Hello all new to the jk world. So here's the issue I have a 13 wrangler 86k 6spd trans. It is sometimes making a noise like gears that are not quite aligned. Its not grinding it shifts and drives good. But its like a gear shaft that is ever so slightly bent and its mostly in 3rd gear and mostly when its cooler out like mornings. Its actually my wife's jeep and she is big time ocd. It was in an accident not a huge one but she says since then its made this noise. Right now I have the front driveshaft out to see if it was coming from the front axle. My suspension is that its trans related. I am very mechanically inclined. Worked on planes trains and cars all my life. (Just for a little background) trying to describe the noise is a little difficult. Any help would be very welcomed. Thank you. Z

a little update it happens in 2,3,4,5 gears.....

 

Just based on your description of it happening in certain gears and mostly in 3rd, I don't see how it could be anything axle or diff related. The R&P gears in the diff don't care what gear the transmission is in and if there was an issue you'd hear something wrong across the full gear range. Also, removing the front DS in this case isn't going to quiet any noise if it was in the diff. All of those internals are still turning as the tires rotate on the pavement. The front DS is just spinning for funzies (via the tires rollin') unless it's in 4WD.

 

Try piutting the Synchromesh oil from Amsoil in there and get rid of the Mopar stuff. Similar noises on son's 2016 and Amsoil shut it up and smoothed out the shifts. And it was noisy.

 

Hey all thanks for your input
sixty4x4 I put royal purple in the trans case. The amzoil stuff is like a 5w30 weight oil isn't it? I saw some people have done that but wasn't sure if it would hurt the trans. Is there an 80w90 synchromesh oil?
thanks Z

 

Amsoil make the correct oil for the synchros. Son uses it and a night and day difference in noise and shifting smoothly

 

RP synchromax is only 7.5 cst. Amsoil MTF is 10.1 cst. For the last ~40K miles I've been using Redline MT-90 which is 15.5 cst. All the cst viscosities are the 100C values. I've tried all these, and a few others. I'm towing up mountains in hot weather, so my preference is biased toward higher viscosity -- Higher operating temperatures will lower the actual operating viscosity, so using an oil with a higher rated viscosity tends to compensate.

Anyway, the lower the viscosity the higher the noise, power, wear, and mpg -- The usual trade-offs, and CAFE requirements dictate leaning toward the lowest of possible viscosity choices for the OEM.

I can't detect a power or mpg loss, but it is quieter and there's less metal on the magnetic drain plug with higher viscosity gear oil. Cold weather startup shifting is a tiny bit slower with the MT-90, but these synthetics just don't thicken like regular gear oils in cold weather.

Suggest trying the Amsoil MTF as Sixty4x4 recommended, it's a relatively cheap test. I ran it for about 100K miles, pretty good in all weather.

EDIT: Sometimes you'll see the viscosity for manual trans fluid expressed like engine oil (5w-30 for example) and sometimes like gear oil (75w-90 for example). These are two entirely different viscosity rating scales where the viscosity numbers are not equivalent, so one needs to look up the actual cst at 100C or use a conversion chart to compare the viscosity. For example, I Just did a quick look at Redline MT-90 which is rated 75w-90 using gear oil viscosity grading, and 15w-40 using engine oil viscosity grading -- Same exact oil rated under two different grading standards.

 

And just a note to most of our brothers and sisters that run manuals - that is if you have recently bought a manual Jeep I suggest the first thing to do is change the manual transmission oil first thing. This is just in case someone put incorrect and cheaper oil in.