How to Identify a 700R4 Transmission
So you think you might have a 700R4 transmission in your ride, but you’re not quite sure? Don’t sweat it, this transmission can be tricky to identify since it’s so similar to other popular GM transmissions like the 4L60. But with this handy guide, you’ll be able to ID a 700R4 in no time.
I’m gonna break it down for you real simple-like with some key tips to look for, so you can know what you’re working with under the hood. Whether you’re looking to do a rebuild, need to order the right parts, or just want the satisfaction of figuring out what transmission you have, I’ve got you covered.
Here’s the skinny on identifying a 700R4:
- It was used in GM vehicles from 1982-1993 – This was the heydey of the 700R4, so if your ride is from this era, chances are good you’ve got one.
- It’s a 4-speed automatic overdrive tranny – The “4” in 700R4 stands for 4-speed. And it’s an automatic with overdrive capability in 4th gear.
- Check the bolts around the transfer case – Raising the vehicle and peeking at the bolts is the easiest way to ID it.
- It looks a lot like a 4L60 – These transmissions are crazy similar. The 700R4 came before the 4L60 and they share some parts.
- It’s made of cast aluminum – The 700R4 uses cast aluminum for the case and components making it light and strong.
- Length and weight – Coming in at 23.4 inches long and weighing 155 lbs, she’s not petite but not a heavyweight either.
- Gear ratios – First gear ratio is 3.06:1, second is 1.63:1, third is 1:1, and fourth is 0.70:1. This combo gave great acceleration and fuel economy.
- Input and output shafts – The input shaft has 30 splines while the output shaft has 27 splines. This helps identify the 700R4.
- 16-bolt pan – Most 700R4 transmissions came with a 16-bolt pan from the factory. Exceptions existed, but it’s a good starting point.
- TV cable – Uses a TV (throttle valve) cable to control line pressure based on throttle position. Important for proper function.
- Lock-up torque converter – Locks up in 4th gear to improve fuel economy. Only operates when engine conditions allow it to lock.
- Removable bellhousing – Has a removable bellhousing like most automatics, allowing for easier installation and transmission work.
- 27% overdrive 4th gear – This tall overdrive gear gave it great highway mileage for the time while maintaining performance.
- 450 lb-ft max torque – Built stout from the factory, able to handle up to 450 lb-ft torque from high-performance engines.
- Replaced by 4L60E – The electronically controlled 4L60E succeeded it in 1993 with the new computerized controls of the day.
- Popular swap transmission – Thanks to its strength and overdrive gear, it’s still commonly swapped into hot rods and custom vehicles today.
So in a nutshell: if you’ve got a 1982-1993 GM ride with a 4-speed auto, start checking for those key clues like the TV cable, bolt pattern, and gear ratios to positively ID the transmission as a 700R4.
Digging Into the Origin Story of the Legendary 700R4
Before we dive deeper into identifying the 700R4, let’s take a quick walk down memory lane to see where this transmission came from. Knowing the backstory can help give clues as to where you might find one.
The 700R4 was born in the early 80s when fuel economy became a big concern. GM needed a modern transmission with an overdrive gear to allow vehicles to have both quick acceleration and increased fuel mileage.
They started with the old reliable TH350 3-speed automatic and added an overdrive 4th gear and lock-up torque converter – essentially transforming it into a 4-speed overdrive. This innovative transmission was dubbed the 700R4.
The “700” refers to the new transmission family it belonged to, and the “R4” means it was a 4-speed rear-wheel drive automatic. (You might also come across the 700R4’s little brother – the 200R4 – which was the lighter duty front-wheel drive version.)
The 700R4 first appeared in 1982 GM vehicles like the Chevy Camaro and Pontiac Firebird. It was an instant hit – providing improvements in both performance and fuel economy over the TH350. This made it a crucial player in GM’s vehicle lineup through the 80s into the 90s.
Over a decade of refinement went into the 700R4 before it was eventually replaced by the more advanced 4L60E electronically controlled transmission in 1993. Even still, the 700R4 secured its place as one of the most legendary automatic overdrive transmissions ever produced.
This little history lesson gives us some key points for identifying the 700R4:
- Used in GM vehicles from 1982-1993
- Originated as an upgraded version of the TH350
- Was innovative for adding overdrive and lock-up torque converter
- Improved acceleration and fuel economy over previous transmissions
- Found in a wide range of GM rear-wheel drive cars and trucks
If you’ve got an 80s or early 90s GM ride – especially a performance model – chances are good a 700R4 is bolted up behind that engine. This background helps narrow our search.
