Tag: transmission

The Mighty Tremec Manual: behind the transmission @Hemmings

The Mighty Tremec Manual: behind the transmission @Hemmings


Two decades into the new millennium, it’s the undisputed Golden Age of performance. Not only can your order 1,000 reliable horsepower with nothing more than a phone and a credit card, but you can find the project to wrap around it just as easily.

But whether you buy a crate motor, an entire vehicle or have your dream quarter-mile car built for you, the very next step is finding the right transmission to put all that power to the wheels. And while Tremec has been building the most reliable manual transmissions in the business, there are two major features of your new drivetrain that’ll need to be addressed:

  1. Bellhousing Alignment: Your new Tremec manual transmission has been engineered to provide the driving experience you’ve come to expect from the best name in the business, but there’s a very important link in that chain of power that shouldn’t be overlooked: the bellhousing. Literally standing between the motor and the transmission, making sure the bellhousing is properly chosen and aligned is the difference between the strongest and weakest link in your new drivetrain chain. The tech experts at Tremec can guide you through the basic tools you’ll need and the procedure to align your bellhousing correctly.
  2. Driveline Installation: Once the bellhousing and transmission are in place on one end and the rearend has been mounted on the other, it’s time to spec your new driveline. While the correct universal joints and input shaft are necessary, there are three rules to making sure the driveshaft is balanced and will spin freely:

a) Universal joint operating angles at each end of a driveshaft should always be at least 1 degree.

b) Universal joint operating angles on each end of a driveshaft should always be equal within 1 degree.

c) For virtual vibration-free performance, u-joint operating angles should not be larger than 3 degrees

Read on

The Ultimate Hot Rodding Stick Shift Transmission – Cadillac Lasalle @Irontrap


The next major installment in the Hot Rodding 101 series Matt dives into the Cadillac Lasalle Transmission. The 37-48 Cad/Lasalle was THE transmission that was used in a ton of hot rods that were built during the “heyday” of hot rodding. The Cad/Lasalle can be a bit of a confusing transmission, as there is a lot of differences and versions out there. Matt takes us on a crash course on the Cad/Lasalle to help you learn about this great transmission!!

Ford C-6 transmissions – Jim O’Clair @Hemmings


Strength and heft: Good candidates for racing and hauling

In situations where your Ford, or any other engine has had performance improvements, it makes sense to also upgrade the transmission’s performance. For years, the Ford C-4 automatic was a reliable three-speed automatic transmission for many Ford products, and is fine for most 289, 302 or 351 engines that have received modest modifications. A later-model AOD overdrive unit that has been tweaked is one alternative, and certainly a Toploader manual transmission is another. However, for engine modifications, in which increases of more than 400 or 450 horsepower have been achieved, or for racing purposes, you should consider an automatic and changing from your C-4 or AOD to the stronger Ford C-6.

In case you were curious: Cutaway view of the Ford C-6 and typical Ford transmission identification tag

Ford began using the C-6 as a heavy-duty replacement for the C-4 in 1966. It was originally designed for Ford big-block engines. You will find them in Ford full- and mid-sized cars up until 1980, and in many light duty trucks and Broncos until 1990. Because of the C-6 transmission’s strength, you will find many of these units in four-wheel drive applications, however, because they are attached to a transfer case, they lack the necessary tailshaft for two-wheel drive applications. Still, these are viable conversion candidates, if you can locate a tailshaft assembly to mate to them. The C-6 is also used behind many 429 or 460 engines swaps.

The C-6 has a 17-bolt oil pan shaped similar to the state of New Mexico; mostly square, with a pronounced jog in the pan at the passenger-side rear. Units built after 1975 have a deeper pan than earlier transmissions. A vacuum modulator is mounted just above this jog in the valve body. The oil screen is metal and brass, and can be washed out and re-used when a fluid change or other service is performed.

Four-wheel drive versions use a stepped fluid pan, and the filter has an extension tube on it to lower the filter further into the pan. The bellhousing is integral to the transmission, and the dipstick is located on the passenger side just behind the taper of the bellhousing. The thickness of the bellhousing is different on some engines. You will find a narrow and shorter bellhousing on a 351W or 351C, which will be compatible with all small-block Ford, engine displacements. The 351M and 400 engines, as well as the 429 and 460 have a wider and taller bellhousing, which is compatible with the big block engines. First gear ratio is 2.46:1 and second gear is 1.46:1. Third gear is 1:1 and reverse gear is 2.18:1. These are practically the same ratios that Ford used on the later AOD overdrive transmission (with the exception of the 0.67:1 overdrive gear).

