The Saginaw recirculating ball steering box was used in just about every Chevrolet built. There were a couple of ratios used from a lazy 16:1 in the trucks and big cars up to an ultra-quick 12.7:1 in Camaros. We have been working on a ’70 Z28 Camaro, and at first we were thrilled with its quick ratio steering. The slightest input on the steering wheel turned the car. It was almost like getting a new toy. Eventually, the fun factor wore off and we were left with a car that was twitchy and a bit stressful to drive on the highway.
With just 2-3/4 turns lock to lock, it takes very little steering wheel input to turn the car a lot. Slow-speed driving and pulling into a parking spot were awesome. Once we got the car up on the highway is when our issue with the quick ratio arose. Just looking over our shoulder to check the blind spot made us turn the wheel slightly, but that slight movement was enough to change lanes. Again, it’s something we could tailor our driving style to compensate for, but thanks to modern technology, we don’t have to.
Borgeson, a company that has been in the steering and U-joint business since 1914—that’s 100 years, folks—has a cure for our twitchy steering woes in the way of a remanufactured 700-series variable ratio steering box. The 700 box is from a later application and offers better feel than the older boxes, thanks in part to better internal components. The variable ratio offers a quick final ratio, with only three turns lock to lock, but it’s not overly sensitive on center for stable highway driving. Basically, when the wheel is around the center, it has a ratio of about 16:1, which gives you a bit more stability at slow speed. Now once you start to turn the wheel, the ratio speeds up as you get further from the center. And by the time you get to the end of the steering, you have a 13:1 ratio.
Since we are talking about a power steering box, it’s gonna need a pump and some other accessories to support it. Borgeson had everything we needed, except the fluid. We picked up a new power steering pump, lines, and a rag joint to round out the upgrade. At this time, we also decided to get new steering components like the centerlink, tie rods, and pitman arm from Performance Suspension technologies (PST), so there will be no slop in our new steering system.
One question you may have before we get into the install is, why didn’t we convert to a rack-and-pinion setup? Well, we replaced everything in our steering system and even upgraded the box—and still came in at half the price of a typical rack conversion.
1. We had Jeff Grantmeyer from Borgeson tear open variable and non-variable boxes and explain the difference between the internals. First, let’s get into some common items. Here we have the steering gear case in the center. Above that is the sector shaft, top cap, and lower sector bearing. To the left we have the rack block/worm gear, and on the right is the torsion bar valve assembly and the endcap.
2. Sector teeth on left are variable ratio. There is a wider spacing with a larger center tooth. This effectively changes the final ratio of the gearbox as the steering gear moves off the center tooth and on to the shorter outer teeth. The worm gear rack piston assembly ratio is constant; the actual ratio change comes from the difference in sector tooth height.
Sector on the right is square ratio. This has the same constant ratio throughout the range of steering motion. The ratio from the worm gear/rack piston assembly is transferred squarely to the pitman arm.
3. The rack block/worm gear assembly on the left is a square ratio. You can see the tooth spacing, much like the square ratio sector shaft, is even and constant. The assembly on the right is the variable. Notice the uneven tooth spacing with the larger deeper cut for the corresponding sector tooth. Both of these assemblies have the same worm gear ratio. What is making it variable is, again, the cutting of the teeth on the sector and rack block.
4. Now let’s get into the wrenchin’. We used a pickle fork to free the centerlink from the pitman arm.
5. After using a crescent wrench to remove the large nut on the pitman arm, we used the proper puller to slip the pitman arm off the end of the output shaft. Without this puller, this task will be pretty dang difficult, so make sure you have rented, bought, or borrowed one before you start your swap.
6. Next is the power steering pump. We loosened it to remove the belt and then took the entire pump with brackets off the front of the motor. We sat the assembly on the inner fender for now. We are going to do the rest of the teardown on the bench.
7. We removed the pinch bolt from the rag joint connection on the box. A little persuasion with a prybar freed the joint from the box.
8. The box is the last component to come off. Since the pump and hoses are still hooked to the box, the help of an assistant is needed to wrangle all that stuff out. If you are doing the job all by yourself, we would suggest removing the lines and taking out the box and pump in separate pieces.
9. Now it’s time for some new stuff. Borgeson has these rag joints in stock, and they are pretty much ready to go. All we needed to transfer over to the new unit was this bracket. Rag joints are designed to dampen vibrations and isolate the steering wheel. They are not made to accommodate an angle. If you don’t have a straight connection, then look to a U-joint. But in stock applications like ours, a rag will work great.
10. We used the new hardware in the Borgeson kit to install the new rag joint.
11. Before we installed the box, we made sure it was in the center. To put the box in its center position, we turned the input shaft all the way to the right. Once it hit the stop, we turned it the other way till it hit the other stop, counting the turns as we did. This box has a three-turn lock-to-lock count, so we turned the shaft 1-1/2 turns to put it in the center. We used the factory hardware to hang it from the frame. We left the hardware a bit loose for now. We will come back and tighten it all the way once everything is hooked up.
12. After some cleaning and a fresh coat of paint, the pitman arm is installed. The output shaft has four master splines on it, so the pitman arm can go on in four locations, but since we centered the box, we knew pointing straight back was the correct position.
13. We needed to rob the brackets and pulley off the original pump to transfer them to the new Borgeson unit. We used an impact gun to remove the nut. Once we had everything swapped, we tried to install in on the motor. We found that the new pump housing created a clearance issue with the return hose.
14. Here is a side-by-side shot to show our issue. The return protrudes from the new housing square in the middle and this ended up hitting the block, preventing us from even getting all the bolts in. Since we know our housing worked, we are going to swap them out.
15. First thing we did was loosen the hardware on the rear of the pump. There are two items that must be loosened: one bolt, one stud. Then we completely removed the hose fitting.
16. Under the fitting is a spring and a valve. These must be kept in this order to function properly, so keep that in mind when tearing yours down. The valve and spring are what determines the pressure of the pump.
17. The pump has an O-ring seal that will make taking the pump out of the housing a bit difficult. Since the O-ring seals on the housing, we don’t want to pry on the housing at all to separate the parts. We used the loosened hardware as a push point that allowed us to simply push the pump out.