Don't Let Dynamic Racing Transmissions' Name Fool You. They Can Build a Great Street C4 for Your Vintage (or Late Model) Ride
Our fully rollerized Street & Strip C4 (PN DT4S4R) is capable of handling approximately 500 horsepower, more than our 289 will ever see (then again?). Any more than that and Dynamic recommends their Mighty Mite C4 with a manual shift valve body.Since our hardtop V-8 conversion alsorequired a bellhousing, we orderedan OEM bellhousing throughDynamic under PNDA4B2.
Our Project '66, while encompassing a full restoration, is also tackling the well-worn quest of converting a six-cylinder car to V-8 specs. While we've previously covered suspension, brakes, chassis stiffness, and steering, we're now involved in our drivetrain buildup for our hardtop. Our previously installed Currie Enterprises Super Eight rear fitted with a 3.25 gear and their traction-sensing differential center section will be able to handle our 289's power with ease. But what about what goes between our hotted-up (yet stock-appearing) 289 and our beefed-up (but also stock-appearing) rearend? What we needed for our project was an equally capable, well-built, performance-oriented C4 transmission that retained an outwardly stock appearance, but could handle whatever our 289 could throw at it.
Getting a performance-built C4 isn't something you can usually do with your local transmission shop. Quite often, a stock-level rebuild is the extent of their abilities. We felt the best alternative to our problem was a mail-order transmission for our project car. First and foremost, we didn't have a transmission to rebuild in the first place. Second of all, an experienced performance transmission mail-order company would be able to build what we needed and ship it to our door ready to go (or almost ready, as was our case--more on that in a minute).
After seeing what's out there in the realm of performance C4 transmissions, we chose to work with Dynamic Racing Transmissions. Their level of options, build quality, and quick turnaround were all factors that helped us pick up the phone and call. After discussing our 289's proposed specs, rear gear ratio, tire size, and our intended use of the hardtop with Dynamic's J.R. Miller, he felt our best bet would be one of their fully rollerized Street & Strip C4 transmissions with optional Vasco-Jet input shaft and their solid-strength forward drum. We'll go into these details in the captions, but needless to say, this brute of a C4 will handle all we can throw at it.
Our C4 transmission arrived via truck freight complete and ready for installation. We, however, decided to go the extra length and detail the transmission to look more correct (and fit it with the correct manual lever), as the transmission arrives painted semi-gloss black. The manual lever on the Dynamic C4s is cut off to allow the use of an aftermarket shifter (which follows industry standards). You can add an aftermarket bracket or install a factory lever, which you'll have to procure on your own. But shy of this one concern and the detailing (optional for you non-show types), the transmission will bolt in with no modifications or problems.
1 For less parasitic drag, and improved performance and fuel economy, we opted to have Dynamic build our Street & Strip C4 with their optional C4 roller internal set (PN DA4R1). The fully rollerized parts are made possible after Dynamic tosses the factory plastic thrust washers and re-machines key parts to accept a roller bearing. This is a must-have option for those using high rpm engines or for those who will see sustained highway rpm's with steep gears. | 
2 In this "exploded" view, you can see the various parts that make up the roller set, which include, from left, the low/reverse drum, reverse ring gear, and reverse planet carrier in the front row. In the back row, from left, is the input shell, full roller planet pinion, and forward drum. | 
3 This closeup of the full roller planet pinion set shows how the planet pinions are now riding on full roller bearings top and bottom. This is how Dynamic can easily get these parts to survive such harsh lives. |
4-a The Dynamic solid strength forward drum (PN DA4D1) is another Dynamic exclusive trick used to allow their C4s to live long, healthy lives. If you look closely in the center of picture B, you can see a yellowish coloration in three "peanut"-shaped areas. On the stock Ford drum, these areas are machined openings that can cause deflection within the walls of the drum under heavy application of power. | 
4-b Dynamic uses only the late 26-spline drums with five-clutch disc capacity (and made from the correct material) for these modifications. Once the correct drum core is obtained, the cavities are filled with a special compound and then the drum is re-machined, increasing its strength and power capacity. | 
