Drivetrain swap questions: 4.2 258/T176/D300 to 2004 5.3 vortec/NV4500/D300

[1984CJ-EIGHT]

So I've been putting around in my semi-finished 84 Scrambler with a recently rebuilt T176 and D300 setup, and the original 4.2. I haven't veered too far away from home or taken it trial riding yet because I am still in the test driving phase. It's a fun little rig but a bit of a pig when loaded down or going up hills, and a 3:31 gear rear end doesn't help.

I guess I can't leave good enough alone, since I 'accidentally' found and bought a drop-out Vortec LM7 5.3 from a 2004 Chevy Avalanche, with 100K miles, and leak tested near perfect (1-3% per cyl), for a great deal. Having several Coronas and then 'just checking out some stuff' on Ebay is generally dangerous, as I'm sure many of you can agree. Anyway, the complete harness, ECU, fuse box and FBW pedal are included with it....arrives next week.

So for the LS Swap, my original thought was to buy the adapters from Novak or AA and keep the T176/D300. After adding up the swap parts, I'd be looking at around $2050 for the bellhousing, adapter plates, motor mounts, clutch and flywheel, driveshafts, etc. I do still have 2 driveshafts from a T5 setup, so maybe I can use those too.

Well damn, I thought, maybe I should just go after that NV4500 I really wanted...its just a bit more (about $750-1K of parts). I can buy a newly rebuilt one for about $2300, no core required. I can still use my rebuilt D300 and bolt it to the NV4500 as is. I don't need to clock it to flatten it, as I have a 2.5" lift and don't do any hard-core high-center-type crawling. I do however, like to get on the throttle every once in awhile, and I hate to put the little T176 in jeopardy, as tough as it is. Also, I can just put a used Chevy bellhousing on it and standard LS clutch and flywheel. I may even get to keep the driveshafts. My rear drive shaft is a bit short due to the lift anyway, so a longer drivetrain may help. Looking back at what I'm writing I kinda sound like I'm trying to rationalize a not-so-rational decision. Good thing I'm out of beer.

For those who have done this swap, here are my questions while pondering the NV4500. Thanks in advance, if you chose to respond:

I know that the T176 is 10.25" long. NV4500 is 12.37" long. That's 2.12" added to my drivetrain.
So....
1. Would I likely have to move the engine backwards or forward? An LS swap typically means that it has to be moved forward to make room against the firewall. Either way (T176 or NV4500), I will have to add motor mounts to the frame to move it.
2. Would the new engine & tranny position mean a shorter rear and longer front driveshaft or vice versa? Where does the length get added....how much to the front and how much to the rear, generally speaking?
3. What bellhousing clutch/flywheel combo (part numbers) should I get? I'm hoping to order most everything from Rock auto.
4. What parts/numbers for the hydraulic clutch swap?
5. What do you think I can get for the 258 and T176? The 258 Has lots of upgrades, elect ignition, new weber carb, etc. The T176 has around 25 miles on it since new bearings, seals and synchros. I may be able to recoup some $$.
6. Since the transmission shop says I can make the NV4500 to order (that's all he builds), what gears would you recommend? I plan on doing some light trail riding/crawling, and some highway driving to get there, about 50 miles away. 4:11 rear end will prob be added later. I will need the standard Chevy input shaft to the 5.3, but....not sure about the output to the Dana300...can't remember.

I plan on keeping the 5.3 mostly stock. 300 hp is more than enough for me. I'm sure there are other costs, ie, motor mounts, cross member fabrication parts, misc fabrication, etc that I'll have to consider. As far as the rest of the drivetrain, I have one piece rear axles and thats about the only upgrade I have there...for now. The only thing I may swap in the near future is the rear end for a 3:73 (if I stick with the T176) or 4:11 (if I go with the NV4500).

Anyway, thanks for reading the long post, hopefully any helpful answers will assist someone else who has the same questions.

