Transmission upgrade for an XJ, NP231, Atlas or Dana 300...

Well, I was going to wait to do this upgrade till the stock transmission went out (the Peugeot 10) and replace the transfer case at the same time. Right now I have the Peugeot transmission, and the 21 spline NP 231 with a 4.5" lift on an 88 Cherokee with a stock I-6. Dana 30 from a 98 up front, and a Ford 8.8 rear with LSD. Also 4.10 gears and 33's. When the Peugeot goes, I am upgrading to the AX-15 transmission. Now I have been reading a bit more lately into transfer cases, and figured I would throw something up here to see if I could get some real world input instead of just reading stuff from the Advance Adapters catalog and books and such.

As of now I am leaning towards an NP 231 (newer 23 spline) with the HD upgrade, and defiantly a Slip Yoke Eliminator. I figure since I have it apart, I will go all out for it. I see this as probably the cheapest option, and probably easiest as I would have less custom work to do.

There are 2 other things I am considering however:
1. Possibly an Atlas 2 or 4 speed. I am not too familiar with this one, hence posting here. It seems like a great option, but the rig will mainly be a DD, and light-moderate trail rig so I need to have the speedometer for sure, and I would want to have the SYE with it as well. In doing the bit of looking I have into this, it seems to be the most expensive option, which is more than likely going to mean it won't happen.
2. The other option I am looking at is the Dana 300. Of what I know, it seems like an older model. Someone suggested I look into this one as an upgrade option and so I am. As mentioned above, I would be needing the speedometer hookup, and the SYE. Not too sure how easy it would be to use this one in place of the NP 231, but I am considering it as an option. Also not sure of cost at all.

Basicly I am wondering some advantages and disadvantages to each of the 3 options I have above, and if anyone has possibly done any of these setups, how did/do they work and how easy was it to set an XJ up to use with it?

Thanks for any help anyone can offer, I look forward to any response.

Paint

or a moderate trail rig i see no reason on going to a atlas or d300, just run a 231

ROBZ95Xj said:

or a moderate trail rig i see no reason on going to a atlas or d300, just run a 231

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Years down the road it will eventually be switched to a strictly off road rig. I should have put that in the thread, my bad. I will also be using the XJ for towing. Initially it will just be small boats and gear trailers for the Dive team, but as I get more into off roading, it will be using it to tow other vehicles, and a horse trailer. I guess this would be more of a long term upgrade for later. Rather do it now, well when I do the transmission, then have to do it a second time down the road.

Paint

I would leave it with an NP231 until it becomes a strictly offroad rig. If you want the best of both worlds, start collecting the parts now, keep an eye on the classifieds here, craigslist, and whatever else you want. If you do this you can pick every part up whenever it comes along for a bargain price.

Swapping the TC later is only 6 bolts and some linkages, it's not much of a job compared to swapping the transmission.

Paintballpsyco2369 said:

Years down the road it will eventually be switched to a strictly off road rig. I should have put that in the thread, my bad. I will also be using the XJ for towing. Initially it will just be small boats and gear trailers for the Dive team, but as I get more into off roading, it will be using it to tow other vehicles, and a horse trailer. I guess this would be more of a long term upgrade for later. Rather do it now, well when I do the transmission, then have to do it a second time down the road.

Paint

Click to expand...

like kastien said its real easy to swap out a tcase down the road, do you have $230 to shell out for a atlas at this point? i just dont see a need for one on a mild rig with 33's

kastein said:

I would leave it with an NP231 until it becomes a strictly offroad rig. If you want the best of both worlds, start collecting the parts now, keep an eye on the classifieds here, craigslist, and whatever else you want. If you do this you can pick every part up whenever it comes along for a bargain price.

Swapping the TC later is only 6 bolts and some linkages, it's not much of a job compared to swapping the transmission.

Click to expand...

I was not aware it was that easy to swap lol. When I do the upgrade, it will be the AX-15 and the upgraded 231 minimum. I was considering the Dana 300 and Atlas as alternates to the 231 to save time at a later point of upgrade if they really were "that much better". For now, I would be looking for parts, hunting and accumulating them until that day comes when I can do it all at once.

