4.11 vs 4.30 Gears for AX15 and 33s

[Pax84]

I’ve been reading over the multiple posts of what gears to go with for 33s and I can’t seem to find a definitive answer. The bronco is a daily and will see the highway, and sometimes some trails. I’m running an explorer 5.0 with a xe264 cam and soon an AX15 transmission. I want a useable 1st and 5th gear, so I’ve narrowed it down to 4.11s and 4.30s. Would 4.30s be too low for a useable first gear? I figured I’d get some opinions before I flip a coin and go with one or the other.

 

[Yeller]

I’d do the 4.30, that would get you exactly the final drive that Ford put in the explorer. There's some difference in the OD ratio between the 4r70 and the AX15 but not enough to make a huge difference. I have 33’s on our explorer so I’ve done a fair amount of digging.

 

[Jdgephar]

On 33s, I would stay with 3.50s. I don't know what you have now for a transmission, but if you assume the 3-speed then you get this:

1st goes from 2.99 to 3.83. Much better than the 3 speed 1st.
2nd on the ax will be in-between your current 1st and 2nd.
3rd on the ax will be in-between your current 2nd and 3rd.
4th is 1:1, just like 3rd on yours.
5th is overdrive, which you don't have today, and gets you lower RPM on highways.

I would love to have the ax-15 on mine which has 33s and a 3.50 rear gear.

Gear ratios for the AX15 are: 3.83, 2.33, 1.44, 1.00, 0.79, for first through fifth.

If you're doing the AX swap, see how it does with the 3.50s first. You can always change the gear later if you don't like it.

 

[acropilot]

I'm running 3.50s with 33s with the ax15 transmission and a pumped up 302.Starting from a stop in first gear is no problem and cruising at 70 mph on the highway shows 1900 rpm.It feels like a close ratio gear box 1st through 4th and then you have a nice overdrive.I think 3.70s or 4.10s would be great but mine works good enough for me so i'm going to stick with it.I usually shift into 5th at about 55 mph.

 

[Pax84]

Currently have 35s,3.50s, and 4 speed. My T19 has a decent 1st, but it doesn’t feel low enough. 4th is nice at highway speeds. I don’t want to be spinning too much higher, I’m at about 2400 at 70, 2000 at 60. I’d like to get more out of first, but not too much where I can’t use it, and keep my “overdrive” I have now.

 

[rjrobin2002]

I loved 4.56 gears with an ax15 and 35s. So I would do 4.33 for 33s.

 

[Yeller]

4.56 is what is going in the explorer with a 4r70 and 33’s. The 4r does have a deeper overdrive than the ax15, the explorer 5.0 likes to spin. I just need to make my mind up to keep the ifs or not.

A lot depends on where you drive too. For us at home, elevation is 6-800’ and fairly flat, it’s fine with the 3.73’s. Add elevation over 3000’, or hills, or wind and OD is useless. If we drive it west, once we get to the Oklahoma border OD gets turned off and doesn’t come back on until we return. Same going to Arkansas, get near the boarder and it gets turned off.

As a note, if you calculate the difference of a stock explorer tire size and gear ratio of 3.73:1. Then calculate the difference with 33’s you get 4.30:1. So taking advantage of the Ford engineering it would have 4.30:1 if they had put 33’s on from the factory.

 

[Viperwolf1]

Currently have 35s,3.50s, and 4 speed. My T19 has a decent 1st, but it doesn’t feel low enough. 4th is nice at highway speeds. I don’t want to be spinning too much higher, I’m at about 2400 at 70, 2000 at 60. I’d like to get more out of first, but not too much where I can’t use it, and keep my “overdrive” I have now.

What's the 1st gear ratio in your T18? Seems there were several versions.

You can keep 60 mph @ 2000 and 70 mph @ 2400 with the .79 overdrive if you change to 33" tires and 4.10 gears. 4.30 gears would put you only 1-2 mph slower at those rpms.

 

[Tricky Dick]

When in doubt go deeper.

 

[Pax84]

4:1 1st with the T19. I pulled it out of an 80s f250 diesel, pretty sure they didn’t get the 5:1 first.

 

[Viperwolf1]

4:1 1st with the T19. I pulled it out of an 80s f250 diesel, pretty sure they didn’t get the 5:1 first.

With your current setup you should see 17.8 mph in 1st @ 2400. With the Ax15, 33's, and 4.10 gears you'll see 15 mph in 1st @ 2400. With 4.30 gears that changes to 14.3 mph. Not much difference. If you might go back to 35s the 4.30 gears would be a better choice.

 

[rjrobin2002]

I gear lower because these things really dont need to cruise at 80mph, they are just too narrow and short wheelbase if it's lifted.

I gear mine to cruise at about 65mph and about 2400rpm.

 

[rjrobin2002]

Either look good to me.

 

[.94 OR]

I gear lower because these things really dont need to cruise at 80mph, they are just too narrow and short wheelbase if it's lifted.

I gear mine to cruise at about 65mph and about 2400rpm.

As I get older, I tend to agree.
Too many trips with the speedo pointing at 5:00!

 

[Pax84]

I think the 4.56 gears would make 1st too low. I tend to keep the bronco under 75 on the highway, it does get sketchy afterwards. Also I’m fairly confident I will stick with 33s.

 

[Broncobowsher]

I would lean more at the 4.30 gears. The cam will bump the power curve up the RPM slightly. Small cam, so just a tiny bit. Broncos are heavier than people think they are, aero can make a brick look good. They have a lot of drag that makes them hard to compare to even modern SUVs.

As for 1st not being usable, not really an issue. My daily driver has a 4.3 1st. I use 1st in parking lots and off the line from a dead stop. Any sort of roll, or even a downhill start, 2nd is generally fine. When I had the NP435 in the Bronco I would use the granny in parking lots to creep down the rows and into parking spots. I like a low 1st gear.

 

[Pax84]

Seems like 4.30 gears make the most sense, I appreciate all the replies.

 

[jmangi62]

I loved 4.56 gears with an ax15 and 35s. So I would do 4.33 for 33s.

Yep,this.I have 4.56s with 35s and they are monster gears. I can chirp the tires in any gear hehe.

 

[ntsqd]

In a Dana 44 the closest that you can get to a 4.30 gear is 4.27:1 I just had two sets of these put in the Wagon's 44's. They're a pretty uncommon axle ratio, I'm not sure if OEM Dana gears in this ratio are still available for the 44. Only the rear set int eh Wagon are as I could not find two Dana gear sets. They flat DNE of a D60. Can find that ratio, but not in Dana brand gears.
FWIW I'm running a 4L65E and 33-10.50's on the Wagon.

 

[R0kcrwlr]

I had a ax15 on one of my broncos with 33's engine was around a 250-300hp engine with 4.10 and it seemed good except when I was on the freeway around 60-65, I felt it needed more rpm. I eventually swapped to 4.30 and I felt happier with the gearing. If you have 347 or 351w I would probably recommend 3.73 but with the explorer 302, I would do 4.30.