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TeraFlex 4:1 reduction or NP241

27K views 51 replies 27 participants last post by  Junior F-Nis 
#1 ·
I am looking to get a little more gearing in low range. I have a 2003 Wrangler SE with the 2.4L and the NV1500 manual 5 speed transmission. I have done the research regarding the two and I know that both would be compatible with the 23 spline output shaft of the transmission.

So, given the choice which option do you think is better? Durability? Ease of install? Positives/negatives? Anything you can think of.

Kyle
 
#42 ·
On that note I picked up a Tera 4:1 from Sam's offroad for around $850. Works great, no noise... well except at higher RPM's in low range.
They sell blemished ones that are cheaper and the only thing I noticed was that mine wasnt all shiney when I got it...
They only have these blemished ones from time to time so you would just have to check every now and then to see if they have any in stock.
http://www.sams4x4store.com/index.html
 
#19 ·
The 2003-2006 model year SE's with the 2.4L have a NV1500 transmission which has the same spline count as the tranny behind the 6cyl. So in my case I could use one, unlike the 2.5L which had the AX-5 and a 21 spline out put shaft. So yes it was just the older 2.5's that you couldn't.
 
#16 ·
I bought one of the original 4:1 kits from Tera and got it for $500 because a customer thought it was too noisy. I never really had a problem. I rebuilt it with a new input gear when I swapped the engine/trans a few years ago. Slightly louder, and puked out the fluid through the vent (straight onto the exhaust).

I rebuilt it again last weekend with a new chain and output bearing and it's now considerably louder than before (I should mention that I'm running it with only a front shaft as I work out some other problems but did before the rebuild as well). Still pukes fluid, so today I received a catch-can from Summit that I'll install on the vent.

Never had a problem with the case/gears/shifting.

Paul
 
#22 ·
Paul, try bumping up the vent tube size to 3/8" to reduce the capillary action that keeps fluid in the vent hose. Sometimes that will let it drain back into the case rather than keeping it in the hose where more fluid accumulation will eventually push it out.

Currie had to do the same with their Fab 9 housings to stop gear oil from puking out the vent lines.
 
#17 · (Edited)
I've had my Tera Flex 4:1 for about 7+ years now with no problems. One benefit is that you don't need to mess with the drive-shafts or shifter...easy install. Took me and a friend about an hour and a half to install it. It "whines" in low range, but only when I'm in a higher gear and at higher RPMs--like 3K+. ...but I should really be in 4H then anyway.

EDIT: No leaks from mine either. ...I think I paid about $700 for it. I don't think I'd pay any more than that.
 
#23 ·
Before I did either of those cases with your drivetrain, I would get a doubler in front of the t-case, cut the motor mounts loose and slide the motor forward exactly the depth of the doubler.

No driveshaft mods, you have the room, you can modify the fan shroud, you can bend the trans shifter, and you need all the gearing you can get.

The Rubi case while being a great case, is a pig. It's not much smaller than an Atlas II and it's only 4-1. I've installed a few, the customers are very happy, but it's still a pig.
 
#26 ·
That is a great idea, I don't think I would have to modify the fan shroud either because it is an electric fan and the shroud may be a total of three inches long with a good 10 inches between the motor and shroud.

However... I travel a lot for work (by a lot I am gone 80% of the year) so this upgrade is going to be about 5 days before a trip to NC and AR with some friends for some wheeling. I know it probably isn't the smartest thing to choose an upgrade based on the amount of time it takes to install. But right now that is the case.

Honestly I think what I will do is go with the 241 or the Tera still (No still haven't made up my mind) and move the motor forward and add the doubler the next time I am home to work on the Jeep, because you are right with this motor I do need all the gear I can get, which is why I am wanting to do the 4:1 before the trip. I am tired of feathering the clutch, and that is with 4.88's in the diffs. Again thank you for that idea!

