1976 C120 drive belt tension

[76-C120 20]

Hello all.  I have a 1976 C120 that I just replaced the drive belt on.  The roll pin through the connecting rod from the clutch to the pully broke, so the the belt was pretty well smoked as a result. Now I have the new belt (part number 7473) in and replaced the roll pin and DAAAAAAMN... there's a lot less throw in the clutch and the difference between disengaged and engaged is about a nanometer.  With that said, I expected it to be tighter, but I'm not sure I can deal with this and not end up with whiplash.  Is there some step I missed? Any way to adjust this so it allows the belt to slip more before snapping my neck and picking the front wheels up off the ground?

[Maxwell-8 4,277]

mhh Bit the same problem as my 1974 raider 10.

It is also on or off, but I do experience a small delay when the clutch is depressed.

[76-C120 20]

I can get it to slip and not throw my head off, but like I said, the difference between engaged and not is very short.

[rmaynard 15,518]

Considering that you are using the correct OEM belt. I don't know what to tell you. Clean, shiny pulleys might help. The "belt" clutch to me is the worst design amongst a whole lot of good designs by the engineers at Wheel Horse. I have a '77 B-100 which is exactly the same set-up as yours. It does the same thing. My 857, Commando 8, and 701 also do the same. The 701 is the worst. My 12 year old grandson has learned to feather the clutch, but sometimes it gets away from him and the front end goes off the ground. So many of the older Wheel Horse's ads feature housewives riding and waving like there's nothing to it. But my wife won't get on a manual transmission horse, and she can drive anything. 

[Maxwell-8 4,277]

38 minutes ago, 76-C120 said:

I can get it to slip and not throw my head off, but like I said, the difference between engaged and not is very short.

Maybe let the belt slip on purpose, cleaning the pulleys and working in the belt. 

[daveoman1966 3,752]

2 comments:  1) The BELT GUARD must be on.  2) These are NOT syncromesh gearboxes...every start must be from DEAD STOP.  

 

[Maxwell-8 4,277]

42 minutes ago, daveoman1966 said:

2 comments:  1) The BELT GUARD must be on.  2) These are NOT syncromesh gearboxes...every start must be from DEAD STOP.  

 

or you end up with no gears and lots of metal flakes in the tranny oil.

[wallfish 17,014]

Is that an actual OEM belt or a "the same" equivalent from another supplier? A rubber sided belt will certainly grab quick as $%!* so it should be a cloth covered belt.

Understanding the clutching action is actually the belt slipping on the engine pulley helps to narrow down a solution to try and get it to slip more during pedal movement. A new belt tends to have some memory in it from the packaging too so wearing it in as suggested like letting it slip and driving up to an immovable object like a wall or tree and running plenty of tension on it could help. Just be careful and ready!!!! If there are belt guides around the engine pulley like little rods around the belt, maybe they are holding the belt  too tight into the pulley groove. They should be about 1/8 inch off the belt when it it's tight. Same for the belt guard if there's a tab on the bottom it can be adjusted. If the pulleys are rusted or especially if they're painted it can be either slip or grab just like you have. no in between. The idea is to get that belt to slip on the engine drive pulley a little more which would solve the quick starts.  Easier said than done but take a good look at why it's not slipping as the belt should only grab when it's somewhat forced into the groove. 

Have any of the pulleys changed? Even a larger idler pulley can change the clutching time. Does the pedal have a lot of swing to it or is it like it's already half pushed down?

Post some pictures with belt guard off

[Snoopy11 5,714]

12 minutes ago, wallfish said:

Is that an actual OEM belt or a "the same" equivalent from another supplier?

Yeah, my thoughts exactly. What you could do is go an extra inch on the belt size, which would give you more play with the clutch. Very important to note where you bought the belt. 

 

My thoughts.. buy original from Lowell... 

 

Don

[Darb1964 1,044]

This is not a fix but I always get my eight speeds moving at low throttle, then throttle up after moving. I can't control my left leg very well so that works for me.

[76-C120 20]

2 hours ago, wallfish said:

Thanks all for the thoughts... I'll grab some pics in the morning.  The belt is a genuine Wheel Horse.  Nothing has been repainted, and it's 99% original 1976.  It's been garage/shed kept since new, so rust it's really bad.  The belt guard is in place, wouldn't dream of running without it.  I expected it to have more bite, but dang, not like that.  Guess the old one was really stretched.

 

[gwest_ca-(File Mod) 11,050]

The pedal return spring may be weak from use/age. A stronger one gives you more control.

A drop of oil on the pivots will also help.

[kpinnc 12,111]

Is the little tab over the idler pulley bent like the one in the pic below? That tab should grip the belt as the clutch is depressed, effectively stopping it. 

 

You should have to loosen or remove the idler pulley to change the belt if the tab is in the correct position. The one in the picture is actually wrong. It's been bent so many times be the previous owner that I may never get it right again.

