totalloser

Cut and paste from my writeup on another forum.

This is general information regarding improving steering force/response. Following data assumes 1200 psi pump pressure.

Stock box appears to be a Saginaw type 708 with 3.25" bore. The force on the piston divided by the leverage loss from the gear to pitman interchange (4:1 loss-Gear radius of 1.5", pitman length of 6") gives 2490 pounds force AT THE TIE ROD.

AGR box (junk don't buy one) appears to be a 708 with a 3.5" bore for 2886 pounds at the tierod. This is a stock box on many vehicles. Junkyard score may be possible.

I went with my stock box tapped with a 1.5" cylinder with a 3/4" rod. Smaller rod is better, as the steering force/speed will be less uneven. The retraction force on mine (the weaker direction) is 1590 plus the stock box force of 2490 for a 64% increase in force over stock. YOU MUST SECURE YOUR RAM WELL. If it slips, ALL your steering force will go to slipping the ram. NO STEERING!!! Also, the force will rotate your steering linkages before steering forces will turn your knuckles. I have found NO FIX for this other than custom steering. I addressed this issue by having a solid centerlink tie DIRECTLY from knuckle to knuckle, and having a draglink attach to dual ballbearings at the centerlink. This prevents rotation of the steering from ram forces.

This assembly DID NOT WORK. The pump did not make adequate flow or pressure at idle to even turn steering with major hydraulic advantage. I installed a PSC high flow pump, and now it steers like a small car. I will note that I shimmed the relief spring to the tune of .120", but I do not recommend this to anyone else. If a seal fails, you are in deep trouble. If you shim the spring make sure to bore the shim to allow the screen part of the piston to pass through the shim, or it may stick (like a suction cup) to the shim making your steering/brake assist fail. The AGR box is a rebuildable core at best and the retainer on the pressure seal for the pitman shaft may puke out. I put up a thread on the incorrect bearings used in this product.AGR = Junk steering.

PUMP EDIT: I recently had the pump apart to remove yet another stray piece of shell bearing from that damned AGR box (it hung up the relief piston) and had found this http://westtexasoffroad.homestead.co...rsteering.html site, so I decided to do a side by side comparison of the port size of part #1 in the first picture. Stock port was just over .136 #29 (.0145"sq) drill size. PSC was .161 #20 (.0204"sq) drill size. This is a bump of approximately 41% in the business port. There is a port on the side of this assembly that constantly bleeds fluid out. I drilled my PSC out .005" just as a minimal experiment with a #19 drill for a .166" hole with .0216"sq for a bump of 6%. The difference was SURPRISING. I find myself wondering if this mod is the only difference with the PSC pump.

My advice to anyone planning to improve the steering force is to put in a PSC pump first and foremost *or do the relief port mod detailed below*. It requires a cooler, and I used a 15x7.5" transmission cooler from Summit. It comes with a hose, but you will need more hose. DO NOT USE FUEL HOSE, it's not tough enough. It fits PERFECTLY to the side of the a/c in front of the intercooler. Comes with fasteners. Note: will not fit here on Autos- that's where the tranny cooler is.

If the force is still not adequate, consider a box, and then possibly tap it for a ram. The pump made more difference in steering force than the big 3.5" box OR the ram assist. Highly recommended. It will make your steering at idle perform as if you were gunning the engine.

If anyone is particularly interested in how to make my 1.5" dom steering using OE tie rod ends, I would be happy to share that too. It requires a lathe, hydraulic press, welder, special tap for tie rod threads, and uses your stock adjusters.

Addendum; Why the steering sucks on these trucks
1. Frame flexes at the steering box mount making steering sloppy
2. Power steering pump delivers anemic performance at idle due to rpm/flow issues
3. Track rod bushing flexes adding to 1.
4. Tie rod arms at knuckles are closer to the pivot point making for tighter, but weaker steering. Also, this makes it impossible to have a direct line between the knuckles-steering requires funky bend which sets the stage for death wobble and premature tie rod wear

Fixes;
1. Steering box brace. Can't say enough about these things. They work deceptively well.
2. Relief port mod or high flow PSC steering pump as noted above.
3. Polyurethane replacement bushing or a new track rod. Napa's seems pretty good, but I don't know much about the many aftermarket options.
4. You MUST run a steering stabilizer shock absorber on the tie rod (drivers side link) The OE setup that has a shock absorber only on the draglink to the steering box is inadequate. Some have one some have the other, some have both from the factory. It's purpose is to prevent a sustained oscillation of the steering from the links flopping up and down-IE death wobble. Its very difficult to overcome the leverage loss on the shorter steering arms of the knuckles. I settled on ram assist and full custom steering to accommodate the ram (the ram will rotate the stock linkages before ANY assist takes place) but a junkyard 708 3.5" and a high flow pump might do. Keep up with aftermarket goodies- the big box may still be available.

