Revolution Gear & Axle GM 10-Bolt 8.5in/8.6in 4.10 Ratio Face Hobbed Ring & Pinion Set
A 4.10 is the ratio people reach for when a GM 10-bolt truck or car needs more pull without going all the way to deep crawler gearing. Typical reasons: a half-ton Silverado or Sierra that moved to 33 inch tires and now feels lazy, a Tahoe that tows a camper and keeps hunting between gears, or a classic Chevelle, Camaro or C10 that needs a quicker launch. This Revolution Gear & Axle GM10-410DC is a new 4.10 ring and pinion for the GM 8.5 inch and 8.6 inch 10-bolt, and it is cut face hobbed, the same style GM uses on its own gears.
The pinion is splined to the driveshaft yoke and drives the ring gear, which is bolted to the differential carrier. With 4.10 gears the driveshaft makes 4.10 turns for each turn of the axle shafts, so the engine sees more leverage at every road speed. That is how a regear cancels out the effect of a taller tire: the tire makes the final drive taller, and a numerically higher ratio brings it back down.
Face hobbed gears look different from the older face milled style. The tooth depth stays the same from the heel to the toe, and Revolution says the 2-cut process with lapping runs quieter and carries more load than face milled teeth. It also changes setup: Revolution's chart lists a tighter backlash window for 2-cut gears in this axle than for 5-cut gears. Revolution's specification block for this set lists standard rotation, a 30-spline pinion, an 8.5 inch ring gear, ten 7/16 inch ring gear bolts, 8620 steel, and a 2.56/2.73 carrier break.
Count the cover bolts and check the ring gear size. This set is only for the 8.5 and 8.6 inch 10-bolt; the smaller 7.5, 7.625 and 8.2 inch 10-bolts look similar from the outside and take different gears. On 1999-and-later trucks, the RPO code on the glove box label tells you the factory ratio, and our axle code and gear ratio guide shows where to find it. Before settling on 4.10, run your measured tire height through the chart in our regear after bigger tires guide. If the job is noise rather than tire size, compare the cost of new gears against a bearing rebuild with a GM 8.5 master bearing kit.
The listing and Revolution's product page fit this set to the GM 8.5 inch and 8.6 inch 10-bolt. That covers a long run of GM rear axles, from classic cars and C/K trucks to 1999-and-later half-ton pickups and SUVs, but bearing sizes, axle spline count and housing details changed over the years, so match the axle you actually have. Because the listed carrier break is 2.56/2.73, this 4.10 goes on the same carrier series GM used for the common 3.08, 3.42 and 3.73 ratios, so most owners reuse their carrier. If you are not sure what is under your truck, send us the year and VIN and we will confirm it. For other ratios, see the Revolution 3.73 set for milder tire changes and the Yukon 4.56 set for 35s. Our 8.5 / 8.6 ring and pinion buyer's guide compares the options.
Plan on new bearings, a pinion seal and a crush sleeve with the gears. Revolution's setup chart gives these figures for the 8.5 and 8.6: 0.037 in starting pinion depth, 14-19 in-lb pinion bearing preload, 0.004-0.007 in backlash for 2-cut gears like this one (0.006-0.010 in for 5-cut), 65 ft-lb on the ring gear bolts and 60 ft-lb on the bearing caps. Use the original pinion shim as the starting point, then read the contact pattern with marking compound on both sides of the teeth. The 8.5 carrier installation kit covers carrier bearings and shims, and a crush sleeve eliminator makes preload easier to hit. Fill with 75W-90 gear oil, adding friction modifier if the carrier is a clutch-type posi. Drive gently with no towing for the first few hundred miles, change the oil after break-in, and on newer trucks reprogram the ratio and tire size so the speedometer and shift points come back to normal.
| Brand | Revolution Gear & Axle |
| Part number | GM10-410DC |
| Fits | Revolution Gear & Axle GM 10-Bolt 8.5in/8.6in 4.10 Ratio Face Hobbed Ring & Pinion Set |
| Type | Ring & Pinions |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
No. It is made for the GM 8.5 inch and 8.6 inch 10-bolt only. The 7.5, 7.625 and 8.2 inch 10-bolts use smaller gears with different carriers. Check the ring gear size or the axle code before you order.
Usually not. Revolution lists this set with a 2.56/2.73 carrier break, which is the same carrier series as the common 8.5 and 8.6 ratios, so the existing carrier normally carries over. Confirm your carrier before teardown, especially if it is an aftermarket posi or locker.
It is a common pick for trucks on about 33 inch tires and for street cars that want a quicker launch. Engine, transmission and how you drive all matter, so check your numbers in our regear after bigger tires guide before buying.
New pinion and carrier bearings, races, a pinion seal, a crush sleeve or crush sleeve eliminator, and ring gear bolts. A master bearing kit or carrier and pinion install kits cover these. On a 4x4, the front axle must be regeared to the same ratio.
Revolution's chart lists 0.004-0.007 in for 2-cut gears in the 8.5 and 8.6, tighter than the 0.006-0.010 in listed for 5-cut gears. Always confirm with the contact pattern.
Use 75W-90 gear oil, with friction modifier for clutch-type limited slips. Drive gently and avoid towing for the first few hundred miles, then change the oil.
