Those with a Jeep Steering Box
10-14-2006, 01:45 PM
#1
Advanced
Thread Starter
Member Since: Apr 2003
Location: Columbus IN
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
Those with a Jeep Steering Box
I recently installed a Jeep Box on my car. The road feel is better but turning the steering wheel is way too easy. Do others with the Jeep Box feel the same way? I'm use to my daily driver Mazda that has a bit more drag when turning the steering wheel which is a rack. I thought about a steering damper. Does anyone have any experience with a steering damper or stabilizer?
Thanks,
Tom
Thanks,
Tom
10-14-2006, 02:17 PM
#2
Burning Brakes
just purchased mine
Haven't put mine on yet, but I bought a manual center link and was wondering the same thing. as the manual drag link has provision for the damper I believe. Any experts on this please chime in as I would like to know as well.
10-14-2006, 02:56 PM
#3
Safety Car
Same here. Installed mine last April. It is way too sensitive. I believe there is a way to slow it, but, forgot where I saw the info. Car tends to dart when turning.
Fred
Fred
10-14-2006, 03:01 PM
#4
Race Director
Member Since: Nov 2000
Location: Waterloo ontario Canada
Posts: 11,872
Likes: 0
Received 9 Likes
on
9 Posts
I too find the steering effort minimal and tend to over react to small animals darting on the roadway. It is a fast ratio that can get you in trouble fast if you are suprised by the unexpected.
10-14-2006, 03:08 PM
#5
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by FKING1
Same here. Installed mine last April. It is way too sensitive. I believe there is a way to slow it, but, forgot where I saw the info. Car tends to dart when turning.
Fred
Fred
10-14-2006, 08:16 PM
#6
Race Director
In order to get "road feel" back the hydraulic flow needs to be reduced.
Cars generally use around 1.5 gpm and trucks up to 3 gpm and up to 1500psi. I believe the vette uses around 950psi. Generally, a lighter vehicle needs less flow and pressure.
One way is to remove the flow control valve that is behind the pressure port fitting and make a smaller orifice and larger return ports. This would require access to a lathe and mill and a basic understanding of hydraulics. It will also increase fluid temp and a cooler should be installed.
Another possible way would be to lower the pump rpm thus lowering the flow, but I doubt this would be easy or realistic.
Another way possibly, would be to eliminate some of the vanes making the pump a much smaller displacement.
There has been available sort of crude flow control valves that are externally adjustable and should work, but plumbing space could pose a problem.
Apparently, ps pumps for rack and pinion have less pressure and flow too, but I don't have the specs on them.
Older Chrysler/Federal pumps had a 2 stage flow control valve integral that gave more at idle and less at rpm. This could probably be used in whole or just the valve adapted to a Saginaw pump.
There are millions of these pumps out there, so I wouldn't recommend doning these mods on your primary pump. Try on a junk yard piece.
Cars generally use around 1.5 gpm and trucks up to 3 gpm and up to 1500psi. I believe the vette uses around 950psi. Generally, a lighter vehicle needs less flow and pressure.
One way is to remove the flow control valve that is behind the pressure port fitting and make a smaller orifice and larger return ports. This would require access to a lathe and mill and a basic understanding of hydraulics. It will also increase fluid temp and a cooler should be installed.
Another possible way would be to lower the pump rpm thus lowering the flow, but I doubt this would be easy or realistic.
Another way possibly, would be to eliminate some of the vanes making the pump a much smaller displacement.
There has been available sort of crude flow control valves that are externally adjustable and should work, but plumbing space could pose a problem.
Apparently, ps pumps for rack and pinion have less pressure and flow too, but I don't have the specs on them.
Older Chrysler/Federal pumps had a 2 stage flow control valve integral that gave more at idle and less at rpm. This could probably be used in whole or just the valve adapted to a Saginaw pump.
There are millions of these pumps out there, so I wouldn't recommend doning these mods on your primary pump. Try on a junk yard piece.
10-14-2006, 10:20 PM
#7
Advanced
Thread Starter
Member Since: Apr 2003
Location: Columbus IN
Posts: 61
Likes: 0
Received 0 Likes
on
0 Posts
I was thinking about something like this to give the steering wheel a little more feel to it. What do you guys think?
http://cgi.ebay.com/ebaymotors/Refle...ayphotohosting
http://cgi.ebay.com/ebaymotors/Refle...ayphotohosting
10-15-2006, 08:10 AM
#8
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by noonie
In order to get "road feel" back the hydraulic flow needs to be reduced.
Cars generally use around 1.5 gpm and trucks up to 3 gpm and up to 1500psi. I believe the vette uses around 950psi. Generally, a lighter vehicle needs less flow and pressure.
