Fourth Gear Grinds a Little

[nate6472]

Most of the time, when I engage 4th gear, there is a slight grind (just enough to get the wife's look of "can't you drive a stick shift"). I have changed the oil to Lucas Heavy Duty and it still occurs.

[daveb]

what's your idle speed?

Most of the time, when I engage 4th gear, there is a slight grind (just enough to get the wife's look of "can't you drive a stick shift"). I have changed the oil to Lucas Heavy Duty and it still occurs.

[nate6472]

No special adjustments have been made, the idle speed adjuster in the cabin is all the way to the left (low).

[daveb]

I've had trucks where the idle was a bit too high making shifting difficult although usually that is in the lower gears, as with most transmission problems.

No special adjustments have been made, the idle speed adjuster in the cabin is all the way to the left (low).

[Tim Smith]

I can't imagine it's the idle unless you are shifting into 4th from a dead stop. In which case, I think the looks you are getting are deserved.
< ducking >

Maybe the syncro? Have you tried slowing your shift into 4th down a little to let the gears mesh up a bit better?

[jac04]

I'm not sure what the specs are for the Lucas Heavy Duty oil, but sometimes the syncros don't like limited slip additives. You can try an oil without LS additives (which can be difficult to find) and see if that helps.

[KingSlug]

Have you tried to double clutch? If you can DC and the sound goes away then its a syncro.

Jared

[nate6472]

What do you mean by double clutch?

The grind is less if I shift slower (take more time between 3 and 4).

[nate6472]

It is really labeled "heavy gear oil" for semi-trucks.

[LaneRover]

I would go along with the synchro is going. By double clutching they mean. Putting in the clutch to remove it from gear then while it is in neutral putting letting the clutch out and then putting the clutch in before you go into 4th.

Does it do this at all down shifting into 3rd?