QA42 Snow Thrower Input Shaft/Chain Sprocket

[drhntrrmw]

I have read a few different posts on the snow throwers input shaft sliding back and forth in the needle bearings causing the chain sprocket to rub and wear the chain tensioner. I have the same issue and I am aware of the solution to shim it with washers but what exactly is suppose to keep the shaft from moving back and forth??

Thanks,
Rob

[ol'George]

A washer on either side of the sprocket keeps it centered in the aluminum yoke as you saw,
and the sprocket is retained to the shaft, keeping everything where it belongs.
Pretty simple setup and it works.

[Berwil]

The bigger issue is what is moving the sprocket side to side. When the thrower goes up and down, the drive shaft changes length by way of its slip joint. All too often a lack of maintenance (grease) causes the slip joint to bind/lock up and put side pressure on the sprocket. This causes it to eat into the yoke. Pull the slip joint apart, clean it, grease it, and keep it greased (be sure the u-joints are timed correctly when you put it back together). This will prevent the sprocket from chewing through the yoke and your new shims.

Bill

[drhntrrmw]

On mine the shaft is moving not the sprocket. The drive shaft is free and extending and shortening as it is supposed to.

[Yosemite Sam]

Originally Posted by drhntrrmw

On mine the shaft is moving not the sprocket. The drive shaft is free and extending and shortening as it is supposed to.

I may be missing something, but with the sprocket being pinned through the shaft. If the shaft is moving, the sprocket is also moving.

The sprocket on the auger being aligned with the sprocket in the tensioner is also very important.

Since there is no side to side adjustment on the tensioner the auger sprocket needs to be aligned with the tensioner sprocket or the auger sprocket will continually try to pull the tensioner sprocket off to one side.

The pin and the pin holes that attach the tensioner to the thrower housing also wear and are often times somewhat sloppy. The bolts need to be adjusted to hold the sprocket straight with the chain to keep from wearing the tehsioner, sprockets and chain.

[PeterJ]

What YosemiteSam said, "The bolts need to be adjusted to hold the sprocket straight with the chain to keep from wearing the tensioner, sprockets and chain." That is why there is an adjuster bolt on each side of the sprocket, to keep it straight.

PeterJ

[SLS327]

I shimmed the sprocket on a bb36 snowthrower too. There is only one tensioner bolt on these but it lined up with the side sprocket. This one has trouble on the lower end where the half-shaft connects to the gearbox, the setscrew keeps working loose and then the joint slips on the shaft to touch the bearing. But, anyway thought I'd post the shim picture.
DSC04466 (400x266).jpg

[ol'George]

Put a shim between the yoke & the needle bearing like you did on the side of the sprocket.
It will help reduce the wear on the end of the bearing.
IIRR the initial design of the housings were such as the captive needle bearing was shorter than the housing so axial thrust harmlessly was taken on the housing surface.
As hours operation built up the housing wore for various reasons.
If the end of the bearing that retains the needle rollers wears off, the needles can work out and that is not a good thing.
The engineer did put a cotter on the yoke end of the shaft so the yoke could not get off completely off with loosened set screws, preventing several problems I can think of.
it is a simple design that works & worked much longer than I'm sure they ever dreamed.

[Yosemite Sam]

If the inside of the drive shaft yoke, the transfer shaft, the transfer shaft key way, or the key is worn, I don't believe you will ever be able to keep it tight.

Replace all of the worn parts, clean the grease from the set screw hole and use a set screw with thread locker on it.

If all else fails, you might try a cup point square head set screw with thread locker.

I personally, refuse to use any kind of a shaft with a worn key way because it is nearly impossible to keep the mating part tight. If the parts won't say tight the repair bill will continue to grow.

Can't tell from your picture, is you drive shaft in time?

[SLS327]

you mean if the knuckles are lined up together forms like an H on the inner pieces and not offset 90 degrees? yes pretty sure they are in time.