library.
I’ve learned a ton from Palazzolo and I’m sure you will too.
– Larry Webster
Detroit Editor
Popular Mechanics magazine
This project has been an interesting journey for me. I learned that there is so much information and new things (and some old things) about axles. I realized that I learned so much by putting my experiences into text. I also made many new friends and strengthened relationships with old ones. I sincerely thank everyone who helped, either directly or indirectly, with the writing of this book.
Tony Nausieda for the opportunity to pursue this book, reviewing draft text, loaning me hardware and even letting me crawl around his barn at sub-zero temperatures to get the last few coveted photos. We all should be so lucky to have such a great friend.
Randy Golda and James Walker for taking the time to review the draft at the proverbial eleventh hour.
My longtime friend, Ward Bowerman, from Torsen for taking his personal time to review Chapter 4 and provide valuable insight and encouragement.
Jason Bock was instrumental with Chapters 4 and 6 and reviewed the draft text and all of the in-depth discussions about theory and practice of assembly steps and differential function.
The entire team at Drivetrain Specialists, specifically Sandy Rissman and Rob Gutowski, for treating me like part of their extended family and allowing me unrestricted access to their shop, parts, and mechanics. Without their openness and cooperation, this book would have never been possible. There was never a time when they did not accommodate any of my requests for support and help.
The countless folks who willingly shared comments and photos for inclusion: Ralph Traycoff from Auburn Gear, Darlene Oleksik from Eaton Corporation, and the teams at GKN Driveline, Strange Engineering, and Winters Performance.
Steve Wesolowski and his team at Dana Corporation for advice, motivation, and pictures when I needed them most.
Randy Shafer for not only taking and editing many of the photos, but for going the extra mile and teaching me how to correctly take and edit photos. He has truly been an invaluable asset to me and this book.
Ray Kuczera for his support and willingness to help. He was always there to remind me how important it is to share as much information as possible with as many people as possible.
Last but by no means the least, I thank my wife, Kathy, for persevering through this book while she was pregnant with our twin boys. It has proven to be quite a challenge for us. To my wonderful mother-in-law, Marilyn Kelley, who sacrificed months of her personal life to help out with the twins, so that I could finish this manuscript on time. There are not many in-laws who would make such a huge personal sacrifice. I am blessed to have both of you ladies in my life, supporting this endeavor and me. You never reminded me how difficult this was on all of us and, instead, offered support and continuous encouragement. This book has become a family affair that is not my book but rather our book. Thank you.
My first experience repairing axles was a front axle on a 1981 Buick Riviera. This was quickly followed by numerous Mustang 7.5- and 8.8-inch rear axles and then GM 10- and 12-bolt axles. There have been countless repairs of vehicles since then.
It seems that rear axles are a bit of a mystery even to the most seasoned mechanics. While we are comfortable with engines, brakes, and suspension, few are at home with rear axles. I’m not certain why this is the case—most axles only require minor maintenance to be trouble-free. Perhaps mechanics don’t get enough practice to stay sharp or maybe it stems from a bad experience of working on an axle. Either way, most shops do not like working on them.
My intention is to help you understand the theory and practice of rear axles. With this information, you can determine if you want to tackle your axle repair yourself. If you come to the conclusion that you would like someone else to perform the work, then at least you will understand what is involved and how to find a good shop. Rear axles are the only part of a car that utilizes a hypoid gear set. This requires some special training, tools, and skill to work on correctly. That being said, it is not beyond most competent mechanics and even the weekend repair person. It does call for attention to details and a large amount of patience.
In addition to providing some information to allow you to diagnose and repair your driveline, I also want to explain some of the terms that are used. I have found that many of the issues surrounding understanding rear axles can be traced back to simple lack of knowledge of the terms and what they mean. It can be very difficult to communicate with someone when you do not understand the language that they are using.
As you have modified your engine and transmission and probably had an axle failure, you probably have heard all types of recommendations. For example, “You need 4.10s with 35-tooth spline axles and a locker.” My hope is that this book helps you decide if 4.10s make sense based on your vehicle’s transmission ratios, tire size, and intended usage. Do you really need 35-tooth spline axle shafts? Make certain that the upgrades you make meet your end objectives and your aren’t just wasting your hard-earned time and money. Even if you do not do the work yourself, you need to be able to assess the shop that is giving you advice and service.
With the advent of the Internet, much free advice is available and often pushed. I caution you that, at times, the advice is worth what you paid for it.
I must also make an admission before going too far. I started out as a mechanic and while this is still my hobby, my formal schooling is as an engineer. As an engineer, I tend to explain theory and how it can be reinforced with math. The math in this book is there to help explain and reinforce the topics, but don’t panic if math is not your strong point. The topics and repairs discussed can be understood if you decide to skip the math. For example, in Chapter 6 I discuss hypoid gearing and manufacturing. Chapter 6 should be a reference for any future repairs regarding hypoids. My intent is to provide information that you won’t find in a normal shop manual while still covering the shop manual fundamentals. That being said, a manual on your own specific differential and driveline will be helpful, but I’ve gone to great lengths to pack as much information into the text and make sure that all of the facts are correct.
So when someone provides you with good advice like, “A Ford 9-inch is the best way to go for your car,” be a little leery and do your own research to get the best solution for your needs. This book will be your guide for determining whether that’s true or not. The key is to enjoy the work and, with the help of this book, achieve great results.
REAR AXLE FUNDAMENTALS
The automotive drivetrain may be the least understood part of a vehicle. After reading this book, you will have a better appreciation of the complexity, and simplicity, of the components that make up the rear axles, differentials, and driveshafts. With the information in this book, you will be
