lately, the tranny has been grinding putting it into 5th gear. The dealer did the clutch TSB and its still grinding,

the mechanic claimed it was because of the 35" tires, which really measure 33 1/2" now. With the stock gearing. He said the bigger tires are to much for the gears, and the outputs spinning to fast.

After I told him its been regeared to 5.13 he acted confused, and said thats what the Jeep tech told him, but thats what they are blaming the grinding on.

it wont grind if you ease into 5th gear, but if the RPMS are up, it hits..

 

It sounds like your clutch is not quite releasing all the way. Check your clutch pedal free play, the slave cylinder may not be depressing the throwout bearing far enough. The comment about tire size and input shaft speed is BS, the reason for syncronisers in the transmission is to equal shaft speeds so the damned things can be shifted at speed. A bad syncroniser blocking ring is not selective about shift speed on the shifter, if it's bad it will snick shifted slow or fast, so I don't think you have a syncroniser problem. Just a few thoughts my friend.....

 

they said the synicros were perfect. If it were the clutch, wouldnt the other gears grind?

Its only when the RPMS are high that hit grinds, if the RPMS are low, it wont hit...

 

Pig ( if I may call you that) A syncro's smooth operation depends on the premise that the input and output shaft speeds are able to be matched by the syncro blocking ring absorbing the energy of the faster shaft and matching the speed of the shafts together so the splined syncro can slide freely and effectively ''shift'' the gear. This absolutely depends on the clutch disc being completely and totally disconnected from the engine flywheel. If the disc is being spun the slightest bit by anything other than it's own inertia, it will overcome the syncro's ability to match the shaft speeds and you will get a grind or snick. A bad slave cylinder sometimes will present itself as difficulty going into first or reverse, hard shifts, clutch pedal free travel failure, or a shift grinding or sometimes snicking. All gears are not affected always, sometimes only one gear is affected, sometimes you get all the symptoms. Go figure! Just some food for thought....

 

Mine also just started grinding going 4th into 5th... but only when I'm gunning it and the RPMs are high.

If I put a short pause between 4th and 5th and let the RPMs settle, no grind. However, this just isn't right and it really worries me that I'm doing damage when i forget to be so gentle.

Some posts I've found on the forum mention that it may be a clutch issue? Something has got to be off, but just ever so slighty. Is there anything I might be able to adjust myself with some good instructions? I hate to take this kind of issue to a mechanic...

FYI stock suspension, stock tires, stock 4.10 gears. and I drive it like I stole it.

 

how do they know the synchro's are fine, you can't see them unless the trany is apart

 

They said the tech took it apart. It doesn't matter now. That jk got totalled. The new one kicks out of gear. But nothing like the old one