Seven hardened steel bushing drivers and two handles for removing and installing case, pump and drum bushings in GM 6L80 and 6L90 six-speed transmissions.
If you have a GM 6L80 or 6L90 on the bench out of a 2006-up Silverado, Sierra, Tahoe, Yukon, Escalade, Camaro or Corvette, and the teardown turned up scored drum journals, brass on the magnet or a bushing that spun in its bore, this kit is the set of drivers you install the replacements with. It is seven hardened steel stepped drivers and two handles, the same layout as the 104BDMK style 6L80 driver kit, each head turned to one specific bushing diameter in this transmission.
A 6L80 runs on a stack of thin steel-backed bushings rather than needle bearings at most of its rotating joints. Sonnax lists the set in its 6L80/6L90 bushing kit: the 2-6/3-5-R hub front and rear bushings, the stator support bushings that ride on 1.115 and 1.476 inch journals, the 1-2-3-4/3-5-R drum bushing, the case bushing, the 4-5-6 clutch drum bushing, the front and rear center support bushings, the output shaft bushing and the pump bushing. Several of those also act as oil seals for clutch feed circuits, so the bushing has to finish perfectly round and square to the bore. Each driver in this kit has a pilot that centers in that bore and a shoulder that loads only the bushing edge, so the force goes in evenly around the circumference instead of on one side, which is what egg-shapes a bushing or shaves aluminum off the case. The larger heads also let you seat the front seal flat in the pump.
Bushing wear shows up as pressure loss, so start outside the case. Gears Magazine's 6L80 article walks through comparing actual mainline pressure at the test port against commanded EPC pressure; a unit that cannot hold commanded pressure has a leak somewhere between the pump and the clutches. Our 6L80 pump failure symptoms guide covers telling a pump problem from a leak further back. Once the unit is apart, measure each journal and bore, and replace any bushing that is over clearance, scored, or sitting at a different depth than it was installed at. Most rebuilders replace the full set once the case is open, because a single tired bushing can wipe out a new set of seal rings.
This kit is listed for the GM 6L80 and 6L90 six-speed rear-wheel-drive automatics from 2006 on, in Chevrolet, GMC, Cadillac, Hummer, Pontiac and Holden applications. The 6L90 uses a longer case and heavier internals but shares the bushing sizes this kit is cut for. It is not for the 6L45 or 6L50, which take a different bushing kit, and not for the 6T70/6T75 front-drive transaxles. The drivers are tools only; no bushings come in the box. If you are unsure which unit you have, read the RPO code on the glovebox label (MYC is a 6L80, MYD a 6L90) or send us your year and VIN. Everything else we stock for this unit is on the 6L80 parts page.
Before you remove an old bushing, note its depth and where any oil hole or groove points, then collapse it or pull it out without cutting into the bore. Clean the bore and check it for burrs. Choose the driver whose pilot slips into the bore without slop, lube the new bushing with Dexron VI, and press it in under an arbor press with steady force until the shoulder seats or it reaches the original depth. Sonnax warns against hammering precision bushings, so save the handles for spots a press cannot reach and use light, even blows there. Check the finished bore with a bore gauge and confirm the shaft spins freely. The bushings come from your rebuild kit, such as the 6L80E master rebuild kit with bonded pistons, and while the drums are out an input drum air check tester proves the new seals hold before the unit goes back together.
| Transmission | GM 6L80, 6L90 (2006-up) |
| Replaces | 104BDMK style 6L80 bushing driver kit |
| Includes | 7 bushing drivers, 2 driver handles |
| Material | Hardened steel |
It is sized for the bushings in the 6L80/6L90 case, pump, stator support, center support, drums, hubs and output shaft, and it also seats the front seal. Bushings themselves are not included.
It is listed for the 6L80 and 6L90 only. The 6L45 and 6L50 use a different bushing set, so confirm your RPO code (MYC or MYD) before ordering.
Use an arbor press wherever the part will sit square. Sonnax warns that hammering precision bushings can distort them. Use the handles with light, even taps only where a press cannot reach.
Measure them all and replace any that are scored, loose, out of clearance or moved from their original depth. Most rebuilders replace the full set while the unit is apart.
Dexron VI, the fluid the 6L80 runs on, or a clean assembly lube that is compatible with it.