5 While it may sound like a trivial concern, we needed a C4 dipstick and tube for our new transmission. Dynamic carries this great replacement under PN DA4F1 for case-fill and PN DA4F2 for pan-fill applications. The dipstick is a modern equivalent that has a locking grip to prevent transmission fluid pressure from pushing the dipstick out, a problem in high-rpm situations. For the show crowd, simply slide an OE Ford dipstick into the tube when needed. |
6 This driver-side angle shows the manual lever location, just forward of the low/reverse servo piston cover. In the stock OE floor shift configuration for the Mustang, the manual lever points upward and is connected to the shifter with a steel shift linkage rod. Due to the fact that the C4 cores used by Dynamic come from many varied sources (trucks, column shift, etc.), it is almost impossible to provide the correct lever for the application, thus the manual lever is cut down to allow the use of an aftermarket shifter. This is an industry-wide solution, no matter what vendor you use. | 
7 When we spoke with J.R. at Dynamic about the manual lever and our options, he explained that there are two popular choices. We could either add an aftermarket bracket to the existing lever (bolt on or weld on) or we could replace the modified manual lever for an original uncut lever with the correct orientation. We knew a friend with some disassembled C4s and were able to pick up a stock manual lever. Replacement requires removal of the transmission pan, but it is quite painless. | 
8 When it comes to torque converters, Dynamic uses TCT (Torque Converter Techniques) models matched to each application's specifics. For our Street & Strip C4, Dynamic had TCT build us a 10-inch Street & Strip model with a 3,000-rpm stall speed converter featuring full furnace brazing, a 360-degree mounting ring with anti-ballooning plate, triple bearings, hardened pump hub, and more for the best in streetability and performance. |
The Detailer's Touch
Getting the Dynamic C4 to look the part is not a difficult problem. Since the transmission comes completely painted, the surface is already relatively clean. A simple once-over with some form of degreaser to rid the case of any residual assembly oil will suffice before painting. We had good luck with the typical aluminum paints available on the market in spray can form. After masking the output shaft and seal and a few other key areas, we gave the Dynamic C4 three good coats of paint and allowed it to dry overnight. The next day, we broke out the detail brushes and painted the servo covers and attaching bolts, the adjustment bolts, jam nuts, and pan bolts with a natural-finish paint. To finalize your detailing, you can always add the correct paint blotches or stripes, but don't overdo it. If you're not sure what to add, don't put anything on it. You can always go back and add the markings later.
What's in the Street & Strip?
While Dynamic carries several models of C4 transmissions, including their popular Comp, Roller Comp, and Mighty Mite C4s (capable of over 1,000 hp!), we chose their Street & Strip model, simply called the S&S for our project. The S&S C4 will shift for itself fully when in drive and does not require any driver interaction (hence the street part of the name), but it can still be manually shifted for performance (the strip part, naturally). Standard items in the S&S include improved quality clutches and bands, an increase in the number of clutch discs, Teflon sealing rings (for instant sealing without wear), extra-wide babbit bushings, and a recalibrated valve body. All of these standard modifications will increase the durability and life of the C4, while improving shift quality and feel. A nice firm and quick shift is what you will feel with a Dynamic S&S C4.
J.R. cautioned us on one durability area of the Ford C4s design, though. The front pump and support area can be a weak spot when coupled with highway gears (such as a 2.80 or 3.00) due to the amount of torque multiplication required by the transmission. So, upgrade your rear to a 3.55 or better and your C4 will live longer.
We also optioned the Vasco-Jet input shaft on our S&S buildup, as well as the aforementioned solid-strength forward drum and full roller set. Since we've already described the modified drum and full roller set in the main article, we'll discuss the value of the Vasco-Jet shaft here. If you look carefully at the solid-strength drum image in caption 4B, you will see that the splined inner hub has a flat section on each side, often called a blind spline. In a factory C4, the input shaft is splined equally around its circumference, leaving these two areas where there is no contact between the drum and the input shaft. The Dynamic Vasco-Jet shaft, while also stronger than other "hardened" shafts, is machined with a pair of corresponding splines to fit the blind spline areas on the forward drum, giving it 100-percent contact and greater strength--a Dynamic exclusive.