Thanks again in advance!

 

[ag4ever]

I have the parts to install an LS / NV4500 / NP241c in my ‘82 project. Just have a stalled project due to other things being higher priority.

The NV4500 came stock behind 2003 era 2500 Chevy trucks with 6.0 engines, so bellhousing, flywheel, clutch, hydraulic throw out bearing are all stock Chevy parts.

To see what gear ratio works, I use http://www.grimmjeeper.com/gears.html

Keep in mind the NV4500 is VERY heavy! And shifts very slow, no speed shifting. If I was collecting parts, I’d opt for an AX-15. It should be plenty strong given how light the CJ-8 is.

 

[ag4ever]

Forgot to add, I have the novak motor mounts, they are weld in and are nice.

Everything from them has been great.

 

[mwqpd11]

258 up to $1k
T176 $600-$800

 

[1984CJ-EIGHT]

Thanks ag4evr, appreciate the feedback.

Yeah, I had an NV4500 when I first started the project, and it must have weighed 200-250 lbs! It was thinking that I was going to have a hard time installing it without removing the tub. I also had the rare 241v passenger drop tcase. Then I said nah, let’s just get this thing on the road. Haha.

I guess one thing I didn’t consider was what would be involved if I had to perform maintenance on it. I removed, rebuilt and reinstalled the t176 and d300 by myself. I doubt I could do that with the nv4500. A new clutch job would be a bear.

Are you removing the tub to install the drivetrain? Not sure how well the tub fits over the big tranny either. At first I thought you were going to offer to sell it to me, but sounds like your project will eventually move forward!

I’ll take a look at the motor mounts from Novak.

Thanks again, good luck!

 

[1984CJ-EIGHT]

258 up to $1k
T176 $600-$800

Thanks, that helps. I would be happy with 1500 for both

 

[ag4ever]

I plan to have a 1” body lift, so that should help the shift tower. My project is completely ground up, so it will be a bare frame with everything added, then the tub dropped on it.

 

[Boomer]

Keep in mind the NV4500 is VERY heavy! And shifts very slow, no speed shifting. If I was collecting parts, I’d opt for an AX-15. It should be plenty strong given how light the CJ-8 is.

I had a 1997 Dodge Ram 2500 with an NV4500 behind the Cummins 6BTA. The NV4500 won’t ever be confused with a sport car transmission, but I thought it shifted pretty nicely. It definitely doesn’t have long, clunky throws like say the T18 or SM420/465. The GM NV4500 type top cover/shifter works even smoother, and you can buy a short throw shifter kit for it that even further reduces the throw length and makes for quicker shifts.

I like the AX-15 except for its 3.83 1st gear ratio. The typical NV4500 has a 5.61 1st gear and the rarer, oddball early GM one has a 6.34 1st gear.

 

[1984CJ-EIGHT]

Thanks guys, good info here. If it shifts close to the T176, I'll be plenty happy. If I go with the nv4500, it will be awesome to have the granny gear with plenty of torque with 3:73 or 4:11s and still being able to cruise at 2k rpms / 65 mph. Best of everything.

Question.....I hope an NV4500 expert can answer this....

So I have the Dana 300 with the standard Jeep 23 spline input. I just rebuilt it so I hate to tear it open again to swap out the input shaft for a standard Chevy 32 spline. It's also another $450 to buy the adapter from Novak.

Solution: they shop who is offering to build me an NV4500 is saying he can add swap out the output shaft to a 23 spline shaft during the rebuild, no extra charge. I guess there was a Dodge 23 spline shaft that was used on earlier Dodge NV4500s, before they went to 29. He's just not sure whether to install a Chevy or Dodge tailhousing to make it bolt up to the Dana 300 transfer case. Frankly, neither do I. I was going to take out the Dana 300 and take it to his shop to ensure that it bolts up. However, I just put it all together and I kinda want to keep driving my Jeep until the drivetrain is dialed in and ready to install.

