I am active duty military currently serving in Guantanamo Bay, Cuba with limited resources and I'm hoping you guys help me identify a solution to get my jeep back on the road.
I ordered Novak’s NP231J Master Rebuild Kit for my 2001 Jeep TJ with the 2.5L I4 and AX5 transmission, had it shipped to another active duty member who then flew with it to Cuba. I ordered this kit for a rebuild because mine would not shift out of 2H so I suspected something wrong internally. I found out after disassembly that the previous owner installed an indicator light switch with a longer shaft which prevented the shift plate from moving. Since I already had it removed and open I opted to pursue rebuilding.
While installing the front output bearing the case cracked so I had to use another front case half. Below are the details of the original case contrasted to the replacement (older) case:
Original case: NP231J. Assembly Number 5209 9364 AB. Serial Number 6 28 00 03. Ratio 272
Replacement case: NP231J. Assembly Number 5300 6094. Serial Number 6 27 89 2. Ratio 272
I disassembled the replacement case, successfully replaced the bearings with those from the Novak kit and installed the original input gear and planetary gear (along with all the other components from the original case) into the replacement case. I bench tested it and it turned smoothly and shifted correctly 2H/4H/N/4l. There was notable bearing/annulus gear noise when turning it on the bench but it was thought to be because it was "dry" and had not yet been filled with ATF. I installed the transfer case, filled it with ATF 4+ and test drove it in idle a short distance in my neighborhood. It shifted well but was still very noisy compared to the old transfer case. The noise was louder at higher speeds and subsequently louder in each gear from 2H to 4L. There was NO noticeable noise in reverse and it sounded just as it did prior to rebuild. Also, in 4L there was a "squeak" that was very repetitive with each revolution of the output shafts that was not noticed on bench testing but only under load.
I have since removed the rebuilt case and bench tested it. I cannot reproduce the squeak in 4L but the bearing/annulus/planetary noise is just as noticeable with fluid as it was without. This is when I remembered reading that pre-1994 gears have a slightly different cut. So, I took my replacement case planetary and input gear and tried to place it in the annulus gear of the original case: it would not fit. This led me to check other compatibility issues. The replacement case input gear would not fit my transmission output gear (21 splint, 27mm in diameter). The input gear has a larger diameter to receive a different transmission gear. I do not know which transmission the replacement case came from, it was from a junkyard.
As I see it I may have the following options:
1) Find a replacement NP231 front case half from a 1996 or newer which, if my research is correct, would have the "newer" cut annulus gears.
2) Continue to use the replacement case housing and instead use the replacement case's planetary gear with the older style gear cutting. This would require finding a replacement for the input gear to be compatible with my AX5 transmission.
Are there any other options I may not have considered? I cannot purchase a whole new NP231 because there is no way to get that here to the island. The only "freight" we are able to receive would have to come by USPS and takes 4-6 weeks in most cases.
Any ideas or suggestions? Anyone with a case half they would sell and ship to a friend of mine in the states?
I ordered Novak’s NP231J Master Rebuild Kit for my 2001 Jeep TJ with the 2.5L I4 and AX5 transmission, had it shipped to another active duty member who then flew with it to Cuba. I ordered this kit for a rebuild because mine would not shift out of 2H so I suspected something wrong internally. I found out after disassembly that the previous owner installed an indicator light switch with a longer shaft which prevented the shift plate from moving. Since I already had it removed and open I opted to pursue rebuilding.
While installing the front output bearing the case cracked so I had to use another front case half. Below are the details of the original case contrasted to the replacement (older) case:
Original case: NP231J. Assembly Number 5209 9364 AB. Serial Number 6 28 00 03. Ratio 272
Replacement case: NP231J. Assembly Number 5300 6094. Serial Number 6 27 89 2. Ratio 272
I disassembled the replacement case, successfully replaced the bearings with those from the Novak kit and installed the original input gear and planetary gear (along with all the other components from the original case) into the replacement case. I bench tested it and it turned smoothly and shifted correctly 2H/4H/N/4l. There was notable bearing/annulus gear noise when turning it on the bench but it was thought to be because it was "dry" and had not yet been filled with ATF. I installed the transfer case, filled it with ATF 4+ and test drove it in idle a short distance in my neighborhood. It shifted well but was still very noisy compared to the old transfer case. The noise was louder at higher speeds and subsequently louder in each gear from 2H to 4L. There was NO noticeable noise in reverse and it sounded just as it did prior to rebuild. Also, in 4L there was a "squeak" that was very repetitive with each revolution of the output shafts that was not noticed on bench testing but only under load.
I have since removed the rebuilt case and bench tested it. I cannot reproduce the squeak in 4L but the bearing/annulus/planetary noise is just as noticeable with fluid as it was without. This is when I remembered reading that pre-1994 gears have a slightly different cut. So, I took my replacement case planetary and input gear and tried to place it in the annulus gear of the original case: it would not fit. This led me to check other compatibility issues. The replacement case input gear would not fit my transmission output gear (21 splint, 27mm in diameter). The input gear has a larger diameter to receive a different transmission gear. I do not know which transmission the replacement case came from, it was from a junkyard.
As I see it I may have the following options:
1) Find a replacement NP231 front case half from a 1996 or newer which, if my research is correct, would have the "newer" cut annulus gears.
2) Continue to use the replacement case housing and instead use the replacement case's planetary gear with the older style gear cutting. This would require finding a replacement for the input gear to be compatible with my AX5 transmission.
Are there any other options I may not have considered? I cannot purchase a whole new NP231 because there is no way to get that here to the island. The only "freight" we are able to receive would have to come by USPS and takes 4-6 weeks in most cases.
Any ideas or suggestions? Anyone with a case half they would sell and ship to a friend of mine in the states?
