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John, Master Automotive Technician
Category: Car
Satisfied Customers: 9176
Experience:  ASE A1-A8 & L1 Master GM Tech 40 years experience
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GMC sierra denali: with quad steer..miles per..better mileage..pulling

Customer Question

I have an ''03 GMC sierra denali LT1500 with quad steer - typically on vacation l drive about 10,000 kilometres getting an overall average of 15.2 miles per imperial gal. or 18.6 litres per 100 km - my question is can l, should l, change my 4.10 rear axle ratio to get better mileage - l''m not concerned about loss of pulling power - all l carry is my 800 lb motorcyle - what would the % of changes be with whatever ratios are available to me and what would it cost to get it done?
Submitted: 9 years ago.
Category: Car
Expert:  John replied 9 years ago.


There are several different axle ratio's to choose from.I would not go below the 2.39,next is 2.56,2.70,2.73,2.93,3.08,3.23,3.42 would be the highest ,or it would not be worth the change.A 2.73 would be a nice change & you would notice (I believe) 25 to 35% difference in fuel mileage on the highway.Driving habits,tire pressure,load,wind resistance all play a factor in fuel mileage.To replace this ring gear & pinion you are looking at 2200-2800 dollars depending on the parts prices & the labor rate in your area.

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Customer: replied 9 years ago. vehicle is also a constantXXXXX would any gears in front/transfer gears have to be changed? or would be affected?.....any effect on the abs?........would the computer have to be reprogramed.....and finally would the axle housing/case have to be changed?
thanks again
Expert:  John replied 9 years ago.
I don't believe there would be any concern about the front gear set.The computers ,Powertrain & ABS would need to be reprogrammed because the MPH will calculate different when you change the ratio.The rear axle housing won't have to be changed ,if you stay with the same size ring gear.