Does anyone know what I need to make these two units bolt to each other? Not only what tailhousing but is it going to work? Are the shafts the same length?

Any advice appreciated!!

 

[sdsupilot]

Do you still have the 241C? Is there a reason you want to use the Dana 300 vs the 241? I have a 241C in my 8 behind a 700r4. I really like it, not that the 300 is a bad choice either. The 241 has more front driveshaft clearance and shifts much nicer. It also use factory parts to attach to a chevy NV4500.

I would be hesitant to downgrade the strength of the NV4500 to adapt to the Dana 300 personally. That said your stock front or rear axle will likely break long before that output shaft.

 

[1984CJ-EIGHT]

Another update. Trans shop says he also has a rebuilt passenger drop NP208 transfer case that he can throw in for $300. Decisions, decisions. I wonder if the NV4500 and NP208 drivetrain will be too long for my Scrambler. it also has a slip yoke which I'm not familiar with. Has anyone run this combo before? He also reminded me that he has the external slave cylinder setup (older) NV4500, which may be better in case it ever needs replacing. I guess I just need that larger chevy bellhousing.

 

[1984CJ-EIGHT]

Do you still have the 241C? Is there a reason you want to use the Dana 300 vs the 241? I have a 241C in my 8 behind a 700r4. I really like it, not that the 300 is a bad choice either. The 241 has more front driveshaft clearance and shifts much nicer. It also use factory parts to attach to a chevy NV4500.

I would be hesitant to downgrade the strength of the NV4500 to adapt to the Dana 300 personally. That said your stock front or rear axle will likely break long before that output shaft.

Thanks for the recommendation. No, I sure wish I did still have it, although it may have needed a rebuild. I can't seem to find one under 2k that is rebuilt. I found this 208 (post above) that has a passenger drop for $300 (discounted since I'm buying the NV4500 and he has this 208 ready to go) that should work, and fit simliar to the NP241, I believe, with the exception of the slip yoke on the 208. I've read about how much better the 241 is, but I figure this rebuilt 208 should last plenty long for the type of driving I'll be doing. It will have a custom made skid plate to protect the aluminum housing. Do you know if the 241 case is about as long as the 208?
Thanks again!

 

[1984CJ-EIGHT]

I plan to have a 1” body lift, so that should help the shift tower. My project is completely ground up, so it will be a bare frame with everything added, then the tub dropped on it.

Thats the way to go. I thought about trying to lift my tub with an engine hoist, not sure it that will work, but I may try. I'd love to see it when it's on there!

 

[1984CJ-EIGHT]

I had a 1997 Dodge Ram 2500 with an NV4500 behind the Cummins 6BTA. The NV4500 won’t ever be confused with a sport car transmission, but I thought it shifted pretty nicely. It definitely doesn’t have long, clunky throws like say the T18 or SM420/465. The GM NV4500 type top cover/shifter works even smoother, and you can buy a short throw shifter kit for it that even further reduces the throw length and makes for quicker shifts.

I like the AX-15 except for its 3.83 1st gear ratio. The typical NV4500 has a 5.61 1st gear and the rarer, oddball early GM one has a 6.34 1st gear.

Yeah I think keeping the drivetrain as close to original will make things easier with less conversion kits and whatnot. I'll consider the short shifter but I'll probably leave whats in there.
Yeah, I think the NV4500 I'm getting has the 6.34 1st gear since it's the external hydraulic slave cylinder model. I'll probably start in 2nd more often than 1st gear!
Thanks for your input!

 

[sdsupilot]

Thanks for the recommendation. No, I sure wish I did still have it, although it may have needed a rebuild. I can't seem to find one under 2k that is rebuilt. I found this 208 (post above) that has a passenger drop for $300 (discounted since I'm buying the NV4500 and he has this 208 ready to go) that should work, and fit simliar to the NP241, I believe, with the exception of the slip yoke on the 208. I've read about how much better the 241 is, but I figure this rebuilt 208 should last plenty long for the type of driving I'll be doing. It will have a custom made skid plate to protect the aluminum housing. Do you know if the 241 case is about as long as the 208?
Thanks again!

