It’s time for a regear. It’s so long overdue and just having shredded a second transmission, the constant hunting between 5th and 6th with every tiny hill makes me cringe.

Im torn whether to go with 4.56 or 4.88s. With 37s and the 6l80s 0.67:1 6th gear and how heavy the truck is I’m leaning toward 4.88s. However I do like to cruise 85-90 on road trips. Was hoping to stay at 2500rpm at 85 and both of these options will put me on either side.

Anyone have any experience to offer?

 

Well when I get to the gear hunting hills I Paddle shift my 6L80 into 5th and climb the hill when I'm loaded up with weight, then go back to Auto from manual shift.
But I feel your pain.
Not smart enough to recommend a Ratio for your needs. At 85 MPH ..your a 100 Ton Steam Locomotive raming down the highway. LMAO. I don't run that speed. Normally I'm cool at 70-75 MPH.

 

maybe the spicer calculator can help you
https://spicerparts.com/calculators/...rpm-calculator

 

https://www.hummerforums.com/forum/h...-4-56-a-48469/

I did a write up on my experience with the upgrades I've done to my truck including the 4:56 install, I have true 37" tries also

an experienced tuner (someone who knows Gen IV's) can save your trans

with the supercharger I would stick with the 4:56 gears

Neal

 

Yep I read your post about how happy you are with 4.56s and it’s what’s got me thinking 4.56s.

and I should have the trans issues sorted now. learned a lot of stuff lately. I’ll probably make a whole post about it. Tore into the trans myself replaced bushings, bearings, pistons, seals, clutches and steels. Added an extra friction in the 4-5-6 clutch and in the 3-5-r clutch. Zip kit in the valve body, new to me rear planetary, billet cover converter. Tuned out all the lockup slip, only locks up in 4,5,6 with an aggressive shift map that makes it drive like it’s half the weight it is.

anyway if you’re happy with 4.56s I’m sure it’ll be plenty for me.

 

Lol. It’s an Atlanta thing. Even the 18 wheelers run 85 around here. It’ll actually run 85+ pretty good. Around 75 you really feel the wind resistance and it won’t do it but after 85 the rpm are a little more in the power band and it’ll cruise there as long as it’s perfectly flat. Not something I do on a daily basis only on the occasional road trip.

 

A few times in passing on the interstate I have hit a little over 90 MPH.. It felt like a Cinder Block punching thru the wind. The H2 is no SR-71...LMAO.

 

I hit 112 in Mexico once

 

Holly ...You Know What!!!

No Chance of front end lift...Big Block of Steel rolling down the Highway..LMAO.

 

My H2 is supercharged with 37'' tires and I am running 4:88 gears. Cruise at 75 to 85 with no problem, the mpg sucks .