After doing some more digging today, I am not if the Dana 300 is as viable of an option right now. I managed to find out it is a passenger side drop, so I would have to flip it to even use it, plus get an adapter to use with the AX-15 and then all the little stuff to convert it over and such. I still like the idea of a more powerful one though so...
As for the Atlas, a friend of mine actually suggested it to me. I think it is way more than I would really ever need, but that is always subject to change with time lol. My main issue there is the cost.

My goal in looking for stuff now is twofold. On one hand, I save time and money later by having it done already. On the other (more viable option for me now) I get the know how now, and I can start accumulating the parts until I have them all, then when the day comes, I am ready to go. The only issue I see there, is I was planning to do transfer case and transmission at the same time. Realistically I think I can easily do the 231 and its upgrades easier and cheaper than the Dana 300 or the Atlas.

So I guess I should rephrase my original posted question, if I was looking for something down the road to build up the rig even more, which would be the best option?

On another note, the same person suggested a NV-4500 for a transmission upgrade. Kind of the same logic in my mind here comparing it to the AX-15. I think it is WAY more then I need. More so than that, they are EXTREMELY more than my budget will allow in the foreseeable future. Hence why I decided to stick with the AX-15. Also why I think the Atlas is more than necessary, that is more or less a cost driven decision. I figured I would still keep it as an option so that if the opportunity permits it, and it is "that much better" I may be able to wait longer until my budget permits me to get one.

The final concern I had really with it, is gas mileage. How much might a Dana 300 or Atlas affect the mileage compared to a 231?

ROBZ95Xj said:

like kastien said its real easy to swap out a tcase down the road, do you have $230 to shell out for a atlas at this point? i just dont see a need for one on a mild rig with 33's

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I thought the Atlas's were A LOT more than that? Given I have not see really many "outside prices", mostly just the Advance Adapters catalog. I know catalog prices are always WAY higher than "outside" prices, but are they really that much different?

As I mentioned above, I also think the Atlas is way more than I need. It was suggested by a friend, and I figure I would keep it as an option at least for now so...

Thanks again for the input.

Paint

Pretty sure that was a typo on Rob's part - more like $2300 would be in the right range.

Yeah, it's really not that difficult... with the transmission out of the rig, it takes about 5 minutes to separate the two with the right tools. With the transmission still in, a little longer, but still not a big deal at all.

Most people use a D300 with an NP231 chopped up and used as a range box before it (at least, from what I've seen) - i.e. they make an output shaft for the NP231 that fits into the D300 input, cut the front output portion off the housing, weld on a blockoff plate, make a clocking ring and custom back half of the case, etc. That way you can combine the 2.72:1 gearing of the NP231 in low-range with the 2.6:1 from the D300 low-range to get a low-low gearing of 7.07 (approximately.)

A D300 box is a gear driven box instead of a chain driven, not sure how that will affect gas mileage compared to an NP231 but it probably is not all that significant. In normal on-street operation the box is a passthrough (1:1 ratio, front output disconnected) and the only loss is frictional from the lubrication system.

Don't forget the 241OR tc. New for $1300...

o-gauge-steamer said:

The final concern I had really with it, is gas mileage. How much might a Dana 300 or Atlas affect the mileage compared to a 231?




I thought the Atlas's were A LOT more than that? Given I have not see really many "outside prices", mostly just the Advance Adapters catalog. I know catalog prices are always WAY higher than "outside" prices, but are they really that much different?

Paint

Click to expand...

t cases wont affect fuel milage, and yes that was a typo, prices for a atlas start out at 2300 with the 32 spline frt output(there no reason for the smaller output if your spending that much on a case) mine with the 4.3 lowrange and 1300 flanges came out to be a lil over 2600 to my door

o-gauge-steamer said:

Don't forget the 241OR tc. New for $1300...

