Six 0.062 in 3-4 clutch frictions for the GM 4L60E, 4L65E, 4L70E and 700R4, OE 8642174 and 8654145, to rebuild the pack that burns first.
A Silverado, Tahoe, S10, Camaro or Corvette with a 4L60E that pulls hard in first and second, then flares or just revs up when it should grab third, has very likely cooked its 3-4 clutch. This is the replacement pack: six 0.062 in friction plates sold as Tri Component 77104K-6, interchanging with GM 8642174 and 8654145. If you only need the 3-4 clutch, or you want fresh 3-4 plates to go with an overhaul kit you already own, this saves you buying a full friction set.
The 3-4 pack sits in the input housing and applies on the 2-3 upshift, then stays applied through fourth. That means every mile at highway speed is spent with it holding engine torque. Sonnax points to the thin factory backing plate as the leading cause of 3-4 distortion and burnup, because it flexes during apply and lets heat build unevenly across the plates. Low line pressure and leaks in the third-gear oil circuit, such as a worn input housing seal or a bad 3rd accumulator, make it worse by letting the pack apply soft and slip. Put a modified engine in front of it, or tow with it, and this is reliably the first clutch to fail.
Pay attention to which gears are missing. Transmission Digest ties missing 2nd and 4th to the 2-4 band and sun shell, while a burnt 3-4 pack takes away 3rd and 4th, so the pattern tells you where to look. Then pull the pan: heavy dark friction material points at a clutch, while metal flakes point at hard parts such as a shell or planet. Our 4L60E shift problems guide covers which gears go missing for which failure, and 4L60E common problems and fixes explains the pressure faults that burn this pack in the first place.
These frictions fit the 4L60E, 4L65E and 4L70E from 1993 on and the TH700-R4 from 1982 to 1993. Stack count is the detail to watch. Sonnax describes stock 700-R4 and 4L60E 3-4 packs as five or six frictions depending on application, while the 4L65E and 4L70E run seven. One 6-pack covers a five or six plate 4L60E. A 4L65E or 4L70E needs one more plate, and builders running a seven-plate pack in a 4L60E housing use thinner steels and a matched backing plate to make room. Measure your stack before you commit. See everything else we carry for this unit on our 4L60E parts page.
| Position | 3rd and 4th clutch (3-4 clutch) |
| Quantity | 6 friction plates |
| Thickness | 0.062 in |
| Fits | 4L60E, 4L65E, 4L70E 1993-up, TH700-R4 1982-1993 |
| Interchange | GM 8642174, 8654145, 28168AM, 342-1002, 74100C, A74100C, B61108X, 77104X |
| Part number | Tri Component 77104K-6 |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
For a stock five or six friction 4L60E or 700R4 pack, yes. The 4L65E and 4L70E use seven frictions from the factory, so those units need an additional plate.
A burnt 3-4 clutch pack is the most common cause. Pan debris helps confirm it: friction material points at the clutch, metal points at hard parts.
Replace any heat-damaged steels and the 3-4 piston seals, and inspect the input housing, 3rd accumulator and pump. Low apply pressure is what burns this pack, so fix it or the new plates will fail.
Yes. Soak them in clean ATF for at least 30 minutes before stacking so the lining is fully saturated.
Yes. They are listed for the TH700-R4 from 1982 to 1993 as well as the 1993-up 4L60E family.
