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Wifey gave the nod for 4.56s!

Discussion in 'General Chevy & GM Tech Questions' started by kinson33, Apr 19, 2013.

  1. Marcus A.

    Marcus A. Rockstar

    4.56 gears and 33" tires is very close to 4.10 and 245/75R16(30.5"). If you put 32" tires its roughly a 4.23 gear. I've looked at putting 4.56s in my '03 3/4 ton burb. Let us know what it cost to have installed.
  2. kinson33

    kinson33 Member 1 Year 100 Posts

    I have a shop north of Denver that will do it for $250 on solid axles, and around $350 for the front. Sorry fell of the radar there, new job. Trying to get the gears done tomorrow or wednesday!
  3. pmackiniv

    pmackiniv New Member

    what gear size would you suggest for a 1996 GMC Yukon with a 6" lift on 35's?
  4. stchman

    stchman Active Member 1 Year 1000 Posts

    Did you re-program the ECU to tell it about the new gears in your differential(s)? If no, you need to.

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    I would go with 4:10 gears.

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    IMO just doing what you talk about is not good enough. Hypertech, Diablo, etc. allow the user to program the ECU with tire height and axle gears. This will make sure the ECU shifts the transmission correctly.
  5. pmackiniv

    pmackiniv New Member

    What would be the best search to put into google to find 4:10 gears, and how much does something like that cost to get done?
  6. kinson33

    kinson33 Member 1 Year 100 Posts

    Most definitely.





    Respect your opinion, but disagree from prior experience.

    4.10's are a stock option with 31" tires, with 35's I would definitely do 4.56 to keep your engine at the normal operating range. You will notice bogging down especially when trying to pass people on the highway. Then to make up for it the truck will kick down a gear putting the RPMs over 3000.

    Make it easy on your engine and trans and do 4.56's with 35's. Probably get better fuel mileage too, not that we can do much for these trucks other than a 4bt swap ;)

    I know plenty of people happy with 4.56's even with 33's (setup I'm doing, still waiting on install...)

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    I picked up a used SuperChips (#2715) for cheap and it allows me to choose the gear ratio, tire size, and a few other basic power options. Not as good as some of the tuners you can find here, I just got lucky and happened to come across a used one that wasn't vin locked.

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    So far my cheapest quote for labor (from a reputable shop) is $1100. I'm waiting to hear from a guy who rebuilds axles for one my bodyshop clients. The garage owner races cars as well works on all sorts of chevys, unfortunately very booked up though. As soon as I can get a quote from him I'll know which way I'm going, only reason I'm holding out is b/c my bodyshop client told me the garage he uses might be able to do it for around $600... we'll see.
  7. stchman

    stchman Active Member 1 Year 1000 Posts

    My 2008 Silverado had 3.73 gears and 275/55-20 tires (they are 32" tires) and had no bogging whatsoever. The acceleration was very good. So for 33" tires, 4.10 gears will give you quite a bit more torque. I would only put 4.56 gears if I had 35" or taller.

    Just my opinion.
  8. dsfloyd

    dsfloyd Epic Member 5+ Years ROTM Winner Gold Member 1000 Posts

    I don't disagree with this. A programmer is still on my list. But at the time having the speedo correct was more important (when adding up costs), and with the 4.10s haven't noticed any shifting issues.
  9. kinson33

    kinson33 Member 1 Year 100 Posts

    We're on the same page.

    I've got 33's now. Not fearing the 4.56's with the 33's, but my next set of tires will be 315's (34.8") or 35's. Whatever I can find a decent deal on. If I get a company car might go with a body lift and try to squeeze 37's but I would be back at square one with that big of a tire and the gearing haha!
  10. kinson33

    kinson33 Member 1 Year 100 Posts

    Gears are in!

    Couldn't be happier with the setup so far. Only 100 miles on them, still breaking it in. Won't romp on it until I put some more miles on then get the fluids changed.

    Already love the difference on the highway, doesn't downshift at every incline anymore. With my 35's and the 4.56's I'm at roughly 2200 RPM at 70mph, finally have my passing power back.

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