The transmission is 33-1/2 in. long, including tailshaft (on 2WD applications), which makes it 3 in. longer in overall length than the C-4 and 2-3/4 in. longer than an AOD or AOD-E. The transmission mount location is 22-1/2 in. from the front of the bellhousing, which makes it a good candidate for replacing a Chrysler 904 or a big block 727 automatic as well as the Turbo Hydra-Matic 700R-4 GM or Ford AOD overdrive transmission with minimal adaptation of the crossmember. When swapping into Turbo Hydra-Matic 350, Powerglide or some Ford C-4 applications it will be necessary to move the crossmember back about 2 inches, in addition to using a bellhousing adapter plate, shortening the driveshaft and changing the slip yoke. The C-6 is a bulky unit, measuring over 16 inches tall and 20 inches wide, so it may be necessary to modify the shifter tunnel on the driver’s side to accommodate the shifter linkage and complete this conversion. All of the pertinent transmission comparison dimensions are listed in the parts locator section of our online website, http://www.hemmings.com/parts-locator.

The C-6 can handle more than 500 hp without major modifications. It is also very heavy–204 pounds, so have a transmission jack or plenty of help handy. The C-6 holds 24 pints, including the fluid in the torque converter. C-6 transmissions used type FA hydraulic fluid, which was designed specifically for Ford transmissions, until mid-1977, and then converted to Dexron/Mercon late in the 1977 model year. The easiest way to tell what fluid you should be using is to check the dipstick. The stick will reference either the FA specified fluid or an M2C138-CJ specification, which is Ford’s designation for Dexron/Mercon.

You can locate a C-6 transmission by looking for one of these production vehicles:

Donor cars you are looking for will have an engine size between 351 and 460 cubic inches; however, you will have to find units from a 351W to bolt directly to small-block applications. These are most commonly found in trucks. Larger engines sizes will have the bigger bellhousing and will not bolt up to small-block applications without an adapter plate.

When looking for one of these transmissions at your local junkyard, we recommend you also buy the flexplate, shifter and torque converter. You’ll want to grab the kickdown rod or cable as well, if it is not still attached to the transmission. Using the proper flexplate is important. As with the AOD transmission we featured a few months ago, Ford V-8 engines used two 164-tooth flexplates. An engine balance design change was made by Ford in the 1980s and will determine if the flywheel on your donor transmission is the correct one for your application or not. Ford engines built from 1969-’81 with the C-6 transmission used a 28.2-ounce, externally balanced flexplate which is 117/16 inches in diameter. The Ford part number is E0AZ-6375A. Ford engines built after 1981 used a flexplate that was a 50-ounce, externally balanced flexplate with the same 117/16 inch diameter. The Ford part number is E2AZ-6375A. When making this conversion, you can use the original 1969-’81 C-6 flexplate found on 302s and 351s built before 1981, but a 164-tooth, 50-ounce flexplate would be required for any small-block Fords that are newer than 1982.

When installing a C-6 into an early FE engine (352, 390 and 427), which was internally balanced, you need to find an aftermarket 164-tooth flexplate with no weights to replace the original 184-tooth unit. For engine conversions where you are mating a C-6 to a 460, you will need a different externally balanced flexplate, Ford number D9TZ-6375A. This fits all of the 460 engines newer than 1979. All three of the above-listed Ford part numbers are available from any of a number of suppliers for around $50. The 31-spline output slip yoke required to hook your driveshaft to the C-6 is also available new. The Ford part number is C7SZ-4841A. This yoke accommodates either a Spicer 1330 series U-joint or a Cleveland S55-series joint. Replacement adapter joints are made by many manufacturers to mate your existing driveshaft to the C-6 slip yoke. The starter from a C-4 vehicle will work fine, however, the AOD starters have threaded holes and you will have to drill out the threads or get yourself a C-4/C-6 starter. These are available from most part stores for less than $50.

Read on

Ford-O-Matic Transmission – Jim O’Clair @Hemmings


Introduced in the early 1950s, parts of this transmission’s basic design are still used in today’s models

Ford’s first automatic transmission, which appeared in its 1951 models, was referred to as the Ford-O-Matic. This basic unit was designed by Borg-Warner and would become the platform from which many later model automatic transmissions would evolve.

