The Horse with no name...

[-Nathan-]

My rule of thumb with 4.0 RBV's is 33's=4.56 gears, 35's=4.88 gears. And thats with a 4.0, with anything smaller than that, go lower. Even with 4.56's and 33's on my first ranger I wished I had gone with 4.88's. Very rarely do you ever hear people complaining of their gearing being too low, everyone always wants more gearing. If youre going to go through the hassle of re-gearing, go low and do it right the first time.

 

[86MUDRCJ]

I plan to run 5.13 with 37's and a 2.9. But thats as far as id like to go with it being a dd.

 

[Flash Gordan]

My rule of thumb with 4.0 RBV's is 33's=4.56 gears, 35's=4.88 gears. And thats with a 4.0, with anything smaller than that, go lower. Even with 4.56's and 33's on my first ranger I wished I had gone with 4.88's. Very rarely do you ever hear people complaining of their gearing being too low, everyone always wants more gearing. If youre going to go through the hassle of re-gearing, go low and do it right the first time.

I would like to take the gear low. But being my DD eventually, when is going low going too low? I need to figure out which gears to run and still make it streetable.

 

[kryptonitecb]

Search google for a jeep gear calculator. There's a really good one that gives you 2 columns to compare against. I put the stock 4.0 numbers against the tire size I want to run to find the best matchup. In the end I found the 4.0 with 37's ran closest to stock rpm's with 5.13 or 5.38 gears.

Sent from the road while ignoring traffic

 

[dhkonrad]

Mines a DD and the 5.13s really aren't that bad. A little low if you do a lot of freeway diving, but I don't mind driving a little slower on the freeway. I think it came out to be like 2800 rpm at 65mph

 

[Flash Gordan]

Mines a DD and the 5.13s really aren't that bad. A little low if you do a lot of freeway diving, but I don't mind driving a little slower on the freeway. I think it came out to be like 2800 rpm at 65mph

2800?!? Seriously? I wouldn't be able to keep it on the road if I had to buy fuel for those gears. I need to keep the RPM's down.

 

[kryptonitecb]

At 65 that's about right

Sent from the road while ignoring traffic

 

[Flash Gordan]

Not the cars and trucks I've been driving. 2100-2200 should be the max rpm speed at 65 mph.

 

[kryptonitecb]

Each engine has its own optimum rpm. You can't use a generic rpm range to determine your gearing needs.

Sent from the road while ignoring traffic

 

[dhkonrad]

And lower rpm doesn't NECESSARILY mean better mpg... before gearing I could pull 85 mph and be at like 2600 rpm. I got like 12 mpg...

 

[Flash Gordan]

And lower rpm doesn't NECESSARILY mean better mpg... before gearing I could pull 85 mph and be at like 2600 rpm. I got like 12 mpg...

And after gearing, what's your fuel mileage like at 85 mph?

 

[6.2]

2800 is high for freeway at 65 mph.

I'm sitting at around 2200 ish at 65 mph and get 19 MPG.... 2800 is to high For mpg purposes.

Before my tire size increase (in only on 32's now) I was doing 65 @ 2400 or so. And getting 17-18 mpg.

4.88's would probably be pretty good for 37's and a 4.0 IMO.

 

[Flash Gordan]

But imho the maximum size tire that I think a D30 will handle is 35's. And even then I'll probably have to weld a truss on it. I've got a set of 31's but eventually I'd like to throw some 33's on. Still need to build some Ironman 4x4 arms. Hopefully my shipments from eBay and Currie get here soon.

 

[86MUDRCJ]

One of my buddies is running 35's on his d30 without a truss, but to each their own. Ive never seen justification to build a truss on such a small axle. As far as gearing he put 4.88 and as soon as he broke the gears in he was talking about going up to 5.13, bit again its all up to what you wanna do. Its your truck.

 

[Flash Gordan]

One of my buddies is running 35's on his d30 without a truss, but to each their own. Ive never seen justification to build a truss on such a small axle. As far as gearing he put 4.88 and as soon as he broke the gears in he was talking about going up to 5.13, bit again its all up to what you wanna do. Its your truck.

Can I ask, what exactly was he doing when his gears broke?