Professor Morris in the laboratory. Photo: Joe Bonnello Author: Professor Tommy Morris
This month's lesson: Introduction to Power Steering Systems
Welcome to the 20th class in Dirt Sports University Series. We have finished up on Shocks and Suspension with the completion of our 19th class in the June issue. In the future, when some new suspension technology shows itself, we may do an update class on the new subject material.
THE UNIVERSITY: If you are new to the Dirt Sports University Series format, let’s take a moment to give you a little background on it. In the making of the University Series we wanted to have a classroom format to help pass along knowledge to our readers from experts in various subjects. Our goal is to bring you the information you will need to formulate the best decisions for your particular project. Along the way on this journey we hope that you will also find your place with regard to how much money you will need to plan on investing into your vehicle to do the job properly. No one ever said that off-road vehicles were cheap to build, buy or have. It is actually quite the contrary, as you are most likely going to spend more than you ever imagined. Just getting your hands on a vehicle is usually only the entry fee into the sport, as you will then need to use it and have fun. Next you will need to maintain and, most likely, fix something that broke on it. Then the cycle repeats itself over and over. We could get into project planning spreadsheets, cost analyses, budgets and all the good stuff that a good company would do for a project, but that would be no fun. For myself, I would rather look for a tall building to leap from. Those finance subjects would take a whole class or two to cover properly, and then would only leave us all bummed out about all the time and money we are going to light fire to in the quest of our off-road passion. With that said, let’s get back to the fun of abusing credit cards and tearing stuff up.
WHERE ARE WE HEADED: As we looked at where to take this class following shocks and suspension, several suggestions were tossed around and so we shifted gears, tossed a coin in the air and landed on power steering systems for the next subject matter. Next to shocks and suspension, the steering system is another one of those seemingly black holes that plays a major part in what your vehicle needs to operate safely. Hopefully what you learned on how to understand, tune and improve your suspension system has made your vehicle faster and easier to control. Now, most likely, one of your next challenges is to keep it steered in the right direction without the steering feeling sluggish or kicking back in your hands. To really enjoy driving your vehicle, the steering system must add to your comfort level and feeling of security, not challenge it. Hopefully we can shed some light on where the current power steering systems originated from, and then onto where the industry has progressed to today. If only there were a crystal ball to see the future ahead.
CLASS SCHEDULE LENGTH: There is no telling exactly how many classes it will take to give comprehensive detailed explanations of all of the power steering system components. As you noticed with shocks and suspension, there are lots of details involved with each part of the system, and power steering is no different. As you consider how hydraulic oil under pressure, working in conjunction with the steering wheel in your hands, powers the tires to steer in the direction you want to go, there is more than you can see going on from the outside.
HOW WILL WE GET THERE: With each new subject matter that this class will embark on, we will take a moment to reflect on the history of its development. All of the neat, cool products that are on the market today did not just happen overnight. Most are the result of a lot of hard work, pain and suffering, along with brain cells being damaged for many people. And I’m not necessarily talking about how hard they were thinking about fixing their problems, but the abuse the human body was put through just driving their off-road vehicles. Many times it was not a brilliant engineer coming up with solutions, but the school of hard knocks with grassroots racers pondering their problems out in the garage late at night. Solutions to parts failing often came from looking at another vehicle over at a friend’s shop and how that different component could get put into their beauty. This process of failure and adaption has happened over and over again to the point where today advanced racing vehicles can literally be purchased over the counter. It was not that long ago that, if you wanted something, you had to design it and make it yourself.