Popping the Hood: Key Areas to ID a 700R4
Alright, we covered the backstory. Now it’s time to get our hands dirty and identify the specific features that set the 700R4 apart. Let’s dive under the hood and look at some of the best ways to visually ID this transmission:
1. Check the Transmission Pan Bolt Pattern
The transmission pan is a great place to start. Since the pan has to mate up to the bottom of the transmission case, automakers devised bolt patterns to ensure each transmission matched up with the correct pan.
The 700R4 was made with a 13-bolt and 16-bolt pan:
- 13-bolt – This was used on early 80s GM trucks and some third-party applications.
- 16-bolt – The most common OEM 700R4 pan. Used on the majority of rear-wheel drive GM cars and trucks.
So peek under your ride, drain the ATF to access the pan if needed, and count those bolts! 16-bolts likely indicates a 700R4, but even a 13-bolt pan will get you heading the right direction.
Pro Tip: Transmission pans can sometimes be swapped later, so also check for other identifying marks from the manufacturer.
2. Spot the Throttle Valve (TV) Cable
Another great identifying feature is the TV or “throttle valve” cable. This cable connects the transmission to the throttle body, allowing the transmission to sense throttle position and adjust pressure accordingly.
The 700R4 uses a TV cable system from the factory. Look on the passenger side of the transmission bellhousing for a cable that runs up to the carburetor or throttle body. If it’s there, you can be sure you’ve got a 700R4.
The TV cable is a key component that allows the transmission to shift properly based on throttle input. Make sure it’s adjusted correctly or shifting will suffer.
3. Check the Case Casting Numbers
Many OEM transmissions have an ID tag or casting number right on the case. With the pan dropped, take a peek at the driver’s side of the transmission to see if you can spot a tag with some identifying numbers and letters.
Here are a few examples of 700R4 case casting numbers:
- MD8 = 1982-1984 700R4
- MN4 = 1986-1989 700R4
- MQ4 = 1990-1993 700R4
Seeing those prefixes (MD8, MN4, MQ4) cast into the case is a dead giveaway you’ve got a 700R4 transmission.
4. Count the Splines on the Input and Output Shafts
To be 100% sure you’ve got a 700R4, you’ll need to verify the input and output shaft sizes:
- Input shaft – Has a 30-spline count
- Output shaft – Has a 27-spline count
This 30/27 spline combo was exclusive to the 700R4 and helps identify it from similar transmissions.
You may have to remove the torque converter to see the input shaft. Getting to the output shaft may require pulling off the tailhousing. A little work, but it’s worth it for a positive ID.
5. Verify the Gear Ratios
The gear ratios are another way to conclusively identify a transmission. To check them in a 700R4 you’ll need to open it up, but here are the factory specs:
- First Gear – 3.06:1
- Second Gear – 1.63:1
- Third Gear – 1:1
- Fourth Gear – 0.70:1
Matching up those ratios confirms you’ve got a 700R4. No other transmission shares that exact combo.
Pro Tip: Snap a pic of all the casting numbers and stampings inside the case and on the internal parts for future reference.
So there you have it – five ways to sleuth out the 700R4 by checking the pan, TV cable, case casting, splines, and gear ratios. A few simple checks under the hood or digging into the guts will help you confirm the transmission.
Common 700R4 Applications
To give you a better idea of the vehicles the 700R4 was used in, here’s a quick list of common applications:
GM Cars:
- Chevy Camaro
- Pontiac Firebird
- Chevy Monte Carlo / El Camino
- Oldsmobile Cutlass / 442
- Buick Regal / Grand National
- Cadillac Seville
GM Trucks:
- Chevy K Series Pickup
- GMC S-15 / Sonoma
- Chevy S-10 / S-10 Blazer
- Chevy Suburban / Tahoe
- GMC Jimmy / Yukon
- Hummer H1
Other Vehicles:
- AMC Eagle
- Jeep Cherokee (1987-2001) XJ
- Isuzu Pickup
- Mitsubishi Mighty Max Pickup
So if you’ve got an 80s or early 90s GM rear-wheel drive ride, chances are good a 700R4 came stock. Even some non-GM trucks and SUVs used them too.
Knowing the common vehicle applications gives you an idea of where to start hunting if trying to source a used 700R4 transmission. Hit up salvage yards, online forums, and clubs for these vehicles to locate a good takeout.
Real World Examples – Spotting a 700R4 in the Wild
Let’s take a look at a couple real world examples of identifying and verifying an unknown transmission as a 700R4:
Mystery Transmission #1
Our first scenario is a 1982 Camaro Z28 picked up from a buddy. It supposedly has the original engine and transmission, but there’s no way to know for sure. How can we ID if it’s really a 700R4?
