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Tremec 4050 jku

402xjeeper

Active member
Joined
Jun 8, 2021
Member Number
4030
Messages
41
Anyone put a tremec 4050 5sp ik a jku yet? I am about to do so on a near stock 13 jku Rubicon. Eventually to be on 37"s 5.38 gears ect. I need a dd, ovelander crawler. This is much more of a chalenge than building a more specialized rig.
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Since it's not stated I'm going to assume you have the standard NSG-370 manual transmission, so I have to question why you would go through the process on a stock engine setup?

Also, you should delete your duplicate post.
 
The 370 sucks. Try shifting fast from 5th to 6th...It almost always try's to go into reverse. When I hemi swapped mine switching to the Getrag 238 was one of the best upgrades I've done. I don't have any info on the 4050 but the 6.16 first gear would be neat.
 
buc4x said:
The 370 sucks. Try shifting fast from 5th to 6th...It almost always try's to go into reverse. When I hemi swapped mine switching to the Getrag 238 was one of the best upgrades I've done. I don't have any info on the 4050 but the 6.16 first gear would be neat.
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For the record, I own a 2011 Jeep JK with the NSG-370 and it's my daily driver. I don't find it to be problematic nor do I have any issues shifting from 5th to 6th. But everyone has a different experience with it.

I could understand swapping transmissions with an engine swap, the NSG-370 is not know for high torque handling. But we're talking about the standard 3.6l v6 that comes in a 2013. To me it's a waste of time and money with little gain, so I question why.
 
Will Scarlet said:
Eeper overdSince it's not stated I'm going to assume you have the standard NSG-370 manual transmission, so I have to question why you would go through the process on a stock engine setup?

Also, you should delete your duplicate post.
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The 370 needs a 5th gear syncro. The 4050 has a much lower 1st gear, and a deeper overdrve. The 3.6 is a good motor, wide powerband. With no other changes my crawl will be 102 -1, and my cruise rpm will be even lower. Plus if I do ever motor swap this has the torque capacity.
 
Will Scarlet said:
38For the record, I own a 2011 Jeep JK with the NSG-370 and it's my daily driver. I don't find it to be problematic nor do I have any issues shifting from 5th to 6th. But everyone 38has a different experience with it.

I could understand swapping transmissions with an engine swap, the NSG-370 is not know for high torque handling. But we're talking about the standard 3.6l v6 that comes in a 2013. To me it's a waste of time and money with little gain, so I question why.
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The crawl ratio change is equivalent to 5.38 to 1 r+p swap. The wide rpm band on a v6 works better than a narrow banded motor such as a tdi with bigger gear splits. The ratios after I get to that part of the build will match the best combo ever offered by jeep..t-18 + warn overdrive!
 
Got the bellhousing! To clarify I may or may not go down to 5.38 gears, but if I do I get a crawl of about 130-1, and the cruising rpm of a 370 6 sp with 4.88 gears. As to a waste of money, many would say any jeep is, I think "tons" and motor swaps, and roof top tents are bigger ones!
 
Just know you're going from 5 usable gears + OD to 3 usable gears + a crawl gear and an OD. Hopefully running the 5.38s will make up for the wide ratio. My experience with wide ratio trans, even behind a V8 was not great. Always seem to be between gears.

I don't see why they didn't make that trans a 6 spd. But I guess they were just going after a new, lightweight Nv4500.
 
I have done nv4500 swaps at a previous job, they sre way too big for a jeep. The 4050 has less gear spread than the muncie 465 that I used to run. I agree that you may get 4 usable gears. 1st through 4th if I go 37"s on 4.10 r + p. 2nd through 5th on 5.38s. I would have gone to 4.88s and35-37s and the stock 6 speed if it had not started to shift noisy into 5th. I will date myself a little, but I loved idling up and down lions back in 2nd gear low range, even being on the throttle coming down. A properly geared 4x4 makes all the difference.
 
402xjeeper said:
The 370 needs a 5th gear syncro. The 4050 has a much lower 1st gear, and a deeper overdrve. The 3.6 is a good motor, wide powerband. With no other changes my crawl will be 102 -1, and my cruise rpm will be even lower. Plus if I do ever motor swap this has the torque capacity.
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402xjeeper said:
The crawl ratio change is equivalent to 5.38 to 1 r+p swap. The wide rpm band on a v6 works better than a narrow banded motor such as a tdi with bigger gear splits. The ratios after I get to that part of the build will match the best combo ever offered by jeep..t-18 + warn overdrive!
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I like the thought process here, which is what I was after for my original post here. Still, I rather rebuild the NSG-370 then spend for a new transmission, but that's just me.

Just to state, I was just curious about your reasons for doing this. How you spend your money is all up to you.

Good luck and I'm interested on how this turns out for you. :beer:
 
Will Scarlet said:
I like the thought process here, which is what I was after for my original post here. Still, I rather rebuild the NSG-370 then spend for a new transmission, but that's just me.