totalloser

Update on significant REALLY easy power steering pump performance upgrade:

So after looking at this powersteering(link) for a while, I still didn't really understand why the port size made so much difference. Hitting my old college textbooks didn't sort it out either, so I decided to take a close look at how the relief valve actually works. It's a lot more complicated than it looks.

The pump delivers pressure to BOTH sides of the relief piston.

Stage1
When at idle, the flow passes through the side port on the pressure line fitting, and then down the center. Pressure is regulated by the relief valve INSIDE the piston on the other end dumping back into the reservoir through a small hole in the side of the piston.

Stage2
If the pump is spun at a slightly higher speed, the flow capacity of the piston internal relief valve is overcome and pressure builds up pushing the relief piston back (the internal relief creates less pressure on one side, and the piston's external spring is overcome allowing it to slide back) This allows flow to pass the face of the piston and deliver more flow down the center of the pressure fitting.

Stage3
If the pump is spooled high enough, the piston will push back further and the piston face will pass the relief port in the pump to dump excess pressure into the reservoir. This limits maximum pressure AND flow.

After looking more carefully at how the psc pump was assembled, I found why they used a weaker piston relief spring. The weaker spring allows the piston to pull back sooner and allow more flow into the pressure fitting when at stage2. They also didn't screw the internal relief all the way in which would also help the relief piston push back and allow more flow at just off idle.

The problem, is that you still need to be just off idle to see most of the benefit of the PSC pump. So I think I found a VERY simple way to have your cake and eat it too.

The side port that all your flow at idle must pass through was (or mine was) .120" (#31 drill) I drilled it out to .136" with a #29 drill. I currently have the center port drilled to .166" with a #19 drill to allow maximum flow.

The way I see it, internal relief will open at the same pressure, and the piston relief spring will still relieve at the same pressure. But the flow at low rpm is FANTASTIC compared to stock, or even the PSC. My high flow PSC pump basically had an overdrilled center port (drilled to .161" versus stock at appx. .136") a weaker external piston relief spring, backed off seat in the internal relief piston, and a heavier pump wear plate spring (the one that pushes the pump sections together under the circular cover plate)

I chose the heavier wear plate and piston relief springs to allow stock pressure (which the PSC would not generate) and drilled the center port on the pressure fitting out to .166" using a #19 drill. This allows more flow at main piston relieving pressure. Then I drilled out the side port on the pressure fitting from .120" to .136" to allow more flow at idle.

It is working VERY well. Most folks won't need the flow I do because I am running a hydraulic ram, but I'll point out that there is a LOT of interchangeability on these Saginaw pumps, so you could easily pick up a junkyard pressure fitting, drill it out, and if it doesn't suit you, just put the old one back in. And this mod can easily be done with the pump IN THE TRUCK. Just suck out the fluid, pull the pressure line (18mm) and the pressure fitting (1"). Mod it, put it back in, and bleed the system.

At this point, I don't recommend shimming the pressure relief spring behind the piston. More flow at idle seems more important. Higher relief pressure is what damages things-like pops out seals, ruptures lines etc. But higher pressure does increase steering force.

Use this information at your own risk. I am providing the best information I can. All I can say is that it's working out great for me.

If I were to do it again, I'd probably leave the PSC fitting center port at .161" but drill the side port just a bit larger than the .136" I drilled it to. I may drill the side port out bigger at some point, but I'm STOKED with how it works right now.

nickg

I replied on the other thread that you put up, I did drill the center port, but was unclear on which side port to drill, I tried to drill the piston (piece with spring in it) but it just turned the edge on my drills.
I found no difference with the center port drilled (at least nothing I can physically feel)

can you clear up which is the side port??

totalloser

When you take the piston out, you have to take that ported bolt (for lack of a better description) off. This is the part you center drilled. If you look at the part where the piston contacts, there is a port on the side of it. This is the side port I am referring to drilling.

It could be that these mods made more difference for me because I am running ram assist. I dunno.

BTW I was having trouble with those endless ads on my stone age dial-up net connection-probably why I didn't reply.