3520 HST Issue

Hayloft · Aug 5, 2018

HST pedals suddenly moving on their own.
By using both feet the Fwd/Rev pedals can still be pushed down and tractor will move accordingly but take feet off pedals and Fwd pedal goes to full Fwd on its own. Yep, I checked the pedal return spring and is not broken. Any other ideas? Could this be a controller module ?
Thanks for your inputs.

Aquamoose · Aug 6, 2018

Both pedals drop to the floor?

Hayloft · Aug 6, 2018

No, one pedal at a time, the Fwd pedal if you just let it go on its own.

Aquamoose · Aug 7, 2018

I’ve had that spring break on me, you absolutely certain you’re looking at the right spring? It’s attached to this lever with a roller bearing on it. It’s completely mechanical & there’s no controller.

Hayloft · Aug 7, 2018

Well I will definitely look again. Did yours break on the pedal end ?
Thanks/Regards

Aquamoose · Aug 7, 2018

The spring that pushes the roller bearing down on the “V” broke and that allowed the pedal to fall either way. It’s a powerful spring and I replaced it with one from Ace hardware. You’ll need to find the broken spring to take with you.

It’s hard to get to it but not impossible. From what you’re describing, I’m quite certain that it’s what it is.

FastEddieR · Aug 7, 2018

I'm on my third pedal return spring. PITA to change out. Last time I removed the floor panel to get to it, it was easier to install because I could then loosen the adjusting nut, then retighten it after the spring was installed. The first two times I was under the tractor with vice grips, long needle nose pliers, and a curse jar that filled up REALLY fast! LOL

Seems like poor design to me, along with too brittle of a spring that fatigues and snaps after awhile. I ordered two factory replacement springs, but am using a spring from Ace hardware - it's not as strong and the pedals feel "mushy" but I hope the metal fatigue won't happen for quite awhile.

Hayloft · Sep 13, 2018

Appreciate the comments. Mine didn't appear to be broken at first...but it just had to be it. And sure enough spring had bit the dust.
I also removed the floor/deck panel for easier access. Its a pain job for sure. Works again but dealer replacement spring was not as hefty as my original and the pedals feel a bit mushy so I may step up another size to regain that "normal" pedal feel.