Overdrive?
 

Ok, excuse my ignorance on this, but I have a couple of questions;
1) Does the H2 have an overdrive?
if it has one...
2) Has anyone modified one to obtain better drive/shift setup?

If it doesnt...
3) Is there a way to put one in that will better the drive-ability of the 4 speed tranny?

Re: Overdrive?
 

Yes, thats what the switch/button showing the little trailer located just below the A/C controls is for. So when you are towing, the shift points change to help give you more torque to haul stuff. When you press that button, a light on the dash should also come on telling you that your overdrive is off.

Re: Overdrive?
 

Wait?
So the '03 tranny with its 4 speed tranny is already in overdrive?

I am trying to understand this so basically we already have an overdrive unit on our transmission?
Yes???

And if so, then really we are just a 3 speed transmission with an over drive unit?
Is that what is being said?

And if we didnt have an "overdrive unit" then is it possible to put one on?
http://www.gearvendors.com/

I know trying to mate up a 6 speed tranny isnt an idea since you need the tranny, the shaft, the computers, and the programming (or maybe I am wrong), but I thought if maybe we had an overdrive that could be modified to make the transmission run better
(maybe even act or run something like the old 4+3 transmission the Vettes had)

Re: Overdrive?
 

I cannot speak for the 03 models as this was the first year for the H2's. I have an 07 model. But when I engage the tow/haul switch, I notice the shift points change to higher rpm's and I get more torque when going up steep hills on the highway. They may not call this an "overdrive" per se, but it performs just as an overdrive would.

Re: Overdrive?
 

[quote=jsbihn]Wait?
So the '03 tranny with its 4 speed tranny is already in overdrive?

from what Edmonds.com has for the specs on 2003 H2,,, the HUMMER has a 4 speed transmission but it does not say over drive,,, so I do not think it has a OD feature ~Richard

Re: Overdrive?
 

Its a 4l65e. 3rd gear is direct drive or 1:1 ratio, 4th is overdrive

Re: Overdrive?
 

Thanks HT for the clarification and thank you to everyone for the info.

3 gears plus over drive...... yep that explains the crappy gas mileage.

So the next question is there a way to swap the overdrive unit out and modify it?
Or is it internal with the trans (meaning it is not a separate unit).

Just wondering HT, is there a better trans that could swap out with the 4L65e to give 1) better gas mileage 2) extra gears
I know they did the later models with the 4L60 (right?) and it has 5-6 gears but I also heard that swapping that in would be expensive and a nightmare that as it was stated "you would be half way to a diesel conversion"

Re: Overdrive?
 

The 4l60 and 4l65 are essentially the same transmission. the 4l65 has more planet gears in the planetarys. If I remember correctly the 4l60 planetarys had 4 planet gears in the planetaries and the 4l65 has 5. Ratios are the same or close too same just a stronger planetary gear. Overdrive is inside the transmission not a separate unit.

Re: Overdrive?
 

So then what can be done for those who have a '03 when looking to have a better gearing setup (like that of the later models?)
Is there any trans that can swap right in with better performance and such?

Just wondering in case
1) the trans goes out
2) if i start looking for a BIG engine swap I figured if it wasnt a big deal I would swap in a better trans

Re: Overdrive?
 

Im not a trans tech, never work on them. Not sure what can be done in those regards. later model transmissions will have different control modules so not likely feasible to do a swap like that. Find a good transmission tech and he should have some ideas.

Re: Overdrive?
 

In the 4 speed over drive range is .696:1 compared to the 6 speed in a 2008 H2, 6th gear ratio is .667:1 so you wouldn't gain much with that swap anyway as for as on overdrive gear goes.

Re: Overdrive?
 

1st Gear Ratio
4.027

2nd Gear Ratio
2.364

3rd Gear Ratio
1.532

4th Gear Ratio
1.152

5th Gear Ratio
0.852

6th Gear Ratio
0.667

Reverse
3.064

Re: Overdrive?
 

1st Gear Ratio
3.059:1

2nd Gear Ratio
1.625:1

3rd Gear Ratio
1.000:1

4th Gear Ratio
0.696:1

Reverse
2.294:1

Re: Overdrive?
 

Your transmission has 4 forward gears and a torque lockup. A lot of people mistake this for a gear when watching the tach. You'll see the RPM's drop when it kicks in.