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Hatu

NP 435 v NV3550 or NV4500

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Been reading up on these transmissions and I don't really understand why people here are recommending the NP435 over the stock 3 speed. Looks to me like the NP345 is pretty much the same thing as the stock 3 speed with a granny gear and since the EB already has a granny in the transfer case, what's the advantage of the NP435?

 

Both the NV transmissions have an overdrive high gear and a better ratio spread in the first 4 gears. So it seems to me they will give you better highway travel and better ratio choice whether you're crawling or driving on the street.

 

I'll be using the Bronco as an occasional driver, with a few trips a year to the local Sand Dunes, or the Coral Pink dunes over by Kanab, (about 60 miles away) maybe a trip to Moab and then used as a hunting rig in the fall.

 

From what I can tell, the two NV transmissions are about the same thing but the 4500 is a lot stronger. I can't imagine wanting a lot more power than the 302 can generate in stock form, but that may change in the sand; seems like that's the only place the 302 may be a little weak.

 

All that being said, it looks to me like the 3550 would do the job with capacity to spare, better gearing and a nice overdrive gear for getting to the dunes or Moab. Where is flaw in my thinking here?

 

Hatu

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To put it plainly, the NP435 is stronger than any of the transmissions you mentioned. The first gear, or granny gear, is double, actually almost 2.25x, the crawl ratio that the original 3 speed is. The original 3 speed is nothing more than a boat anchor. It is a very weak transmission in comparison to the NP, a T-18 or either of the NVs. The NVs have the advantage of having a "highway" gear where the NP & T-18 don't. They are geared the same as the original at 1:1. But to compare the NP to the original 3 speed is like comparing me to a gorilla. The NV3550 also has a 1st gear crawl ratio almost half of that of the NP. Any way you cut the cookie, the NP is the lowest geared transmission that is a "standard" swap. If you look at a graph with the crawl ratios here is where you are with your final first gear ratio. I am going to use my EB for an example because I know my gears & transfer case.

 

With 4.10/4.11 axle gears & a T-shift transfer case here is what you would be looking at:

Original V8 3-speed: 30.16:1

NP435: 67.48:1

T-18: 63.73:1

NV3550: 40.44:1

NV4500 (5.61 1st gear): 56.58:1

NV4500 (6.32): 63.74:1

 

The lower geared 4500 is the 2nd best crawler transmission to the NP. The 3550 is just 1/3 better than the original tranny.

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To put it plainly, the NP435 is stronger than any of the transmissions you mentioned. The first gear, or granny gear, is double, actually almost 2.25x, the crawl ratio that the original 3 speed is. The original 3 speed is nothing more than a boat anchor. It is a very weak transmission in comparison to the NP, a T-18 or either of the NVs. The NVs have the advantage of having a "highway" gear where the NP & T-18 don't. They are geared the same as the original at 1:1. But to compare the NP to the original 3 speed is like comparing me to a gorilla. The NV3550 also has a 1st gear crawl ratio almost half of that of the NP. Any way you cut the cookie, the NP is the lowest geared transmission that is a "standard" swap. If you look at a graph with the crawl ratios here is where you are with your final first gear ratio. I am going to use my EB for an example because I know my gears & transfer case.

 

With 4.10/4.11 axle gears & a T-shift transfer case here is what you would be looking at:

Original V8 3-speed: 30.16:1

NP435: 67.48:1

T-18: 63.73:1

NV3550: 40.44:1

NV4500 (5.61 1st gear): 56.58:1

NV4500 (6.32): 63.74:1

 

The lower geared 4500 is the 2nd best crawler transmission to the NP. The 3550 is just 1/3 better than the original tranny.

 

Hmm, I see what you're saying, but it seems like you're completely focused on crawling. I may do a little crawling, but I'm thinking I'm going to use the Bronco more for fun at the sand dunes and as a hunting rig than just rock crawling. And if I'm not going to trailer it, I sure would like to have that overdrive. The sand is where you need the gearing and more power and those things shouldn't hurt the ability to climb when I'm hunting.

