Tech article by Jon Hanna (Admin)
Automatic Transmission Intro
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| Transmission: | |
| C4 3 speed automatic | |
| Sources: | |
| 1973-1977 Broncos as well as several other Ford cars and trucks from 1964-1981 | |
| Identification: | |
| Unlike the other transmissions in this article, the C4 has a removable bell housing. Also see the transmission pan image above for identification. | |
| Adapter required? | |
| Because the C4 was a stock option on Broncos an aftermarket adapter isn't needed if you can find a stock unit. If not there are aftermarket adapters available. | |
| Pros: | |
| This is the simplest, most straightforward and least expensive automatic transmission option because it was originally available on 1973-1977 Broncos. Find a donor Bronco with a C4 and transfer parts. Although the C4 was originally designed for smaller V8's it has a strong aftermarket following and can take a lot of abuse if built properly. | |
| Cons: | |
| The C4 has a fairly high first gear without the modern advantages of overdrive. In completely stock form the C4 can be a little weak for high output engines. | |
| Cost: (Approximate) | |
| Transmission: $150-500 used and $500-1400 rebuilt (expect to pay near the upper end of this range if you are getting your C4 out of a 73-77 Bronco. Adapter kit: $500-550 | |
| Drive Shaft Mods: | |
| Total transmission is approximately 1.5" longer requiring some drive shaft modifications. | |
| Bell housing: | |
| The C4 came behind small block Ford engines and will bolt up to your 289-302-351 engine. | |
| Modifications needed: | |
| Very few modifications are needed if using a C4 out of a Bronco. |
| Manual Transmission Gear Ratios | 1st | 2nd | 3rd | 4th | 5th |
| Bronco 3 spd (6 cyl) | 3.41 | 1.86 | 1.00 | ||
| Bronco 3 spd (8 cyl) | 2.99 | 1.75 | 1.00 | ||
| NP 435 | 6.69 | 3.34 | 1.79 | 1.00 | |
| T-18 | 6.32 | 3.09 | 1.69 | 1.00 | |
| Toploader (Close ratio) | 2.32 | 1.69 | 1.29 | 1.00 | |
| Toploader (Wide ratio) | 2.78 | 1.93 | 1.35 | 1.00 | |
| Toploader (Overdrive) | 3.29 | 1.84 | 1.00 | 0.81 | |
| ZF | 5.72 | 2.94 | 1.61 | 1.00 | 0.76 |
| NV4500 (Dodge) | 5.61 | 3.04 | 1.67 | 1.00 | 0.73 |
| NV3550 | 4.01 | 2.32 | 1.40 | 1.00 | 0.78 |
