The Numbers Dont Lie GM..Increase in Tire size = Re-gearing The Diffs.

Discussion in 'Chevy Truck Talk & GM News' started by the phantom, May 4, 2012.

  1. ahmitchell1

    ahmitchell1 Rockstar 4 Years ROTM Winner 1000 Posts

    So I stopped by rocky ridge and they beat me all around the bush saying the stock gearing was more than enough.i didn't wanna be to big a jerk, but I guess they don't expect anyone to haul anything or pass on the highway. So I'm guessing rocky ridge wouldn't cover the cost of the regear. I'm glad I have the 3.73
  2. the phantom

    the phantom Epic Member 5+ Years ROTM Winner 1000 Posts

    Yeah thats just wonderfull!! We can throw the numbers right at them in black and white and still they wont admit that its wrong to put them size tires on with that kind of gearing. I will find out in 2 days if anything can be done. I realize theyre are a lot of trucks out there that they never regeared I Just cant believe that with this many trucks sold nobody has complained. Unless they have and it falls on deaf ears. Basically the only thing they have on me is that I knew buying it that it had 3.42 gearing but It took me about 100 miles to know for sure that its not right.
  3. ahmitchell1

    ahmitchell1 Rockstar 4 Years ROTM Winner 1000 Posts

    Hopefully your dealer will talk them into paying for it or you get something worked out. I think if I went up to 35s I'd being throwing in 4.10s
  4. SouthEastBeast

    SouthEastBeast Member ROTM Winner

    Dying to know how this all turns out! I'm currently shopping for a lift for my truck as well and mulling over the gear options, quotes are 1700.00 to 2000.00 for just the rear gears by the way. Every person I've talked to has a different "opinion". I've found that EVERY SINGLE PERSON trying to sell me a lift says absolutely positively that you do not need to change out the gears to go to 35's. (mine are 3.73) Yet EVERY SINGLE PERSON posting online that has already had it done swears you do- either no power or destroying transmission/t. converter within 30k miles.... I believe the latter!
  5. the phantom

    the phantom Epic Member 5+ Years ROTM Winner 1000 Posts

    Found this chart. This is basically where Im at for rpms with the 3.42 gearing
    The chart below looks at these same figures but assumes you have installed the larger LT315/70/17 tires or any other 34"/35" diameter tire.
    [TABLE="class: tableborder"]
    [TH="class: tdunderline, width: 100"]Gear Ratio[/TH]
    [TH="class: tdunderline"]4L80E @ 60 mph[/TH]
    [TH="class: tdunderline"]6L80E @ 60 mph[/TH]
    [TH="class: tdunderline"]4L80E @ 70 mph[/TH]
    [TH="class: tdunderline"]6L80E @ 70 mph[/TH]
    [TD="class: tdunderline"]3.08[/TD]
    [TD="class: tdunderline"]1331[/TD]
    [TD="class: tdunderline"]1189[/TD]
    [TD="class: tdunderline"]1552[/TD]
    [TD="class: tdunderline"]1387[/TD]
    [TD="class: tdunderline"]3.42[/TD]
    [TD="class: tdunderline"]1477[/TD]
    [TD="class: tdunderline"]1320[/TD]
    [TD="class: tdunderline"]1724[/TD]
    [TD="class: tdunderline"]1540[/TD]
    [TD="class: tdunderline"]3.73[/TD]
    [TD="class: tdunderline"]1611[/TD]
    [TD="class: tdunderline"]1440[/TD]
    [TD="class: tdunderline"]1880[/TD]
    [TD="class: tdunderline"]1679[/TD]
    [TD="class: tdunderline"]4.10[/TD]
    [TD="class: tdunderline"]1771[/TD]
    [TD="class: tdunderline"]1582[/TD]
    [TD="class: tdunderline"]2071[/TD]
    [TD="class: tdunderline"]1846[/TD]
    [TD="class: tdunderline"]4.56[/TD]
    [TD="class: tdunderline"]1970[/TD]
    [TD="class: tdunderline"]1760[/TD]
    [TD="class: tdunderline"]2298[/TD]
    [TD="class: tdunderline"]2053[/TD]

