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[theapriliafreak]

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[carlover]

You could do it if you found donor front and rear axles with 4.10's. Im running 32's with 3.27's and it sucks. Ill be upgrading to 4.10's within a week or so by swapping out the whole rear axle.

What gear ratio are you running now???

 

[unclemeat]

4.10 ratio for street driving, 4.56 if you wheel or just want better performance. I have 33s muds and 4.56 ratio, and am very pleased with the modification.

 

[JDraper]

Hey quick question for you guys, I have a '93 X with the 5.5 Superlift suspension kit and 33' BFG Mud Terrains. But I have the stock gears. My gas mileage is horrible and I think my motor is on its last leg. I was wondering would it be easier on the motor and on gas by switching to 4.10s? what are the pros and cons to it? And is it expensive to do? This is just a daily driver I hardly ever Off road so... let me know.

Go directly to 4.56's...I have a '94 on 33's with 4.56 gears, and it's just about right for driving on the road...

 

[Maniak]

You also need to figure what speed your road driving is.

We have 4.10s and 33s and at 70mph we are turning 2100 rpms. If I drove the speed limit we would be even higher.

with 4.56 gears 70 mpg would put me at 2400 or so. At 75 I'd be spinning way to fast for a daily driver.

If you don't do longish drives then it won't matter as much. I have a 70 mile round trip work commute.

If you go to too much gear it will be like driving a mid 80s truck.. They were setup to go 55 and if you drive 75 you are really spinning the motor.

~Mark

 

[pughman]

You also need to figure what speed your road driving is.

We have 4.10s and 33s and at 70mph we are turning 2100 rpms. If I drove the speed limit we would be even higher.

with 4.56 gears 70 mpg would put me at 2400 or so. At 75 I'd be spinning way to fast for a daily driver.

If you don't do longish drives then it won't matter as much. I have a 70 mile round trip work commute.

If you go to too much gear it will be like driving a mid 80s truck.. They were setup to go 55 and if you drive 75 you are really spinning the motor.

~Mark

what tranny gear did you use to get your speedo back right ?

 

[Maniak]

I don't remember which size we used.. I don't even think you can reliably go by that. Factory speedo gear will be different between vehicles with different rear end ratios.

I did it by using math to figure how far off we were going to be and then I looked at what size driven gear we had. I then got the gear that was the correct percent bigger.

You need to kow your currnent and new gear ratio and tire size too figure what difference in % you need on your driven gear. Then uou need to know your current driven gear size to to find what you need.

~Mark

 

[pughman]

was 3.08 went to 4.10, tire size is 32.50 in Diameter from a stock 235x75 15

 

[JDraper]

You also need to figure what speed your road driving is.

We have 4.10s and 33s and at 70mph we are turning 2100 rpms. If I drove the speed limit we would be even higher.

with 4.56 gears 70 mpg would put me at 2400 or so. At 75 I'd be spinning way to fast for a daily driver.

If you don't do longish drives then it won't matter as much. I have a 70 mile round trip work commute.

If you go to too much gear it will be like driving a mid 80s truck.. They were setup to go 55 and if you drive 75 you are really spinning the motor.

~Mark

At 75 mph, I'm turning about 2600-2700 rpms with my 4.56's, which isn't too bad. I drive mine on the highway, and it runs pretty good. I'm getting about 14-16 mpg out of it right now on 33's

 

[Arthur]

i have open differential 3.08 right now on 31s and it sucks... goin to 4.10 asap

 

[Maniak]

was 3.08 went to 4.10, tire size is 32.50 in Diameter from a stock 235x75 15

Going from a 3.08 gear ratio and a 29" tall tire to a 4.10 gear and 32" tire would make your speedo read about 20.5% off.

At 2000 rpms your speedo used to read 56, now it reads 46.5

That means you need to speed up your speedometer so you need a smaller driven gear. One that is about 20% smaller than what you currently have.

~Mark

 

[pughman]

Going from a 3.08 gear ratio and a 29" tall tire to a 4.10 gear and 32" tire would make your speedo read about 20.5% off.

At 2000 rpms your speedo used to read 56, now it reads 46.5

That means you need to speed up your speedometer so you need a smaller driven gear. One that is about 20% smaller than what you currently have.

~Mark

sweet! thanks , thanks !, ill go look at the one i have now, the tranny is out any way.....

 

[Arthur]

There are calculators for that kind of thing on this website...if that helps any http://www.4lo.com/

pugh doesnt really need to know how fast he's going... he's a cop he doesnt get tickets!

 

[JDraper]

what is the link that has the calculator so you know how much to adjust your speedometer by?

And pugh doesnt really need to know how fast he's going... he's a cop he doesnt get tickets!

The search tool is your friend See the link below. Found by entering "Gear Calculator" into the search box...

http://www.explorerforum.com/forums/showthread.php?t=153160&highlight=Gear+calculator

 

[pughman]

im not good at them calculators...

and it looks like my gear is white, what color is smaller then white ?

 

[JDraper]

im not good at them calculators...

and it looks like my gear is white, what color is smaller then white ?

IIRC, white is a 23 tooth gear. I think I run a black gear (20 teeth) for 4.56's with 33's and it's accurate within 5%.

 

[mysticclam]

Wow, with 33s and 4.56s Im at about 2800 at 65. Thats in 5th gear which may be a bit lower than top gear on the auto but still, seem high. I used a GPS to calculate my speed.

 

[Maniak]

Wow, with 33s and 4.56s Im at about 2800 at 65. Thats in 5th gear which may be a bit lower than top gear on the auto but still, seem high. I used a GPS to calculate my speed.

Something doesn't add up.. The m50d transmission's 5th gear is .79:1

using the calc here (http://www.4lo.com/calc/gearratio.htm) and a few others I came up with the following..

32.5" tall tire (33" tires are rarely 33") with a .79 transmision ration, in high range (1:1), with a diff ratio of 4.51:1 @ 65mph the engine should be turning at 2420 rpms..

You already checked your speed, and you know your gear ratio. The only thing left is either s slipping clutch or something isn't what we expect it to be. If the tire size was only 28" tall (which really isn't possible for a 33" tire unless its really really low on air) the math would come out as 2800 rpms.

~Mark

 

[mysticclam]

Yeah, Im stumped. I made a template for my speedo using the numbers I got off the gps and it matched the speed at the dyno gave me during my last emissions test. Almost seems like my fifth gear is 1 to 1 but it is higher than my forth. ?????
The guy who did my rear gears fubar'd the job so everything came apart after 700 miles. Since I cant drive It I cant recheck it right now.

 

[Alanslinky]

Just out of curriosity does everyone here with 4.56 gears when they go on long road trips to go wheeling tow their rig or just drive it long distances turing 2500 rpm? The only reason I ask is because I tend to drive from CT and VT and back a lot and had been thinking about going to a lower gear ratio so I can put on larger tires, but then wasn't sure as to what that would do to my motor on long trips like that.