Regearing?
 

Alright guys I need to regear my '08 SUT from the stock 3.73's..what would my best option be? Keep in mind that mine is the new 6-speed. My 3.73's just aren't strong enough to push 38's with 20's. Help please!

Re: Regearing?
 

I went with 4.56s. I have 37s. With the 38s, you might want to go to 4.88s. Depends on how much you travel on the highway, and how much time offroad.

Re: Regearing?
 

Right now it's more highway than offroad..my truck is about 90% street 10% offroad

Re: Regearing?
 

Check out this 'gear calculator': http://www.4lo.com/calc/geartire.php

My 05 had 4.10s stock, when I move to 37s it started to drag ass, so punched my info in the 'calculator' to find out what gears would give me an effective ratio closest to stock.

The tire size change had reduced my effective ratio to 3.88 and the calculator indicated that 4.33s would put my effective ratio back up to the stock level. Since they don't make 4.33s I went to the next 'lowest,' 4.56s, and have been a happy camper every since.

Re: Regearing?
 

It's showing me at 4.05..do you think 4.10's would be enough?

Re: Regearing?
 

I did 4.88's with 38" Toyos and it made a HUGE difference. That gearing works well with my new 40's as well.

Re: Regearing?
 

Does yours have the 4-speed tranny or 6? Mine has stock 3.73s with a 6-speed. I punched my numbers in the gear calculator and it's saying I should move to 4.10s

Re: Regearing?
 

those 6 speed tranny's are crazy. i drove my buddies 08 yukon denali and that thing was just stifting like crazy. seemed like at cruising speed, it didnt know if it wanted to be in 5th or 6th.

regearing should help with MPG and the pickup right? ive noticed mines a bit sluggish off the bat and it stays in 2nd gear longer than it used to. is this normal with a lift and larger tires?

Re: Regearing?
 

Yes it should help both MPG and pickup..surprisingly though my I reset my CPU after the lift and I'm currently getting 11.5 hwy/city driving, which is brilliant for me. I would like to regear though because my shifting is getting sh*tty and slow, feels like my tranny is slipping. I took it in the shop to see if my tranny was okay and I think it's just my gears not being strong enough..I slip from 1st to 2nd kinda..

Re: Regearing?
 

I have the 4 speed.

I always wonder how accurate those MPG readings are after I've changed the gearing, tire size, and used a tuner.

Re: Regearing?
 

I still think it's pretty close..course I'm not stompin on it either..just cruisin mostly besides hwy. I think at worst i'm getting 10

Re: Regearing?
 

Yeah, I try not to get too caught up in it. I just tell myself I'm getting more than what shows. Haha

Re: Regearing?
 

I've got the 4-speed...

If the calculator says 4.05-4.10 then the 4.10s would put the performance closer to what you were used to before the tire size change. But to really get things back in order you should also use a programmer to let the 'computer' know that you've change the tire size and gear ratio; that should get your shifting and whatnot straightened out.

Re: Regearing?
 

I have a programmer. I'm using a superchips flashpaq at the moment.

Re: Regearing?
 

You should be good to go then...looks like the Flashpaq allows you to adjust tire size and gear ratio just like my Cortex.

With some 4.10s and a re-program you should get your pep back, your shift points and cruising speed will be closer to normal, your speed-o will read correctly, and you may even get a whole MPG out of it.

Re: Regearing?
 

Not a WHOLE MPG!!!! ;) Yes it's either 4.10's or 4.56's..

Re: Regearing?
 

How much did it improve your MPG?

Re: Regearing?
 

so 4.10 or 4.56 are good for 38" tires? i think im going to start with a tune, but im gonna take mine to a shop that has a AWD dyno to do a custom tune.

Re: Regearing?
 

A custom tune will probably be the best. You probably need to look at 4.56 to 4.88 gears. I believe you have stock 4.10s. I think I may go with 4.56 because I'm not sure 4.10s will be that much of a difference. Do any of y'all know a good place to find gears?

Re: Regearing?
 

www.trailduty.com...more specificially: http://www.trailduty.com/index.php?c...0cd11dd8a5fc9b

Re: Regearing?
 

If you struggling with the idea of 4.10 vs. 4.56 then I would suggest using the calculator to see what your highway cruising RPM's will be, if you will be fine with the 4.56's then I would go that route as it will likely yield better mileage and pick up around town and have a minimal effect on highway mpg's.

