I'm not sure if I like manual steering.
07-13-2006, 11:27 AM
#16
Three Wheelin'
There's more info on converting a PS rack to manual (including a link back to an older post on RL) here...
http://951forums.com/forums/index.ph...indpost&p=5211
FYI, the rack teeth and pinon are fluid-free from the factory, only grease there. I do NOT recommend draining your PS rack fluid, as that fluid is used to lubricate the bearings in the valve tower and the bushings in the rack. Also, you must be sure the tie rod boots and equalizer line are still intact, as those keep the tie rods clean from dirt and water, so they hold their grease and last.
Simply removing the PS belt will result in the extremely heavy efforts, as you have now converted your rack into an arm workout machine, with a fluid damper/resistor to work each time you turn the wheel. The piston on the rack must force the fluid back into the valve and then back into the low pressure side of the cylinder. Thats were those excessive efforts come from.
Here, I'll copy/paste the guts of my previous post:
How to turn a power rack into a manual rack and actually live with it:
1. Piston chamber - must remain filled with ATF in order to keep seals sealed and bushings lubricated. Proper way to do this would be (editied from the linked post after I rebuilt my own rack) to remove the entire piston assembly shown in this picture (photo credit to Travis at Rennbay)...
Then you can cap off the pressure ports after filling the cavity with ATF fluid. Since nothing will be pressurized, its likely your seals won't leak ever again. Unless they were really blown out. Its possible you could also use regular grease, whatever you're using on your rack/pinion teeth, but I'd recommend ATF fluid as thats what the bushings (which carry all of the forces in the steering system) were designed to be bathed in.
2. Pinion tower - 4 ports on this. Plug up three of them and run the fourth (highest one) to your resevoir. This area also needs to be kept full of fluid to properly lube the bearings. There is no "pumping" action up in the valve tower when unpowered.
3. Valve/pinion drive flats shim - the pinion (gear that engages the rack) and the valve (part connected to the input shaft) are two separate parts that are joined by a torsion bar. With the pump running, when you twist the wheel, the valve senses the amount of torque you're inputing to the rack and provides an increasing amount of assist as the angle of twist in the torsion bar increases. There's usually about 15 degrees of twist allowed before the valve reaches a mechanical stop on the pinion called the drive flats. This mechanical stop is there to limit the max amout of twist in the event of a pressure loss or torsion bar failure. When you disconnect your PS pump, you obviously loose all assist and must now twist the wheel through that 15 degrees or so in either direction before you can apply anything more than a few ft-lbs of torque on the steering wheel. This is a large factor in the "mushiness" felt by those running PS racks without the belt connected. The easy fix is to just take up the free rotation between center and each drive flat. This can be done with shims relatively easily.
I haven't disassmbled my valve as I intend to keep the PS functionality. Proper disassembly would involve removing at least one of the dowels holding the torsion bar in place (one is on the input shaft, one is below the valve near the pinion teeth), and you may have to remove the bolt holding the pressure relief valves/springs in as well.
(photo credit to Bruce at Arnnworx.com)
Once you get apart, you should see some mating flat surfaces between the input shaft and the pinion side. Shim up the play between the two, and you're done.
4. Boots/rack teeth/equalizer line - Boots must be intact and sealing properly. Their entire job is to protect the inner tie rods, and they need to do this on both manual and power racks. Slather the rack teeth with a healthy amount of sticky grease (moly works fine), but definitely don't pack it in. And you must keep the equalizer line installed and intact. This is the line that transfers air from one boot to the other as the rack is stroked. If you leave this off, you may as well just run without boots and plan on replacing your tie rods every few months.
And that's it. Summary: you must keep fluid in the rack to keep it from eating itself to bits unlubricated, disconnecting the piston ports from the valve ports will lower turning efforts, proper steering maintenance items must still be attended to, and install shims to remove the free play in the valve/pinion assembly.
After you do all that, you should have a "true" manual steering rack (probably with a heavier ratio), that should last for a long time.
http://951forums.com/forums/index.ph...indpost&p=5211
FYI, the rack teeth and pinon are fluid-free from the factory, only grease there. I do NOT recommend draining your PS rack fluid, as that fluid is used to lubricate the bearings in the valve tower and the bushings in the rack. Also, you must be sure the tie rod boots and equalizer line are still intact, as those keep the tie rods clean from dirt and water, so they hold their grease and last.
Simply removing the PS belt will result in the extremely heavy efforts, as you have now converted your rack into an arm workout machine, with a fluid damper/resistor to work each time you turn the wheel. The piston on the rack must force the fluid back into the valve and then back into the low pressure side of the cylinder. Thats were those excessive efforts come from.
Here, I'll copy/paste the guts of my previous post:
How to turn a power rack into a manual rack and actually live with it:
1. Piston chamber - must remain filled with ATF in order to keep seals sealed and bushings lubricated. Proper way to do this would be (editied from the linked post after I rebuilt my own rack) to remove the entire piston assembly shown in this picture (photo credit to Travis at Rennbay)...
Then you can cap off the pressure ports after filling the cavity with ATF fluid. Since nothing will be pressurized, its likely your seals won't leak ever again. Unless they were really blown out. Its possible you could also use regular grease, whatever you're using on your rack/pinion teeth, but I'd recommend ATF fluid as thats what the bushings (which carry all of the forces in the steering system) were designed to be bathed in.
2. Pinion tower - 4 ports on this. Plug up three of them and run the fourth (highest one) to your resevoir. This area also needs to be kept full of fluid to properly lube the bearings. There is no "pumping" action up in the valve tower when unpowered.
3. Valve/pinion drive flats shim - the pinion (gear that engages the rack) and the valve (part connected to the input shaft) are two separate parts that are joined by a torsion bar. With the pump running, when you twist the wheel, the valve senses the amount of torque you're inputing to the rack and provides an increasing amount of assist as the angle of twist in the torsion bar increases. There's usually about 15 degrees of twist allowed before the valve reaches a mechanical stop on the pinion called the drive flats. This mechanical stop is there to limit the max amout of twist in the event of a pressure loss or torsion bar failure. When you disconnect your PS pump, you obviously loose all assist and must now twist the wheel through that 15 degrees or so in either direction before you can apply anything more than a few ft-lbs of torque on the steering wheel. This is a large factor in the "mushiness" felt by those running PS racks without the belt connected. The easy fix is to just take up the free rotation between center and each drive flat. This can be done with shims relatively easily.
I haven't disassmbled my valve as I intend to keep the PS functionality. Proper disassembly would involve removing at least one of the dowels holding the torsion bar in place (one is on the input shaft, one is below the valve near the pinion teeth), and you may have to remove the bolt holding the pressure relief valves/springs in as well.
(photo credit to Bruce at Arnnworx.com)
Once you get apart, you should see some mating flat surfaces between the input shaft and the pinion side. Shim up the play between the two, and you're done.
4. Boots/rack teeth/equalizer line - Boots must be intact and sealing properly. Their entire job is to protect the inner tie rods, and they need to do this on both manual and power racks. Slather the rack teeth with a healthy amount of sticky grease (moly works fine), but definitely don't pack it in. And you must keep the equalizer line installed and intact. This is the line that transfers air from one boot to the other as the rack is stroked. If you leave this off, you may as well just run without boots and plan on replacing your tie rods every few months.
And that's it. Summary: you must keep fluid in the rack to keep it from eating itself to bits unlubricated, disconnecting the piston ports from the valve ports will lower turning efforts, proper steering maintenance items must still be attended to, and install shims to remove the free play in the valve/pinion assembly.
After you do all that, you should have a "true" manual steering rack (probably with a heavier ratio), that should last for a long time.