Developed as a three-speed automatic, the Ford-O-Matic used a cast-iron case and would normally be started in second gear. For this reason, you often see the Ford-O-Matic referred to as a two-speed, although the only actual two-speed units were produced from 1959-’64, and they had aluminum cases.

A sprag was added to the planetary assembly in 1958 so that you could select whether to start out in first gear or second, and the Ford-O-Matic name was changed to Cruise-O-Matic. They were later upgraded to the FX and MX series Cruise-O-Matics, then the single FMX transmission, and eventually, they evolved into the overdrive AOD transmissions used in the 1980s and 1990s Ford cars and trucks.

The Ford-O-Matic was manufactured in three different case sizes. It was initially offered in both small-case from 1951-’60 and medium-case from 1951-’68 (often referred to as the Merc-O-Matic); large-case versions were also used in 1958-’65 Lincolns.

The 1951-’60 three-speed models can be identified by an oval aluminum tag mounted on the left side of the transmission case just above the oil pan; 1961 and newer units have a tag on one of the oil pan bolts.

Transmission ID numbers were three digits long from 1951-’54 and started with “1P”; 1955 and newer Ford-O-Matic ID numbers were four letters and started with “P.” The ID number will tell you if you have the small, 97⁄8-inch case or the medium, 107⁄32-inch Merc-O-Matic case.

Large-case units were 107⁄8 inches from 1958-’60 and 115⁄8 inches long from 1961 to 1965. They can be found in 1958 Edsels; 1958-’60 Mercurys and Lincolns; 430 V-8 equipped Thunderbirds, and 1961-’65 Lincolns.

Read on

GM TH700R-4 transmission – Jim O’Clair @Hemmings


Another low-buck automatic conversion that could very well pay for itself

Several months ago we highlighted the Turbo Hydra-Matic 200-4R transmission as an automatic overdrive transmission for the economy-minded. The addition of an overdrive gear to any three-speed transmission, be it an automatic or manual shift, can improve fuel mileage and help decrease the wear and tear on your engine.

This month we will discuss the big brother to the TH200-4R referred to by General Motors as either the TH700R-4 or their later designation for it, which was the 4L60 transmission. Although some transmission installers feel that the low first-gear ratio and high second-gear ratio do not make the TH700R-4 the best racing transmission, there are quite a few adaptations you can perform to make it a race-ready drivetrain component. Weighing 184 lbs. this transmission can easily handle power torque ratings up to 650-lbs.ft. of torque, while propelling as much as 8,500 lbs. of payload down the pavement. This makes the TH700R-4 a prime candidate for a swap into any GM rear-wheel driver as a replacement for a TH350, Powerglide, TH400, or TH200-4R.

The TH700R-4 was the first overdrive automatic transmission used in GM cars and trucks in 1982, designated as a Hydra-Matic MD-8 transmission according to GM’s RPO codes. The quickest way to identify one of these units in a vehicle is by the square 16-bolt oil pan. The governor and speedometer drive are both located on the driver’s side of the transmission, the sleeve for the speedometer gear can be found in the tailhousing of the unit. TH700R-4 transmissions use a lock-up torque converter, and they use an electric control solenoid to operate the lock-up function. The electrical connector for this solenoid connector is also on the driver’s side of the transmission case.

Initially, the TH700R-4 came with a 27-spline input shaft from 1982-1984. Later production units were equipped with a 30-spline input shaft. Although the later 30-spline version is more desirable, both units can be interchanged if a torque converter with the proper spline count is also used. For the most part, you will find TH700R-4 models using the standard 153-tooth GM small-block flexplate; however, there are 168-tooth Chevy big-block and 166-tooth Pontiac flexplates available in the aftermarket. A detent or TV cable controlled the passing gearshifts. Several different detent cables were used depending on the vehicle the donor transmission came from. Later versions of this transmission, referred to as the 4L60E (1993 and up), used an additional electric kickdown solenoid to engage the passing gear; however, for this article we will be focusing on the earlier TH700R-4 and the 1990-’93 4L60 units.

TH700R-4/4L60 transmission shift ratios are: First, 3.06:1; Second, 1.625:1; Third, 1.00:1; OD, 0.69:1; Reverse, 2.29:1.

