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Worn syncros


bruceco

TJ Enthusiast
Joined
Dec 9, 2017
Messages
106
Location
Woodstock, ON, Canada
I have had my 2000 tj on the road for the 2nd summer now. Only 3000 miles the first year. It is a 4 ltr 5 speed. It has 180,000 miles on it and i am sure the original gearbox but with a rebuilt motor 40,000 miles ago.I have no other history but I am trying to contact earlier owners to see if a clutch or another gearbox was ever put into it.Anyway when I shift I have to go halfway and then fully in a second later otherwise it will grind in all gears. I changed the tranny oil and it had a lot of brass shining away in it.I went to the right oil recommended by the forum hoping that was the problem. It has been 300 mile so far and still the same. Any ideas or should I just live with it.The clutch if fully engaged.
 

fourpointzero

TJ Enthusiast
Joined
Jun 1, 2016
Messages
992
Location
New Jersey
Im not a mechanic, but from the description, sounds like synchros. Pretty common w high mile transmissions, and (may need correction here) believe you have the first year TJ w the NV3550. Ive had my personal experience w that trans and it was a PITA since new to me as a used buyer.


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bromel

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Joined
Oct 11, 2018
Messages
260
Location
Montauk, NY
Yeah the NV3550 is notorious for synchro problems, especially in 2nd gear. Try using Redline MTL, which can make grinding a little better, but it's no miracle tonic for a worn-out transmission. If you replace, I'd go with an AX-15 from Novac, which you can get new for like $1500.
 
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Chris

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Sep 28, 2015
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40,068
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Salem, Oregon
The NV3550 is notorious for synchro issues as previously mentioned.

If it does indeed have 180k on the original transmission, then you are definitely due for a new transmission or a rebuild.

The smart thing to do in this case (and what most do) is ditch the NV3550 and put in an AX-15. You can get the AX-15 for much cheaper, and Advanced Adapters and many others sell them brand new. It's just as good (if not better) than the NV3550 and bolts right in.
 
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bruceco

TJ Enthusiast
Joined
Dec 9, 2017
Messages
106
Location
Woodstock, ON, Canada
Thanks for the info.I put the redline in as mentioned in the winter when I changed all the fluids.2nd gear is the worst of mentioned.Thanks for all the info as mentioned above.You guys always know your stuff and it is my first jeep. I don't put a lot of mileage on it and after all my frame repairs,brakes etc I am only driving it in the summer so maybe next winter when I have it parked I will make the tranny change.
 

fourpointzero

TJ Enthusiast
Joined
Jun 1, 2016
Messages
992
Location
New Jersey
Exaclty as Chris and Bromel suggested, I did. Ditched my turd NV tranny and bought a brand new AX-15. But not before attempting a failed rebuild. Parts were scarce and the results of the reman was a complete failure. Lost a lot of time and money in the process, trying to save money. Hard lesson to swallow.

Bought mine locally in NJ from Rockland Standard Gear Inc. Another hard lesson learned: DO NOT TRUST ANY RANDO ON EBAY. Too many false advertisers who dont stand behind their claims.


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bromel

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Oct 11, 2018
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260
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Montauk, NY
Exaclty as Chris and Bromel suggested, I did. Ditched my turd NV tranny and bought a brand new AX-15. But not before attempting a failed rebuild. Parts were scarce and the results of the reman was a complete failure. Lost a lot of time and money in the process, trying to save money. Hard lesson to swallow.

Bought mine locally in NJ from Rockland Standard Gear Inc. Another hard lesson learned: DO NOT TRUST ANY RANDO ON EBAY. Too many false advertisers who dont stand behind their claims.


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Did you get the Terminator transmission?
 

fourpointzero

TJ Enthusiast
Joined
Jun 1, 2016
Messages
992
Location
New Jersey
Did you get the Terminator transmission?
Yep, and for the record, the name means nothing! Its a marketing tag. Their AX-15 is direct from Japan. No different than any other trans sold new via another vendor. But it’s certainly better than the NV. The one in my TJ was noisy, terrible shifting into 2nd and 3rd. As soon as it started to pop out of 5th, I was done w it. Oh, almost forgot, it was soooo whiny you could hear it in 1, 2, and 3 up the block.


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g.hayduke

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Feb 19, 2019
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267
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New Mexico
Just in case, since nobody else mentioned it. Does it grind going into reverse when you are stopped after having the clutch out in neutral for a few seconds?

If so, could be that your clutch is not fully releasing which can cause symptoms similar to what you described.
 

fourpointzero

TJ Enthusiast
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Jun 1, 2016
Messages
992
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New Jersey
No, reverse grinds because from what I was told, there’s no synchro for reverse. To eliminate the grind, shift into first then immediately to reverse. Thats what I used to do on my NV and currently do w my AX15.

To answer the other question about direct bolt-on: the AX-15 is a direct fit. Pull the NV, remove the bell housing, attach the bell housing to the AX, then bolt in the trans. Lets not forget the shifter. According to Rockland, some shifters don’t direct fit. Mine, (2001) attached w no issues.


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reddvltj

TJ Enthusiast
Supporting Member
Joined
Apr 15, 2019
Messages
239
Location
Challis, ID
No, reverse grinds because from what I was told, there’s no synchro for reverse. To eliminate the grind, shift into first then immediately to reverse. Thats what I used to do on my NV and currently do w my AX15.

To answer the other question about direct bolt-on: the AX-15 is a direct fit. Pull the NV, remove the bell housing, attach the bell housing to the AX, then bolt in the trans. Lets not forget the shifter. According to Rockland, some shifters don’t direct fit. Mine, (2001) attached w no issues.


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the NV 3550 does have synchronized reverse the AX15 didn't
 
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g.hayduke

TJ Enthusiast
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Feb 19, 2019
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267
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New Mexico
No, reverse grinds because from what I was told, there’s no synchro for reverse. To eliminate the grind, shift into first then immediately to reverse. Thats what I used to do on my NV and currently do w my AX15
You should be able to go into reverse after holding the clutch in for a few seconds without grinding with or without a reverse synchro. If the clutch is fully releasing, the input side of the tranny should stop spinning within a couple seconds at idle and the output side is stopped if the vehicle is stopped. No need for a synchro.

I have driven manual transmissions for 50 years and counting. I have never had to go into another gear before reverse to avoid grinding EXCEPT when the clutch is not fully releasing.