Powerglide Transmission Handbook
The last time the El Camino ran, it wouldn't go anywhere — that was more than a decade ago.
Before that, it sat for nearly 18 years. At this point, it's been dormant for almost 30 and everything is either atrophied or significantly deteriorated.
Putting my Grandfather's El Camino back on the road isn't going to be a simple undertaking.
I could simply attempt to find the culprit keeping the transmission from pressurizing the torque converter, but, after 50+ years, it's probably time for a rebuild anyway.
That's where the Powerglide Transmission Handbook comes into play: This job is too important to me to allow anyone else to do it and before I read this book, I didn't know how to rebuild a Powerglide.
That sounds like a recipe for disaster, I know, but I'm very familiar with automatic transmissions and I've successfully rebuilt quite a few major components over the years, so, let's see what this book has to offer and whether or not it can help you with your 'Glide.
The Powerglide Transmission Handbook was written by the late Carl H. Munroe nearly 20 years ago. Munroe was a veteran racer and the owner of TSR Racing Products in Gilsum, NH — a shop that specializes in Powerglides and other drivetrain racing components.
This book is the culmination of his work with GM's aluminum Powerglide — work that began with the broken transmission in his Super Gas competition car and led to the opening of his shop. It covers both factory and race applications from removal to installation — including the all-important stuff in-between: rebuilding them for your driver or modifying them for your race car.
Follow along for a chapter by chapter review of this thorough manual:
Chapter 1: Powerglide History & Identification
The aluminum Powerglide was produced from 1962-1973 and Chapter 1 covers each and every year. That coverage includes its development, its applications, and its use as a racing transmission. While Chapter 1 discusses the entirety of the Powerglide's history, it spends the majority of its 19 pages exploring the identification of its various components. Unlike a lot of books that only cover part numbers for identification purposes and move on, the Powerglide Transmission Handbook makes a detailed inquisition into every transmission variation and their major parts. After you're finished with this chapter, you'll have a thorough explanation of how to distinguish a factory Powerglide in all its permutations.
Chapter 2: How the Powerglide Works
One of the keys to finding success with an automotive hobby lies in knowledge. The more you know, the more details you can weave into a larger understanding, the more effective you'll be when engaging with it, and there aren't many places where that's more prevalent than with the automatic transmission. Luckily for you, the Powerglide only has two gears and is one of the simplest to comprehend. While you don't need to know the entirety of an electrical system to diagnose an electrical problem, with an automatic, you have to know and understand what all of its hydraulic circuits and related components do to effectively diagnose and repair one. Thankfully, the author, Carl H. Munroe, has you covered. Chapter 2 is extremely thorough and he goes over every single aspect of this transmission. If you read this chapter enough to fully grasp all the information he shares in it, he'll give you the foundation you'll need to tackle your own Powerglide.
Chapter 3: General Transmission Service
When I read the name of this chapter and the next, "In-Car Maintenance, Repairs & Adjustments," I was a little confused. They seemed to me to be the same thing.
Don't worry, they aren't.
This chapter focuses on general rebuilding information for the Powerglide. That is to say, what you need to understand about the factory components and replacement parts, in order to make educated decisions while rebuilding your transmission. It also covers some interesting aspects of transmission fluids, as well as assembly lubricant, cleaning, and thread repair advice. This information is excellent and borders on engineering-level knowledge, but, instead of going deep into theory, it keeps the focus on how the materials science and engineering behind the components effect how to choose them during the rebuilding process.
I really wish this kind of information was in every automotive book — enthusiast or professional.
Chapter 4: In-Car Maintenance, Repairs & Adjustments
The Powerglide Transmission Handbook really is thorough. When I pick up a book on rebuilding an engine, I don't expect to learn things like maintenance and how to adjust the way it runs while in the car — not so, here.
In it, Chapter 4 covers everything you can do to a Powerglide in a car for a factory application. From what I can tell, it covers all the maintenance, all the repairs, and each and every adjustment.
Because the list is extensive, I'm going to divide it into three parts:
- Fluid level check
- Fluid and filter replacement
- Vacuum modulator canister and modulator valve
- Extension housing
- Governor, governor support/rear pump, and speedometer gear
- Oil pan, valve body, and throttle valve
- Servo cover, servo piston, and spring
- Park pawl, park pawl bracket, and spring
- Shift lever, detent plate, and shift lever seal
- Band (there's only one in a 'Glide)
- Throttle valve and throttle valve linkage
Chapter 5: Specialty Tools for the Powerglide
So, you wanna build your own 'Glide?
You're going to need a lot of special tools.
I could've told you that without reading the book. While I haven't rebuilt an automatic transmission before, I've done manuals, rear ends, and lots of extensive engine work, including assembling my own for the 347. Just looking at the kinds of subassemblies inside an automatic would be enough to clue me in to the need for specialty equipment.