One way is to remove the flow control valve that is behind the pressure port fitting and make a smaller orifice and larger return ports. This would require access to a lathe and mill and a basic understanding of hydraulics. It will also increase fluid temp and a cooler should be installed.
Another possible way would be to lower the pump rpm thus lowering the flow, but I doubt this would be easy or realistic.
Another way possibly, would be to eliminate some of the vanes making the pump a much smaller displacement.
There has been available sort of crude flow control valves that are externally adjustable and should work, but plumbing space could pose a problem.
Apparently, ps pumps for rack and pinion have less pressure and flow too, but I don't have the specs on them.
Older Chrysler/Federal pumps had a 2 stage flow control valve integral that gave more at idle and less at rpm. This could probably be used in whole or just the valve adapted to a Saginaw pump.
There are millions of these pumps out there, so I wouldn't recommend doning these mods on your primary pump. Try on a junk yard piece.
Cars generally use around 1.5 gpm and trucks up to 3 gpm and up to 1500psi. I believe the vette uses around 950psi. Generally, a lighter vehicle needs less flow and pressure.
One way is to remove the flow control valve that is behind the pressure port fitting and make a smaller orifice and larger return ports. This would require access to a lathe and mill and a basic understanding of hydraulics. It will also increase fluid temp and a cooler should be installed.
Another possible way would be to lower the pump rpm thus lowering the flow, but I doubt this would be easy or realistic.
Another way possibly, would be to eliminate some of the vanes making the pump a much smaller displacement.
There has been available sort of crude flow control valves that are externally adjustable and should work, but plumbing space could pose a problem.
Apparently, ps pumps for rack and pinion have less pressure and flow too, but I don't have the specs on them.
Older Chrysler/Federal pumps had a 2 stage flow control valve integral that gave more at idle and less at rpm. This could probably be used in whole or just the valve adapted to a Saginaw pump.
There are millions of these pumps out there, so I wouldn't recommend doning these mods on your primary pump. Try on a junk yard piece.
Originally Posted by JIML82
The discharge fitting in the back of your power steering pump controls the maximum flow of oil that your pump will discharge at something like 1200 engine rpm. Any engine speeds greater than 1200 rpm should not cause the pump to discharge any more oil.
Therefore, here is a quick test to see if you need more flow from your pump. Find a vacant, large parking lot. Drive in the lot at about 15 miles per hour. Try to whip your steering wheel about one half of a revolution to the right or left (as if you were suddenly trying to avoid something running into the road ahead of you). If you complete the maneuver with plenty of power assist - you have sufficient pump flow. If you suddenly find that your power assist is gone while whipping the steering wheel, then you may require more pump flow.
The throat of the discharge fitting is a major controlling element as to the amount of oil that the pump discharges. It isn't quite as simple as just drilling out the throat of the discharge fitting. If you take a fitting out of the pump and look closely at it, behind the hex head is an o-ring. Just behind the o-ring (somewhere on the diameter) you will see a very small hole. That hole is called the P-hole and it communicates pressure back to the pump and regulates the flow control plunger behind the discharge fitting. That is why some people have complained about jerky steering when they have drilled out the fitting. They have disturbed the surface finish of the throat of the discharge fitting and/or may have caused a burr to cover the P-hole.
By going in and disturbing the diameters and surface finishes, you really don't know what you might end up with. But if you want to try, here is a guideline.
As a rule of thumb, for every 0.016 inch on the diameter that the throat is opened up, the pump will flow an additional 1/2 gallon per minute.
0.1144 inch throat diameter = 2.0 gallons per minute
0.130 inch throat diameter = 2.5 gallons per minute
0.144 inch throat diameter = 3.0 gallons per minute
One other word of caution: The more flow out of the pump, the more back pressure is caused as the oil flows through the hoses and through your steering gear valve. More back pressure; the more the pump has to work; the more the pump works, the more heat is generated in the power steering system. You should strongly consided a return line fluid cooler to bring down the steering system temperature.
Therefore, here is a quick test to see if you need more flow from your pump. Find a vacant, large parking lot. Drive in the lot at about 15 miles per hour. Try to whip your steering wheel about one half of a revolution to the right or left (as if you were suddenly trying to avoid something running into the road ahead of you). If you complete the maneuver with plenty of power assist - you have sufficient pump flow. If you suddenly find that your power assist is gone while whipping the steering wheel, then you may require more pump flow.