[wallfish 17,014]

8 hours ago, 76-C120 said:

  I expected it to have more bite, but dang, not like that.

Yeah, not good as that condition can be dangerous.  Probably awesome if you're a 15 year old only doing wheelies!

 

15 hours ago, 76-C120 said:

there's a lot less throw in the clutch

That's an indication of a shorter belt. If the pedal is now in a position like it's pushed 1/2 way down compared to what it was before then something changed. Normal condition would position the idler pulley up near the top of the belt guard with the pedal released. Full motion of the idler pulley could be limited causing the issue. Pics of the roll pin fix might help too.

[76-C120 20]

Here are the pics... 

 

For the roll pin fix, I was able to get the broken one out and bought a new one.  I also included a pic of the belt cover, all the tabs are in place.  I had to adjust the clutch linkage so it would engage the safety switch.  For the idler pulley, yes, I have to remove it to get the belt off, so that tab should be in the correct position.

[daveoman1966 3,752]

Another cracked hoodstand...have seen a bunch of these over the years.  

[76-C120 20]

19 minutes ago, daveoman1966 said:

Another cracked hoodstand...have seen a bunch of these over the years.  

I have a welder.  I had to fix the belt cover.  The tab that mounts to the engine was broken when I took it apart.

[Snoopy11 5,714]

Hey, @76-C120... one question for you. So... when you installed the belt, did you take it out for a run?

 

I would say, if you haven't, take it out for a good run, get the belt nice and hot... and see if it doesn't stretch out by itself. It could be a matter of the belt getting seated into the pulleys better.

 

Don

[Snoopy11 5,714]

And when I say ...out for a run... I mean an extended run... 30 minutes or so... in high gear... altering engine idles sporadically. 

 

Don

[Snoopy11 5,714]

2 hours ago, 76-C120 said:

For the idler pulley, yes, I have to remove it to get the belt off, so that tab should be in the correct position.

That is pretty odd. You should not have to take the idler pulley off to get the belt off. 

 

You should just be able to push the clutch in, and reach down and pull the belt off the idler pulley. Obviously, if the belt is not the right size (i.e. not stretched out enough)... getting the belt on/off will be a lot harder. BUT, you still shouldn't have to take that pulley off... hmm... 

 

Don

[pfrederi 17,741]

4 minutes ago, Snoopy11 said:

That is pretty odd. You should not have to take the idler pulley off to get the belt off. 

 

You should just be able to push the clutch in, and reach down and pull the belt off the idler pulley. Obviously, if the belt is not the right size (i.e. not stretched out enough)... getting the belt on/off will be a lot harder. BUT, you still shouldn't have to take that pulley off... hmm... 

 

Don

 

 

With a welded tab you usually do have to at least loosen the idler pulley to get the belt in.

[Snoopy11 5,714]

Just now, pfrederi said:

 

 

With a welded tab you usually do have to at least loosen the idler pulley to get the belt in.

Seriously? Mine is welded... 

 

Don 

[Snoopy11 5,714]

Okay, so I think I understand now. So... the tab is not providing enough clearance to get the belt onto the pulley... thus why he has to remove the pulley to get the belt onto the pulley, then re-install. 

 

Well, even though that is a pain in the behind, it has to be done...

 

Don

[Snoopy11 5,714]

I think the original belts from Wheel Horse were not kevlar, rather, they had polyester cords. Therefore, the belts stretch.

 

I think this is the issue here... the belt needs to get stretched out a bit. 

 

13 hours ago, gwest_ca said:

The pedal return spring may be weak from use/age. A stronger one gives you more control.

A drop of oil on the pivots will also help.

 

The return spring should be tense enough so that the belt stretches a little over a ride or 2...

 

Don

[Snoopy11 5,714]

19 hours ago, rmaynard said:

Considering that you are using the correct OEM belt. I don't know what to tell you. Clean, shiny pulleys might help. The "belt" clutch to me is the worst design amongst a whole lot of good designs by the engineers at Wheel Horse. I have a '77 B-100 which is exactly the same set-up as yours. It does the same thing. My 857, Commando 8, and 701 also do the same. The 701 is the worst. My 12 year old grandson has learned to feather the clutch, but sometimes it gets away from him and the front end goes off the ground. So many of the older Wheel Horse's ads feature housewives riding and waving like there's nothing to it. But my wife won't get on a manual transmission horse, and she can drive anything. 

All of that may be true. However, if you spend enough time on a Horse, you learn it... how it acts, what it likes, and what it doesn't. 

 

I have the manual trans/clutch, and have one of the highest output motors on the forum as well as pulley swaps. If anyone is going to complain about how the clutching system works, it should be me. This thing could literally be dangerous if you don't know what the heck you are doing. Practice has made me pretty darn good at it. I have learned how to completely control the tractor.

 

Having said that, I would not let an inexperienced person use this tractor. Only if I am supervising and have properly instructed them. These tractors have to be man-handled. 

 

Don

Edited November 24, 2021 by Snoopy11