Gears
 

What gears should I go with running 38's? I was thinking a 4.56 or 4.88. I want it to pull like it did before I put 38's on it and I still want be able to go 80 mph.

Joe would know best, He runs 37" tires and I'm not sure if he has swapped gearing in it. What gearing do you have now? 3.73? I would think 4.88 is gonna be a bit much but 4.56 should match pretty good to the tire size. What transmission do you have?

No more then 4.56's up to about 42" tires...

From stock to 37's I would stick with 3.73's or 4.10's, 37's and 38's 4.30's and then 38's up to 42's 4.56...

Its a Diesel, the TQ makes up for any loss due to the bigger tires. And you have limited RPM's to make any power.

i never got gears for mine (not yet atleast) but the ppl i talked to said if i ran 4.11s with my 37s it would be like stock tires on a 3.73.

Gears
 

Thanks guys I am gonna go with the 4.56 Just wanted to make sure. This is my first diesel to try to decide on gears for.

Re: Gears
 

I think I would go with 4.10s or 4.30s butthats just me. 4.56s just seem like they would be to low.

Sent from my DROIDX

Your mileage will be crap, just be prepared. When your crusing down the road you will be above 2000 RPM and that kills mileage.

not to steal his thread but i have a related question. as i said above the ppl ive talked to said 4.11s would put me back to stock gearing so my question is would running 4.11s spinning 37s kill my alrdy bad mileage

Yea I was thinking that it already sucks now. My dad has a97 powerstroke with a 5 speed and 4.10's with stock tires and I think it runs around 2500 at around 70 or 75 but it's pulling what ever you got behind it. That's the way I want mine to pull with 38's on it.

i think some 4.10s would do you well, if not 4.30s but thats as steep as i'd dare to go, you can always add more power too :tu:

I had no issues pulling what ever I wanted with stock 3.73's and 37's... I did 4.30's because I thought it would be some amazing change... Its just annoying.

good word of advice Country429, CSIPSD has been there done that, i swear the guy knows everything to know about these trucks, i'd just take his word for it, i have and it hasn't done me wrong

A friend of mine put 4.56 in a 05 superduty with a 6.0 with a set of 37's under it and it does well. My other concern is egt's at highway speeds. Are they going to be really high turning that kinda rPm. Now with 3.73's pulling a 25 foot gooseneck with four Polaris rzrs on it it's all I can do to run 70 mph and the egts run from 1000 degees to 1200 and sometimes will alittle higher for a seccond going up hills.

he also has another gear then you do too..

Higher RPM's lower EGT's... The worst thing you can do when working the truck is lug it.

That being said, high RPM's kill MPG.



Have you corrected your speedo? Or are you running 80mph when your speedo reads 70...

You right I forgot a about the 5 speed

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I have not corrected the speedo it is 10 off

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So 4.30 it is, That's why I come here for questions I can usually get my answer without even making a post.

Honestly I would not go bigger then 4.30's...

Speedo is off a percentage, as the speed goes up, the MPH differance gets larger. Changing the gears will not fix the speedo being off. You need to have the GEM module reprogramed to correct the speedo.

dont tell him that, it will go to his head. then he will try to make us all bow before, joe the powerstroke master.

Keep it up... And I wont come over this weekend and finally fix your pile.


:moon:

:bow2::bow2::bow2: all hail joe!