Ford C6 3-Speed Heavy-Duty Automatic · Ford/Lincoln · Expert rebuild service since 1987. Lifetime warranty. Free diagnostic.
1966–1996 Ford F-100/F-150/F-250/F-350, Bronco; 1966–1989 Mustang (big-block), Thunderbird; 1966–1979 Lincoln Continental; used behind 390/427/428/460 FE and 351M/400/460 engines
| Configuration | 3-speed automatic, heavy-duty design for high-torque applications |
|---|---|
| Gear Ratios | 1st 2.46:1 · 2nd 1.46:1 · 3rd 1.00:1 · Rev 2.18:1 |
| Fluid Type | Ford Type F ATF (preferred) or Mercon |
| Fluid Capacity | 11.0 qts total, 6.0 qts service refill |
Same throttle valve system as lighter Ford automatics, but the consequences are more severe in the C6 due to the high-torque applications it backs. Low line pressure from TV wear accelerates forward clutch failure.
Symptoms: Slipping under hard acceleration; flare on 2-3 shift; delayed engagement from Park
The forward clutch is engaged in all forward gears and takes the most abuse in high-torque, towing, and off-road applications. Contaminated fluid or low pressure wears the frictions quickly.
Symptoms: Slipping in all forward gears; no Drive engagement; burns ATF smell
The C6 uses an external adjustment screw for the intermediate band. If left unadjusted for extended service intervals, the band glazes and loses 2nd-gear holding force.
Symptoms: Slipping in 2nd gear; band adjustment screw has no effect; RPM flare on 1-2 upshift
Complete disassembly. All clutch packs replaced with heavy-duty Alto kits. Intermediate and low/reverse bands replaced. TV system inspected and adjusted. Valve body rebuilt with new separator plate. Heavy-duty input shaft inspected. Full soft parts kit. Converter flushed and flow-tested.
Type F ATF every 30,000 miles. Adjust intermediate band every 30,000 miles — it's an external adjustment, no removal required. Do not tow or haul at max capacity with degraded fluid.
The C6 is a heavy-duty unit designed for big-block and high-torque applications. It has a larger, stronger case, bigger clutch packs, a heavier-duty pump, and a higher torque rating. The C4 is for small-blocks only.
A properly rebuilt C6 with a shift kit handles 600+ hp. It's one of the most popular transmissions for high-performance Ford builds due to its strength and simplicity.
Likely forward clutch wear from high-torque loading. Could also be low line pressure from a worn TV plunger. We'll do a pressure test to confirm which before recommending a repair.
The adjustment screw is on the driver's side of the case. Tighten to 10 ft-lbs, then back off 1.5 turns (early C6) or 2 turns (later C6). It's a common DIY service item.
Yes — the C6 has excellent aftermarket support from Sonnax, Alto, and TransGo. We stock all common rebuild parts and can complete most C6 builds in 2–3 days.
Free diagnostic, written estimate, lifetime warranty. Chicago's C6 rebuild specialists since 1987.
