Cub Cadet 124 - Speed Surging While Moving

[Bobbar]

Hello All,

I have a 1967 124 that I've been using for 3 years now for mowing and plowing. And over the last season or two I've noticed an intermittent surging or jerking motion while driving on a slight decline. I realize some slack is going to be normal, but I wanted some opinions as to whether I should be concerned.

There's one point in my yard that's on a slight decline with some uneven ground, and the tractor feels like it speeds up slightly as it rolls into a depression, slows and recovers, then kinda jerks it's way back out. And a slight oscillation in speed continues for a moment where it levels out until I start up a slight incline nearby. My foot remains off the clutch, and engine speed is solid the whole time.

I've noticed an even more pronounced surging motion while slowly reversing uphill in the driveway. It almost feels as though the wheels are oval shaped...

If I rock the tractor while off and in gear, it feels fine to me. Just a slight rotation of the wheels and driveshaft.


A little maint. history:
The drive plate is original, but the pins had been sheared off at some point in the past, and the previous owner (my grandfather) had drilled new holes and installed some hacked off bolts to repair it. I've since replaced those with new higher grade bolts, as the old ones where very worn on the sides.

The clutch is fairly new and engages smoothly with no squeaks. I try to keep it well adjusted. It has one clutch clip installed. The holes are slightly warn and oval shaped, but play in the drive shaft couldn't be more than a few 16ths of an inch.

The trans oil was replaced not long after I got the tractor (3 years) with SAE 30 oil. I have no idea how long it had been since the previous trans oil change, but the oil looked OK aside from a few small chips of metal. Gramps wasn't one to be too bothered by grinding gears...

Let me know what you think.

Thank you,
Bobby

[J-Mech]

There is backlash in any gear drive tractor. The bigger the trans (number of gears) the worse it can be. Totally normal. It's likely that it has always been there, you just only recently noticed it. Or, it may have some wear somewhere. It's nothing to be concerned with. Don't worry about it. As a preventative measure, just check the driveline to be sure that all the roll pins are tight and the clutch and other components aren't working loose.

[DieselDoctor]

You might want to check and make sure the motor mounting bolts are tight as well.

[Bobbar]

Originally Posted by J-Mech

There is backlash in any gear drive tractor. The bigger the trans (number of gears) the worse it can be. Totally normal. It's likely that it has always been there, you just only recently noticed it. Or, it may have some wear somewhere. It's nothing to be concerned with. Don't worry about it. As a preventative measure, just check the driveline to be sure that all the roll pins are tight and the clutch and other components aren't working loose.

I'd considered the possibility that I'd just now noticed it. Worn roll pins in the drive shaft were also on my mind, I'll have to dig in there and take a closer look. All that stuff has definitely gone 50 fracking years without replacement or inspection. (Damn these tractors are tough!)

My imagination had occasionally drifted into broken teeth in the transmission, but that would certainly have to be more apparent. That's the main reason for this post. I'm just picking people's past experience hoping to quell my paranoia.

Thanks for the input!

[Bobbar]

Originally Posted by DieselDoctor

You might want to check and make sure the motor mounting bolts are tight as well.

That's an interesting thought. But I've definitely leaned on the motor quite a bit recently while removing the carb, adjusting tappets, points, spark plug and so-on and haven't noticed any unusual movement.

I'll be sure to give her a good and firm wiggle the next time I get it out.

Thanks!

[ironman]

How 'bout a slotted out flywheel hub?

[J-Mech]

Originally Posted by ironman

How 'bout a slotted out flywheel hub?

It's a gear drive, not a hydro.

[olds45512]

I wonder if the engine is getting wore out and lacks the compression to hold the tractor back. How does the engine run? Does it smoke?

[ironman]

Originally Posted by J-Mech

It's a gear drive, not a hydro.

OOPS! my bad. So my next guess is hydro linkage?

[ol'George]

Originally Posted by ironman

OOPS! my bad. So my next guess is hydro linkage?

If it is not a hydro, I would think it has no "hydro linkage"