The throat of the discharge fitting is a major controlling element as to the amount of oil that the pump discharges. It isn't quite as simple as just drilling out the throat of the discharge fitting. If you take a fitting out of the pump and look closely at it, behind the hex head is an o-ring. Just behind the o-ring (somewhere on the diameter) you will see a very small hole. That hole is called the P-hole and it communicates pressure back to the pump and regulates the flow control plunger behind the discharge fitting. That is why some people have complained about jerky steering when they have drilled out the fitting. They have disturbed the surface finish of the throat of the discharge fitting and/or may have caused a burr to cover the P-hole.
By going in and disturbing the diameters and surface finishes, you really don't know what you might end up with. But if you want to try, here is a guideline.
As a rule of thumb, for every 0.016 inch on the diameter that the throat is opened up, the pump will flow an additional 1/2 gallon per minute.
0.1144 inch throat diameter = 2.0 gallons per minute
0.130 inch throat diameter = 2.5 gallons per minute
0.144 inch throat diameter = 3.0 gallons per minute
One other word of caution: The more flow out of the pump, the more back pressure is caused as the oil flows through the hoses and through your steering gear valve. More back pressure; the more the pump has to work; the more the pump works, the more heat is generated in the power steering system. You should strongly consided a return line fluid cooler to bring down the steering system temperature.
I also found these:
...KRC power steering flow control valves in different sizes/flow rates. I'm trying to find out more.
Anyway, how does the steering feel with the Jeep box AND the Hydroboost?
Last edited by saudivette; 10-15-2006 at 09:16 AM.
10-15-2006, 09:15 AM
#9
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
How does 1.05 GPM sound noonie? Any input here Norval?
I've found a place that sells the different rate discharge ports but dunno if I supposed to post the link. PM me and I'll send it to you if anyone wants it...
I've found a place that sells the different rate discharge ports but dunno if I supposed to post the link. PM me and I'll send it to you if anyone wants it...
Last edited by saudivette; 10-15-2006 at 09:18 AM.
10-15-2006, 12:38 PM
#10
Race Director
Originally Posted by saudivette
How does 1.05 GPM sound noonie? Any input here Norval?
I've found a place that sells the different rate discharge ports but dunno if I supposed to post the link. PM me and I'll send it to you if anyone wants it...
I've found a place that sells the different rate discharge ports but dunno if I supposed to post the link. PM me and I'll send it to you if anyone wants it...
Originally Posted by JIML82
The discharge fitting in the back of your power steering pump controls the maximum flow of oil that your pump will discharge at something like 1200 engine rpm. Any engine speeds greater than 1200 rpm should not cause the pump to discharge any more oil.
The discharge fitting in the back of your power steering pump controls the maximum flow of oil that your pump will discharge at something like 1200 engine rpm. Any engine speeds greater than 1200 rpm should not cause the pump to discharge any more oil.
If you suddenly find that your power assist is gone while whipping the steering wheel, then you may require more pump flow
The throat of the discharge fitting is a major controlling element as to the amount of oil that the pump discharges. It isn't quite as simple as just drilling out the throat of the discharge fitting. If you take a fitting out of the pump and look closely at it, behind the hex head is an o-ring. Just behind the o-ring (somewhere on the diameter) you will see a very small hole. That hole is called the P-hole and it communicates pressure back to the pump and regulates the flow control plunger behind the discharge fitting. That is why some people have complained about jerky steering when they have drilled out the fitting. They have disturbed the surface finish of the throat of the discharge fitting and/or may have caused a burr to cover the P-hole.
I'm assuming the jerkyness referred to is when it was drilled out too large creating a larger flow than the pump is capable of, thus creating a catchup situation for the pump.
Any good machinist is capable to do this without burrs etc.
One other word of caution: The more flow out of the pump, the more back pressure is caused as the oil flows through the hoses and through your steering gear valve. More back pressure; the more the pump has to work; the more the pump works, the more heat is generated in the power steering system. You should strongly consided a return line fluid cooler to bring down the steering system temperature.
The vette pump is just a vane pump (just like an air die grinder) and is basically for a low pressure system using more flow than pressure (although you can't separate the two).
As far as using a hydroboost and getting heavier feel you may have to use the standard pump settings for the hydraboost and use an external flow control for just the steering (2 different requirements)
As I said earlier, there are millions around and you can tinker for cheap. The is modding, so you can't go to Gm for specs to cover specific situations.
Here is http://www.heidts.com/images/art1.pdf a link to an external flow control that can be externally adjusted.
10-15-2006, 03:31 PM
#11
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Hey noonie, I stand corrected mate. I saw that Heidt's adjustable power steering valve after I made the post and was going to come back to it later, but you beat me to it. That looks better for my application (Jeep box and Hydroboost) than fitting the smaller discharge port in the pump. That would gurantee full flow/pressure for the brakes and variable flow/pressure to suit my "taste" in steering feel...
