gearing advice

[j.barrett]

Hello everyone, I'm trying to to figure out what gear ratio would be best in my truck. It's a 2000 , 2500 ,automatic. Stock gears in it are 3:54 and I put 37 inch military tires on it.. I am planning on gearing it but I need advice and opinions on what ratio to have installed....

4:10 ? Or 4:56?

, if I do 4:10 I can use stock carriers, if I go 4:56 I have to buy new carriers.

what is the best for towing or all around.

[TFaoro]

Best for towing would be to drop the tire size so you aren't stressing the entire drivetrain so bad. Wheel bearings, tie rod ends, ball joints ect are going to have a much shorter life. If you're dying to keep the 37's I'd put 4:10s not 4:56

[CTcummins24V]

37s? Wow! Daily driver or strictly tow rig? If you get 4.56s and you ever want to sell your truck or downsize your tires your truck will not be fun to drive.

[CSM]

I would recommend a set of dynatrac ball joints with 37s.  They will make the replacement much easier.  

[flagmanruss]

I bought my truck (or more was sold a bill of goods by dealer) with 4:10s.  I bought it new.  With the OEM optional 265/75R16 tire size, this is still TOO LOW.  I end up towing in OD when I can because the alternative is a screaming engine or drop my speed to 50.  I feel 4:10s was a mistake for me.  The standard gear ratios give (apparently) plenty of power, quieter cruising & better econimy.  I've never got over 18mpg. 

 

If you want to run big tires, figure out the ratio to correct for it.       

[angus]

3.55 is a great all around gear with OEM tires.. I know there is a formula to recalculate for different tires, but I currently don`t know where to find it.. Maybe someone else can chime in???

CTcummins24v makes a good point, if you ever decide to sell??   You could probably locate a used set of 4.10 axles if you looked hard enough, but that might not be low enough with 37s"?  WOW!

[j.barrett]

It's a tow rig mainly. I drive it about once a week.. with the 3:54 gears it's awesome on the freeway, but towing up step grades is not to good.. I wouldn't mind down sizing tires but I'm running recentered h1 wheels that are 16.5

[j.barrett]

I appreciate all the feed back. Thanks everyone

[Gamble]

I am fairly certain the 3.73 gear ratio is the cut off for carriers.  You can go up to that from a 3.54 but not past it without a carrier from a 4.10 truck.  Those military tires are ridiculously heavy.  I have 35's with 4.10's and while its great for towing, I would happily go back to a 3.54 for the extra RPM's and ease of highway travel.  4.56 is to deep in my opinion.  You will definitely get some grunt out of them, but you will be cranking her hard at highway speed.

[98whitelightnin]

My truck also has 4.10 and it pulls great but my mileage suffers too, 16.5 is best I have gotten. I think 4.10 would be the way to go for you or sell the wheel and tire setup and move back down to a 33-34" tire.

[Me78569]

Here is a gearing calc I put together. 

 

 

depending on what you use your truck for you will need to go with 4.56 or 4.10's I doubt you could tow well with 4.10's as the rpms at 55 are to low at 1400. you would have to leave it in 3rd. 

 

 

mopar1973man gearing calc.xlsx

[Mopar1973Man]

Again... 3.55 gears here with 235/85 R16 tires (31 inch) and towing is awesome good power and pulling grades. 37" tires your going to need the 4.10's for sure. Also highly suggest the exhaust brake as well as the 3rd gen brake upgrade because of the leverage value those huge 37's put on the brakes.

[Wild and Free]

I say 4:10, easy to find and good all around with bigger tires. 4:56 would be ok with your current tire size but if you backed down you would not be happy, you could drag race from light to light with 40K in tow.

[JAG1]

It's a tow rig mainly. I drive it about once a week.. with the 3:54 gears it's awesome on the freeway, but towing up step grades is not to good.. I wouldn't mind down sizing tires but I'm running recentered h1 wheels that are 16.5

Why can't you slow down for using 3rd gear on the uphills (tow haul mode)? It's easier on the truck. That's why I always let the other guys running uphill just go by and pass. They seem to like doing that a lot but I see the poor truck just giving everything its got on some loads.

[Mopar1973Man]

Why can't you slow down for using 3rd gear on the uphills (tow haul mode)? It's easier on the truck. That's why I always let the other guys running uphill just go by and pass. They seem to like doing that a lot but I see the poor truck just giving everything its got on some loads.

 

Agreed... Even with stock tires I back down to 55 MPH and grab 4th (1:1 direct) and run the grades. It not "how fast" you can climb the grades but "how many" times can you do it.

[flagmanruss]

I don't have as much power as some of you guys.  The XZT+ made a noticeable difference in power for towing though.  When I tow the toyhauler on the Interstate...   I know it's not recommended but I'll run in OD...  down hill & on the flat.  The problem is "What's flat?"  Little bumps in the road, I usually leave in OD if I have enough speed going in.  If not, or the hill proves longer/steeper, I'll  be ready to cut the speed & hit the OD switch off.  If I'm facing a big grade I know I'm going shift down. 

 

I just can't make my whole trip at 50-55mph & I can't stand the screaming engine to rev up to 65.   

 

Unlike other vehicles I own, the speedometer is dead nuts on (against the TomTom GPS)...  or was with the OEM Michilin's...  I'll need to watch with the new Coopers.  It would be nice if it cut the gearing some.     

[Me78569]

I tow with the EGT gauge when it comes to when to kick it out of OD. 

 

next question is what mods do you have in your tranny?  It puts a TON of stress on the converter lockup clutch to tow in OD if you are on the throttle.  Sure the engine can pull it, but can the tranny hold it?

[AGPTurbo]

I think the 3.55 gears are the stuff in these trucks. I was skeptical when I bought mine but have learned to love them. As for towing, no problem with towing in OD, just take it out when it feels like it's starting to struggle. I installed my gauges this winter and towed our camper to Fla. and back with no issues at 70 mph. The tranny gauge never went over 130 on the interstate at all. Only time I noticed it struggle is when I'd lock up the converter in 3rd a touch too early with the mystery switch and it would give me a little shudder which I would cure by getting out of the throttle. Stock trans BTW.

[JAG1]

It' cool just to slow down anyhow, enjoyable, you get  better gearing when you can watch all the cute ladies going by

[santan40]

This is good stuff! I have been thinking about putting in 4:10's and putting on a newer set of OEM wheels (17" or 18"). And thus taller tires. I currently have 3:55 and would like a little more power for the mountains. I have some mild power train upgrades but have gotten gun shy, my best friend had a second gen with Edge Juice with Attitude, he could smoke me on the hills.......but now he is pushing coolant out of the cylinder head! Maybe just install 3:73's and keep stock wheels/tires.