Also keep in mind that while 4.10's will get you back to stock RPM's you are still moving a larger amount of unsprung weight with larger wheels tires so you likely will still be a bit short on performance vs. stock with the 4.10's.

Re: Regearing?
 

I think that just convinced me! I will look at 4.56s on trailduty.com for a decent price. Thanks for the help guys! I would have known what to do if I had the 4-speed but I wasn't exactly sure with mine.

Re: Regearing?
 

what have we determined would be good on the 4 spd? and how will the gearing effect highway driving along with city driving? i dont wanna be cruising at 65mph and 2500RPM or anything.

Re: Regearing?
 

I guess I don't see how 'how many speeds' your tranny has would effect a person's decision on what gears to purchase for the diffs.

It's all about the ratio of the drive shaft to the diffs...unless I'm missing something.

Re: Regearing?
 

For your truck I've seen/heard 4.56s and 4.88s..charles06 runs the same setup as us and he has 4.88s, he loves them.

Re: Regearing?
 

I too am running 4.88's and 40's on the tires; I love it and drives great on city streets and on highway. The only part where I am having a power struggle is when I get going over 70mph and there is any incline in the road. This will cause my ride to struggle a little bit on power and causes it to jump into 3rd gear. I am rocking the 4 speed too though, so I know that the power distribution will be different if you have a 5 or 6 speed, so keep this in mind.

I have been researching to see what is going to be the best option for me to fix this dilemma. I want to avoid the supercharger based on the ridiculous cost, so I am looking into the following: a turbo, a custom tranny, any little upgrades like a throttle body spacer, any other custom works to get the added muscle I need to roll at higher speeds. If it comes down to it and I end up having to go the supercharger route, than I will more than likely buy a new crate engine that is more powerful than my existing one and spend the $5 G's towards something that won't blow up.

Then again, I am always open to feedback from you pros out there who have been there, done that...

Re: Regearing?
 

Get a DMAX conversion!

Consider this....The GEICO commercial with the little piggy flying down a zip line of a snow capped mountain - Just before he passes the chump on the opposite zip line, he pauses and says "Pure Adrenalin...Weeeeee....Weeeeee?Weeeeee" That is the exact feeling you'll have after driving a DMAXed H2! GET A MF DMAX conversion!!! You will not be sorry. 'Nuff Said!

Re: Regearing?
 

for what....around 25K.... there has to be a cheaper way to get good power without going boosted or swapping in a diesel.

Re: Regearing?
 

I'm still able to pull up slight inclines without the truck downshifting at speeds over 70mph. I think the long-tube headers made a big difference, too.

Re: Regearing?
 

i think im going to start with a tune before i jump into gears. that will be my last resort if i dont notice any improvement from the tune.

Re: Regearing?
 

You won't. Same thing I did.

Re: Regearing?
 

I'd just do the gears...it's not terribly expensive or complicated...and it has DEFINITE gains that you will DEFINITELY notice.

...and, plus, you may be up for a diff fluid change anyway. Kill two birds with one stone.

Re: Regearing?
 

I absolutely recommend 4.88's if you're going to spend the money for new ring and pinions. Throttle response will be dramatically better and if you choose to run 40's down the road or tow, you'll make it easier for your motor to get the power to the wheels.

Re: Regearing?
 

This has become a good little thread..;) keep it up! And charles06 would you please post some pics of your rig!!

Re: Regearing?
 

I know. I know. Still being lazy.

I agree with the 4.88's. You won't notice the 4.56's enough.

Re: Regearing?
 

actually, before i bought my truck off the lease, i had all the fluid flushed and changed. now running royal purple in the diffs.
wont a tune be needed anyways if the gears are changed? not to mention i dont have my speedo matched up right.

Re: Regearing?
 

so 4.88's will be good with 38" tires? what will i notice after having them installed? and will anything be compromised?

Re: Regearing?
 

Correct...you'll need to tune for the gears and tire size.

Re: Regearing?
 

Your highway cruising RPM will be higher but it should jump off the line...well, as much as a big metal box can 'jump.'

Re: Regearing?
 

will these work? http://www.amazon.com/Precision-GM9F.../dp/B003EM73FQ