Hydrostatic Drive or linkage/spring problem?

COMPLETE NEWBIE TO THIS FORUM and looking for your experience to guide me to a fix.

The hydrostatic transmission on our John Deere LT 166 Lawn Tractor just scared the heck out of me last weekend. For 19 years the drive would stop as soon as you removed your foot from the forward or reverse pedals. The first failure was when reversing, it would not stop reversing until I pushed a bit on the forward pedal. Forward travel released as soon as forward pedal was released. My first thought was there must be a spring on the reverse pedal/cable that broke. But shortly later the forward travel started sticking and not releasing until the reverse pedal was applied. So now both forward and reverse don't disengage without help from the alternate pedal assist. The day of this problem was a 35 f degree day and I was mowing damp leaves.

Tried to go online to look for a parts list drawing to see if there are springs to be looked at. But I wasn't having much luck getting this info online.

So:
Are there external springs on the drive pedals/cables external to the hydro trans or are the "springs" or hydraulic stop in the transmission?
Or might I just have some wet leaves causing a sticking issue with the drive pedals/ cables?

Looking for likely scenarios of the problem and likely cures.

:welcome:
You should be cleaning the hydro drive down at the end of every season.
A long tube air duster works wonders.
If you follow the control rod down to the drive you will find a pair of short lever arms with a spring between them.
Replace the spring it is what returns the pedals.
Give every place where one thing moves against another a good shot of dry lithium spray grease after blowing them clean.

bertsmobile1 said:

:welcome:
You should be cleaning the hydro drive down at the end of every season.
A long tube air duster works wonders.
If you follow the control rod down to the drive you will find a pair of short lever arms with a spring between them.
Replace the spring it is what returns the pedals.
Give every place where one thing moves against another a good shot of dry lithium spray grease after blowing them clean.

Click to expand...

Thank you for the reply!
I watched a video today about rebuilding a JD hydrostatic transmission and saw a spring for the forward and reverse drive “ centering” and thought, dang this problem is in the transmission. But now I am hearing a simpler repair with one or two external springs to the hydrostatic transmission may be the issue.

It all depends upon the hydro.
most have all of the centering springs & linkages outside.
JD for some reason like using boxes that have the brake on the inside, running in oil.
There will be comprehensive step by step instructions about how to set up the control pedals in the JD Technical manual.
They are available from JD as paper or digital download and well worth the money.

Thanks for the tips!
I ordered the tech manual from John Deere and should be able to figure this out once the manual gets delivered through the Christmas mail rush. I will have all winter to read up on what needs fixed/replaced.

Enjoy your spring and summer.

Got the tech manual and see there is a gas strut that should be centering the forward/reverse pedals.
The problem occurred mowing/mulching slightly snow covered leaves. I am hoping that snow and leaf clippings were causing the problem. Come spring in Michigan I will clean and lube the drive rod and drive pedals at their pivot points and check that gas strut.

Your mower has a Tuff Torq K51 ( JD of call them T 51, same unit )
see it here https://www.tufftorqservices.com/instance1/servlet/WebDispatcher?mode=pap&item=K51A%20003683-006264&url=https://www.tufftorqservices.com/instance1EnvEEdefault/html//Pic-A-Part/K51A%20003683-006264.htm
Note there is no return mechanism inside the box

bertsmobile1 said:

Your mower has a Tuff Torq K51 ( JD of call them T 51, same unit )
see it here https://www.tufftorqservices.com/instance1/servlet/WebDispatcher?mode=pap&item=K51A%20003683-006264&url=https://www.tufftorqservices.com/instance1EnvEEdefault/html//Pic-A-Part/K51A%20003683-006264.htm
Note there is no return mechanism inside the box

Click to expand...

Understood. The video I watched were of K46 Tuff Torq rebuilds. The K51 is a bit different. I am betting your first recommendation of cleaning and lubing the drive rod “linkage” will cure or greatly improve the sticking issue.

Thank you for sharing your thoughts. You have been most helpful!

bertsmobile1 said:

Your mower has a Tuff Torq K51 ( JD of call them T 51, same unit )
see it here https://www.tufftorqservices.com/instance1/servlet/WebDispatcher?mode=pap&item=K51A%20003683-006264&url=https://www.tufftorqservices.com/instance1EnvEEdefault/html//Pic-A-Part/K51A%20003683-006264.htm
Note there is no return mechanism inside the box

Click to expand...

Thank you for your help. You nailed it and I thank you for sharing your experience.

I thought I was going to find leaf mulch stuck in the drive linkage but there wasn't a flake of leaf mulch in it. Just 18 years of grass clippings that had probably freeze dried over our winter. I brushed it out, and then blew it out, and then sprayed it down with a dry lube and the drive was working flawlessly just like it did before last November.

Going to be about 6 weeks until it is placed back in service. 8 to 14 inches of snow expected there tonight.

Hope you had a great summer and your winter isn't as brutal as ours, but I do like the change of seasons.

Excellent result
Actually a "brutal winter " would be good.
Field dams are all dry, ground moisture level is critically low so lots of water over winter will be most welcome.

A good clean down and lube of the linkages at the end of every season works wonders.