I'd still like to hear from anyone who already has the Hyrdroboost and Jeep box installed.
I'd still like to hear from anyone who already has the Hyrdroboost and Jeep box installed.
10-15-2006, 05:06 PM
#12
Drifting
Member Since: Oct 2003
Location: VetteMOD
Posts: 1,426
Likes: 0
Received 1 Like
on
1 Post
St. Jude Donor '05-'07
You will be OK with Hydroboost and Jeep box conversion. The Hydroboost unit uses very little flow and has a pressurized accumulator that will allow full pressure assist to the brakes even if flow is diverted to the steering gear.
What is important here is not restricting flow to the point where you might lose hydraulic assist with quick steering inputs (collision avoidance as described above).
What is important here is not restricting flow to the point where you might lose hydraulic assist with quick steering inputs (collision avoidance as described above).
10-15-2006, 05:24 PM
#13
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Thanks BBShark. I guess it would be a matter of installing one of the Heidt's valves and going out in a big open space and yanking the wheel around and adjusting it to suit.
I don't want the steering mega light once I've installed everything...
I don't want the steering mega light once I've installed everything...
10-15-2006, 10:00 PM
#14
Le Mans Master
Member Since: Jul 2000
Location: Saginaw Michigan
Posts: 6,001
Likes: 0
Received 98 Likes
on
81 Posts
It is possible to decrease the valve response in the steering gear by decreasing the amount of flow from the power steering pump. I say response because although the steering effort may seem to increase, actually what is happening is that because of the decreased pump flow it is taking longer for the steering gear valve to generate assist pressure. (As long as it FEELS better, then why NOT?)
Now here is the problem. I most cases by the time that you reduce the flow from the pump (down into the 1.5 gallon/minute range) so that it is sufficient to make a decent change in steering effort (response) you run the risk of pump catch. Here is what happens. If you try to make a quick steering maneuver (such as trying to avoid something running into the street in front of you) there is not sufficient pump flow to push the rack piston inside your gear rapidly one way or the other. What happens is that you have a sudden, dramatic increase in steering effort. Even though you may be traveling at a decent rate of speed, the steering effort suddenly increases to above manual steering levels as you try to make the evasive maneuver.
Now some cars and light trucks have used an Electronic Variable Orifice valve (called EVO) on their pumps. The valve screws into the back side of the pump and replaces the discharge fitting. The valve receives a Pulse Width Modulated signal from a computer. It reduces the flow (down into the 1.2/1.5 gallon/minute range) as vehicle speed increases. Here is the important part. Most EVO steering systems also have a steering wheel rotation sensor built into the steering column. As soon as you try to quickly turn the steering wheel, the rotation sensor signals the computer which immediately opens the EVO valve to full flow. So you don't have the pump catch problem.
There were (are) some Japanese pumps that had a small mechanical valve built into the pump that decreased the flow somewhat. (Nothing as dramatic as 1.5 gallons/minute). These pumps were advertised as having "droop flow" output. In all of my years of evaluating competitor vehicles (ones that didn't use Saginaw pumps or gears) I could never feel the change in effort from those Japanese droop flow pumps.
Jim
Now here is the problem. I most cases by the time that you reduce the flow from the pump (down into the 1.5 gallon/minute range) so that it is sufficient to make a decent change in steering effort (response) you run the risk of pump catch. Here is what happens. If you try to make a quick steering maneuver (such as trying to avoid something running into the street in front of you) there is not sufficient pump flow to push the rack piston inside your gear rapidly one way or the other. What happens is that you have a sudden, dramatic increase in steering effort. Even though you may be traveling at a decent rate of speed, the steering effort suddenly increases to above manual steering levels as you try to make the evasive maneuver.
Now some cars and light trucks have used an Electronic Variable Orifice valve (called EVO) on their pumps. The valve screws into the back side of the pump and replaces the discharge fitting. The valve receives a Pulse Width Modulated signal from a computer. It reduces the flow (down into the 1.2/1.5 gallon/minute range) as vehicle speed increases. Here is the important part. Most EVO steering systems also have a steering wheel rotation sensor built into the steering column. As soon as you try to quickly turn the steering wheel, the rotation sensor signals the computer which immediately opens the EVO valve to full flow. So you don't have the pump catch problem.
There were (are) some Japanese pumps that had a small mechanical valve built into the pump that decreased the flow somewhat. (Nothing as dramatic as 1.5 gallons/minute). These pumps were advertised as having "droop flow" output. In all of my years of evaluating competitor vehicles (ones that didn't use Saginaw pumps or gears) I could never feel the change in effort from those Japanese droop flow pumps.
