Transmission

[paint.roper]

So I am looking at putting in a new tranny and I don't mean the dude wearing womens clothes
I currently have the NP435 and am looking to move up to a 5spd. What is the preferred tranny to go with? I am looking at the ZF, NV3550 or the NV4500. I want to be able to do some offroading, but able to drive highways as well.

 

[DirtDonk]

I say they're all good choices, with pros and cons to each. But no cons that would really be a deal-breaker for any of them.

ZF and 4500 are both large truck transmissions that require (I think) a 2" body lift or tunnel modifications. Both require adapters to the transfer case, but the ZF can just bolt right up (relatively speaking) to the bellhousing of the 302, while, if I remember, the 4500 requires an adapter.
Both have lower 1st gears than stock or the 3550.
Both shift better than an NP435, but are still somewhat truck-like in their feel. Overdrive is decent on both.
Both would likely require driveshaft modifications to to the longer overall length.
Only the ZF was available in a Ford, so for the purist would be the choice in that regard.
Pricewise though, I'm not sure about the initial acquisition (though the 4500 seems to be more common?), but you can save a few bucks by not needing an adapter for the ZF.

The 3550 on the other hand, is smaller and lighter duty than the other two, with a taller 1st gear. Priced new, they're not far from a 4500. Priced used though, around here you can often find a 4500 cheaper than a 3550.
The size allows you to fit them with no driveshaft mods (roughly 1/2" different from stock, if that). They supposedly shift a bit smoother, but I'd say they're close to the same in shift feel to the other two.

I"m probably missing something, but all in all, they're all three good choices, with lots of proponents here in the forums. I'm sure you'll get lots of personal experience stories here.
Me? I'm going 3550, mainly because of the size and weight.

Paul

 

[Boss351]

3550 smaller unit 4.0:1 first from the looks of the install kit in Jeffs and W/H looks like the way I would go my $.02

 

[paint.roper]

Thanks guys, I have 351w in and I know they make the adaption kit to go either way. I was thinking of the zf because it seems to be more heavy duty. But I would prefer to not have to do too much modifications. Seems like whenever you start modding too much, something else behind it gets all out of whack.

 

[01JLH]

I have both the 3550 and 4500 in my two broncos. The 4500 drives like a big truck, very heavy duty. The 3550 has a much more on road freindly feeling as compared to the heavy duty feeling. One plus to the 3550 that I really like is the fact that the shifter comes out in the perfect spot in the trans tunnel. The 435 and ZF generally require the brace across the trans tunnel to be cut and modified on the firewall side and the 4500 requires the same type modification on the back side of the brace. I personally prefer the round hole cut in the middle of the sheetmetal for the 3550 to trimming the brace that also supports the body mounts at the firewall in the footwells.

 

[grant_71]

I am putting my flame suit on for this one, but dont over look the M5OD-R2. If you are not doing any serious off roading (crawling, heavy bogging, or desert racing) it will work fine. They get a bad rap because the lighter duty versions in the Ranger Bronco II were absoluely horrible. And the full size versions had a plastic plug that would go bad over time, but there is a metal update kit available for that. I plan on putting one in my next project, we have on in a fullsize bronco (much heavier, and us used mainly for towing) and have not had a single problem w/ it.

Also around here, I can pick up used ones for 2-300 vs 8-1000 for a ZF.

 

[John Marinan]

I'm waiting for Advance Adapters to make a transfer case bracket for AX15. Should be done this summer. It's the latest model of the AX15 that can take 400 lbs of torgue.

 

[rwill]

What kind of $$ FOR AN ax15?

 

[Broncobowsher]

What kind of $$ FOR AN ax15?

From my understanding the stock Jeep AX-15 isn't that great. It isn't until you spend the money to have (what is now basicly a custom transmission filled with expensive parts) do they get strong. So do you want the price for a junkyard gem or for the built version?

 

[paint.roper]

What about the amount of torque the 351w puts out? I am not aware how much it is, but if it is more than 300ft/lbs. Then wouldn't the NV3550 be the poor choice since it is only rated up to 300?

 

[Crawdad]

What about the amount of torque the 351w puts out? I am not aware how much it is, but if it is more than 300ft/lbs. Then wouldn't the NV3550 be the poor choice since it is only rated up to 300?

I too was pondering a 3550, but my 351W has had some mods upgraded, such as RV cam, new intake, BC shorty headers with dual exhaust. I maybe pushing over the 300 torque.

 

[patrickk1]

The nv3550 is rated at 300ft/lbs @ 7200lbs GVWR. Since non of our rigs weigh even close to that much, I believe that's how people get away with it.

 

[DirtDonk]

I would agree that it could end up being near maxed out in that department, but really only if you've got a heavy Bronco and a built motor. It's obviously more than enough for a Jeep with a 6cyl engine, but the trans was also used in limited amounts in 1/2 ton trucks with V8's from what I've heard here. Never actually searched that info out, but it seems plausible.

It's been said that the 300 lb rating was at a heavier GVWR, as in those heavier pickup trucks, so when you put the same box in a lighter vehicle, it's capabilities go up.
That, and the fact that there are lots of 3550 users here with zero issues, leads me to believe that it would be ok for someone who's easy on their equipment and isn't over-building the engine and chassis.
I wonder how many are behind 351's though? Might be worth another POLL to see just how many are in higher torque applications, or if they're all behind mild 302's instead.

When in doubt though, and in lieu of further information to the contrary, go big.
So if you're thinking that it's going to be borderline, or if you tend to use your vehicles hard, I'd choose one of the other heavier duty boxes.

Paul

 

[paint.roper]

Thanks for the input, not really any serious upgrades on the engine beyong EFI, but I think you are right Dirt. Would rather have a unit that is rated to handle the torque, than one that might fail because of it. Is the dana 20 the preferred transfer to match it up with?

 

[John Marinan]

Check Rockland Standard Gear, " The Terminator" and Advance Adapters for the new AX15 that they are selling. They appear to be the same new units that have all of the problems from the earlier units eliminated. Looks good to me, but I'm no authority.

 

[ak68]

393w stroker with nv3550

I have a 393w stroker built for torque and am using the nv3550. I have had absolutely zero problems with this tranny. I don't abuse it but don't baby it either.

 

[GrillMaster]

What are the best transfer case options for the 4500 and the ZF?