nv4500 vs t18?

[nc wagoneer]

After what seems like forever the garage my dad and I have been building over the past 6 months is FINALLY getting finished this weekend! The j20 will get rolled in within the next couple weeks and the teardown will begin. After my dad bought his 6.2 diesel suburban, I became impressed with the motor and how well it has towed and the mpg provided (84 k1500 suburban 3.73 gears and 700r4) with a fully stock and smogged c-code. So my plan is to use a j code 6.2 mated to an nv4500 or t18 in the j20. I know the overdrive will help out on the highway but is the extra $500-1000 for an nv4500 worth it? I am pretty sure my j20 has 4.10's so the overdrive would help but will it outweigh the costs since I'll mostly be at 35-50 mph? I'll be keeping my d20 so thats also another factor.

[Mudbull]

I havnt seen them side by side, but the NV4500 is defiantly more substantial, I would also imagine that the NV4500 has more of an aftermarket support for rebuilds. I don't know of how hard it is to bolt a t18 to a 6.2, but obviously the nv4500 would be a stock bolt in process.

As far as the overdrive goes, I had a 0.78 overdrive 4spd in my car before switching to a t56 6spd with a 0.5 overdrive (3.54 rear gears) I went from a best of 15.5mpg to 20mpg and I can now cruise at 80mph turning 2000rpm. If you were planning on a lot of highway time the reduction in rpms, vibration, noise, lower wear rate is worth it to me, the fuel savings is a bonus. But it all boils down to what you plan on using it for.

[Stuka]

As far as torque ratings go, they are not too far apart. T18's were put in dump trucks, and are listed as a heavy duty trans. The weak link is the D20 that came bolted to them. The outputs are notoriously weak if you really work them.

However, a T18 is not the trans to put behind a GM engine as it requires finding a bell housing that will work. T18's only came in Jeeps and Fords. An SM465 would be quite a bit easier as they are already a GM pattern. And they came with NP205's, which are WAY stronger than D20's.

The NV4500 is a great trans, you will have to find a bell housing, unless you can find the more rare GM version. Which go for a lot more money than the dodge version.

What size tires will you be running? In my J10 I run 4.56's with 34's and its not freeway friendly, but is fine on the HWY. 4.10's with 31's would be similar.

[nc wagoneer]

I will be running 31-32's on the j20. I have a place I'm town that I can get adaptors made pretty cheap, (or next to nothing if I can do it in shop class). I don't want to switch out the d20 for an np205 for two reasons 1.it will hang below the frame and 2.from my experience with one in my dads f350 it doesn't have enough of a gear reduction for the terrain and things I'll be using it for. I have heard about ranger overdrives being used on our jeeps but they don't list a jeep t18 overdrive. Can the ford overdrive unit be adapted? If I could put on a ranger overdrive later on I would really like to go with a t18. It will only see 55-65 TOPS and VERY RARELY until I graduate (planning eci 2015 or 2016 and ouray 2017) and most driving till I go cross country will be 35-50 mph around the back roads.

[Stuka]

I will be running 31-32's on the j20. I have a place I'm town that I can get adaptors made pretty cheap, (or next to nothing if I can do it in shop class). I don't want to switch out the d20 for an np205 for two reasons 1.it will hang below the frame and 2.from my experience with one in my dads f350 it doesn't have enough of a gear reduction for the terrain and things I'll be using it for. I have heard about ranger overdrives being used on our jeeps but they don't list a jeep t18 overdrive. Can the ford overdrive unit be adapted? If I could put on a ranger overdrive later on I would really like to go with a t18. It will only see 55-65 TOPS and VERY RARELY until I graduate (planning eci 2015 or 2016 and ouray 2017) and most driving till I go cross country will be 35-50 mph around the back roads.

D20 Low Range = 2.03:1

NP205 Low Range = 1.97:1

They are basically identical. I have no experience with ranger overdrives, so no clue on what they can be adapted to.

[rocklaurence]

Go with the NV4500 as the T18 with granny LOW in a diesel equals a 3 speed w/o over drive. Unless, your rock crawling your J20

[Stuka]

Go with the NV4500 as the T18 with granny LOW in a diesel equals a 3 speed w/o over drive. Unless, your rock crawling your J20

It's a 3sp with any engine unless you are hauling or towing. With my old Cherokee, I used 1st offroad, and when towing. Or if I just had to drive real slow.

[AwesomeJ10]

I've been running a GM NV4500 in the honcho for the past 4 years. It's not the one with the super low first gear, but it's still a pretty low first gear. I take off in first about half the time and second the other half. 5:38's and 42's and tons.

That 5th gear will help more than you think. It opens up the possibility of comfortably driving it long distances. I know you aren't planning on doing that, but ya never know.

An NV4500 shifts WAY, WAY, WAY better than any T18. Much faster and smoother. Although the 4500 is no sports car tranny either.

