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K3WE's avatar
K3WE
Explorer
Sep 26, 2018

3/4 Ton Suburban Transmission.

This is a fuzzy DISCUSSION post. After getting a new Chevrolet 1500 6-cyl truck for work vs. our Trailer vehicle (2011 3/4 Ton Suburban)- the Suburban seems to perform awful- nasty shifting habits and crummy mileage.

I know it's an apples to oranges comparison, but with a light utility trailer (~3000 lb), the 1500 actually pulls nicer AND gets better mileage than the Suburban pulling the same trailer.

I'd almost swear that it all comes down to how the computer is programmed on the transmissions....The 6 cyl usually is running at a lower RPM (yes, it drops down for hill climbs, but the Suburban is MUCH WORSE- seems like it doesn't like to pull and really likes to be running 3000 RPM- with the lighter trailer!).

Now- for the camper (Old 7000 lb, 27 ft TT), The 1500 seems to have very inadequate springs and the six might come up a little short on power AND would very likely get crummy mileage. (Never actually hooked it up, but it takes very little to squat it down)

Still, I feel (yeah feel) that the Suburban should perform better and upshift more when on level or slight downgrades (It spends lots of time in third and fourth gear....I get it that maybe 6th isn't called for but sometimes it almost refuses to go into 5th....3500 RPM on a slight downgrade!

I guess the real question here is if anyone can comment on a newer 3/4 ton Suburban vs. an older one and if the shift patterns and gas mileage have improved markedly?

(PS- oh for a good ole four on the floor :-) )
  • gbopp wrote:
    K3WE wrote:
    we can get 15-16 on the highway (not towing)...maybe I should leave the tranny alone?

    FWIW, my 97 Suburban 1500 4WD got 15-16 not towing. My 2008 Suburban 1500 4WD gets 15-16 not towing.
    If you're getting 15-16 on a 3/4 ton Suburban not towing, it's probably not going to get much better.


    My post here is more about shifting behavior...comfortable vs. rather ugly. Still my 1500 (4-door, short bed, 4WD) is routinely getting well over 20 MPG (25 easy with a tail wind). It's lighter than a 1500 'Burb, but don't think the aerodynamics are much better.
  • hawkeye-08 wrote:
    It sounds like you might be using tow/haul mode with that light trailer. If so, that is why it revs up before shifting. I use tow/haul when towing our travel trailer (9-10k lbs loaded), but don't for smaller trailers.


    I know what you are talking about- and to muddy the water our "light trailer" is the back of an old F-250. It is a light trailer and is probably OK without tow haul. BUT if we put 2000 lb of stuff in it, it becomes a moderately heavy trailer...and I respect your comment that you don't NEED tow haul for really light work, but there's also that 'rule' that you do tow haul for ANY towing. (And for the record, I have done a LOT of towing without Tow Haul (even with the camper)...sometimes I forget to punch the button after a gas stop)...Yeah it's often better WITHOUT tow haul...but still not as nice as the 1500 WITH tow haul on.

    My comment is that the Suburban is almost always shifting nasty- Tow Haul mode does affect the pattern- but it's mediocre vs. kinda bad.

    The 1500 is comfortable either way- AND is much more willing to go into higher gears on level ground.
  • I think what you may be experiencing is the difference between power to weight ratios. The 1500 truck with the V6 still has 285 HP and 305 lb ft of Tq but its power to weight ratio with the same smaller trailer is probably better on paper and faster in the seat of the pants.

    Hook the TT to the V6 and the handling and power will probably be noticibly different.

    The 3/4 ton may not have much of a drop off between the smaller trailer and the larger. That’s the nature of bigger trucks.

    I hope that helps and makes sense.

    Thanks!!

    Jeremiah
  • K3WE wrote:
    SidecarFlip wrote:
    Or 3 on the tree....

    Get the transmission re programmed. My wife has a 3500 Suburban Denali and it shifts just fine. Far as mileage goes any Sub is a tank so don't expect much, especially if it's 4wd like my wife's. Her's gets maybe 12 on a good day.


    Thanks for your excellent reply- I LOVE actual experience! AND now you make me feel guilty-LOL- we can get 15-16 on the highway (not towing)...maybe I should leave the tranny alone?

    I forgot to say that the SUSPENSION of the 3/4 ton really does a nice job with the camper (used to tow with 1/2 ton...it worked and it was LEGAL, but it was loaded past "comfortable".) Towing mileage...sucks...but that's camping.


    We don't pull anything with ours, it's a grocery store and dog hauler. Has the biggest V8 and it's a comfortable, confidence inspiring vehicle.
  • K3WE wrote:
    we can get 15-16 on the highway (not towing)...maybe I should leave the tranny alone?

    FWIW, my 97 Suburban 1500 4WD got 15-16 not towing. My 2008 Suburban 1500 4WD gets 15-16 not towing.
    If you're getting 15-16 on a 3/4 ton Suburban not towing, it's probably not going to get much better.
  • It sounds like you might be using tow/haul mode with that light trailer. If so, that is why it revs up before shifting. I use tow/haul when towing our travel trailer (9-10k lbs loaded), but don't for smaller trailers.
  • SidecarFlip wrote:
    Or 3 on the tree....

    Get the transmission re programmed. My wife has a 3500 Suburban Denali and it shifts just fine. Far as mileage goes any Sub is a tank so don't expect much, especially if it's 4wd like my wife's. Her's gets maybe 12 on a good day.


    Thanks for your excellent reply- I LOVE actual experience! AND now you make me feel guilty-LOL- we can get 15-16 on the highway (not towing)...maybe I should leave the tranny alone?

    I forgot to say that the SUSPENSION of the 3/4 ton really does a nice job with the camper (used to tow with 1/2 ton...it worked and it was LEGAL, but it was loaded past "comfortable".) Towing mileage...sucks...but that's camping.
  • Or 3 on the tree....

    Get the transmission re programmed. My wife has a 3500 Suburban Denali and it shifts just fine. Far as mileage goes any Sub is a tank so don't expect mush, especially if it's 4wd like my wife's. Her's gets maybe 12 on a good day.