Kyle
 
#24 ·
terra is junk!! i went rounds with them on my kit..there warranty well there is none.they have a clause that says you cant go over 25mph with it in low.my kit lasted 2 weeks..junk junk junk..i tore it apart and the little bronze bushings are cheap junk.
get the rubi case...32 spline outputs.wide chain,1350 yokes,10 times stronger case. there is no comparisent to the terra 231. the rubi case is 100 times better.
 
#27 ·
You also have a good point! About the yokes and overall better strength of the case! I think if I can find out if a drive shaft place in my area has a turn around time of less than a few days I will go the 241 route. I don't mind if the spedo doesn't work for this trip, but kinda need those drive shafts!

Also out of curiosity, what motor did you have when you trashed the Tera? As mentioned earlier I only have the 2.4L, which I think has a peak hp of 142 at the crank...
 
#29 ·
I had a Teralow 4:1 kit in my 97 TJ behind my AX-15. Mine was noisy too. Only in Low Range, but noisy yes. It was worse before it broke in some. Never had any leaking issues from mine, but the main input bearing at the planetary's failed twice. The first time it failed, I contacted Teraflex and they warranty'd it as it was within the time constraints. While they had it, they replaced my chain and all the bearings in it as well. All on their dime. A couple years later it failed again. You could have taken a picture of the two failures and not been able to tell the difference. I tried to get a hold of Teraflex with no success. Email, phone call. Nothing. So I went to Advance Adapters and purchased a 4.3:1 Atlas II. Much happier with that. As for your case, I would go with the 241 if possible. I have heard pretty good stuff about that TC.
 
#34 ·
You guys keep mentioning the speed limitations for the Tera unit in 4low. Don't our stock transfer cases have the same limitations? I know the limit in 4hi is 55mph, I don't have my owners manual to reference it right now.

Really though, if I have to travel faster than 25mph I would be in 4hi.

I am still leaning toward the 241 though just for the upgrade in strength over the 231 overall, depending on the drive shaft turn around in my area.
 
#35 ·
Its not the speed so much as the input rpm. After mine exploded tera told me that it isn't supposed to be spun faster the 2500 rpm's. You can achieve that with any motor in low range. I personally know of 4 blown tera lows (one was mine) but I live in michigan where snow, mud, and sand are everywhere. I love my Atlas!
 
#43 ·
I know a guy that blew up his Tera-Low gears in his NP231 4 times.
The last time it fractured the case. He gave up in disgust and bought an Atlas II.
 
#37 ·
It's not that you can't exceed 2500 RPMs. They just don't recommend it be done for extended periods of time.

Here is what it says in the installation guide:
High RPM Warning
Do not exceed 2500-3000 RPM for sustained periods of time when using the Low231 in low range.
Avoid high engine speeds when using the Low231 in low range in 4th or 5th gear with manual transmissions or with high gear automatics. This is common when driving in snow, mud, or sand. Because the gears are turning 50% faster and with the high gear ratio, it is possible for input speeds to reach 6500 RPM and cause damage to the transfer case.
We recommend using a lower gear in high-range for higher speeds rather than running the Low231 at extreme RPM’s.
http://www.teraflex.biz/low-231-hd-transfer-case-23-spline-long-input.html
 
#40 ·
I don't think so. The Rubicon came out as a 2003 model which was the same year Jeep switched over to the 2.4L SE with the NV1500 5 speed manual which has the 23 spline output, then all of their transmissions has 23 spline outputs.

Maybe look into Advance Adapters?
 
#45 ·
Because there is little info out there about t-case swaps with my motor and tranny combo, I want to keep this updated for the next guy.

I know some of you are going to think I'm an idiot, and we will see I guess. I ended up going with the Tera unit. My reasoning is that I have about 5-6 days from the time I get home to the time the trip is to get everything ready, so I really didn't have the option to spend time getting drive shafts/yokes adjusted for the NP241.

I am going to continue to keep the thread updated. If I break it I'll let you fawkers know! :flipoff2:
 
#47 ·
Nearly July, hows your Terra kit doing? I'm looking to out either a 231 with TF in, or install a 241OR (if I can find one) in my 98 ZJ with Auto. Not sure if anyone has has experience with the ZJ 44RE auto working with the 241OR???
 
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