Replaces all 21 friction plates across the five clutch packs (C1-C5) in a GM 8L90 8-speed during an overhaul, with BorgWarner OE-supplier material.
This is a complete friction plate set for the GM 8L90 eight-speed automatic: 21 BorgWarner friction plates under kit number 35445KIT, enough to restack all five clutch packs during an overhaul. The 8L90 sits behind the 6.2L V8 in 2015 and later Silverado and Sierra 1500 trucks, Tahoe, Yukon and Escalade SUVs, the Camaro SS and ZL1, the Corvette and the Express and Savana vans. If your teardown found burnt, glazed or worn-through frictions after a slip, flare or 3-4 neutral complaint, this is the friction side of the rebuild in one box.
The 8L90 gets eight forward speeds and reverse from four planetary gearsets controlled by five multi-plate clutches. Every gear holds three of the five clutches applied at once (the clutch names below list the gears each one works in), and every shift releases one clutch while applying another under computer control. That clutch-to-clutch timing is why worn frictions show up so quickly: the module expects each pack to grab at a learned pressure, and when the lining is glazed or the clearance has grown, the off-going and on-coming clutches no longer overlap cleanly. BorgWarner is a long-time supplier of friction material and released its own 8L90 friction plates for the aftermarket in 2019.
Plate counts and sizes below are from the kit listing. Packs are named by the gears they hold, the same naming Sonnax uses for the 8L45 and 8L90 solenoid circuits:
It is frictions only. Steels, seals, gaskets, pistons and the filter are not included.
Not every 8L90 shudder needs a teardown. GM bulletin 18-NA-355 traces the common 25-80 mph shudder to the converter clutch and calls for a fluid exchange to Mobil 1 Synthetic LV ATF HP, so rule that out first using our 8L90 common problems guide. A 3-4 neutral can also be a solenoid connector swap or a missing check ball, and our 8L90 3-4 clutch failure guide shows how to separate those from a burnt pack. Sonnax also warns that worn pressure regulator bores can push line pressure past 415 psi, which cracks castings and destroys drums; if that is what burnt your clutches, fix the valve body too or new frictions will follow the old ones.
The kit is listed for the GM 8L90 and 8L90E from 2015 on. It is not an 8L45 kit; the smaller 8L45 uses different clutch sizes. Plate counts and dimensions can change between production updates, so measure two of your old plates from each pack against the list above before you start the build. If they do not match, send us your year and VIN. All 8L90 parts are on our 8L90 and 8L45 collection page.
| Fits | GM 8L90 / 8L90E, 2015 and later |
| Part number | BorgWarner 35445KIT |
| Plate count | 21 friction plates |
| C1 (1-3-5-6-7) | 4 pcs, 0.074 in, 42T, 7-9/16 in OD |
| C2 (4-5-6-7-8-R) | 4 pcs, 0.065 in, 21T, 6-5/16 in OD |
| C3 (2-3-4-5-6-8) | 5 pcs, 0.065 in, 23T, 6-13/16 in OD |
| C4 (1-2-7-8) | 5 pcs, 0.057 in, 36T, 7-11/16 in OD |
| C5 (1-2-3-4-5-R) | 3 pcs, 0.081 in, 48T, 7-5/16 in OD |
| Condition | New |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
21 plates covering all five 8L90 clutch packs: 4 for the 1-3-5-6-7 clutch, 4 for the 4-5-6-7-8-Reverse clutch, 5 for the 2-3-4-6-8 clutch, 5 for the 1-2-7-8-Reverse clutch and 3 for the 1-2-3-4-5-Reverse clutch.
No. It is friction plates only. Pair it with an 8L90 overhaul kit for seals and gaskets, and add steels if yours are blued or scored.
No. The kit is sized for the 8L90. The 8L45 uses different clutch dimensions.
Usually not. GM bulletin 18-NA-355 ties the common 25-80 mph shudder to the torque converter clutch and calls for a fluid exchange. Replace frictions when a teardown shows burnt or worn plates.
DEXRON HP, the fluid GM specifies for the 8L90. Soak each plate at least 30 minutes before stacking.
