Jump to content

Unofficial Home of Old Simplicity & Allis-Chalmers Garden Tractors

Simplicity725

Simplicity 725 Transmission Shift Issue

Recommended Posts

Simplicity725

Hi all,

So the other day I finally got my ‘64 725 going after sitting in my shop taunting me for the past six months.......but now I’ve found that the tranny gets stuck in second and is REALLY difficult to shift it out. Like bash-it-with-your-fist-with-all-your-might kind of difficult. Seems like the shift fork/gears aren’t meshing properly? Any suggestions? The guy I bought the tractor from gave me a spare trans when I bought the tractor (that’s always a good sign) although he did tell me that his step father bought a transmission for this tractor because the one in it went bad, but he couldn’t remember if he actually got around to swapping transmissions or not.

Share this post


Link to post
Share on other sites
Bill725

FYI, some of the issues with the original 725 transmission are:

1) The 725 transmission was designed with axle tube bushing rather than needle bearings like used in the later year transmissions. The bushings wear out and then take the axle seals out. Needle bearings eliminated this issue.

2) The RH differential gear is roll pinned to the wheel hub. The roll pins can fail. Later models have the gear permanently attached to the hub to eliminate this issue for a more robust design.

3) The 725 differential is an open differential, meaning there is no internal spring to provide limited slip. The 725 uses (2) angular torque screws on the RH hub to provide pressure on the axle shaft for the LH wheel to provide limited slip. Newer models have internal differential springs which is a more robust design.

Therefore, if your 725 has the original transmission, and your spare transmission is of the newer style, you may want to switch to the newer style because of the reasons stated above.

  • Like 1

Share this post


Link to post
Share on other sites
dhoadley

Bill, could you show us what to look for to know the difference between the 2? I was gifted a 725, not running, that I haven't yet begun to mess with. (like a dozen other projects :$ ) Thanx, Dave

Share this post


Link to post
Share on other sites
Simplicity725
15 hours ago, jlasater said:

or...possibly rusty or sticking ball detents on the fork shafts.

Any way to remedy that without disassembling the trans completely?

Share this post


Link to post
Share on other sites
Bill725

To see the axle bushings you would have to remove the axle seals. If you have (2) angular screws on the RH wheel hub, then you have the original open differential.

Share this post


Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now


×