Trans goes into high range while in 4th gear.

[ajones115236]

Hi I got a Mack GU713 with a Mack 13 speed in it and the driver says when he preselects high range while in 4th gear the trans shifts into high range. I verified this and found it only does it when it is in 4th gear. First, second, and third it waits till it passes through neutral to shift to high range. Any ideas? 

[Joey Mack]

Sounds like a worn detent for the shuttle. You say 4th. But over to the right and down is 5th. Before i go too big, what recent work was done to the trans, shift cover for example ?

[ajones115236]

On a Mack 13 speed 5th is on the high side. No work has been done to this unit in a long time. 

[Joey Mack]

Can you post a picture of the shift pattern decal? I have rebuilt enough 2130/2180 tranny's to know a bit, But i am curious... 

[Joey Mack]

I want to see what a T-313 looks like..

[ajones115236]

[Joey Mack]

got it.. I figured it was called low instead of 1st. after you posted. I am at odds as to why it doesnt pre-select in all the low range gears. Can you put it in 8th and pre-select low range to see if it trys to shift into low range? you should be able to do this while stopped. Im leaning towards an issue with that shift rail, but still not clear. I have the Mack book for that tranny. I may try to look at it this afternoon. 

[ajones115236]

I just noticed you can do it in 3,4,7,8. All the gears on the far side. That makes a little more sense. 

[Joey Mack]

my guess is that 3/4 + 7/8 are the same shift fork and therefore the same rail.  There should be a detent in the rail that will activate the shuttle valve as you pass through neutral.  I need to post pictures for you, from my book, as well as get the correct description of the parts im talking about. 

[ajones115236]

Any pics would be greatly appreciated sir! 

[Joey Mack]

Ok it will be after 4.