How do I find my rear differential ratio?
Here we present information to assist you in the determination of what rear end ratio you have in your General Motors differential. In the second table you will be able with your RPO code to locate and determine just what rear differential ratio your What rear end ratio do I have in my Chevy General Motors vehicle left the factory with. General Motor rear end differentials are referred to by the diameter of the ring gear, i.e. 8.5 inch, 10.5 inch. Links are provided in the first table set identifying the different rear end types,
see table. Using these tables you will be able to locate the detailed information on replacement parts, upgrades and changing ratio parts and accessories for improving the performance of your vehicles differential. For front wheel drive General Motors ring and pinion replacements please give us a call 800-216-1632.
How does switching your rear end ration help the driver or vehicle performance?
We specialize in matching your tires and axles with the desired differential ratio's, we have a wide variety of gear sets in stock and can recommend and select the best suited differential for your driving application. We will recommend the right gear ratio to match your engine horsepower, transmission specifications and tires that you may have selected.
Thinking about changing tire size we can help, consult our
Look up chart for determination of engine RPM, gear ratio and tire size combination. Larger tires on lifted truck suffer from loss of power, changing the ring gear and pinion to a lower ratio is the answer. Changing rear end ratio can improve fuel mileage, reduce and extend engine life, and/or add additional power for your towing requirements.
Why you need a positraction?
A positraction unit, when your vehicle is negotiating a corner, the outside wheel has to travel a grater distance than the inside wheel. Therefore, the outside wheel must turn faster than the inside wheel. The differential is the device within the axle assembly which, in addition to transmitting the power to each axle shaft/wheel, allows one wheel to turn at a different speed than the other. Without positraction only one rear wheel receives the power. In bad road conditions say, mud, ice or snow traction to one wheel is bound to get you stuck. Installing a positraction provide power to both wheels at the same time, a signifant improvement in traction.
General Motors Production Options. The following Regular Production Option (RPO) codes identify the rear axle and transaxle overall final drive gear Ratios. These codes can be located on the RPO sticker in the glove box or in the trunk on most GM vehicles. Axle codes typically begin with the letter F, G and H. RPO Codes G80,, G81m and G86 indicated that the differential left the factory with a positraction. For positraction replacements and parts see the following
link. Positraction units are available for many General Motor FWD Front Wheel Drive models.
A
chart is also provided which presents Differential cover/cover gasket shapes, a common technique to identify differential ring gear diameter. And a Dana/Spicer
Parts illustration showing how to locate the Dana bill of material number is provided. This is a critical number to ensure that you find correct parts the first time. For example Dana used in some cases 3 to 4 different ring gear widths for say a Dana 35 ring gear, so the set up is not the same for each gear category.
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SOURCE:
http://www.drivetrain.com/parts_catalog/ring_and_pinions/what_gear_ratio_do_i _have_in_my_gm_or_chevrolet.html
