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Grinding when shifting up/down from 3rd

9K views 6 replies 7 participants last post by  GrassKicker 
#1 ·
97 TJ, 5 speed man transmission. 81,000 mi.

I'm getting a brief grinding noise (like when you don't have the clutch depressed and try to shift into a gear) when I shift into 3rd or down to 3rd. I don't get it if I upshift or downshift into 3rd by waiting 1-2 seconds before I move the shifter into gear and keep the clutch pedal depressed. This doesn't happen 100% of the time and seems to happen only after traveling 3-4 miles after it warms up a bit. I've also on very rare occasion gotten it when moving to/from 4th, more on 3rd gear though.

So basically, If I hesitate to shift into 3rd it behaves just fine. And occasionally I do have difficulty downshifting into 3rd, 2nd and 1st and have to release the and press the clutch pedal once and then I can move the shifter, like it doesn't want to go into gear. Or if I push a little harder it goes into gear w/o releasing and pressing in the clutch.

Any thoughts? Clutch issues? Otherwise it's runs great, not odd noises or anything.

Thanks!
 
#5 ·
If they are basically the same symptoms as the original poster, chances are that your transmission syncros are worn significantly. Typically a bad clutch will be a problem consistantly in all gears.

I suggest you drain the gear oil in the transmission and check for gold flakes in it (syncros are brass). You might try refilling it with redline mt 90 as suggested above...it may help prolong it a while and could help make shifting smoother, or maybe not...hard telling until you try it.
 
#6 ·
^^time to change the transmission fluid. That will certainly help, but it's a relatively temporary fix.

Learn to shift without grinding. Even if your synchros are completely gone, the transmission will function fine as long as you rev match the gear changes. Waiting a pause while shifting up allows the shaft to spin down to the same speed as the next gear. I always do this with all my cars to prolong the life of the transmission. When shifting down, release the clutch in neutral and blip the throttle to bring the shaft speed up to the lower gear (double-clutching). I usually only double-clutch when I know the difference in gear speeds is significant.
 
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