Both the TH700R-4 and the 4L60 versions have an overall length of 30-3/4 inches except in the Corvettes, which measure 29-7/8 inches overall. All other important dimensions such as bellhousing bolt circle and location of the transmission mount are listed in the parts locator section of our website at http://www.hemmings.com/parts-locator/transmissions.html.

You can find a donor transmission from one of these General Motors vehicles:

o 1984-’91 Buick Electra, LeSabre and Estate Wagon

o 1991-’92 Buick Roadmaster

o 1990-’92 Cadillac Fleetwood Brougham

o 1982-’92 Chevrolet Impala and Caprice

o 1983-’93 Chevrolet Camaro and Pontiac Firebird

o 1983 Chevelle

o 1982-’92 Corvette

o 1985-’91 Chevy Astro Van

o 1982-’93 S-10, T-10 and Sonoma small pickups and Blazers

o 1991 R and V series Suburbans up to 3/4 ton

o 1982-’93 C and K series pickups up to 3/4 ton

o 1982-’93 G series vans up to 3/4 ton and full-size Blazers

o 1991-’92 Olds Custom Cruiser station wagon

o 1991-’93 Olds Bravada

o 1986-’88 Pontiac Bonneville

o 1987-’88 Pontiac Grand Prix

o 1983-’86 Pontiac Parisienne

Read on

The Ford AOD Transmission – Jim O’Clair @Hemmings


Add a gear to your automatic and recoup the cost in gas savings

Ford used the Cruise-O-Matic C-4 transmission for almost 20 years behind six-cylinder and small V-8 engines in literally millions of production cars. This three-speed workhorse was replaced in 1982 by the light-duty C-5 transmission, which was discontinued in 1986. Because of gas mileage mandates from federal requirements, Ford redesigned the C-4 into an overdrive automatic to lower highway driving ratios resulting in better highway MPG ratings. They called this replacement transmission the AOD, meaning automatic overdrive, and it became Ford’s first automatic four-speed offering. Because the AOD is basically a retooled C-4, many classic car owners have discovered they can substitute this overdrive transmission into their ’60s and ’70s production vehicles relatively easily and reap the benefits of a lower final gear ratio and decreased wear and tear on their vintage small-block V-8 engine. The AOD was used originally on ’80s and early-’90s Ford, Lincoln, and Mercury products and in the F-series pickups and E-series vans as well. Because Ford used these transmissions in so many production vehicles, the Ford AOD is relatively easy to locate at used parts yards and can be purchased for a reasonable price. The Ford AOD does not need a computer to function properly either. The throttle valve function is mechanically activated and the torque converter lock-up function was contained entirely within the transmission case. Ford later used this transmission as a basis for their newer overdrive versions, the electronic-overdrive AOD-E, which was used beginning in 1993 and in the 4R70W which was used on 1999 and up production cars and trucks.

The AOD transmission can be identified by its 14-bolt oil pan. The pan is basically square, but the back two corners are tucked in a little tighter than the front corners, making the pan look six-sided. Many of the original pans also have “Automatic Overdrive” and “Metric” stamped into them. The metric is true only because the internal parts are metric, but the external mounting hardware to install the transmission is not. You can also check for a tag attached to the transmission itself. This is located on the driver’s side on the bottom bolt that attaches the tailshaft to the transmission body. This tag will have a three-letter code on the top of the tag that will say PKA. The AOD has the neutral safety switch mounted above the valve body on the driver’s side of the transmission and the speedometer drive cable is attached to the vehicle speed sensor on the driver’s side as well. This transmission uses a throttle valve linkage or cable assembly to regulate the shifts. The AOD is definitely bulkier than the C-4, weighing in at about 150 pounds, a full 40 pounds heavier than its predecessor. The majority of AOD transmissions have a close-ratio 2.40:1 first gear, but some SVO-equipped Mustangs and some 1992 and 1993 trucks came with a wide-range AOD with a 2.84:1 ratio. The overdrive ratio for all AODs was .067:1. You can purchase aftermarket-rebuilding parts that will adapt the standard 2.46:1 ratio transmission to the wide-ratio 2.84:1 configuration.

Read on

Evapo-Rust and Ultrasonic Cleaner Meets Model B Transmission Parts


As you can see the caps above were still in a pretty rusty state and this was after some soaking in paraffin.

