Cub Cadet 123 Vibration

[Mossmanxjt]

Hello,

I just got my first Cub Cadet. It's a model 123 that is in pretty good shape for a working tractor. It has a 48" mowing deck and a 42" snow thrower for the winters. I have a question for the forum. I just recently got it running after cleaning the carburetor, replacing the air filter, installing a new starter/generator belt and adjusting the PTO clutch.

Just test driving it around the yard today I noticed a vibration that may or may not be normal. At about half throttle or better there is enough vibration to be felt quite noticeably through the seat and steering wheel. Also the hood eventually vibrates free from the rubber washers that secure it's aft edge. The amount of vibration increases with throttle and does not change when the PTO is engaged or disengaged.

It doesn't feel like it's going to shake apart but it is more than I have felt on newer garden tractors. I know the engine on the narrow frame tractors is hard mounted to the frame so perhaps it's normal. Thanks in advance for any advice.

Regards,
Mike

[Cubby guy]

Welcome, Mike.

Some vibration is normal on the "Thumper" engines (single cylinder). If you have someone close by with a similar model, give their machine a quick test drive. I have a Quiet-Line model 800 with the rubber ISO mounts; not too much vibration until the mower kicks in.

The hard-mount styles do transmit more shakes to the frame, seat, etc. Check the motor mounts and be sure they are all snugged to spec. Most of the newer lawn/garden tractors are v-twins, and usually rubber-isolation mounted so those are normally smoother.

Again, welcome to Only Cub Cadets. Put on the coffee, pull up a chair and stay awhile.

[Berwil]

I would make sure the engine mount bolts are tight and check the driveshaft/rag joints for any wobble.

Bill

[Cubby guy]

I forgot to mention, ( however, Berwil did remember) that the driveshaft flexible couplers [A.K.A. 'Rag joints'] can be a cause of vibration....

Does it still shake with the clutch pressed down?

if not, the flexible couplers could be the issue.

Regards

Cubby Guy

[Mossmanxjt]

Thanks for the advice. I will check the engine mounts to make sure they are snug and check the rag joint. Is there a torque spec for the mounting bolts or just make sure they are snug.

Regards,
Mike

[Cubcrazy]

Welcome to OCC!

[Mossmanxjt]

Regarding the rag joint, on a hydrostatic does the driveshaft always turn even in neutral with the brake fully depressed?

Another issue I noticed is that the neutral return mechanism connected to the brake overshoots neutral a bit. With the brake locked down there is a slight grinding noise from the hydrostat when starting. If I release the brake enough to move the selector lever I can put it fully in neutral and there is no noise. I looked up the procedure in the service manual to adjust the linkage and it is on the to do list.

-Mike

[ACecil]

Welcome to OCC! Enjoy your 123!

[Berwil]

Originally Posted by Mossmanxjt

Regarding the rag joint, on a hydrostatic does the driveshaft always turn even in neutral with the brake fully depressed?

Another issue I noticed is that the neutral return mechanism connected to the brake overshoots neutral a bit. With the brake locked down there is a slight grinding noise from the hydrostat when starting. If I release the brake enough to move the selector lever I can put it fully in neutral and there is no noise. I looked up the procedure in the service manual to adjust the linkage and it is on the to do list.

-Mike

Yes, the driveshaft on a hydro is always spinning at the same speed as the engine, there is no disconnect or clutch.

The whine is a common problem when the neutral brake return is out of adjustment, sounds like your on the way to fixing that one.

Bill

[Mossmanxjt]

Thanks for the help guys! Eventually I am going to to a tear down and restoration. Maybe in the fall when the grass stops growing.

-Mike