What Gears do I have?

[nsxxtreme]

I have a 700r4 transmission np208 transfer case.
Doing 65mph in overdrive my engine is at 2000 rpms. Checked with Tach and GPS.

With a couple calculators seems like I have 4.56 gears. I haven't cracked the axles open yet to check them. Once I crack the axles how can I be sure what I have? I would be actually shocked if someone actually changed the gears.

I just purchased 2 sets of 4.56 gears. So hopefully the shop I bought these from will return them.

 

[4X4HIGH]

Need to know what size tires.

 

[AJMBLAZER]

Engine wouldn't hurt either.

 

[romeolimagolf]

When you open your diff, look for a stamp on the ring gear. The ring gear is stamped with the part numer, and the tooth count. Here you will see the numbers "45-11", meaning the ring gear has 45 teeth and the pinion gear has 11. To find the ratio, simply divide the ring gear number by the pinion gear number.

 

[nsxxtreme]

I have 35" BF goodrich tires.

 

[4X4HIGH]

I have 35" BF goodrich tires.

You have 4.56 gearing then. At 65mph you should actually be turning between 1991-2020 rpm's depending on exact measured tire diameter. Most BFG 35's measure in right around 34.5"

 

[nsxxtreme]

Thanks I think I am going to check a 1,2,3rd just to be sure.

That's some extra money I can now save a spend on something else like ORD rear shackles and the steering brace.

 

[4X4HIGH]

I wouldn't bother checking other gears. I would pull the diff cover and either count teeth and do the math or check for the stampings. While you have the cover off you can inspect the gears and condition of the diff then refill with fresh fluid. This has never hurt anyone before. Diff fluid and tranny fluid are the number one over looked fluids on any vehicle.

 

[nsxxtreme]

Checking other gears and speeds I'm fairly sure it has 4.56s. Which is great!! Hooked the boat up today towed it around and it did ok. Tried going up a steep hill behind the house and it didn't do so well. I had to drop the tranny down to first in order to make it up the hill. Oh well this is as as good as its probably going to get.

What temperature thermastat should I be using. My motor doesn't get much hotter then 150 degrees.

 

[4X4HIGH]

Checking other gears and speeds I'm fairly sure it has 4.56s. Which is great!! Hooked the boat up today towed it around and it did ok. Tried going up a steep hill behind the house and it didn't do so well. I had to drop the tranny down to first in order to make it up the hill. Oh well this is as as good as its probably going to get.

What temperature thermastat should I be using. My motor doesn't get much hotter then 150 degrees.

Do us all a favor and please fill out your profile, it will help us help you faster without having to ask for info all the time.

Is your rig carbed or FI? If you have FI then you need to be running a 195* t-stat, if it's carbed you can get away with a 180* t-stat.

 

[nsxxtreme]

TBI, I'm not sure what the part store gave me but I'll pull it out and take a look. I think they gave me to cool of one though.

 

[4X4HIGH]

Too cold of a t-stat with a FI rig will result in loss of power and poor fuel mileage. The ECM reads coolant temp through the CTS (Coolant Temp Sensor) and if it's too cold then it will never go into closed loop operation and none of the other sensors come into play as then the ECM puts the truck in "run safe" mode.