should replaced sprockets when I replace chain. Is that always the case? Are their measurements or tolerances that can be measured to see if I should replace mine when I install new chain?

In my experience you'll need to replace the gearbox sprocket but not always the rear sprocket. If the sprocket has become pointed or hooked it should be replaced. Sprockets are cheap compared to chains so it's wise to fit new ones. Here's an example of a badly worn FJ gearbox sprocket



Stuart

[roverfj1200]

New chain new sprockets... Thats the way I play the game.

[Mark Olson]

The current methodology is replace all at once or you will cut chain life in half.

Something else interesting from a previous thread suggested keeping an odd number of teeth with an even number linked chain. So as long as one of the sprockets is an odd number the chain will wear evenly. Has to do with the link touching the same spot on the gears over and over .
Not sure if this is voodoo but factory was a 17 tooth on fj's with a 110 link chain. The early fj's had a 41 sprocket and the 89 and later had a 40. A lot of guys have gone to a 18 tooth for mileage but haven't reported early chain failure.

So like I said , could just be voodoo science but now you have all the latest garblegook .

[Bones]

Actually Mark,  the later models came out with a 39 tooth rear sprocket. I remember reading it in a magazine somewhere, but not sure if it only applied to european models or not. Mine had one on it when I got it and was told it was standard gearing. Trivial I know, but I thought I'd put it out there.

                                 

[ribbert]

The current methodology is replace all at once or you will cut chain life in half.

Something else interesting from a previous thread suggested keeping an odd number of teeth with an even number linked chain. So as long as one of the sprockets is an odd number the chain will wear evenly. Has to do with the link touching the same spot on the gears over and over .
Not sure if this is voodoo but factory was a 17 tooth on fj's with a 110 link chain. The early fj's had a 41 sprocket and the 89 and later had a 40. A lot of guys have gone to a 18 tooth for mileage but haven't reported early chain failure.

So like I said , could just be voodoo science but now you have all the latest garblegook .

Mark is correct, don't be a cheap bastard, it will cost you more in the end. The golden rule is to always replace all three components at once and I don't think you'll find any one here that would argue with that, even with me posting it.

On the matter of odds & evens, while fearful of starting a discussion on the subject, old habits die hard and I have always adhered to that voodoo science for just that reason. My current gearing is 18/41.

However, modern chains make the advantages of doing so far less relevant and I wouldn't be running out and changing them nor sweat it if I had to go evens.

Noel

[Arnie]

Yeah, I'm running 18/42 atm.  Doesn't seem to be a problem.
I've always tried to run 'odd' combination sprockets but I couldn't find a 41 (5 bolt Suz) at the last change.  I'll have to see if I get my 'normal' 50-60K km life from this in another 25-35K kms.

And, to confirm others report.... My FJ had a 17/39 OEM set on when I bought it.

[Mark Olson]

It would seem I  was mistaken and the 91-93 fj's had the 39 tooth sprocket ... Had to check the files section.