Regearing?

[tyler1bo]

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!

[EuroHummer]

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.

[tyler1bo]

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

[guruerror]

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.

[tyler1bo]

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

[charles06]

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.

[tyler1bo]

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

[2010_5thgen]

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?

[tyler1bo]

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..

[charles06]

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.

[tyler1bo]

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

[charles06]

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

[guruerror]

Originally Posted by tyler1bo

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

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.

[tyler1bo]

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

[guruerror]

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.

[tyler1bo]

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

[Bimmer9938]

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.

How much did it improve your MPG?

[2010_5thgen]

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.

[tyler1bo]

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?

[guruerror]

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