Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors


7116 modify front PTO snow thrower to mid PTO

Recommended Posts


Hello all,

I joined a year ago and haven't been back since. I finally have gotten around to getting my 42" AC snow thrower working with my 7116. It came with the front PTO hitch. I cut up the hitch, welded a new cross piece and hanger for the idler pulley on the hitch. That's fine. Now, the thrower has a pulley that runs the auger. It has a belt guard that almost completely encloses the pulley. My belt goes over the thrower pulley and is rubbing on the belt guard both top and bottom.

Has anybody rectified this problem with a similar modification? I'm having trouble removing the thrower pulley which needs to come off so I can remove the 3/4 belt guard and replace it with something that doesn't rub on the belt. As it is now, the auger looks to be spinning at about 5000 rpm.

I have a 500' private road I want to use the thrower on but it's gravel. I don't want to be firing rocks at windows with the force of a slug gun. I grade the road with my plow and a DIY drag behind grader and with some added gravel I keep it in good shape.

Is there a big problem with the way this thrower pulley lines up with the mid PTO hitch? I think I have the belt lined up well and it is the correct belt 147H. I will post some pics soon. I will also post a pic of the under hood decal for belt size numbers. I have never seen one online and from my extensive reading, a lot of people need it.

Thanks for any and all input. I will give full pics and instructions for others once I get this squared away. I'm a semi retired IT geek so I am anal retentive in instructions. At heart I build things which is part of the attraction of the tractor. It ran fine when I bought it for $400 with a mower deck and $200 for the 42" plow and snow thrower. I need to replace the regulator and alternator. I fixed the carburetor with the excellent help from Zippo. Fun to modify the AC plow to work with my 7116 too. Welding is a great skill and i'm just learning with my dads old "buzz box". My welds are described as "bugger welds" by a knowledgeable friend.






Share this post

Link to post
Share on other sites

Based on the pics above, it looks like you bought a "mixed" snow blower setup.  The hitch is for RBTs, that is a 2 pulley hitch without a built in clutch.  The snow blower head is for a FDT tractor.  It has the smaller diameter driven pulley (on the blower) and the driven pulley was mounted directly onto the engine shaft that protruded though the front grill of the tractor as shown in this pic of my FDT B-110:


In your setup, the auger is turning well above design since the driver pulley (cone clutch pulley ) is much bigger than stock driven pulley.

If you're anal when it comes to calculations, you should like this spreadsheet about various snow thrower speeds depending on configuration:


Your current configuration is running about 36% faster than the RBT, cone clutch design. (My calc's use pulley belt wrap data, IMO more accurate that outside diameter data since the belt wrap date takes into consideration where the belt rides in the pulley since not all pulley have the same shape "V") 

I believe the largest pulley you can fit onto the snow blower head shaft is 6-1/2"; the FDT snow blower head "tunnel" is smaller than an RBT tunnel.  Most people seem to like 6", a little faster than design, but not too fast.  The issue with using a smaller diameter pulley is the stock belt is too long since it was sized using a 7" driven pulley.  The 7100 series tractor's sliding PTO pulley adjustment make using a 6-1/2" driven OK (about a 3/4" shorter belt by calc), not sure how it handles a 6" diameter pulley (about 1-1/2" shorter belt).

As to getting the driven pulley off,  when heat and penetrating oil doesn't work,  I take of the chain guard and have tried to pull the shaft out from the driven pulley using a gear puller on the chain sprocket.  If this doesn't work because you're applying to much force with the puller, I then try to drive the shaft into the driven pulley.  I'll use a large diameter socket (say 1") that's bigger in diameter than the shaft, put the open end of the socket on the pulley hub centered on the shaft, stack wood blocks tight against the far side of the tunnel and the socket.  Then I'll drive the shaft into the socket to break it free.  Then use the puller again to move the driven pulley the other way.  You have to be careful about how far the shaft travels because the driven pulley key will interfere with movement.   

Good luck and let us know how you make out.

PS - I looks like you did a great job getting the single pulley hitch pulley lined up.  Here's a pic of the alignment of an OEM hitch:


With your "custom" single pulley hitch, it looks like you aligned the belt with the driven pulley hub facing inward, as was standard for two pulley hitches.   For the single pulley hitches, the OEM position of the hub is facing outward.  A common problem is using an OEM single pulley hitch with the driven pulley on "backwards" (inward facing) which makes for belt issues.  


  • Like 1

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now

  • Who's Online (See full list)

    • SmilinSam
    • RayS
    • bud119195
    • MARK (LI)
    • dince
    • PhanDad
    • fuzzo
    • Talntedmrgreen
    • beanman60
    • BLT
  • Today's Birthdays

      (52 years old)
  • Recent Status Updates

    • Paul M.Murphy

      Paul M.Murphy

      Hello glad I got on this site. I hope to upload a couple of photos of my Simplicity Broadmoor 
      Model 707 Tractor. I have replaced all the belts on it and installed a new ignition switch.
      Have a mower deck which was in poor shape , repaced a couple of bushings and welded the
      deck where there was some holes. The tractor and mower deck came from a friend and the 
      mower deck metal was getting pretty thin. Some new metal was put in it and we also undercoated the underside of the deck. This was done by my friend Greg Toulman.
      I have not put the mower deck on the tractor yet, waiting for Greg to come home and give me a hand. Can you please tell me if there is a manual for the mower deck and where I could get one.
      I would also like to get some moon wheel discs as well.
      I will try and down load some photos of the tractor when my wife shows me how to. 
      I really love driving this tractor and also how well it is made compare today's tractors, especially the flexible rear end and the rollers.
      Tell the next time 
      · 8 replies
    • jbrooks

      jbrooks  »  Talntedmrgreen

      folowing  this from a link at the downloads.  I just rescued an AC 920 with the lambodini diesel. I can' t download  yet .  Where did you find the PDF copy you posted. . I would like to figure out how to adjust the injection pump. 
      I assume it's a bosche, correct
      · 0 replies
  • Adverts