Transmission rattle

Wed Sep 18, 2013 8:39 am

Hello, I have a 49 Cub that has a horrible rattle sound in the transmission. When I bought the tractor and test drove it there was no "bad sounds" in any of the gears. I got home and changed all the oils and ouch here comes this ugly rattle. There is no rattle when it is running and in neutral. The rattle is not as bad in R or 1st and gets worse in 2nd and 3rd. 3rd sounds like air hammer on a bell. When in 3rd, I put my hand down on the lil hump on the leftside of the transmission and you can feel the rattle. I have split the tractor and lifted the rear end to spin the transmission. I removed items from the transmission until the sound disappeared. I believe the rattle to be caused by the rear idle gear. I have replaced the bushing for that gear and I also replaced the pinion bearings. The noisy is still there. Would replacing that idle gear be my answer? I have tried all the oil tricks without making a difference. Thanks for any help.

Re: Transmission rattle

Wed Sep 18, 2013 9:25 am

May not be the same thing but mine will rattle sometimes when you go from reverse to second. I blame mine on a worn shifter, I think it is not coming all the way out of reverse so that the idler gear teeth are still barely making contact with their mate gear when it's in second. If I shift firmly back into reverse, and then firmly into second, it goes away. Long story short, look at your shifter for wear.


Re: Transmission rattle

Wed Sep 18, 2013 9:32 am

That type of noise is tough to diagnose without being there, but the first thing I would do is check the shifter forks for being bent or broken, allowing gears to rub. In addition, you could have a bad bearing on the pinion shaft that goes out the bottom of the transmission to the differential. That shaft as well as the reverse idler turns anytime the tractor is moving, no matter what gear, even just rolling in neutral. Wedge the front axle, and carefully raise both wheels off the ground and with the tractor in neutral try turning the wheels. Note, due to the differential you will have to turn both of them to spin the pinion shaft and reverse idler. Also check the sound if you only turn one wheel allowing the other one to free whee(will turn opposite way). if no noise doing this block the clutch down and try the same procedure in different gears.

Re: Transmission rattle

Wed Sep 18, 2013 10:08 am

I did try the lifting and moving the rear tires. As I was doing this I removed a gear at a time until the noise went away. The only thing left in the transmission was all the pinion gears and this reverse idle gear. When I took the reverse idle gear out the noise was gone. I replaced the bushing in this gear and it still made the noise so I pulled the pinion and replaced those bearings thinking maybe there was just enough play to resonate a sound etc. The reverse gear (350848r1) is a straight cut gear and shows no wear. The reverse idle gear (350870r11) shows the typical abuse from 60 yrs of being jammed into reverse and seems a bit sloppy mesh with the other. They run together all the time so that is why the noise is there in all gears and gets worse when in 3rd.

Re: Transmission rattle

Wed Sep 18, 2013 11:58 am

BTW: Welcome to the forum!!

As you've already experienced, this is a great place for finding answers to your Cub questions.

Re: Transmission rattle

Wed Sep 18, 2013 2:01 pm

Thank you. This place is awesome.

Re: Transmission rattle

Wed Sep 18, 2013 10:24 pm


Coming in a little late but G'day to you and glad you figured it out.

Image to :big smile: Forum Family. And you have come to the right place for all things Cub related. If you click on the Site Rules, Regulations, & Important Information, it will point you to :arrow: the Welcome Wagon wherein you will find links to many useful sites and topics. One of the most important resources are Owner's Manuals, Parts Catalogs and Service Manuals. The Cub Manual Server is the home of the jpg versions and the PDF Manuals -- well the pdf's of course :wink: Enjoy!.