I have an 01 3.9 V6 with the 5 speed manual trans. About a month ago, a mechanic friend and I did a 4.88 ring and pinion swap, added a Lockright locker, and at that time, I also drained and refilled my trans with the Pennzoil Synchromesh gear oil.

Ever since then, when I go to shift from 1st to 2nd at about 2000RPM or so, it will grab into gear hard and grind. It will do the same thing from 2nd to 3rd, but not as bad. All other gears shift fine. However, I found that if when I go to shift from 1st to 2nd, if I don't rev it up to high, and shift at about 1200RPM or so, I can get it to lay into gear smoothly.


Does anyone have any idea whether something like this would be caused from messing up the gear install, the locker, or the oil itself?


Prior to this swap, it shifted perfectly and smooth.

 

Sounds like the syncros in the trans are bad might not noticed it before because of the higher gear ratio.

 

There was a thread the other day about the gear oil for manual transmissions, and how the wrong oil can cause problems. I believe it needs to be something like a 5w-30......

Since this started just AFTER you changed the oil, I would look there first.

 

He's using the correct oil.

Lower gears will mean your shifts will be closer together, for whatever that's worth. It's really hard to diagnose things like this over the internet.

 

Try double clutching..... see if it makes it shift any easier.

(shift to neutral, let out the clutch, bump the gas, push in the clutch, shift to the gear you want.)

 

Yeah, I almost wish I would've waited to change the fluid for a little while after the gear swap, as that would've ruled out another variable.

However, I did use about 2 quarts of Pennzoil Synchromesh when I did the fluid change, which everyone seems to recommend. I guess I will recheck the fluid level tomorrow, and maybe just have to drain and refill with Mopar fluid to see whether that makes a difference.

 

That's actually how I used to mainly drive before this started happening.
Once I started having problems with the gears grinding, I found that the only trick to laying in the gears smoothly would be to take off, and then shift gently into gear around 1400RPM or so. Mainly just to not let the engine wind up. I have to do this from 1st to 2nd, 2nd to 3rd, and then I can shift at any RPM into the other gears without a problem. Reverse is also no problem as well.

It does seem to handle a little better when I am hauling something in my bed. The reason I lowered my gears was so I could run 35" tires, so once I get those on this weekend, I will see if it performs differently.

 

Well, after consulting a few mechanics and thinking about it, I've come to the conclusion that Pennzoil Synchromesh is way too thin of oil for the NV3500 trans, and I'm gonna just go buy some of the Mopar oil tomorrow.

I just hope 2 months/450 miles of driving didn't do major damage to my transmission.

 

I know a dude that rebuilt his charger *** end. Backed out of driveway, put it in drive and spun 900 bucks in parts.