Using our handy identification tips, we spot these clues:
- 1982 model year Camaro – possible 700R4 year
- Has TV cable hooked to carburetor
- Sixteen bolt pan pattern
- Casting number MD8 seen on transmission case
- Input shaft has 30 splines, output has 27
Checking the vehicle year, TV cable, bolt pattern, case casting, and splines verifies that this mystery transmission is indeed an original 1982 700R4!
Mystery Transmission #2
The second example is a transmission purchased used online. The seller thinks it’s a 700R4 but they’re not certain. Here’s what we notice when inspecting it:
- Has no TV cable installed
- Pan is unmarked with 16 bolts
- Casting number not found externally
- Input shaft has 30 splines, output has 27
Even with some missing clues, the unmarked 16-bolt pan and matching 30/27 spline shafts identify this transmission as a 700R4. Proper TV cable and modulator can be added later to get it working right.
These examples illustrate how even a few telltale signs can positively ID a 700R4. A combination of visual cues and verifying internal components goes a long way.
Steps for Proper Installation
Once you’ve identified the transmission, proper installation is key to ensuring longevity and performance. Here are a few key steps:
- Replace fluid and filter – Drain old ATF, replace filter, and refill with fresh fluid before installing.
- Install TV cable correctly – Set proper geometry and adjust TV cable bracket so cable moves freely.
- Torque converter bolts – Use a torquing pattern to tighten converter bolts to spec – usually 35-45 ft-lbs.
- Cooler lines – Install new transmission cooler lines and fittings. Flush cooler too.
- Manual linkage – With engine installed, set transmission manual linkage so park/neutral sends correct signal.
- Crossmember – Torque crossmember to factory specs. Supports transmission weight and reduces flex.
- Start fluid – Add initial fill of ATF and check level with engine running. Top off as needed.
Taking it slow and using good installation practices will give your 700R4 the best shot at a long, happy life in your ride. Proper maintenance keeps this transmission purring for miles to come!
Signs of Problems to Watch For
Even a well-built 700R4 can develop issues over time. Here are some common problem signs to keep an eye out for:
- Slipping – Transmission slips coming out of first gear or between shifts. Could indicate worn clutches.
- Shift flares – Hard shifts or flares, especially when cold. Potential issue with valves or boost valve.
- Burning smell – Burnt aroma coming from transmission. Possible overheating issue.
- Leaks – Check bellhousing, cooler lines, and case for any external fluid leaks. Reseal as needed.
- Shudder / chatter – Transmission shudders or chatters during torque converter lockup. Might need converter replaced.
- No overdrive – Transmission won’t shift into fourth gear overdrive. Often caused by TV cable setup.
If you experience any of these symptoms, it’s best to dig in and diagnose the problem early before lasting damage occurs. A few upgrades can also improve durability if pushing big power.
Going Strong After 30+ Years
The 700R4 transmission made its debut in 1982 and still soldiers on in classic cars and trucks over 30 years later. This just shows how ahead of its time the overdrive design was.
Identifying a 700R4 is pretty straightforward once you know what to look for. Check for the TV cable, 16-bolt pan, and those all-important 30/27 splines to be sure.
This transmission continues to prove its mettle today – whether factory stock or built to handle 1,000 hp. Given some TLC and proper maintenance, the 700R4 has a lot of trouble-free miles left in it!
So there you have it friends – everything you need to know to ID a 700R4 transmission. These great overdrive autos aren’t getting any more plentiful, so get out there and snag one for your project! With this handy guide, you’ll be able to spot a 700R4 with confidence.
Now grab a socket set and let’s get wrenching! That dream ride won’t build itself.
Conclusion
The 700R4 is an iconic American transmission that served muscle cars and trucks from 1982 all the way to 1993. Identifying it takes knowledge of the history, key components, and specifications that make the 700R4 unique.
With the distinguishing features covered here like the TV cable, typical bolt patterns, spline counts, and gear ratios, you can positively identify a 700R4 transmission in your garage or heading for your project.
Whether you’re trying to verify your existing transmission or seeking one out for a future swap, use this guide as a checklist to ID the 700R4. Keep it handy as you inspect potential cores at the junkyard or talk shop with fellow gearheads.
Having the right tools makes any job easier. Now you’ve got the toolbox to tackle identifying this great overdrive transmission with confidence. Here’s to many more miles and memories ahead with the legendary 700R4!