LEARNING FROM THE PAST: I would imagine that many of you have now heard of the NORRA Mexican 1000 that takes place on the Baja peninsula. This event was reestablished several years ago from its early beginnings in the mid 1960s. Yes, even before SCORE International, there were others around. The goal was to bring back as many of the old off-road vehicles from the early days as possible. Lots had gone to the off-road graveyard of “who needs them anymore?” Times have now changed as a growing legion of rabid followers of the rekindled NORRA 1000 Baja event are feverishly hunting down old vehicles with the dream of restoring them back to what they once represented. A good portion of the vehicles participatiing in the NORRA event are virtually the same as they were back in the days when they were state of the art. A few even date back to the late ’60s where the clock started on what we now seem to take for granted. If you are ever around these old vehicles, take a moment to look them over to understand and respect where all the great off-road vehicles we see now once came from. Just about every system in today’s advanced off-road vehicles had very humble beginnings. All of these old vehicles had some sort of steering system that allowed them to be driven. In many case they only had a steering damper to help limit the abuse to the driver from the feeble manual steering systems available then.
Saginaw boxes came in several mounting tab styles and were adapted to many racers. STEERING PARTS THEN: The roots of the power steering systems of today really started back in the late 1960s. Almost all of the buggies had a simple steering box right off of a VW, and most often used on a stock VW front beam. High-tech teams had a steering box from a Porsche that was larger and stronger. Power steering in the buggies was pretty much non-existent for many years. Once you moved out of the buggies into larger vehicles, if power steering did not come stock, then you probably didn’t have it. As time progressed into the mid-’70s for the trucks and other vehicles larger than buggies, pretty much all had common sense hit them and power steering became mainstream. Meanwhile the buggies were still struggling with various contraptions to ease steering effort. As tires got larger and the vehicles faster, steering problems increased. This same issue is really no different today. Keep in mind that there were not the robust rack and pinion power steering systems that are available now. Pretty much all were stock power steering boxes bolted to a stock or modified frame. If you did not have a Saginaw steering gear box, then you were in even deeper trouble, as most other OEM brands were harder to modify for off-road use. The power steering oil pumps might have had some holes opened up to increase flow and bump the pressure up some along the way. As loads and demands on the pump increased, the input shafts on some pumps would break. At that point a custom-made shaft of better material was put in place, but that was about it.
THE EARLY FIX: The name that was the most prevalent early on was Tom Lee and his company Lee Manufacturing. He was involved building steering for Sprint cars and Midgets along with just about anything that seemed to move and needed some steering help. Vehicles for the handicapped were also one of his specialties, with modifications done to ease the steering effort for folks with limited arm strength. This experience would help Lee with the needs of the fast growing off-road community. HE was truly one of the early pioneers who came up with solutions that helped racing progress forward to what it is today. Many in the off-road power steering industry now owe some of their credit to the success of what Mr. Lee started. I personally owe a debt of gratitude to Mr. Tom Lee and his wife Gail. During the heyday of the PPI/Toyota factory program in the late 1980s early 1990s, they opened their doors to me for a good education on everything inside of the entire power steering system. This helped to straighten out some issues that PPI was having with their custom Toyota steering in MTEG stadium racing, as well as the desert-racing program. This input of information helped to win many races and championships for Toyota with Ivan Stewart and the rest of the PPI team drivers. Please take note that there are many suppliers in the off-road community now who produce very good power steering components. They have not been slighted in this, as several will be covered in future classes. It is, however, fair to give some credit where it is due to the early pioneers in the industry. If any have been missed, I apologize.
The spool valve controls power and flow and was often modified for racing use. EARLY BUGGY STEERING DEVELOPMENT: There were many ideas and creations for steering in buggies. Once they got past manual VW steering gear boxes on the front beam section, there were a couple of rack and pinion systems being produced. The steering rams were usually crafted from a shock absorber can and shaft that had mounting pieces welded to them. Being that buggies were supposed to be a somewhat economical way for many to race, the quality of most components suffered from the limited dollars used to produce them. The large aftermarket companies that you see now simply did not exist then. Many of the early buggies swapped out the manual steering for a Saginaw power steering gearbox rescued from a junkyard. This was then mocked up where the old manual box sat and pieces of metal were cut up and fashioned into mounting brackets welded to the front frame area. The stock Saginaw Pitman arm was then creatively modified to connect to the stock VW tie rod ends. For power steering pumps the Saginaw was the choice of most. The Saginaw pump and mounting brackets usually came from the same car or truck as the Saginaw steering box was scavenged from. You could often use the pulley that came on the pump or find what you needed in diameter from another model that used the same pump. By staying with the same vehicle’s pump and steering box, it helped ensure that the pump flow and pressure needed for the matched pair had already been figured out by some smart engineer back at the Saginaw factory. The options of how to get a reliable steering box and pump were simple: scavenge a junkyard for what you needed and then if you had some money, you found someone to rebuild them. If the dollars were really flowing, a new steering gear box and pump were happily purchased new from the parts counter at the local GM dealership. Getting auto parts store remanufactured units was not a very good option as the rebuilding companies did it as cheaply as possible, which usually led to early failures.