Click to expand...

thats 1k to much for a chain driven case

If you are looking to beef up your tcase then do the chevy internals with the wider chain and more planetary gears.
I bought one built with a SYE all new from JBconversions IIRC, wasn't too bad but definatley wasn't 2300. Thinking it was around 1200 shipped to Kodiak, AK.
A few years ago I had done the upgrade from the Ba 10/5 in my 88.
Some advice would be to read alot and build a parts list in an excel spread sheet so you know when you are ready. I had picked parts from different yards. The tranny I selected had was good (the rig was punched in the rear end and totalled).
Make sure you grab all the associated nuts, bolts, linkages, and corssmembers from the doner rig. It suck when you have to go back in the rain and grab them at night while laying in a puddle of oil and water and unknown if you know what I mean.
When you are doing the upgrade you may want to consider replacing the reverse torx crap with real bolts or even studs.

Tire size will determine alot.

Stay with the 231 for now, worry about a beefier t-case later on.

not sure if it was mentioned, but if you go with an ax-15, i would get it with the external slave.

i know i dont look forward to replacing the internal slave on my 89 if it ever goes bad again. had to replace it a few years ago and its a job you only want to do once.

89xj said:

not sure if it was mentioned, but if you go with an ax-15, i would get it with the external slave.

i know i dont look forward to replacing the internal slave on my 89 if it ever goes bad again. had to replace it a few years ago and its a job you only want to do once.

Click to expand...

i had to replace the clutch on my ba 10/5 and i went a head and did the slave/throwout bearing all at the same time. if i ever have to pull it again ill do the same. price isnt too bad either

89xj said:

not sure if it was mentioned, but if you go with an ax-15, i would get it with the external slave.

i know i dont look forward to replacing the internal slave on my 89 if it ever goes bad again. had to replace it a few years ago and its a job you only want to do once.

Click to expand...

Yes that was one of the nicest things about upgrading to the ax-15. I will look at the old bell housing on my ba-10/5 but I think it can be converted to external slave as well. Other model jeeps were set up with an external slave IIRC
I got tired of chewing up seals, the input shaft must've had issues. I had to top off the tranny on a regular bassis. Also got really tired of it getting stuck in 1st gear, seemed to happen mostly when shifting to second while wheeling up an incline.

yes you can set a BA 10/5 up with an external slave cylinder.



Here is what caused me to finally do the upgrade.

kastein said:

Pretty sure that was a typo on Rob's part - more like $2300 would be in the right range.

Yeah, it's really not that difficult... with the transmission out of the rig, it takes about 5 minutes to separate the two with the right tools. With the transmission still in, a little longer, but still not a big deal at all.

Most people use a D300 with an NP231 chopped up and used as a range box before it (at least, from what I've seen) - i.e. they make an output shaft for the NP231 that fits into the D300 input, cut the front output portion off the housing, weld on a blockoff plate, make a clocking ring and custom back half of the case, etc. That way you can combine the 2.72:1 gearing of the NP231 in low-range with the 2.6:1 from the D300 low-range to get a low-low gearing of 7.07 (approximately.)

A D300 box is a gear driven box instead of a chain driven, not sure how that will affect gas mileage compared to an NP231 but it probably is not all that significant. In normal on-street operation the box is a passthrough (1:1 ratio, front output disconnected) and the only loss is frictional from the lubrication system.

Click to expand...

I figured that lol. I guess I never thought about difficulty in doing it, guess it is easier that I was thinking lol. The transfer case and transmission will be setup outside the vehicle and ready to go for when the Peugeot dies, then I can just swap everything in then and be done with it lol.

That i have never heard of, of course I am just starting to look into transfer case stuff so that could be why lol. What kinds of advantages would a setup like that give the user?

o-gauge-steamer said:

Don't forget the 241OR tc. New for $1300...

Click to expand...

Do you mean a 241 (then whatever those letters mean)?

ROBZ95Xj said:

t cases wont affect fuel milage, and yes that was a typo, prices for a atlas start out at 2300 with the 32 spline frt output(there no reason for the smaller output if your spending that much on a case) mine with the 4.3 lowrange and 1300 flanges came out to be a lil over 2600 to my door

Click to expand...

