Overdrive?

[jsbihn]

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?

[fyr145]

Originally Posted by jsbihn

Ok, excuse my ignorance on this, but I have a couple of questions;
1) Does the H2 have an 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.

[jsbihn]

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)

[fyr145]

Originally Posted by jsbihn

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)

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.

[Rico001]

[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

[HUMTECH]

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

[jsbihn]

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"