Belt wont disengage fully '74 C100

[Don in Mystic 2]

My 1974 C100 's drive belt is about 5 years old and visually seems in good shape. The problem is it wont disengage fully, making shifts hard. The tensioner pulley is in good shape as is the "guard" which stands! vertical when in gear. The tensioner bracket moves all the way to the stop as it should. Ive just tried moving the guard a bit closer to the pully and have yet to test it. Any advice would be greatly appreciated!

[rjg854 11,472]

Have you got a picture of what you're posting about?  I'm not clear about what you mean about the "guard" which stands vertical when in gear.  You do have the drive belt cover don't you?  The drive belt cover must be on for your tractor to shift correctly.

[Ed Kennell 38,602]

If the belt retainer on the tensioner pulley is adjustable,  try  rotating it forward a bit so it pinches the belt when declutching.     

[953 nut 55,737]

45 minutes ago, Don in Mystic said:

the "guard" which stands! vertical when in gear.

Is your BELT GUARD that covers the entire belt in place?  The slack at the bottom of your belt when the clutch is depressed will stop the belt from moving IF the nbelt guard is in place. Without the guard to catch the slack it will continue to move.

[Don in Mystic 2]

Ed, I wasnt sure retainer was adjustable (or where to put it). Thanks so much for the advice

[Don in Mystic 2]

the belt retainer is not adjustable on my machine.  Im wondering if the belt got stiffer with age and the lack of flexibility is the cause of my problem. Ive ordered a new belt to rule that out...

[peter lena 8,716]

@Don in Mystic   I live in ledyard ct , about 10 minutes from mystic , pete

[Ed Kennell 38,602]

Is the tensioner pulley rotating completely forward when you push the clutch pedal.      If it isn't, the roll pin that connects the clutch lever to the cross shaft may have sheared.

Draw a line across the lever and the end of the cross shaft to see if there is slipping.   This is on the left side of the tractor.

[Don in Mystic 2]

the tensioner pully does rotate full travel and the mount hits the stop. There is no pedal slippage.

[Gasaholic 226]

As others have said, you need the side cover in place and fastened properly (Ideally with the foot rest installed too) because the lower guide supports bottom side of belt when it disengages.

 

- Also very important, DO NOT try to install the side cover with the clutch pedal depressed - The belt can sag below the metal guide, then it'll shred your belt pretty quickly when clutch engaged. If your side cover does not have that secondary belt guide support (They are spot welded to the cover and can break off, I have even had tractors in where some idiot cut the support off because his belts were shredding!  He was pretty ticked off at having to buy a whole new side cover to fix his problem! ) 

 

Without that lower guide support, the lower long section of the belt will sag as clutch pedal is pressed down, and that sag will drag on the engine pulley, so it never completely disengages. 

 

Also, be sure it is a genuine 7473 drive belt - They are a slightly different profile than the standard FHP 5L and B section belts (Which often are a substitution for the correct part number in aftermarket catalogs - the 5L 820 is the closest match, but still a touch wide so it doesn't sit in the V-Groove of new pulleys properly - making for a fraction of an inch in belt length difference, leading to a slightly "tight" belt until it gets worn in.) 

[Don in Mystic 2]

This was not a factory belt. I purchased it online ( 5L 820 ) but it has served well until this season. Considering it is a 1974 tractor with what is likely the original pulleys,  the 5L should work. Thanks for the advice about the side cover. The metal guide is in place and appears to be in good, usable condition. 

[Gasaholic 226]

If your original 5L belt has served well until now, I would be wondering what changed - If your guides and guards had not been altered and it suddenly started being hard to shift, I'd be inspecting the pulley V-grooves for something like a twig or stone or bit of mud (What we locally called mud wasps sometimes built their nests of mud in such places, as well as between cylinder cooling fins and similar places) which would be lifting the belt out of the groove a bit (You'd notice the clutch pedal vibrating , playing pat-a-cake with your foot..) - If it sat a long time, I'd also check pulley grooves for rust scale.. which lift the sides of belt up and "tighten" your belt - Note: Likewise, pulley groove wear on the sides can make a belt seem to "stretch". 

 

In other words, if it worked fine before this, you gotta think of what may have changed, if you havent had side cover off (or high centered the tractor on a snow bank bending the cover?) and clutch idler & mechanism work fully, I would not be thinking an adjustment of either of those is gonna help if they had been properly adjusted before..  My C-100 uses the up-front part of the side cover as the engine pulley belt guide, so if I had an engagement problem, a visual inspection of that area would be my first step before getting my wrenches out - looking for the tangs on belt cover to maybe have been bent out by some debris (or fraying belt)....  Sort of a step by step process of elimination rather than just tear into it willy-nilly assuming the problem being somewhere deeper..

[gwest_ca-(File Mod) 11,090]

Page 16 of this manual shows the belt guide clearances

1975 is a better copy than the 1974