Auxillary Transmission

[DieselDavey]

Hello,

Any one install an auxillary transmission?

Check this out from gear vendors: http://www.gearvendors.com/cg2wd4s.html

What do you think?

I am considering one after I make the standard mods on my vehicle first...

[DmaxMaverick]

They are good and work in the right application. I don't think you have the right application. If you are after an economy improvement, you will never see a return on your investment. If (a big if) you do manage to improve your mileage, it will be very insignificant compared to the expense, maintenance, and repairs (they don't last forever). Add to that, you won't be able to use it while towing what you are trying to tow. The added weight and parasitic drag would be an albatross.

[DieselDavey]

Thanks again Dmax!

It sure looked interesting! I would love to be able to pass a semi or maintain speed up a hill! This seemed like a good answer!

I guess that the standard mods, and maybe a lower gear ratio (4:10?) is the answer for me...

I pulled my camper from the Detroit area to Northern Michigan last summer. Going up maximum speed was 65, floored all of the way up.

Going home, I was able to get up to 70 a couple times (again, floored all the way)... forget trying to pass anything!

[DmaxMaverick]

I see. You were thinking underdrive? That's a different story, but the end result would still be about the same. To put it simple, you are trying to move too much weight for your gears and power (overloaded). If you are "on the floor" with what you have, adding an aux. tranny won't help, and would probably make it worse. At 65 MPH, you are well away from 1st gear, so you have already downshifted as much as you can while maintaining speed. An aux. tranny would likely create enough drivetrain parasitic loss to prevent you from getting what you have now. The only option you have left is less weight (or wind drag), or more power. Remember, this is still a 1/2 ton truck you are driving. You should only expect so much.

[6.5 Detroit Diesel]

What about the unit from US Gear? Anyone used them? If so, any comparisons to the GV unit? Last time I looked at the GV site, they rated their unit for 26,000lbs GCVW as opposed to US Gear rating their's at 35,000 GCVW. Obviously I will never tow that much, but I would like to hear from someone here who has used these units.

[DieselDavey]

Yep,

I was told that my vehicle was a 2500, only baged as a 1500 due to emissions (when I bought it)...

Turns out I have a "Heavy Duty" 1500.

Think I can "upgrade" this vehicle to the same or close capacity as a 2500?

Everything about my vehicle seems the same as a 2500 except for the gear ratios.

[ak46champ]

I have a Gear vendor over under drive in my K3500, I love it. It drops my RPM's by 500. I cruise at 68mph with about 1550 RPM's. As far as mileage goes, no real difference, maybe a mpg or two. Id does help out on hills when pulling a load, gives you a couple of choices based on how fast you are going and what RPM range you want to be at.

Do you have the instatrack transmission, meaning do you have the Auto 4WD feature in the Suburban?

I have a 99 Sub with the instatrack transmission and I can tell you they do not sell a Gear vendor over drive for that transmission. I tried to put it on my suburban when I got one for the K3500.

If I had to do it over again I would. I really do like the overdrive. It really quiets the truck down and I am sure a mile or two a gallon gain. I have 4.10's in the K3500.

If you have any specific questions about the over drive or anything else feel free to ask.

Brian