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8 LL from high to low grinding

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I have a fuller 8 LL in my tri-axle. When shifting from high to low range, it grinds. At the same time this showed up, when I shift from low low, to low, air feeds back through the shifter. If I move the valve around a little, air stops. I can't find much trouble shooting for the 8 LL on the internet. Any help?

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First find out if the air pressure is staying at about 60 psi.If so and it grinds then remove rear box on the trans and repair.If the pins on the scycho are broken then two things will cause that.One is drive line and U/joint angles and also shifting the hi/low range in reverse.

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The 15 speed Fuller i had in mine started doing the same thing going from HI to LO.

 

Replacing the synchro unit solved it in short order.  That unit is a marvel of simplicity.  Not big bucks, either.

 

 

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