I can also tell you it won't be cheap, even with the instructions to custom make a bunch of them yourself. That's the rub if you want to do your own rebuild work to the complex components in your ride — you know, engines, transmissions, rear ends, alternators, starters, etc. The truth is, that unless you need to do a bunch of Powerglides, its cheaper to have it done by someone else rather than invest in the specialty tools you're going to need.
There is another scenario where investing in these tools is of value — just not monetary value: you're like me. That is to say, you're particular and/or you want the experience of doing this work yourself.
Of course, it's also a good idea to get some experience before you tear into whatever specific component you want to rebuild — like the Powerglide for my Grandfather's El Camino, as an example — by rebuilding others for practice. Based on the use of old components to make the tools described in this book, you'll also need some cores to build them. So, there you go, to do a good job on your own transmission, plan on getting your hands on a few, as well as working on/rebuilding some before you tear into the one that matters. Rebuilding a complex component in a car is never cheap — especially if you intend to do it well — no matter what route you take. However, this chapter offers lots of help with picking out or making your own custom tools — but you'd better have some good fabrication skills, because some of these custom tools require metal work and/or welding.
Although short, Chapter 5 covers more than 16 specialty gadgets you'll need, plus helpful variations of some of those tools and equipment. There are, however, other specialty tools mentioned throughout the book you'll need that aren't mentioned here. Most significant of which are a lathe and/or milling machine, welder, press, and transmission jack — a car lift might be a good idea, too.
Chapter 6: Transmission Removal & Core Disassembly
The title of Chapter 6 says it all. However, what it doesn't say is that the transmission removal section is general and the core disassembly section is both detailed and carefully illustrated with photographs and diagrams.
For the section on transmission removal it covers three applications: 1962-1966 cars, 1967-1973 cars, and Corvettes. It's intentionally kept general because there are too many applications to get specific for each one — you'll need a repair manual (preferably a factory repair manual) for your application to get the transmission out. For the disassembly section, it's broken up into two parts. The first is a detailed written summary of the process needed to disassemble the Powerglide broken down into five subsections. The second part provides illustrated examples of the significant procedures mentioned in the first part with captions for each photo and/or illustration.
After reading Chapter 6, I definitely felt like I had a thorough understanding of how to disassemble a Powerglide — which isn't the kind of impression I get from most of the automotive literature I've read.
Chapter 7: Disassembling Unit Assemblies & Overall Inspection
While Chapter 2 is a very thorough introduction to the Powerglide and its various parts, and Chapter 6 provides a very detailed description of how to remove the major assemblies from the transmission, Chapter 7 is what I would consider to be the real introduction to those assemblies as it carefully takes you through disassembling and inspecting each one — which feels much more real and tangible than the theoretical introduction in Chapter 2. Don't make the mistake of jumping ahead though, understanding how these components work and interact with each other is critical to comprehending the Powerglide, as well as get the most out of this chapter.
As for what assemblies are covered, here's a rundown:
- Main case
- Extension housing
- Reverse clutch pack, piston and pressure plate
- Front pump, stator support and pump gears
- Input shaft
- High clutch drum, piston and clutch pack
- Band and servo piston assembly
- Planetary gear assembly and output shaft
- Manual valve lever and detent guide plate
- Valve body
- Rear pump housing/governor support
When I say thorough, I mean that each part (or group of parts) gets its own section, complete with clear illustrations and detailed descriptions — in fact, the front pump gears get two sections.
Chapter 8: Overhaul & Reassembly of Unit Assemblies
Chapter 8 is very similar in format to Chapter 7, but is nine pages longer to account for the greater detail needed to explain overhauling the various assemblies — and there is a lot of detail for a lot of assemblies; here's a list:
- Valve body
- Main case
- Reverse piston, clutch pack and pressure plate
- Servo piston and cover
- Extension housing
- Front pump
- Rear pump/governor support
- High drum, piston and clutch pack
- Planetary gear set
Chapter 9: Final Assembly
Now it's time for the fun stuff: putting all the shiny parts together.
If you're to this point — as Munroe points out in the beginning of Chapter 9 — you should have all components overhauled and properly set up. This chapter is formatted like the previous two, and the sections include installing the following sub-assemblies in the case:
- Planetary gear set
- High clutch drum, low band and input shaft
- Front pump and thrust washer
- Valve body, filter screen and oil pan
- Rear pump/governor support, governor, speedometer gear and extension housing
- Modulator valve and vacuum canister
There we have it, the transmission is complete. Chapter 9 also includes the final adjustments you'll need to make before tossing your Powerglide back into your ride.
Chapter 10: Torque Converter Design & Operation
Now we move beyond the transmission to the torque converter.
Beyond the transmission?
Yes and no.
