ATC 70 oil pump drive sprocket

[Motorgidd]

Can anyone give me some advice on replacing the oil pump drive sprocket (cam chain side) on an 82 ATC 70? I took the left side case cover off and could see that the drive sprocket is almost smooth, teeth are pretty much gone.

From the little info I could find you have to remove the right side case as well and use a screw driver to thread out the oil pump drive shaft, once that is done you should be able to remove the left side sprocket?:wondering Is there anything I am missing and are there any other special tools required besides the flywheel puller? Thanks.
176327

[shortline10]

You got the right idea now its hands on time.

[Motorgidd]

You got the right idea now its hands on time.

Shortline10, Do you know what direction thread (left or right) the oil pump shaft is?

[shortline10]

righty tighty lefty loosey lol . normal threads .



Shortline10, Do you know what direction thread (left or right) the oil pump shaft is?

[Motorgidd]

righty tighty lefty loosey lol . normal threads .
Gotcha, thanks a lot!

[C.J]

While you got it down I would go ahead and replace that timing chain as well. It looks pretty well used

[Motorgidd]

^^^ Yeah I kind of thought the same thing… I got it all apart and the chain is definitely stretched... I’m going to replace the timing chain, cam chain roller and cam sprocket.

Is it possible to change out the cam chain roller without removing the cylinder head? Can you slide the cam roller up and out through the cam sprocket cover?

[shortline10]

If you can remove the center chain roller that bolts to the cylinder from the bottom it might be doable with out removing the head but I kinda don't thing theirs room . Never tried it .

[Motorgidd]

If you can remove the center chain roller that bolts to the cylinder from the bottom it might be doable with out removing the head but I kinda don't thing theirs room . Never tried it .

Thanks for the reply Shortline. I tried it last night and I was able to get it out through the bottom... New parts are on order and should be here later in the week. Thanks for the help.

[fastatc70]

Take a good look at the crank timing gear. Also loctite the new gear onto the oil pump drive.

[Motorgidd]

Take a good look at the crank timing gear. Also loctite the new gear onto the oil pump drive.

Thanks for the heads up Fastatc70. Crank timing gear looks ok...

I heard you can replace the crank timing gear without pulling the crank, using a puller of some sort. Anybody had luck with that? Just wondering incase I ever do have to replace one.

[shortline10]

Can use a baby dermal cut off wheel to remove the old timing crank sprocket or I use a bearing puller if theirs room for it .



Thanks for the heads up Fastatc70. Crank timing gear looks ok...

I heard you can replace the crank timing gear without pulling the crank, using a puller of some sort. Anybody had luck with that? Just wondering incase I ever do have to replace one.

[Motorgidd]

Can use a baby dermal cut off wheel to remove the old timing crank sprocket or I use a bearing puller if theirs room for it .

Gotcha, thanks. In your experience is it very hard to get the new one pressed on? I would assume you use a piece of pipe that fits over the crank and gently hammer (press) the new one on?

[shortline10]

I use a deep well socket to install a new sprocket , a little WD on the shaft and the new sprocket goes on with a few light taps . Just line a tooth perfectly up with the crank shaft keyway .



Gotcha, thanks. In your experience is it very hard to get the new one pressed on? I would assume you use a piece of pipe that fits over the crank and gently hammer (press) the new one on?

[fastatc70]

Is there a key way for the crank gear or do you have to mark the old gear and press the new gear back in in the same location?

[shortline10]

Line a tooth on the sprocket with the key way , sometimes even from the factory their a little off so I wouldn't go by the old one .


Is there a key way for the crank gear or do you have to mark the old gear and press the new gear back in in the same location?

[fastatc70]

Good to know. The last time I did a gear I put everything together with out the stator plate and aligned the cam and crank with its marks and then removed the flywheel and tap the gear on with heat. It was a pain in the neck.

[Motorgidd]

Line a tooth on the sprocket with the key way , sometimes even from the factory their a little off so I wouldn't go by the old one .

Your right, the 70 I am working on right now is slightly off the keyway. I ended up ordering a crank cam gear, clutch springs and new clutch disks too… I figured while I’m in there I will do just about everything I can.

[Motorgidd]

Just wanted to post a few pics of a puller that I found that works really good for removing the crank timing sprocket. I was starting to get a little frustrated as I could not find a puller small enough or strong enough to get the sprocket off. (I bent the crap out of a smaller, cheap puller... You get what you pay for!) It’s a power steering pulley puller and costs around $25-$30.