tuner or gears for a hummer on warrenty

[slippy]

Im about to get my 37's and i was wondering what you guys thought. i need to regear or reprogram my computer becuase iv been there done that with big tires and have nothing to offset it, it sucks!
im under warrenty right now with 80k, and it goes untill 150k.
the chip can offset the gear ratio but i would have to untune when i go to the shop under warrenty.
Gears would be a one time thing, as long as my diff. doesnt grenade i shouldnt have to worry about it...

[Stellar]

Both..You don't have to have a tuner, but it will recalibrate your speedo for your tires / gear setup, add a lil hp/tq, and give you a few other adjustments that can be beneficial. IMO 4.88 gears is the ideal setup for larger tires, better acceleration and off roading for the Hummer. Especially for here in Moab, UT

[Hellz]

Originally Posted by Stellar

Both..You don't have to have a tuner, but it will recalibrate your speedo for your tires / gear setup, add a lil hp/tq, and give you a few other adjustments that can be beneficial. IMO 4.88 gears is the ideal setup for larger tires, better acceleration and off roading for the Hummer. Especially for here in Moab, UT

i was always under the impression to shy away from 4.88s for any kind of off roading, and dont think about it for serious off roading ( MOAB and such)

[guruerror]

Originally Posted by Hellz

i was always under the impression to shy away from 4.88s for any kind of off roading, and dont think about it for serious off roading ( MOAB and such)

I got the same impression from reading around...not to mention that the lower you go the higher your RPMs will be at highway speeds. I do a fair amount of road trips, so I wasn't trying to drop my comfortable cruising speed and/or decrease my highway gas mileage.

Since I was fine my truck's performance with the stock 4.10s and 35s (especially after the Performance tune from my Cortex), I tried to keep the overall ratio as close to stock as possible when I moved up to 37s. This calculator (http://www.4lo.com/calc/geartire.htm) came in handy in helping me make my decision...I went with 4.56s.

The tune gave me the little extra 'kick' that the truck needed and the gears kept me as close as possible to the overall factory ratio.

[Stellar]

4.88's really wake the H2 up in terms of acceleration and have definitely helped towing my boat. 4.56 and 37's will be close to stock, but if you add larger tires or any additonal weight you'll wish you went with the lower gears. The lower gears also help for crawling and descending on the slick rock trails in Moab.

[Hellz]

but will also sheer more easily than the higher gears....

again, this is from what i have read and what not.
i have no idea how crazy 4x4-ing these guys are doing.

but adding more teeth means something has to give to make room for them.
that is the groove depth.
so shallower depth, means finer teeth, means easier to sheer them off.

[Stellar]

Originally Posted by Hellz

but will also sheer more easily than the higher gears....

again, this is from what i have read and what not.
i have no idea how crazy 4x4-ing these guys are doing.

but adding more teeth means something has to give to make room for them.
that is the groove depth.
so shallower depth, means finer teeth, means easier to sheer them off.

This can happen if quality gear sets are not purchased and installed properly. Larger tires affect your vehicles final drive ratio and if you have not changed your differential gears to match the changes in your tire size then your vehicle is not performing efficiently. Your vehicle will feel sluggish and slow to get going. Your motor will lug and your transmission will be shifting around and working much harder than it should. This causes shorter transmission and engine life and puts greater stress on your drive train components.

Adding taller tires or higher-ratio gears reduces engine rpm at all road speeds and gives the truck less mechanical advantage to help it crawl over an obstacle or get moving from a stop. Lower gears increase engine rpm and acceleration / crawling capabilities. Remember that low gears are higher numerically (4.88 is lower than 4.56).

Adding taller tires can cause the engine to lug below its power band and cause poor performance. To fix the problem, you need to swap to lower-ratio axle gears. But many ?wheelers want gears that make the overall combination even lower than stock to improve off-road performance or increase a vehicles towing abilities.

4 Reasons To Change Your Gear Ratio.

1. OFFROAD PERFORMANCE WILL BE GREATLY IMPROVED
Even a simple change from a 31″ diameter tire to a 33″ diameter tire will affect the amount of available torque by 10%. Lower gearing will enable you to have far greater control when crawl over rocks and other obstacles with greater control and put less strain on your vehicles other components. This will greatly reduce the risk of breakage to hubs, axles, drivelines and suspension components.

2. STRESS TO THE DRIVELINE WILL BE GREATLY REDUCED
Modern day transmissions cost $600 or more to perform a basic overhaul. Driving with even a 10% larger tire will result in the transmission being under the same load as always being driven on an incline. The transmission may not suddenly fail, but the life will definitely be reduced by thousands of miles.

3. MPG and ENGINE EFFICIENCY WILL BE REGAINED
RPM alone does not affect fuel mileage. An undergeared vehicle (as the result of oversized tires) will result in a substantial loss of fuel mileage. Also, just as with the transmission, your engine life will greatly be reduced. Changing your axle gear ratio will stop the motor from having to work so hard and increase your fuel efficiency.

4. TOWING ABILITY WILL BE INCREASED
Changing your vehicles axle ration to a lower gear will increase your vehicles ability to tow efficiently. The engine, transmission and the rest of the drive train components will not have to work nearly as hard when you are towing.