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.http://www.cumminsforum.com/forum/g.../general-diesel-discussion/74718-agr-junk-steering.html?highlight=steering+junk
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.com/powersteering.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.
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.http://www.cumminsforum.com/forum/g.../general-diesel-discussion/74718-agr-junk-steering.html?highlight=steering+junk
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.com/powersteering.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.