The 241 is preferred to the 208 for a couple reasons. The 241 has a better low range 2.72 vs 2.61 of the 208. The biggest in your situation is that you can install a JB conversions slip yoke eliminator and really shorten the overall length. My 4.3/700r4/241C (with slip yoke eliminator) has a 24.5" rear driveshaft. I also used a clocking ring to rotate the transfer case up for better ground clearance.

You could easily rebuild a 241 yourself if you have a basic socket set and a good pair of snap ring pliers. They are much easier to work on than a Dana 300. If you don't use the Dana 300 I would recommend the 241 over the 208 for the reasons above.

 

[1984CJ-EIGHT]

The 241 is preferred to the 208 for a couple reasons. The 241 has a better low range 2.72 vs 2.61 of the 208. The biggest in your situation is that you can install a JB conversions slip yoke eliminator and really shorten the overall length. My 4.3/700r4/241C (with slip yoke eliminator) has a 24.5" rear driveshaft. I also used a clocking ring to rotate the transfer case up for better ground clearance.

You could easily rebuild a 241 yourself if you have a basic socket set and a good pair of snap ring pliers. They are much easier to work on than a Dana 300. If you don't use the Dana 300 I would recommend the 241 over the 208 for the reasons above.

Thanks for the input. I wish I had kept the 241, but I sold it last year. I think I'm going with the 208 for now. I'm also going to see what the driveshaft comes to and hopefully it will be at least 24". I will have to move the 5.3L LM7 engine forward a bit to ensure everything clears the firewall, but not sure what that translates to at the rear. Good thing it's not a CJ5!

 

[Bad Karma]

On my early GM NV4500, I got an advance adapters D300 kit. It has the new output shaft and tail housing.
My 5.3L LM7, i moved it forward, I cant remember why now, but it's a huge pain in the a$$ for radiator/fan clearance. I have actually looked at moving it back...

 

[1984CJ-EIGHT]

On my early GM NV4500, I got an advance adapters D300 kit. It has the new output shaft and tail housing.
My 5.3L LM7, i moved it forward, I cant remember why now, but it's a huge pain in the a$$ for radiator/fan clearance. I have actually looked at moving it back...

Was it maybe due to the heads/valve covers/engine clearance? Or maybe the shifter position? I thought about possibly having to cut the firewall a bit but I hope I don’t have to. I bought a new aluminum radiator when I was fixing up the engine bay, hope I can reuse for the LS swap. Do you have any pics you could share? Thanks for the input!

 

[1984CJ-EIGHT]

So I got the nv4500 and np208 combo yesterday. Rebuilt and ready to roll. So sounds like on an older NV4500 (93-95) the oem bellhousing (I think it’s 15639539) won’t work with a passengers side drop t-case because the external slave cylinder is on the passengers side, and will hit the front driveshaft, unless you have a big lift on it. Advanced adapters sells a bellhousing and slave cylinder kit that moves it to the drivers side but it’s pricey ($600 with all the parts). Anyone know of any alternatives?

 

[Bad Karma]

There is plenty of room behind engine for clearance. Shifter position could have been moved back too.
I was likely cheap/lazy and didn't want to change driveshaft lengths.... ya that's probably it, sounds like something past me would do.
No pics handy, might be one or 2 or 10 in my build thread.

Project "AZZ DRAGGER"

Figure its about time I start a build thread. First a little history lesson.. I've been into Jeeps since before I can remember (and I remember stuff from when I was 4 or 5 years old.) Got my first Jeep (which was my first "car") when I was 16. 1980 CJ-7 on 35" swampers. Not bad for a high...

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