A torque converter in an automatic is similar to a clutch in a manual in that it acts as an interface between the engine and transmission. Unlike a manual clutch, however, a torque converter is reliant on the transmission — specifically, the front pump — to feed it fluid and keep that fluid pressurized so that it can transfer the engine's power, because it doesn't actually provide a mechanical connection between the two that torque can transfer through.
Welcome to the mysteriously-complex hydraulic world of the torque converter.
In Chapter 10, Munroe discusses the factors that make the torque converter work, including both the parts and the forces. Not only that, he also discusses how those parts and forces impact torque converter performance and how they are altered to change converter operating characteristics. Although short, it fits in a lot of information useful for choosing and using a torque converter in a non-stock application — and even includes sections on how performance converters are built and serviced.
Chapter 11: The Drag Racing Powerglide
If you're looking for information on drag racing Powerglides, you've come to the right place. Chapter 11 is far and away the longest chapter in the book at 40 pages — and it covers a lot.
While many people think drag racing is a simple sport, the fact is, that, while the race itself is simple, the variation in the classes and field of competitors makes for some very complicated technical issues, and because the race is so short, the need for perfection and consistency makes it extremely challenging. As mentioned in the text, that creates a demand for a wide variety of transmission applications. In this chapter, Munroe explores how to adapt the otherwise simple Powerglide to meet those needs.
Chapter 11 is split into two parts, components and modifications. The section on components provides a descriptive list of components available to modify the Powerglide. The second section on modifications explains how to make a number of those mods to your 'Glide.
Following are two lists of the respective information covered:
- Valve body pressure relief springs
- Safety Shields
- Engine adapters
- Shorty kits
- Extension housings
- Front pumps
- Input shafts
- High gear clutch hubs
- Shift kits
- Manual valve bodies
- Trans brakes
- Aftermarket gear sets and carriers
- Pinion pins
- Output shafts
- Oil pans
- Quick connectors
- Shift lever and shaft assemblies
- Bands and servos
- Friction and reaction plates
- Nitrous and nitrous-capable torque converters
- Extension housing
- Front pump
- High drum and front clutch pack
- Reverse piston and clutch pack
- Shorty kits
- Gear sets and output shafts
- Increasing line pressure
- Temp gauge
Chapter 12: The Circle Track Powerglide
Chapter 12 is short, but that's okay, because it doesn't need a lot of space. This chapter continues the information in the previous chapter on the drag racing Powerglide with some components and modifications that are unique to circle track racing applications.
I do have a note for this chapter: On page 195, in the caption for the driveshaft yoke, it mentions an acceptable measurement of 1"-1½" for the distance between the extension housing and yoke body. Everywhere else in the book states 1"-1¼". I don't have any factory literature to verify what the correct dimensions are, but be aware that this bit of info could be wrong.
Chapter 13: Reducing Rotating Weight & Friction
Rounding out building the transmission is Chapter 13. Here, Munroe focuses on the modifications you can make to lower static weight, rotating weight, and internal friction. Some can be used on all transmissions, others can only be used in very specific circumstances where torque and horsepower aren't too high, or launch RPM isn't too low.
Chapter 14: Installation & Operation
Chapter 14 provides the specific information necessary for transmission prep and the general instructions for installation, testing, adjustment, and operation in a race vehicle — but not the information for installation and adjustment in an OEM vehicle. It relies on Chapter 6 for installation (reverse of removal) and 4 for adjustments. Also, as mentioned in Chapter 6, it doesn't cover vehicle specific instructions, so be prepared to grab an application-specific repair manual. However, if yours is a stock rebuild like the one I'm doing for the El Camino, it does provide initial testing procedures for OEM applications, so make sure to read the whole chapter.
Chapter 15: Troubleshooting
The last chapter of the Powerglide Transmission Handbook covers troubleshooting for both stock and race units. Although it sounds boring, Chapter 15 is pretty nifty because the author has assembled all this information in one place and made it more accessible than you'll find in repair literature. And, of course, if yours is a performance application, you won't find that guidance in a repair manual for a factory automobile.
This book leaves no stone unturned. That's a tall order for an enthusiast-oriented manual — most leave you with lots to figure out. Outside of how to engineer a Powerglide and how to remove and install one in every unique application that GM put them in, this book really does cover it all.
At 234 pages, the Powerglide Transmission Handbook is healthy by enthusiast standards — but worth it. After reading it, I can genuinely say I feel prepared to tackle the Powerglide in my Grandfather's '67 El Camino — just as soon as I can figure out how to afford to put together a shop to do it in and gather the machines, equipment, and tools to do it with.
Although Carl H. Munroe is no longer with us, after reading his book, it's obvious he really knew the Powerglide and his craft, and he left behind a great book chocked full of valuable advice to remember him by.
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