snowthrower sprocket hits sprocket mounting bracket

jfinney · #1 02-06-2010, 07:35 AM

I had asked a question in another post about how to get the shaft out of the sprocket and got an answer...thank you very much. Now, I want to know why when my snowthrower is running the transfer shaft and sprocket move over to the left so that they rub against the sprocket mounting bracket? I have never used this thrower before and was all ready to try it out today (supposed to get about 6 inches total, with more on the way Tuesday) when I saw that the PO apparently ran it this way for a while because part of the sprocket mounting bracket is worn away. Could I put SAE washers on the outside of the sprocket to keep it from going over and hitting the bracket, or is there something else that I need to look at to fix the problem? Thanks for the help.
Jason

ol'George · #2 02-06-2010, 08:12 AM

Yes a washer wll take up the side thrust. Brass or Bronze is better. when you adjust the chain tension, tighten the outside bolt a smidgeon tighter,
(the side that the sprocket is on/digging into.
that will help angle the bracket to counteract this.
you don't want to go overboard here, just a bit tighter, and grease the zerks.

jfinney · #3 02-06-2010, 08:26 AM

Thanks 'Ol George.
Jason

tukn20s · #4 02-06-2010, 03:33 PM

Jason, how big of a project was it taking everything apart? I was planning on waiting until spring to do mine because I don't want to be out of commission for too long. However, if its not too time consuming, I would like to take care of it before it causes too much damage.

George, what is the process for tightening the chain?

Matt G. · #5 02-06-2010, 04:37 PM

Quote:

Originally Posted by tukn20s

what is the process for tightening the chain?

There's two bolts on the lower part of the cast aluminum "H" shaped piece. Loosen the jam nuts and tighten the bolts such that there's about 1/4" to 1/2" (check the manual for exact numbers) of slack. I'm pretty sure either the tractor's service manual covers this...

jfinney · #6 02-06-2010, 05:23 PM

Tukn20s,
It wasn't too bad of a job. I was going to just put some washers in to shim it, but I have a QA36 I wasn't using, so I took it apart and swapped out the best parts of both to make a nice one. It might take an hour or so unless anything is rusted. Tried it out and everything works well now. Cleaned up alongside of the road in front of my house and it worked well. Good luck with yours. Thanks for the help guys.
Jason

tukn20s · #7 02-10-2010, 07:15 PM

Sorry to steal your thread again, but it was already started so I figured why not use it :biggrin2.gif:

So as I was in the process of taking the sprocket off, I realized that all the set screws (both ends) were loose. So I adjusted the shaft/sprocket and tightend the set screws and everything seems fine. I did the driveway today and there was no sign of the chain hitting anymore.

My question is, would the loose set screws be the cause of the problem or is there still something wrong? I still have intentions of taking the entire unit apart and replacing any worn parts. When I do this, I was planning on putting the brass washers in there anyways to avoid future problems. Will this be ok even if it is working as is?

ol'George · #8 02-10-2010, 08:50 PM

I would think it is cheap insurance.
It will not hurt anything to put in a thrust washer, and the bracket is no longer avail.
When you are working on it, replace the keys as it will tighten up things as well as help to keep the keyways from wallowing out in the bores/shafts.
If the set screw heads are wallowed, replace then also, as they need to be good & tight.
If the drive shaft slides off the sprocket shaft, or gear box while operating, it will make you a very bad day, and the noise will make you have to change your shorts

-----and empty your wallet looking for used parts.

tukn20s · #9 02-11-2010, 09:32 PM

Well when the belt broke and wedged between the pulley and motor that scared the xxxx out of me......so I can't imagine the driveshaft coming loose

One more question and I think I will be done for now! On the front plate of the mounting bracket (that the gearbox bolts to), the l slotted adjustment holes are much wider than the bolt. Mine takes a 3/8 carriage bolt and the slot is nearly twice as wide. So if I use a standard 3/8 washer, it crushes them and bends the bolts. Also, when adjusting the belt, this allows the bracket to slide crooked. Are the slots supposed to be that wide? I was thinking of either making a bushing or a really thick washer that won't bend.

ol'George · #10 02-11-2010, 10:11 PM

Quote:

Originally Posted by tukn20s

Well when the belt broke and wedged between the pulley and motor that scared the xxxx out of me......so I can't imagine the driveshaft coming loose

One more question and I think I will be done for now! On the front plate of the mounting bracket (that the gearbox bolts to), the l slotted adjustment holes are much wider than the bolt. Mine takes a 3/8 carriage bolt and the slot is nearly twice as wide. So if I use a standard 3/8 washer, it crushes them and bends the bolts. Also, when adjusting the belt, this allows the bracket to slide crooked. Are the slots supposed to be that wide? I was thinking of either making a bushing or a really thick washer that won't bend.

There are spacers (4) on the Carriage bolts so the plate can slide with the bolts tightened (like if they were shoulder bolts) that way it is a quick attachment/adjustment.
You can adjust/change/install the belt without loosening the carriage bolts.
Just turn the adjustment wing nut.(belt adjusting bolt they call it)
Sounds like yours are missing,--- probably make them up using small piece of pipe, should be 3/8" inside and fit the slots smugly on the O.D and just a tad longer than the plate is thick- 1/4" long.
on cubcadetparts it is #8-- IH 490125-R1
but the Dimensions Are not that critical.

The spacers for the Qa blower gear box mounting plate are:
Outside: .560
Inside : .390
Length .250
a 1/4" pipe nipple comes close to those dimensions, but is on the smallish side.