Just to state, I was just curious about your reasons for doing this. How you spend your money is all up to you.

Good luck and I'm interested on how this turns out for you. :beer:
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Especially for the price. I really liked the idea of the 4050 when they released it, but after seeing the ratios, and that it's not much if any lighter than a 4500, I don't see the cost justification.

Could probably rebuild the 370 and go 4spd atlas for about the same money and easily be 100-200:1+ crawl.

I do know the 370 is on the ragged edge of its capacity with the 3.6, so if an engine swap is in the plans, I guess it all makes sense.

Also, I should add, I'm not trying to shit on this. But more understand the reasons. I do hope that 3.6 has the power to pull the wider ratios and it works out well. I do like the idea of a granny gear, but I don't like the idea of giving up a usable street gear in exchange. How long till the bronco 7 spd is in junk yards? :laughing:
 
X2. I have Ford's version of this (ZF S5-42) in a few vehicles and I can assure you that you will lose driveability compared to a closer ratio 6 speed. Also 5.38 and 37s is too low for a DD. Go more moderate on your axle gears and get some t-case gearing. Something like 4.56 or 4.88 and either a doubler or 4:1 gears.

I would rather have a doubler or Atlas 4 speed with the stock 6 speed transmission than the insane gaps between the gears that I currently endure. Your V6 will hate those ratios. I have a 300 HP 351W for reference.

If you drive your Jeep now every day - you can see what the ratio split is going to be like by not using 2nd gear and 4th gear. That's basically the ratio shift on the TR4050.
 
FordFascist said:
X2. I have Ford's version of this (ZF S5-42) in a few vehicles and I can assure you that you will lose driveability compared to a closer ratio 6 speed.
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Really depends on your engine.

For a minivan engine that's struggling to push a brick through the air I agree.

For an engine with a wide power band in a vehicle with a better overall power to weight ratio you can get away with much wider splits.
 
arse_sidewards said:
Really depends on your engine.

For a minivan engine that's struggling to push a brick through the air I agree.

For an engine with a wide power band in a vehicle with a better overall power to weight ratio you can get away with much wider splits.
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You're not wrong - however he's not gaining anything by switching. He would be better off spending $4k on a better transfercase than trying to go about this plan.
 
I have the 3.6, nearly stock with a tuner and silicone intake tube, oversized radiator. Plenty of power. I would have gone with an additional reduction box,( that was the original plan) but I am not rebuolding junk that fails at 60k miles on a still bone stock jeep. The trans swap has a packaging advantage. It uses oem drivelines etc. All oem jeep systems will functipn normally, if I need a part while on a trip it will be on the shelf and ready. I have had way custom drivetrains before and they are great and have their place, but the atvantage of a jk is that it is the toyota camry of 4x4s. If I upgrade every failure point, avoid excess weight and custom parts, I can drive it anywhere and wheel.
 
The .74 od with 5.38 is the same final drive as 4.88 with the stock .84 overdrive. I am not commited to 5.38s yet, but the math works. I have run3.55s in a v8 cj7 without overdrive on 33s, Marlin crawler toyota on 35"s w 4.88s v8 5 speed bronco. V6 cjs with many gear combos down to 5.38. I worked at a 4x4 shop and sold a/a, novak. Terralow plus 100s of gear jobs and learned that there is no perfect combo. Nothing is worse than breaking a custom built driveline on Pritchett Canyon early in your(non safari week) Moab trip and having to wait days to get a new one.
 
I can cruise 75 in the jk all stock 4.11/31" tires. The tremec and 4.88s would be about the same on 31"s
 
Well fuck, if you had mentioned the silicone I take boot in the op, we could have avoided all this! :flipoff2:

The taller OD may be nice in oder to run lower r&p. You may want to run numbers on speed/rpm in 4th. When you do have to down shift, that's a much larger gap, probably more similar to going from 6th to 4th in the 6 speed and 4.88s.
 
Your logic is off. You would be better off with a doubler and then taking that money saved and building a spare driveshaft.

It sounds like your mind is made up. You are not gaining anything by going to this transmission - vs the obviously much easier alternative of adding a doubler or Atlas 2. You are taking a low torque, high revving V6 and taking away 2 functional gears for something that is obviously a daily driver (not a rock crawler).

Do what you are going to do, but this is not really that practical of an idea for an overlander type rig.
 
I say swap it, I want to see it done and hear real world vs paper. Even if you did pay too much and have to say it's awesome.

Also, 5.38s and 37s isnt too low :shaking: it's a gasser and a jeep, let the v6 sing. Rubicon is 4.11 and 32s, the extra gearing will help overcome added weight and barn-esque aerodynamics. So what if you skip shift. Some of yall are spoiled and never DD a CJ7 with 2.73/3.08s.

Overlander doesnt need an atlas or doubler.
 
