T90 Issue

Sometimes when shifting from first to second the tranny grinds, usually when warmed up. Not always, if I shift slowly not an issue. Could this be an issue with a bad synchro or low gear oil?
Thanks
Paul

 

Yes.

You need to check the oil first. Have you changed it ever? You should use the 90wt GL-4 gear oil available from StaLube or other sources Amazon.com: Sta-Lube SL24239 API/GL-4 Multi-Purpose Hypoid Gear Oil - 1 gal: Automotive Note that there is no oil seal between the transmission and transfer case, so you should change and fill both.

The blocking rings ("synchro rings") could be worn out. The transmission could have other issues. That's a lot of power for that transmission, though there have been plenty of Jeeps over the years built with that combo. Realize that the more you wind it out, and the faster you shift, the more work the synchros have to do to align the gears. A Jeep is light, and it does not take much power to putt around in traffic. There are "natural " shift points where the gears match speeds - I would strive to drive with as little drama as possible, like into 2nd at 10 mph and 3rd at 20 or so.

 

Gear lube then clutch adjust.

 

Very likely from your description, the second gear syncro is weak (worn). As mentioned above, first check fluid level, or if it dark and has a metallic sparkle, change the oil with fresh gear oil. Fresh oil may help shifting issues..
-Donny

 

I have the same problem. I changed the gear oil to the one mentioned above and it helped, but it still does it. I'm getting ready to work on mine in a few months so I'll let you know what I find out. You will prolly have yours fixed by then though. I have the 4 cyl in mine.