The C4 that was in mine when I bought her had a shift kit installed. It would hold in gear and crisply shift into 2nd chirping the tires. I am planning on putting this C4 into a rolling chassis since I have another motor that I can mate it with just waiting for the right car.

The C4 is a strong tranny and can be built for racing easily.

 

I'm actually enjoying my c4. Having 3.40's, I run 3k at 65-70 mph and it's actually fine. I think it was just irritating when I had the flowies super 40 exhaust on and the droning can make you insane. I've been contemplating t5 or aod, but how often do I really take my car on 15+ miles away from my home and needing the overdrive? Not often. Also, I usually stick to 65 and right side of the freeway so I'm a grandpa driver, but rather not get caught with people flying by. I have my original c4, having slight issues right now, but I might get a broader performance c4 and add the manual valve body in it. I call it a cruiser/street rod, not freeway racer. But I wouldn't worry much about Rpms being around 3k. You'll be good. I've do it for 5 years.

 

The C4 is a great transmission. People have to start thinking about how things were "back then" versus today. Older design engines could easily handle the higher rpms versus today's engines. The reason OD came about is because of fuel economy. Yes, it sounds different having higher revving engines but that is the way it was. Honestly, if the tranny shifts don't head down the road of swapping. Enjoy what you have and stop worrying.

 

+1 to what everyone has already said.

C4's are great transmissions, take care of it and it'll last you forever. Unless you're doing major mods, the c4 will be everything you need on a street car, bar personal preference of course. If you've got low rear gears, I've got 2.80, you'll be just fine and you'll stay in a comfortable rpm range at 70,75 mph.


Eric

 

Welcome to VMF. I swapped from a C4 to a T5 five speed only because I had most of the original parts because the car was originally a 4 speed. I just had to buy a couple of parts to accommodate the the difference between the T5 and the 4 Spd. The C4 I had was fine and I was running about 3000 RPMs around 72MPH with a 3.00: rear axle.

 

The C4 has a 1:1 high gear ratio, the same as a Top Loader 3 & 4 speed, T-10, FMX, C6, etc. My '66 with a Top Loader in 4th, with a 3.00:1 rear gear and 215/65R15 tires sits right about 3,000 rpm at 72mph. To me, that's just about purrrrrrfect.

 

I don't plan on using it as a daily driver, not really interested in taking it to the track. More for crusing on date night but would like some pretty good power to it. Don't like the sound of reading that at 75 it will be at 5500 rpms.

 

Ok, so the car has a 302 with a C4. What gears are in the rear?

 

First, understand the world functioned just fine for many, many, many years without overdrive transmissions. No concerns. Read about RPMs and what they were in the 60s with steep gear sand no overdrive!! We all lived.

 

The Cruise-O-Matic C4 is probably one of the best 3-speed automatic transmissions made. It can be built to survive behind the stoutest small-blocks and has a comparitively low parasitic drag. The rpms at speed will depend on your rear axle ratio. A Gear Vendors overdrive unit can be installed behind it or a newer model overdrive automatic such as the 4R70W installed to lower the highway rpms, albeit at the cost of more parasitic loss. FWIW, there's nothing wrong with cruising all day long with a 289-302-351 at 3,000 rpm other than using more fuel and slightly more engine wear.

 

Welcome to the Forum.Many miles have been accrued with C4 transmissions! Over Drive is a great addition to any highway cruiser. What do you plan on doing with the car? What kind of driving do you plan/expect to do? An automatic OD trans is easier swap than a manual trans swap. Is shifting more rewarding to you? Then the conversion is worth it. Vern

 

I've got a '66 with a C4 and 2.8 rear end. At around 60mph I'm at ~2k rpm. The C4 doesn't have an overdrive, but you could swap in a transmission with an overdrive gear (manual or automatic). What differential ratio does the car have right now?