John Deere 40U - Touch-o-matic calibration

Glen D Anderson · Jan 6, 2023

Good day,

In the process of overhauling the single touch-o-matic unit on our 40U and I'm at the point where the special tool is needed to determine the amount of shims required between the pushrod & check valve. Needless to say I lack those special tools and am wondering if there is an alternative method to achieving success in this process?

TIA

Glen D Anderson · Jan 10, 2023

Surfing the web for info. on tool P/N AM453T I found an excerpt from what I assume might be a sevice manual for an M.

It says that a piece of wire of the correct diameter can be substituted for the AM453T gauge. Basically you use it to determine how much of the port behind the control valve is open before the pin pushes the check valve off of it's seat.

Checking ours it appears to be somewhere around .025" & spec in the OEM 40 service manual states .021" to .030".

Just trying to cover all of the bases as this touch-o-matic unit was having issues where the rockshaft / lift arms bounced rapidly with a raised load. The seals on the piston & end cap appeared to be in serviceable condition when disassembled. Also, with the TOM unit turned on it's side & the check valve installed we filled the cavity above it with solvent & found that it held the fluid for a long time before leaking past, well over an hour. The small relief valves located in the piston end cap also showed no leakage when tested with solvent.

Thoughts?

(quoted from post at 12:13:11 01/06/23) Good day,

In the process of overhauling the single touch-o-matic unit on our 40U and I'm at the point where the special tool is needed to determine the amount of shims required between the pushrod & check valve. Needless to say I lack those special tools and am wondering if there is an alternative method to achieving success in this process?

TIA

John Deere 40U - Touch-o-matic calibration

Glen D Anderson

Member

Glen D Anderson

Member

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