I am not just an overlander, that is the point. Carrying spare drivelines and such is part of the problem. I priced doublers, drivelines, and rebuilding the nv370 and suprise suprise! There is no savings to be had. We spent a lot of time swapping motors into jeeps and toyotas with less hp and torque than the 3.6, not to mention a narrower powerband. The whole 4050 plus all hard parts to intstall (bellhousing, shifter, fork etc.) Was 5200$ delivered. No drivelines etc. needed. The only other thing was possibly a 45 lb flywheel from centerforce, which I would do If I kept the 6 sp. They were 500$. Once I get it in Iwill revisit the tire/gear ratio/ axle combo plan. I almost did the flywheel, nothing crawls like a 225 buick cj did!
 
402xjeeper said:
I am not just an overlander, that is the point. Carrying spare drivelines and such is part of the problem. I priced doublers, drivelines, and rebuilding the nv370 and suprise suprise! There is no savings to be had. We spent a lot of time swapping motors into jeeps and toyotas with less hp and torque than the 3.6, not to mention a narrower powerband. The whole 4050 plus all hard parts to intstall (bellhousing, shifter, fork etc.) Was 5200$ delivered. No drivelines etc. needed. The only other thing was possibly a 45 lb flywheel from centerforce, which I would do If I kept the 6 sp. They were 500$. Once I get it in Iwill revisit the tire/gear ratio/ axle combo plan. I almost did the flywheel, nothing crawls like a 225 buick cj did!
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I saw a jeep instagram overlander with a canoe on the roof, spotless, and condoms on the winch and hi-lift. Did you not wheel it before deciding it needed a different transmission?

So ~$6000 to swap in a tremec. Not the way I wouldve spent the money, but looking forward to hearing your driving impressions vs stock.
 
Synthetic winch line is uv sensitive, but that jeep is my new one. Because I live in Chicago now there is not much wheeling. But I have lots of wheeling experience, 20 some jeeps, 11 rollovers, spotter in early rockvrael comp (ARCA 1999 in a Cambell biilt jeep buggy)opened a lot of stuff in Florence junction AZ. Including axle alley. Not a web wheeler because I suck at social media type stuff. This new jeep and build are because I now need to drivre a long way to wheel. Just because I like to take care of my stuff, like the winch and cable. Is so it will be ready when I need it. My hilift is 30 years old, bought from Rick Pewe for 48$ back when that was a lot of money to me. It still works. I was there when Shannon Campbell built his 1st cj5 on chevy monoleaf springs and multiple yellow shocks. I kept getting ducks on my door handle so I put it on instagram like the tag said hoping it would stop. Tje bottom line is , although jk s are new to me, I know about building and wheeling stuff. The way everyone follows the crowd has led to over size and overweight trail cows, and less finess when running hard obstacles. I spend $ on quality stuff like warn zeon winch, red premium hilift jack, and hopefully this tremec trans and PSC XD steering box, take care of them so the do not fail on me. People used to dream of components that now crawl every mall in the country, we ran the same trails on old junk parts and 31"s that influencers hammer over on ls 40s and tons. I had one set of bfg mudders from the 1st consumer run of special compound rock crawler tires. The were 33" moab edition, the only size available! I think I can build a road drivable super capable jku by judiciously selecting parts from amazon warehouse deals, quality upgrades when things are known to fail. Not falling for if some is good then more is better falacy. After 150 to one more gearing is just to show off.
 
FordFascist said:
Your logic is off. You would be better off with a doubler and then taking that money saved and building a spare driveshaft.

It sounds like your mind is made up. You are not gaining anything by going to this transmission - vs the obviously much easier alternative of adding a doubler or Atlas 2. You are taking a low torque, high revving V6 and taking away 2 functional gears for something that is obviously a daily driver (not a rock crawler).

Do what you are going to do, but this is not really that practical of an idea for an overlander type rig.
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The point is the 4050 is easier, I have made up my mind because I already bought the setup, and posted pics. What is not worked out yet is what r+p ratio and tire combo. The 3.6 tuned has plenty of hp and torque, a wide powerband. I already drop 2 gears to pass on hills etc. I was looking for any one that has tried it already. The jeep will be a rockcrawler, just not a rock buggy or trailer queen. Everyone has it backwards diesels, need more gears because they have a narrower rpm range. A 3.8 v6, or a stock v8 have less speed range in each gear than a higher reving 3.6. The final drive/tire size combo is about torque, brake specific fuel curve, and drag at cruise speed.
 
TRINDU said:
I saw a jeep instagram overlander with a canoe on the roof, spotless, and condoms on the winch and hi-lift. Did you not wheel it before deciding it needed a different transmission?

So ~$6000 to swap in a tremec. Not the way I wouldve spent the money, but looking forward to hearing your driving impressions vs stock.
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Failing syncros forced me to the decision. I am not rebuilding a trans that started to fail a 60k on a still stock jeep. Spend more and fix the failure point.
 
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