Mack 12 speed noisy in 4th gear

[DieselDog5.9]

So we pulled a 6 speed out and put a 12 speed in 3-4 years ago.  The hired driver, (nice guy, just young and inexperienced) had to drive the old R model while the Granite was out of commission for a few days........  Well now 4th gear is noisy in high or low, so thoughts?

I think there are 2 versions of this 12 speed, one for off highway trucks a little lower geared and a highway version, we have the highway version.

Edited June 10, 2022 by DieselDog5.9
spelling error

[mrsmackpaul]

So Im thinking this is a overdrive transmission by your description 

Is it noisy under load, when you back off or when you coast

Is noisy when its cold or when its hot or the whole time ?

[DieselDog5.9]

I was assuming also that it was the overdrive version.  5th being direct?

From the conversation the Owner and I had noisy all the time, hi or low side.

[mrsmackpaul]

If its overdrive 5th is direct and over drive, 11 and 12 

4th gear is 9th and 10th 

You need to  establish what gear box you have first I guess, have look on the LHS of the box about halfway up and it should have some numbers there 

 

Paul