Rough shifting six speed

D

Deadeye

New Member
Joined
Mar 10, 2016
Messages
8
I've got an '05 TJ that is giving rough shifts into second (which is understand is common) and has recently started giving rough shifts into third. It shifts smoothly if I double clutch it or if I move the shifter slowly as I upshift. I changed the oil to Royal Purple Synchromesh yesterday and it took it for a drive and I still have the same issue and the temperature was +5C. Sometimes the rough shifts are even a slight grinding. I should also mention that this keep only has 62,000km (about 38,000 miles).

Does anybody have an idea of what might be going on here?
 
I'm not sure that the RP Synchormax is a GL-4 oil. You need a GL-4 like Pennzoil Synchromesh or Red Line MT90.
 
Make sure your clutch is fully disengaging. Check that the hydraulic system is working correctly. Once you do this you can eliminate that possibility and investigate synchronizer issues.
 
fljeeper said:
Make sure your clutch is fully disengaging. Check that the hydraulic system is working correctly. Once you do this you can eliminate that possibility and investigate synchronizer issues.
Click to expand...
I would think clutch of hydraulic system if it was across all gears but with it being 2nd then now 3rd it would be more of a synchro issue or the fluid not being right.
 
JP98 said:
I'm not sure that the RP Synchromax is a GL-4 oil. You need a GL-4 like Pennzoil Synchromesh or Red Line MT90.
Click to expand...
Redline MTL is actually what is recommended for the NV3550 5-speed and NSG370 6-speed. The slightly heavier viscosity MT-90 is the right choice for the AX-5 and AX-15 transmissions. I agree on the Royal Purple Synchromesh not being the right stuff, its problem is that Royal Purple doesn't say it is 'safe for yellow metals' as needs to be said for a manual transmission.

Royal Purple does say their Max Gear 75W-90 is safe for yellow metals, with those "yellow metals" being the brass synchronizers used inside manual Jeep transmissions. Which when that is left out of their Synchromesh description in their catalog at http://www.royalpurpleconsumer.com/assets/catalog/2016_Royal_Purple_Catalog_Web.pdf tells me it would not be the right choice.

Not to mention I'm no fan of Royal Purple anyway. To me, it is no better than any other brand... it is just over-hyped with a purple dye added for marketing purposes.

Personally, I'd run Redline MTL in the NV-3550 5-speed or NSG370 6-speed. Like you can get at https://www.amazon.com/dp/B000CPCBEG/?tag=wranglerorg-20

And Deadeye, I'd drain that RP Synchromesh due to its long-term effects on the synchronizers. It will not cause any immediate damage short-term but it's not good for them long-term.
 
Last edited:
  • Like
Reactions: JP98
I run the Redline MTL in mine. The 6 spd is notoriously troublesome and ridiculously expensive to repair or replace. Mine does basically what yours does. I find pushing in the clutch quickly and double clutching 1-2 to be the best way to avoid grinding. I also shift slowing and can feel when it is "ready." After I changed to the MTL it did help with shifting somewhat. You could try it and see if it helps yours. Good luck.
 
Rob5589 said:
I run the Redline MTL in mine. The 6 spd is notoriously troublesome and ridiculously expensive to repair or replace. Mine does basically what yours does. I find pushing in the clutch quickly and double clutching 1-2 to be the best way to avoid grinding. I also shift slowing and can feel when it is "ready." After I changed to the MTL it did help with shifting somewhat. You could try it and see if it helps yours. Good luck.
Click to expand...
X2, don't expect any miracle cures for your shifting issue from just using a better lube. Just keep in mind the RP Synchromesh yours is filled with now is not the right stuff.
 
Top Bottom
Back