    ---------- Post added at 07:25 PM ---------- Previous post was at 07:19 PM ----------

    1320 rpms at 60mph will not keep it in 6th gear on flat highway. Maybe if it was a big block or something but its only a 5.3l
  6. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    OK ia m going to stop in tomorrow and check it out,,, I have been putting it off,, every time i go there i want to buy something,,,, but its a lot different the grocery shopping,,, the new produce is like tons of cash,,, at the dealership... I will let you know what i find out tomorrow.... I am really interested in the pricing,,,,,more then the gears and tires, as tires ware out, and i know how to change the gears.... but what they are selling and the prices they ask will be the most interesting for me.......This dealership is one of the largest in western canada, and have a few friends that work there....
  7. reggiecab2000

    reggiecab2000 Epic Member 5+ Years 1000 Posts

    interested to know what they say...i had the 3.42's in my 4.3 with stock tires, and then i moved up to 275/60R20's (33" tire) and just with that i could feel all the power lost, and highway driving was hell on my transmission because it shifted so frequently, i bumped up to 4.10's a couple years back, and although all i needed was calculated to be about a 3.94 or so, i opted for a 4.10 over a 3.73 now im on 305/70R16 tires but theyre still 33's and the power is just a tad above the stock gear/tire setup. i do not even want to imagine what your truck feels like with 35's on a 3.42 diff., but hey maybe that means my v-6 could beat your truck :p
  8. the phantom

    the phantom Epic Member 5+ Years ROTM Winner 1000 Posts

    lol yeah you will beat me by 2 seconds because thats the time it takes to downshift 2 gears to get up and go.:lol:
  9. Dirty Dog

    Dirty Dog Member 2 Years 500 Posts ROTM Winner

    :glasses:Well I am at a disadvantage as i know most of the service guys and manager, and the brass in the sales, i should send in one of the staff from here to talk to a sales guy,,, but that would be like spying,,, and i only use covert acts like this at the dodge dealership...lmao....
    lol yeah you will beat me by 2 seconds because thats the time it takes to downshift 2 gears to get up and go.:lol:

    Read more:

    ,,,,, and this is just to true but funny...lmao:rofl:
  10. the phantom

    the phantom Epic Member 5+ Years ROTM Winner 1000 Posts

    Well I pretty much heard what I thought I was going to hear. I will never get GM to regear the truck. They pretty much avoided my insistance on the fact that the larger tires is dropping the rpm's too much and making it sluggish. The technician that took it for a ride said that the transmission has to learn my driving habits and that it will take about 6-7000 miles to do that. He said that each time it goes through a driving cycle it constantly is changing values in the transmision. It looks at throttle position, rpms, speed ect. ect. blah blah basically what I got. He told me to bring it back after another few thousand miles and we will relook at the situation. I explained that I dont doubt that the transmission is working properly. Im just trying to explain that the rpms are not where they should be because of the tires. When I say that I get "yeah those are pretty big tires" when I mention 11 mpg I get " you are driving a red brick wall down the road." He also told me that the 4L70e that is in my truck is bullet proof and told me that I will not break it. It will shift through to 5th gear at 35-40mph and that is normal. If you want to go he said just "step on it" So in short my next call is to Rocky Ridge to let them know that the transmision is working properly and just see what they say about my concerns with the gearing. Ive seen these trucks go for as much as 65k and If I spent that I would be even more peed off than I already am.

    The tech. also scanned my truck and it had no codes showing and also had no history in it. Then I asked him if it was set correctly for the tires and he couldnt even find that with his scanner. So I dont know maybe I will get another opinion from another dealership. Although my visit today didnt cost me anything. I dont think he was up on the ins and outs of programming the trucks he was just a transmission tech.

    :great:On a good note though I asked about putting an aftermarket rear diff cover on and asked about my CAI that I installed and the tech told me that this dealership is pretty leniant on aftermarket add-ons. He said that you can pretty much do anything to your truck as long as its not what causes a problem for a warranty claim. So Like I said previously that it may be awhile before I get any resolve if any at all. At least my concern is noted at 3200 miles so if my transmission ever has a problem, I Warned Them.
    Last edited: May 11, 2012

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