When you do, you MUST get the fluid from a chevy/gmc dealer. No other type of oil is correct. Nothing. Not even the amsoil synthetic that says it's for an nv4500. As me how I know

[Stuka]

I've been running a GM NV4500 in the honcho for the past 4 years. It's not the one with the super low first gear, but it's still a pretty low first gear. I take off in first about half the time and second the other half. 5:38's and 42's and tons.

That 5th gear will help more than you think. It opens up the possibility of comfortably driving it long distances. I know you aren't planning on doing that, but ya never know.

An NV4500 shifts WAY, WAY, WAY better than any T18. Much faster and smoother. Although the 4500 is no sports car tranny either.

When you do, you MUST get the fluid from a chevy/gmc dealer. No other type of oil is correct. Nothing. Not even the amsoil synthetic that says it's for an nv4500. As me how I know

If you don't have the lower first gear version, doesn't that mean you have a chrysler NV4500? I know the fluid that they use is fine. But I agree newer transmissions are very picky. The NSG375 in my JK is EXTREMELY picky about fluid types. So much so that it literally will not shift into second if you use the wrong fluid.

[nc wagoneer]

I've been running a GM NV4500 in the honcho for the past 4 years. It's not the one with the super low first gear, but it's still a pretty low first gear. I take off in first about half the time and second the other half. 5:38's and 42's and tons.

That 5th gear will help more than you think. It opens up the possibility of comfortably driving it long distances. I know you aren't planning on doing that, but ya never know.

An NV4500 shifts WAY, WAY, WAY better than any T18. Much faster and smoother. Although the 4500 is no sports car tranny either.

When you do, you MUST get the fluid from a chevy/gmc dealer. No other type of oil is correct. Nothing. Not even the amsoil synthetic that says it's for an nv4500. As me how I know

If you don't have the lower first gear version, doesn't that mean you have a chrysler NV4500? I know the fluid that they use is fine. But I agree newer transmissions are very picky. The NSG375 in my JK is EXTREMELY picky about fluid types. So much so that it literally will not shift into second if you use the wrong fluid.

Only the pre 94 gm nv4500's had the super low first gear.

[rocklaurence]

The diesel NV4500s had a 5:1 ish first gear while the gasers were in the 6:1 range--I believe

[AwesomeJ10]

the pre '94 GM nv4500's had the low first gear. 6.x:1

All dodge and all 95+ gm nv4500's are the higher gear 5.x:1

I'm very glad I don't have the 'low' first gear because it would be too low.

[nc wagoneer]

If I remember correctly you CAN get a clocking ring for an np 205 to tuck it up in a fsj frame? I found some scremin deals on sm465/205 combos around here and that plus the cost of a ranger overdrive is still less than what nv4500's are going for around here without a transfer case.

[rocklaurence]

IDK, here in Fl I can get a rebuilt NV4500 for approx $1000 while an overdrive is $1600. After the purchase of the SM465/205 and refresh, its far cheaper to go with the NV4500.

[nc wagoneer]

Around here I can get an sm435/205 combo in decent condition for 250-300 bucks. An nv4500 in the same condition is $1500+ and thats without a $250 or so transfer case. And I kinda like the idea of 8 gears to go through not counting low range in the transfer case

[Cecil14]

And I kinda like the idea of 8 gears to go through not counting low range in the transfer case

You're only going to like that for about 20 minutes. It's going to make your rig absolutely miserable to drive. I thought a T18 would be super awesome at one point too...then I had one...then I hated to drive my truck. It's downright painful to drive around. As mentioned the shifting actions totally sucks. It was literally designed as a dump truck transmission (we had one in a 70s F350 dump truck when I did landscaping). It is NOT a great decision for a trans.

While I have no personal experience I see no reason that an SM465 is going to be any different than a T18. They are essentially equivalent transmissions, both in purpose and era. I could be wrong there, but I'm guessing I'm pretty close.

The NV4500 is definitely the way to go, as is a different t-case. If you want a decent t-case (that's not an NP205), look around for an NP208 or NP241 (think that was the later beefy one). Both will bolt up to the standard NP round pattern and clocked just about any way you like, just watch which side it drops on.

This is one place you really don't want to skimp on cash. Best bet is to find a couple rigs to test drive. Find someone with either trans that's willing to let you take a cruise around the block, that's the easiest way to get a feel for what you're getting into.

You don't want to redo this one later because you're unhappy with your decision. lol I ended up going to an NV3550 in my J-10 and it's been great. I don't haul anything real heavy and I'm not putting out 800ft.lbs so it's the perfect fit.


aa

[Carolinaboy]

This is one place you really don't want to skimp on cash. Best bet is to find a couple rigs to test drive. Find someone with either trans that's willing to let you take a cruise around the block, that's the easiest way to get a feel for what you're getting into.

x2 I've had a 6.2 sm465 in a k30 and it was not a very pleasant combination. You have to remember that you'll basically be using a sm465 as a 3 speed with a horrible gear spread for a low revving 6.2. Take your time and save up some cash and find a nv4500. A nv3550 would work also as long as your not going to turbo and pull heavy loads.