Eaton Detroit Truetrac Differential 32 Spline 3.45 & 3.72 Ring Gear Pinion Ratio 5th Gen Camaro
The Eaton Detroit Truetrac 912A686 is a helical-gear limited-slip carrier for the GM 8.6 in. independent rear (218mm, AAM-built) used under the fifth generation Chevrolet Camaro V8. If your 2010-2015 Camaro SS lights up one tire on every launch, pushes wide on corner exit with the inside wheel spinning, or you are already pulling the rear apart for gears and want a traction upgrade that does not need clutch packs or friction modifier, this is the part. Eaton lists it for 32-spline axle shafts and 3.45 and 3.72 ring and pinion ratios.
An open differential always sends equal torque to both half-shafts, so the tire with the least grip sets the limit for the whole car. The Truetrac replaces the open case with a steel carrier holding parallel-axis helical pinions. When one side starts to spin faster, the gear tooth thrust loads the pinions against their pockets and that friction biases torque toward the tire that still has grip. There are no clutches to wear and no locking event, so it drives like an open unit in normal traffic, works the same in forward and reverse, and stays quiet on the street. That makes it a good match for a daily-driven SS that sees track days or drag strip launches.
Not sure whether a helical unit or a full locker suits your car? Our hard parts catalog carries both, and the guide on open vs limited-slip vs locker differentials walks through the trade-offs.
Put the car on a lift, put the transmission in neutral and spin one rear wheel by hand. If the opposite wheel turns backward freely, the car has an open differential. Next, drain the gear oil and look at it: a fine gray haze is normal wear, but chunks or chipped teeth mean you need bearings or a gear set along with the carrier. If you are chasing a noise rather than traction, our Camaro V8 8.6 ring and pinion master install kit page explains how bearing noise differs from gear whine.
This listing is the Eaton 912A686: GM 8.6 in. IRS / 218mm AAM case, 32-spline side gears, for 3.45 and 3.72 ratio gear sets in the fifth generation (2010-2015) Camaro. The V8 SS uses the 8.6 IRS; the V6 cars use a smaller 7.6 in. IRS and are not a fit. Ring gear mounting can change between ratio series, so check the ratio stamped on your ring gear or your build sheet before ordering. If your car has a ratio outside the two listed, send us your year and VIN and we will confirm. Carrier bearings are not included.
Drive normally for the first few hundred miles so the new bearings and gear contact settle in, then recheck the oil level. For more on how this carrier compares with Eaton's locker, read Detroit Locker vs Detroit Truetrac.
| Brand | Eaton |
| Part number | 912A686 |
| Fits | Eaton Detroit Truetrac Differential 32 Spline 3.45 & 3.72 Ring Gear Pinion Ratio 5th Gen Camaro |
| Type | Differentials |
| Condition | New |
| Ships | Same business day (in stock), from the USA |
| Warranty | 1-year |
No. The V6 cars use a 7.6 in. IRS rear. This Truetrac is for the 8.6 in. (218mm) IRS used under the V8 SS.
No. Carrier bearings are not included. Plan on a new bearing kit or a master overhaul kit for the Camaro 8.6 IRS so the carrier runs on fresh bearings.
Eaton recommends petroleum or mineral-based GL-5 80W-90 and says not to use synthetic gear oil or friction modifier. The helical gears do not need the additive a clutch-type limited slip does.
Eaton lists this case for 3.45 and 3.72 gear sets. Ring gear mounting can change between ratio series, so send us your year, VIN and the ratio stamped on the ring gear and we will confirm the right case before you order.
Yes. A new case moves the ring gear position slightly, so set carrier preload and backlash with shims and check the gear contact pattern before the cover goes back on.