Right now that is WAY outside my price range. So no chance of it happening any time soon unless I win the lotto or something lol.

Stihl029 said:

If you are looking to beef up your tcase then do the chevy internals with the wider chain and more planetary gears.
I bought one built with a SYE all new from JBconversions IIRC, wasn't too bad but definatley wasn't 2300. Thinking it was around 1200 shipped to Kodiak, AK.
A few years ago I had done the upgrade from the Ba 10/5 in my 88.
Some advice would be to read alot and build a parts list in an excel spread sheet so you know when you are ready. I had picked parts from different yards. The tranny I selected had was good (the rig was punched in the rear end and totalled).
Make sure you grab all the associated nuts, bolts, linkages, and corssmembers from the doner rig. It suck when you have to go back in the rain and grab them at night while laying in a puddle of oil and water and unknown if you know what I mean.
When you are doing the upgrade you may want to consider replacing the reverse torx crap with real bolts or even studs.

Click to expand...

Looking to beef it up yes. My main thing with my whole rig build is building it as best as I can, doing it as cheap as possible, while at the same time, doing all that the right way. If a better part is a bit more, I will wait a bit till I can afford it. If the best parts are way out of my range, I will go with what I can work with. After this thread that seems to be the 231 now lol.

New is not really an option for me due to cost. that 1200 is a lot more than I have now, and I have a lot less than that even into the whole rig right now. This one will be built from whatever I can find here, other forums, craigslist and scrapyards so that when the time comes it is ready to go and just drop in when the current one dies as I know it will.

I like the list idea, I will have to start doing as much research into that as possible I think, maybe get something going on here for specific recommendations. It sounds like you did somewhat the same thing I am looking into for the 231 when you built it, any chance you have the parts list still?

I probably will replace that shit, I HATE those bolts... I don't have the ones I need even, I was working on the rig at my buddy's house and we were removing the seat belt bracket bolts, first one came out fine with the impact socket and earthquake impact. The second one managed to crack the socket VERTICALLY! I have broken many sockets, bolts and bits, and I have Never seen one break like that lol. I have most of the wrenches and sockets new, but none of the torx crap so that will more than likely get replaced when I do the swap for sure.

MoparManiac said:

Tire size will determine alot.

Stay with the 231 for now, worry about a beefier t-case later on.

Click to expand...

What range of parts would be suggested to start looking for something bigger and better?

89xj said:

not sure if it was mentioned, but if you go with an ax-15, i would get it with the external slave.

i know i dont look forward to replacing the internal slave on my 89 if it ever goes bad again. had to replace it a few years ago and its a job you only want to do once.

Click to expand...

I asked this earlier up, but what range of years have an external one?

88xj 4.0 31" said:

i had to replace the clutch on my ba 10/5 and i went a head and did the slave/throwout bearing all at the same time. if i ever have to pull it again ill do the same. price isnt too bad either

Click to expand...

I will probably be doing that as well with the AX-15, unless the parts available to me at the time are still good, then will just reuse them I guess.

Stihl029 said:

yes you can set a BA 10/5 up with an external slave cylinder.

Here is what caused me to finally do the upgrade.

Click to expand...

What caused that to happen?

Thanks again for all the input,

Paint

What caused that to happen?

[/QUOTE]
French Built Quality!!!!!
There is a reason why we don't have french built vehicles here any more........................................OBVIUOSLY!!!

For t-case, you can do the 231/d300 setup if you wanted the twin stick/more low range. You could even do the 2-low kit if you wanted.

markaboo929 said:

What caused that to happen?


French Built Quality!!!!!
There is a reason why we don't have french built vehicles here any more........................................OBVIUOSLY!!!

Click to expand...

Lol, I can see lol.

Johnnie Walker said:

For t-case, you can do the 231/d300 setup if you wanted the twin stick/more low range. You could even do the 2-low kit if you wanted.

Click to expand...

For now I think I am going to go with the 231 upgrade, and look into the 231/300 setup for the future.

Thanks again for all the input.

Paint