EARLY TRUCK STEERING DEVELOPMENT: If you were not running a Saginaw power steering box, you were at a disadvantage. General Motors and Chrysler vehicles almost always came with Saginaw steering units, while Fords had Ford-branded steering units. Saginaw had an advantage in this area with different steering box ratios along with steering servo spool valve assemblies that could be interchanged and modified easily for different steering wheel input feel. As the same old story goes, as tires got larger and vehicle speeds increased, so did steering component failures. Once the basic steering components such as relay rods and tie rods were sorted out by the early 1980s, it was the steering gear box sector shafts failing right at the Pitman arm or breaking the center tooth off internally. Also common were failures of the Saginaw pump shaft. All of this was after you figured out how to keep the oil in the system with larger oil reservoirs, along with keeping the high-pressure hose from blowing off under high back feed pressure.
The yellow pencils mark the common sector shaft crack and failure points. Ram assist fittings were added to many boxes to take force loads off of it. CREATIVE FIXES: Several in the off-road truck community were coming up with urethane cushions at the Pitman arm to relay rod connection to help reduce loads back into the steering box. This helped, but was not a final solution to the sector shaft failures. Jon Nelson at Nelson and Nelson Racing ran the Chevy factory team with Larry Ragland behind the wheel. They had suffered several of the common Saginaw steering box failures. Jon’s solution was to remove the steering box from its stock location at the front frame area and put it inside of the cab just under and alongside of the passenger seat. The steering box was now connected from inside the cab to the original front steering linkage assembly through the front firewall along the right side of the engine by a creative setup of bell cranks, urethane bushing mounts and shafts. This seemingly complex solution to their steering failure problems worked out very well and was actually a very simple solution, once you looked at it working. With this now in place, Larry Ragland went on to win even more races for Nelson’s Chevy team.
SAGINAW RAM ASSIST: Not everyone was as crafty as Nelson in the earlier days to mount the steering box remotely, let alone find the room to fit the adaptation in the cab. Once it was finally deemed that the Saginaw steering gear box, acting all alone by itself, could no longer handle the chore of keeping the steering wheel from ripping out of the driver’s hands or the sector shaft from failing, other options were needed. An external ram was added to the Saginaw box system by adding fittings to the existing steering box housing that would allow pressure from the servo to power a secondary ram connected to the steering linkage. This modification takes the high force loads on the steering box and reduces the load between the two hydraulic rams. The original internal ram inside the steering box then got help from the external ram so that the sector shaft carried a greatly reduced load.
IN CLOSING: Hopefully you found this class on off-road history for steering systems informative and were not put to sleep by it. As we move forward, you will start to see how the current steering systems have been influenced and developed from challenges early on. What we have available today has been proven out in the past. Our future will be guided and developed based on where we are now, and it will be interesting to see where it takes us. Remember that at the end of the day you and you alone are the one in control and responsible for your choices, decisions and implementations of any ideas that we put in your head. Be responsible and make your decisions wisely.
HOMEWORK: Take a look around you at various vehicles and the steering systems they use. Just about every phone now has a camera in it, so take lots of pictures. Get a good understanding of what all the parts of the system are. This will help you as we move forward in the next class. If you have missed some of these classes, make the effort to get a hold of what you missed. Remember that knowledge transforms itself into the safety and speed that you need.
Class Dismissed. Professor Tom Morris Dirt Sports University and School of Hard Knocks