 

As far as the strength of these transmissions; I know the NP435 and NV4500 ate much stronger, but they're also heavier and how strong does the trans need to be? I'm not going to build a race 302, the most I would do to the engine is to add a small 4 bbl or Holley Pro-Jection, Headers, maybe a cam and Pertonix kit. I can't see how that would over stress a NV3550.

 

It is good to hear what you're saying, it gives me more perspective to look at before I decide what to do. Thanks for the reply, I really do appreciate it. If I'm missing anything, I would love to hear your comments.

 

Thanks!

 

Hatu

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No, you're looking at it in the right light. To be honest, if I was doing more sand running than rock crawling, I would look at one of the NV trannys too. The NP & the T-18 are definitely "truck" transmissions, and they act that way. There is no speed shifting either of those transmissions. The NV trannys are much smoother in their shifting and their throw is a lot shorter. I think most of the 3550s come out of Jeeps, if I remember correct & the 4500s were used in trucks (up to 1 ton). The 3550 is a "medium" duty trans & the NP & 4500s are "heavy" duty.

 

I look at things more in a crawling manner, because that's how I have built my rig. That being said, and the reason that I bring up gearing is because when I have wheeled with guys who have the 3550 tranny, they literally drive away from me on the smooth parts of the trail because they are higher geared. I don't get there fast at all, but I get there without beating up my rig as much too because of the lower gear set in the NP. Honest opinion, anything you change to, away from the original 3 speed is a huge upgrade and advantage. The 3 speed is basically a car transmission with a transfercase adapted to it, nothing more.

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To put it plainly, the NP435 is stronger than any of the transmissions you mentioned. The first gear, or granny gear, is double, actually almost 2.25x, the crawl ratio that the original 3 speed is. The original 3 speed is nothing more than a boat anchor. It is a very weak transmission in comparison to the NP, a T-18 or either of the NVs. The NVs have the advantage of having a "highway" gear where the NP & T-18 don't. They are geared the same as the original at 1:1. But to compare the NP to the original 3 speed is like comparing me to a gorilla. The NV3550 also has a 1st gear crawl ratio almost half of that of the NP. Any way you cut the cookie, the NP is the lowest geared transmission that is a "standard" swap. If you look at a graph with the crawl ratios here is where you are with your final first gear ratio. I am going to use my EB for an example because I know my gears & transfer case.

 

With 4.10/4.11 axle gears & a T-shift transfer case here is what you would be looking at:

Original V8 3-speed: 30.16:1

NP435: 67.48:1

T-18: 63.73:1

NV3550: 40.44:1

NV4500 (5.61 1st gear): 56.58:1

NV4500 (6.32): 63.74:1

 

The lower geared 4500 is the 2nd best crawler transmission to the NP. The 3550 is just 1/3 better than the original tranny.

 

Good explaination, I will go alittle farther. Work in your tire size too

I run an p435 too, 6.7 granny*2.34low jshiftdana20*4.56 axle gearing=71.5 crawl good enough for good rocks and big tires.

http://www.4x4extremesports.com/index.php?http://www.4x4extremesports.com/calculators.php for calcs

when I do the speed calcs with a measured 36.8 diameter tire (38 inch swampers) I get 2350rpm =55 mph and 65 at 2700 well just about that and with a big tire short wheel base rig thats as fast as I want too go, but I still have a little extra too pass plus any faster and the mpg goes way down since I selected a cam and spark advance setting that gets me full power(max torque not hp )at 2200-2700 on the propane, I dont drive mine on the freeway. But if you need more wheel speed in the sand with the np435 drive it 4 wheel high and use2nd 3rd and 4th. you dont need the granny too start of the line with , you can drive around town with 2,3,4 all day hope this helps alittle more

BBB

Edited by bigbluebronc

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