transmission....gears.......

[FrenchChili]

Ok, lots of people get new ring/pinion when going to bigger tires...

In a previous posted article it said going to higher ratios usually means less contact between the ring and the pinion...more stress on the teeths etc...

So, intead of doing axles, is it possible to get a used tranny with lower gears that would work with the 6...or 4cyl...

Anyone knows the advantage or dis...???:confused:

Any replacement for the common slow-dying AX-15 w/lower ratio??? Is the NV-3500 compatible???

[jeepboy]

Thats what im doing right now. Im just replacing my tranny and transfercase cuz theyre going downhill real quick and i dont want to spend big bucks on gears right now. Im trying to help my astoundingly low crawl ratio (21) every way i can. 3-1 tranny 1st gear + 2-1 4low transfercase gear + 3.54 diff gears = really really fast 4wheeling :eek: .

Logically, or at least my logic says its the same thing as changing diff gears. Im no expert but to me it seems like a no brainer :rolleyes:. Im looking at my rig from a crawl ratio point of view and diff gears will only help it out so much.

I say go for it and tell us how it goes :D

I dont know about the NV3500 though, sorry

[UNSTUCK]

With some adapters, an NV4500 will bolt in. Depending on which one you get, you will either have 6.?:1 or a 5.?:1 first grear. I want to say about 6.5 and 5.4, but cant recall. And these are bullet proof. These go behind big diesel engines, so I think they can handle your 4 or 6 banger. I doen't matter where the location of the reduction is at, trans, transfer, or rearend. The numbers all multiply out. So with a 5.4(much more common)trans, 4.0 case, and 3.54 rear you end up with 76.5. Now your moving slower. And you keep the much stronger rearend.

[TRobertsRN]

Check with Advanced Adaptors and Novak. They make adaptors for many lower geared transmissions. Some are better choices related to lower gears (up to 7.01:1 in a SM420) , strength of components, and lengths. They would know which tranny would be best length wise to limit or eliminate the need for drive shaft changes due to different transmission lengths. Also the longer the drive transmission the more severe the drive line angles. More of an issue with the shorter Jeeps. They will also know what transmissions would or would not need an adaptor if you plan to keep your current transfer case.

Some of the possible replacements will have overdrives and some not. The spicer 18 transfer has an available over drive.

If I was sticking with a manual particularly in a short Jeep I would go with a SM420 or SM465 or T-18. All have low 1st gears and are very strong. I would use a Spicer 18 transfer with 4:1 kit and 25% Saturn overdrive.
With a 4.10 rear this would give you a 114.96:1 crawl ratio and still only turn around 2000 RPM's at highway speeds with 33 or 35" tires.

This was my plan when I could drive a manual. Plan on an automatic now.

If you have no length issues the NV4500 or NV3500 are great choices.
Just remember the more you lift it the more the length of the tranny will be an issue.

[SavageSun4x4]

Ok, lots of people get new ring/pinion when going to bigger tires...

In a previous posted article it said going to higher ratios usually means less contact between the ring and the pinion...more stress on the teeths etc...

So, intead of doing axles, is it possible to get a used tranny with lower gears that would work with the 6...or 4cyl...

Anyone knows the advantage or dis...???:confused:

Any replacement for the common slow-dying AX-15 w/lower ratio??? Is the NV-3500 compatible???
The ideal combo is a 4:1 NV 350, 4:11 diffs and 4:1 transfer case, 31” tires [sound familiar, should be its a Rubicon]. Why did DC use this combo? Several reasons.
1) It keeps the diff/tranny/transfer all within the same numerical number. This helps to equably distribute the torque load. Lets say you find a tranny that has a 6:1 low and a transfer case with a 4:1, but your rear axle is 3:07. This will provide you with a 73.68 overall crawl ratio. Pretty good you say, yes, but the torque is not evenly distributed and it is going to put one heck of a load on that 3:07 R&P. Look to be shucking R&Ps more often than John Boy shucks corn on the Waltons. Ideally, you want to keep you 3 major components within the same numerical range.
2) Crawl ratio: The Rubicon has a crawl ratio of 65.76 which for a Jeep with that tire size its is an excellent ratio. Especially for an engine that gets 80% of its torque, just off idle.

Bottom line: Keep all of your ratios within the same numerical range if you can and develop a crawl ratio somewhere between about 64 and about 107 [running 31-39 inch tires] and you will be just about unstoppable. Even more, you will rarely break.

[SavageSun4x4]

With some adapters, an NV4500 will bolt in. Depending on which one you get, you will either have 6.?:1 or a 5.?:1 first grear.

I doen't matter where the location of the reduction is at, trans, transfer, or rearend. The numbers all multiply out.

You need a NV4500 like you need a banjo to water ski with. The NV3550 will handle 300 lbs of torque in a 7000lb GVW rig. Your not gonna break it.

And, yes it does matter where the reduction is.

[Gasman]

Any replacement for the common slow-dying AX-15 w/lower ratio??? Is the NV-3500 compatible???

An NV3550 is about as close to a bolt in replacement as you can get. I put one in my XJ to replace the craptastic Peugot. It's a nice tranny. If your vehicle is a later model with the external slave ax-15, the NV is really a bolt in affair. Just use your existing flywheel, a clutch for your AX-15, existing slave cyl, and existing CPS. I believe the input shaft diameter is the same after 95'-96'. It should bolt up to the existing tranny mount. You might have to fab t-case linkage but the AX-15 stuff might work. The NV clocked the t-case higher up (but still easily clears the floor pan in my XJ) than my Peugot so not sure if the AX is the same. The only gotcha on the NV is you have to use the special fluid from the dealer (around $7 per quart). Using regular gear oil will quickly trash the synchros and shifting sucks.

[FrenchChili]

U guys r teh best!!!

THX for teh input...lots of info...very interesting