Diff lock valve

Muir hill 101 · Apr 28, 2023

I am about 100 psi low on pressure on differential lock . Does anyone have an idea how many shims to add ? I thought I read something about how much each shim adds but I cant find it now

JIM MN · Apr 29, 2023

As shown in the differential repair section in the 4000-4020 tech manual, showing the differential lock valve; each shim changes pressure 25 to 30 psi. So... add 3 or 4 shims to raise pressure 100 pounds??? The pressure you want, pedal depressed, is 420-480 psi at the test plug.. Warm oil at rated tractor speed...

Muir hill 101 · Apr 29, 2023

Thanks I knew I seen it somewhere. Its not in my 3020 manual and of course not In the i&t thar thing ought to be in the outhouse . Better find my 4020 manual I guess

Muir hill 101 · Apr 29, 2023

What is date on your manual ? What section is the information in ? Its not in either of my books in the section about the valve or in the specifications

JIM MN · Apr 29, 2023

You figured it out!! Mine is -Tech Manual - TM-1006 (Jan-70) for 4020 Tractor S/N 201000-up... Powertrain 50 ... Group 25 differential ... page 25-3 ... adjustments and tests ... differential control valve ... control valve TEST. Yours may be a little different?? But it gives the shim values..... Glad to help!!

Muir hill 101 · Apr 29, 2023

Thank you , I thought I had read somewhere but I guess I didnt . Now I better check the i&t again because it shows late and early models and even has the 6030 .

Muir hill 101 · Apr 29, 2023

Well I guess Ill keep i&t around the information Is there . Replaced both springs in the valve added to many shims got 800 psi ! The big spring was the exact same free length the lower spring was about .050 shorter than the new one

Diff lock valve

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