Post by rccolacc on Jun 22, 2005 16:23:47 GMT -5
I know the 231 swap into a Grand Cherokee has already been written about several times in other forums, but I thought I’d share some things not covered in those articles.
Sorry for my really long post, but I just want to be thorough and clear.
I bought a ’97 Jeep Grand Cherokee in October with a bad viscous coupler on the NP249 (got a sweet deal too because the dealer thought it the Jeep was junk). I’ve been driving around the Jeep with no front driveshaft for the past 9 months while I come up with a NP 231 to put in it.
Over Christmas I bought an ’88 231 that came out of a Jeep Cherokee. It had a 21 spline input shaft, so I pulled the input shaft and planetary gearset out of my 249 and put it in the 231 and installed the whole thing. I realized the gear cut was different between the two input shafts, but I read somewhere (Carl aka Swampy) that as long as you swapped the whole planetary, it would work. It looked beautiful and fit fine, but upon driving it down the street, I noticed it had a loud roaring sound at any speed greater than 10 mph. I replaced a bearing in the tailhousing thinking it was that, but nothing worked. I was forced to put the 249 back in it.
A few months later I bought a 23 spline input shaft from a guy that had it in his 94 Grand Cherokee. I figured it should work since the ’94 shaft was from the early gear cut and so was my case. I put the whole case together, and the other day attempted to swap it in to my Grand. Wouldn’t you know, but it would not fit! The shaft slid over the transmission splines, and the studs went in their holes, but the case was .25” from going all the way on to the transmission. After removing the 231 and comparing it to my 249, I could see the input shafts were different. They were both 23 spline, and they both were the same length coming out of the case, but the ‘94 had a collar on the inside preventing the transmission shaft from sliding all the way in (see cut-away diagram). Andy Westfall put it on a lathe here at school to machine out that collar so the transmission will fit all the way in. Hopefully the third time I install this it will work.
The lesson learned from this swap is get the right year transfer case or you end up working a lot to get it to fit. I should have bought a 95 or newer case and swapped it in. That way my 97 input shaft would fit right on and not make noise.
I also would like to add that I’m getting pretty good at taking apart the 231 and putting it back together. I think I’ve RTVed the case halves together 5 times in the past 6 months doing this swap. I’m also getting pretty good at swapping the transfer case. I pulled the 249, installed the 231, pulled it back off and put back on the 249 in 3 hours this past time. All in a dorm parking lot too! I just hope this next time I do it, it’s the last time.
When this is done I'll do a write-up in the project section. I just wanted to give a report on the progress so far.
-RC
Sorry for my really long post, but I just want to be thorough and clear.
I bought a ’97 Jeep Grand Cherokee in October with a bad viscous coupler on the NP249 (got a sweet deal too because the dealer thought it the Jeep was junk). I’ve been driving around the Jeep with no front driveshaft for the past 9 months while I come up with a NP 231 to put in it.
Over Christmas I bought an ’88 231 that came out of a Jeep Cherokee. It had a 21 spline input shaft, so I pulled the input shaft and planetary gearset out of my 249 and put it in the 231 and installed the whole thing. I realized the gear cut was different between the two input shafts, but I read somewhere (Carl aka Swampy) that as long as you swapped the whole planetary, it would work. It looked beautiful and fit fine, but upon driving it down the street, I noticed it had a loud roaring sound at any speed greater than 10 mph. I replaced a bearing in the tailhousing thinking it was that, but nothing worked. I was forced to put the 249 back in it.
A few months later I bought a 23 spline input shaft from a guy that had it in his 94 Grand Cherokee. I figured it should work since the ’94 shaft was from the early gear cut and so was my case. I put the whole case together, and the other day attempted to swap it in to my Grand. Wouldn’t you know, but it would not fit! The shaft slid over the transmission splines, and the studs went in their holes, but the case was .25” from going all the way on to the transmission. After removing the 231 and comparing it to my 249, I could see the input shafts were different. They were both 23 spline, and they both were the same length coming out of the case, but the ‘94 had a collar on the inside preventing the transmission shaft from sliding all the way in (see cut-away diagram). Andy Westfall put it on a lathe here at school to machine out that collar so the transmission will fit all the way in. Hopefully the third time I install this it will work.
The lesson learned from this swap is get the right year transfer case or you end up working a lot to get it to fit. I should have bought a 95 or newer case and swapped it in. That way my 97 input shaft would fit right on and not make noise.
I also would like to add that I’m getting pretty good at taking apart the 231 and putting it back together. I think I’ve RTVed the case halves together 5 times in the past 6 months doing this swap. I’m also getting pretty good at swapping the transfer case. I pulled the 249, installed the 231, pulled it back off and put back on the 249 in 3 hours this past time. All in a dorm parking lot too! I just hope this next time I do it, it’s the last time.
When this is done I'll do a write-up in the project section. I just wanted to give a report on the progress so far.
-RC