So onto the next stage which involved the double team of Evapo-Rust and the Ultrasonic Cleaner

And as you can see after about a day just soaking in the Evapo-Rust and then a few hours in the Ultrasonic cleaner the results are very pleasing.

Model B Rear Gearbox Mount

The mount as you can see is in similar condition and is currently residing in the paraffin bucket and is destined for the Ultrasonic/Evapo-Rust combo if it it will fit!

TorqueFlite A904 Transmissions – Jim O’Clair @Hemmings


Chrysler’s venerable lightweight is a durable, versatile option

Although the cast-iron TorqueFlite three-speed transmission had been available as early as the 1956 300C and Imperial models, a smaller, more economical version, the light-duty TorqueFlite six, or A904, was first released in 1960 for six-cylinder engines. The A904 transmission could very well be considered the grandfather of most of the Chrysler automatic transmissions to follow.

First introduced for use with the push-button dash controls, the early 904s still used a cast-iron bellhousing and a ball-and-trunnion-style output yoke, but the physical dimensions and weight were smaller than that of the older TorqueFlites. They did not use a flex plate to attach the torque converter; instead, the crankshaft on the six-cylinder engines had a large eight-bolt flange to attach to the torque converter.

Flex plates and linkage shifting were added for the 1963 model year, and the output shaft was converted to a standard slip yoke in 1965, the same year the larger-cousin 727 was released. A904 transmissions were original equipment on all 170, 198 and 225 six-cylinder engines, as well as the 273, 318 and 360 (two-barrel) V-8 engines until 1978.

Derivatives of the 904 include the AMC Torque Command 6, the A909 (a 904 with lockup converter), the A500 (904 with a fourth gear added to the rear of the case), the Baby 904 (Mitsubishi-based compacts, the Arrow and Colt), the A998 (904 with an extra friction plate, usually found in 318-equipped vehicles), the A999 (904 with two extra friction plates, for 360 V-8 engines) and the 30RH (904 with computer-controlled lock-up converter often used in Jeep applications).

Gear ratios remained the same from its inception until 1980: 2.45:1 first gear, 1.45:1 second gear, 1:1 third gear and 2.22:1 reverse. First gear was dropped to 2.74:1 and second was lowered slightly to 1.54:1 when this wide ratio gear set was used in all 1981 and newer 904 transmissions. All 904 transmissions up to 1977 had a hydraulic 10.5-inch converter, although the 1977 models used a low-slip converter of similar size. 1978 and newer 904s all used a 10.5-inch lock-up converter.

Read on

Model A to Model B Transmission Swap 2023 Project


Happy New Year!

I purchased an early Model B gearbox a while back at a good price, (3 years ago!! but never took things any further but now back on the radar) not in the best condition but appears to be serviceable. The other parts I’ve been gathering with the help of John Cochran. (need any Model A bits, he’s your man)

There are a fair number of parts needed to complete the conversion, but I think it’s worthwhile as its a synchronised transmission. The later unit is supposed to be a better option but we’ll work with what we have and it’s a good project to take into 2023.

As you can see some of the parts need some work. There are a number of differences between the Model A and Model B set up. Major items are the clutch housing, flywheel, relocation of the pedals and wishbones just to mention a few.

Made a start on the shift tower which had some rust and debris that has fallen into the gearbox, this however should be easy to remove. The unit was filled will gear oil when I originally purchased it to keep things lubricated during storage. As you can see even with a cursory initial clean up on the shift tower, things look a lot better.

During the clean up I came across the part number which is cast into the casing, stating 40-7222, which was a little confusing as this is the earlier transmission.

A quick check over at the excellent VanPelt site quickly solved the mystery

The 40-7222 shifter housing (known as the “slanted” tower) pictured below was used from 1933 through 1935 models. The B-7222 housing (1932 only) looked the same but had two mounting bosses on the right hand side for the parking brake handle mount. Both early housings incorporated the B-7235 shift lever guide plate (see picture at bottom of this page). The guide plate was discontinued after 1934 production. The early housings used the B-7230 and B-7231 forks through 1933 and perhaps part of 1934 production. The slanted towers used the smaller 7230/7231 shifter forks, but also used the smaller shifter levers. Although it will bolt on to any 1932-52 toploader gearbox case, it can NOT be used with the 1939 and later gear sets with the late style synchronizers. This housing is the single detent type, using the same detent spring and plungers as the 68-7222 housing.

Work continues!