Transmission for high power engine

[LowCountryEB]

I am about to install a 408 stroker (425hp / 455tq). I am currently running a NP435, 4:11's, and 35" tires. I've been told that I should change out my transmission at the same time I swap the engine. What do you guys think?

I've also been told to look at the NV4500 and NV3550. I want a manual transmission. With the amount of power and torque the 408 is going to put down, which transmission do you recommend? Please give me positives and negatives for the NP435, NV4500 and NV3550.

And again, will the NP435 work?

And where is the best place to buy a transmission? And are the adapters from WH's, etc... required with either the NV4500 or NV3550?

 

[Skiddy]

the NP435 are pretty much bullet proof. with that much torque and if you have a heavy right foot, may want to look at the rest of the drive train;D

 

[sykanr0ng]

The NP435 is definitely stronger than the NV3550 so if you want a strong overdrive transmission the ZF5 or NV4500 are your best options.
If you want an overdrive you will also be wanting lower diff gears too.

If you don't want an overdrive the NP435 which you already have is what you need for an engine with that power level.

The NV3550 is rated for 300 ft/lbs of torque by the manufacturer.

 

[thegreatjustino]

If you're staying with the 4.11 gears, I'd stay with the NP435. You may get into the overdrive with the power of that engine, but why spend $3,000 on a transmission and adapters just to get an overdrive? The gas savings will never pay for the transmission.

 

[ScanmanSteven]

I had a 435 but changed to a ZF5. The shifting is smoother and easier. If you don't intend to do much/any off roading then switch to a NP205 transfer case. It bolts to the ZF with no adapter and is basically the stoutest TC you can buy, $250 or less. Depending on your torque curve you might be able to use the OD.

 

[AxlesUp]

NV3550 rated at 300 ft/lbs.
M50D-R2 rated at 330 ft/lbs(near as i could find)
ZF5(s5-42) rated at 420 ft/lbs
ZF5(s5-47) rated at 470 ft/lbs
NV4500 rated at 460 ft/lbs
NP435 rated at 450 ft/lbs(near as i could find)


I would take a good long look at your transfer case and axles. i see broken stuff in your future

 

[sykanr0ng]

NV3550 rated at 300 ft/lbs.
M50D-R2 rated at 330 ft/lbs(near as i could find)
ZF5(s5-42) rated at 420 ft/lbs
ZF5(s5-47) rated at 470 ft/lbs
NV4500 rated at 460 ft/lbs
NP435 rated at 450 ft/lbs(near as i could find)


I would take a good long look at your transfer case and axles. i see broken stuff in your future

Only the NV4500HD (Heavy Duty) is rated for 460 ft/lbs, what the other versions are rated for I have not seen listed.

Whether the NV4500HD is the version that the adapters for a Ford bellhousing and transfer case fit I do not know.

 

[sanndmann3]

I would take a good long look at your transfer case and axles. i see broken stuff in your future [/QUOTE]

Yep, the Dana20 just aint gonna like being bossed around by a 408, especially in low range... I busted 3 before going 205.

 

[LowCountryEB]

How much does an NP205 cost and where is the best place to buy one? Should I consider an Atlas? And what do I need to consider with the axles?

 

[DirtDonk]

While I agree with what was said regarding the 3550 and your intended use, if you lower the gearing in the diffs substantially the trans can live a lot longer. I've got a customer that is absolutely hammering on his 3550 with a big stroker setup like yours and 35's and has not broken it in the three or four years he's been running.
He's a hot rodder from way back and is having nothing but fun in his EB at the shows he usually takes his show cars to. And he practically drag races anyone who looks sideways and smiles at him at stop signs and lights every time he has it out.

And with all that, he's loving his 3550 which I had recommended against because he told me what he expected to do with the Bronco. He just liked the price and the fact that it fit better than most of the others.

That said, I'm leaning to what's already been recommended that, at least in the beginning, you keep the 435 and run it till you decide you want a better shifting setup.
The NP435 is an old-school truck trans with granny low. Someone who's going off road will love to buy it from you, but if you keep it you know it's super stout and can handle most of what you dish out.
You may just decide to change due to it's shifting characteristics being less "fun" than a modern trans. You certainly don't need overdrive, from what I was hearing in your other thread, but that's about the only way to get a modern manual with better shifting.
Unless you go with a Ford Top-Loader 4-speed that is. Great box, small size and good quiet and smooth shifting. But you might have to come up with the shifter mechanism with a little custom work on your end, whereas the NV and ZF transmissions are all right there and ready to go.

Got some decisioning to do still it seems!

Paul

 

[sanndmann3]

How much does an NP205 cost and where is the best place to buy one? Should I consider an Atlas? And what do I need to consider with the axles?

Craigslist is where I got mine. $75 is what I paid. Went thru it and it was like new inside. SO much beefier than a dana 20. the poor lowrange is the 205's only drawback in my mind. make sure you get the Ford style drive side drop...

 

[5001craig]

I would take a good long look at your transfer case and axles. i see broken stuff in your future

Yep, the Dana20 just aint gonna like being bossed around by a 408, especially in low range... I busted 3 before going 205.

I agree. I did everything at once. Pretty expensive but probably where I would have been at some point. Check out my build thread in my sig (except for the trans--I'm running an auto).

 

[Tucknkitty]

I have an ATK built 408 with an NV3550 and 4.56 gears (ARB so open diff most times) on 35s. I am not easy on the truck but I'm also not dropping the clutch at every light. I have not had an issue and I hit 5K+ shifts on the reg...

That power will change the dynamic of your truck and how it drives (obviously) and its not easy to put all that power to the ground, if you're spinning those big tires on dry pavement you're asking for something to break BUT that doesn't mean you cant give it the business from time to time.

On the offroad stuff - slow is fast, let the gear and tq pull you through most things. In the mud, spin away!!!

YMMV
TnK

 

[norm02]

I have an ATK built 408 with an NV3550 and 4.56 gears (ARB so open diff most times) on 35s. I am not easy on the truck but I'm also not dropping the clutch at every light. I have not had an issue and I hit 5K+ shifts on the reg...

That power will change the dynamic of your truck and how it drives (obviously) and its not easy to put all that power to the ground, if you're spinning those big tires on dry pavement you're asking for something to break BUT that doesn't mean you cant give it the business from time to time.

On the offroad stuff - slow is fast, let the gear and tq pull you through most things. In the mud, spin away!!!

YMMV
TnK

Glad to hear that someone is able to use a NV3550 behind a 408ci and keep it alive. I was starting to get scared I'd have to switch to a slush box when the time comes! That being said, have you done anything to beef yours up and what clutch do you have?

 

[Tucknkitty]

If you cant find it - Grind it!!!

I used the center force clutch - listed on the WH website for the NV. My motor was 0 imbalance so I have the corresponding Mcleod flywheel and AA pilot bearing. It gets spendy...

I have a hurst short throw shifter the previous owner installed. If you decide you want to run a manual, you'll have to get the WH EFI clutch equalizer bracket and likely have to grind down the block a bit (sounds worse than it is) to get everything to fit and line up correctly.

With my setup - i rarely start in 1st, mostly second. Drive in 3rd around town and will sit at 2500ish RPM at 70 mph all day long...

But when you go low gear, 1st gear, lock the lockers and let out the clutch old girl will climb anything its nuts.