Post by
VStar650CL »
https://forums.nicoclub.com/vstar650cl-u299034.html
Thu Dec 21, 2023 10:02 am
That's a complicated question, so I need to give you a long-winded answer. CVT trannies have a steel belt riding on a pair of steel pulleys in place of traditional planetaries. Without any sacrificial clutch material, that means they're completely dependent on the quality of the fluid to prevent metal from meeting metal. I.e., when the fluid dies, the tranny dies with it. The flip side is, with good fluid maintenance, there are no clutches to wear out and they can be perpetual motion machines. Since Nissan absurdly doesn't recommend regular changes, a lot of people simply run their trannies into the ground out of ignorance.
That means any used tranny you get will be a crapshoot. However, there is a fairly bulletproof way to make sure you get a good one. That's to obtain the TCM from the donor vehicle along with the used CVT. It happens that it will also save you a lot of programming to go that route, but mainly you can hook up the TCM in the recipient and read the codes out of the used TCM before installing anything. If it has judder codes (P17F1/P17F0) or other pressure related codes, you know immediately that it's a clinker and you can return it to the junkyard with no harm done. If it passes that test, have a look and smell at the fluid. CVT's don't make "ATF soup" like a regular automatic (again, no clutches to speak of) but the fluid shouldn't be dark brown and shouldn't smell burnt. Light brown is okay and they always smell varnishy, that's normal. If it passes both of those tests, freshen the fluid and you're good to go.
Rebuilding is a different matter. There are rebuild kits with a new belt, pulleys, and pump available for most models, but installing them is fairly specialized operation and you're still into a new Valve Body and a complete reprogramming. So unless you have a rebuilder intimately familiar with Jatco CVT's, by the time you're done, you're probably just as well off purchasing a reman from Nissan.
Lastly, with a new/reman or a used one lacking the TCM, expect it to need a procedure for reading the IP Chars and storing them in the new TCM. Most of them behave badly without IP's and some don't even move. On some vehicles with a ROM in the tranny you can do that with the CVTz50 app, but on most you need to scan a QR code or use a CD along with a specialized scanner. That means a trip to the dealer (possibly towed) if you lack the needed equipment.
