Cub Cadet FAQ's
Hydro Trunion Repair
Info stolen from IHCUBCADET.COM
The centering springs in the trunion arm/cam plate joint
allow a small amount of
movement or cushion in the speed control linkage. This is designed into it to
prevent the hydro from bucking you off the seat every time you move the speed
control lever....just like a shock absorber dampens a suspension.
The hydro WANTS to self accelerate....that's why FRICTION is built into the
speed control lever, to hold it in place. If you loosen the friction adjustment
and barely bump the hydro lever it will automatically move to wide open...it's
the nature of the beast.
The centering spring is designed to only compress during speed changes, at all
other times it should be in the neutral position, holding the hydro at constant
speed. If the springs become weak, or the slot becomes elongated (effectivly
decreasing the spring force) they will not maintain their "N" compression when
the tractor is moving fwd/rev. Instead, they will compress and allow the tractor
to "free wheel"/self accelerate downhill, or "bog down"/self decelerate up
hill.....just like a worn out shock, it no longer dampens then holds, it "sort of"
dampens then bottoms out. When you compress the weak springs due to
increased/decreased load you change the effective length of the speed control
linkage and the tractor speed changes accordingly.
Hope that's not confusing, but that's what is happening.
Those same centering springs are also the reason why it's hard to hook 2 hydro
linkages together to make a 4wd...different spring rates/hydro performance/individual
pump differences/etc make the hydros fight each other. Kelly Birkey (owner of the 1450
4wd and 1450 payloader) and a few of the forum regulars had a conversation about
that at RPRU. made for some interesting discussions.
First you have to recognize the problem
Then you get down to fixing it.
There have been several ways but I prefer the methods shown
Once you have everything removed and cleaned up, and your parts assembled,
your ready to begin.
The keystock method is used by many and works very well.
Get some 5/32"x1" keystock and braze or weld it to where
you have these
dimensions for the springs to rest in.
You will end up with something that looks like this or close to it.
As long as your doing it, you just as well replace the springs, They do weaken with age.
Put everything back together and it should look like this,
Once all that is done and everything is back in
place, go to
Operation Neutral Adjust and finish the job up.