Jim
10-15-2006, 10:51 PM
#15
Melting Slicks
Good topic. I never thought about having too much steering.
I also have the hydro and jeep box (neither installed yet).
A dampner like shown in a previous post would help center and slow steering movement but i'm sure it would also make turning lock to lock much more difficult and annoying.
I don't know whats worse....having too much overreaction or losing power assist for a few seconds b/c your flow is reduced with a control valve.
I'm going with a KRC PS pump once I get my engine so those fittings that reduce flow might work out in my situation.
I'll have to research the different flow requirements for the hydro & jeep box before I decide to reduce all the flow out of the pump or just a control valve after the hydro unit.
Good thread.
I also have the hydro and jeep box (neither installed yet).
A dampner like shown in a previous post would help center and slow steering movement but i'm sure it would also make turning lock to lock much more difficult and annoying.
I don't know whats worse....having too much overreaction or losing power assist for a few seconds b/c your flow is reduced with a control valve.
I'm going with a KRC PS pump once I get my engine so those fittings that reduce flow might work out in my situation.
I'll have to research the different flow requirements for the hydro & jeep box before I decide to reduce all the flow out of the pump or just a control valve after the hydro unit.
Good thread.
10-16-2006, 12:28 AM
#16
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Jim Shea
It is possible to decrease the valve response in the steering gear by decreasing the amount of flow from the power steering pump. I say response because although the steering effort may seem to increase, actually what is happening is that because of the decreased pump flow it is taking longer for the steering gear valve to generate assist pressure. (As long as it FEELS better, then why NOT?)
Now here is the problem. I most cases by the time that you reduce the flow from the pump (down into the 1.5 gallon/minute range) so that it is sufficient to make a decent change in steering effort (response) you run the risk of pump catch. Here is what happens. If you try to make a quick steering maneuver (such as trying to avoid something running into the street in front of you) there is not sufficient pump flow to push the rack piston inside your gear rapidly one way or the other. What happens is that you have a sudden, dramatic increase in steering effort. Even though you may be traveling at a decent rate of speed, the steering effort suddenly increases to above manual steering levels as you try to make the evasive maneuver.
Now some cars and light trucks have used an Electronic Variable Orifice valve (called EVO) on their pumps. The valve screws into the back side of the pump and replaces the discharge fitting. The valve receives a Pulse Width Modulated signal from a computer. It reduces the flow (down into the 1.2/1.5 gallon/minute range) as vehicle speed increases. Here is the important part. Most EVO steering systems also have a steering wheel rotation sensor built into the steering column. As soon as you try to quickly turn the steering wheel, the rotation sensor signals the computer which immediately opens the EVO valve to full flow. So you don't have the pump catch problem.
There were (are) some Japanese pumps that had a small mechanical valve built into the pump that decreased the flow somewhat. (Nothing as dramatic as 1.5 gallons/minute). These pumps were advertised as having "droop flow" output. In all of my years of evaluating competitor vehicles (ones that didn't use Saginaw pumps or gears) I could never feel the change in effort from those Japanese droop flow pumps.
Jim
Now here is the problem. I most cases by the time that you reduce the flow from the pump (down into the 1.5 gallon/minute range) so that it is sufficient to make a decent change in steering effort (response) you run the risk of pump catch. Here is what happens. If you try to make a quick steering maneuver (such as trying to avoid something running into the street in front of you) there is not sufficient pump flow to push the rack piston inside your gear rapidly one way or the other. What happens is that you have a sudden, dramatic increase in steering effort. Even though you may be traveling at a decent rate of speed, the steering effort suddenly increases to above manual steering levels as you try to make the evasive maneuver.
Now some cars and light trucks have used an Electronic Variable Orifice valve (called EVO) on their pumps. The valve screws into the back side of the pump and replaces the discharge fitting. The valve receives a Pulse Width Modulated signal from a computer. It reduces the flow (down into the 1.2/1.5 gallon/minute range) as vehicle speed increases. Here is the important part. Most EVO steering systems also have a steering wheel rotation sensor built into the steering column. As soon as you try to quickly turn the steering wheel, the rotation sensor signals the computer which immediately opens the EVO valve to full flow. So you don't have the pump catch problem.
There were (are) some Japanese pumps that had a small mechanical valve built into the pump that decreased the flow somewhat. (Nothing as dramatic as 1.5 gallons/minute). These pumps were advertised as having "droop flow" output. In all of my years of evaluating competitor vehicles (ones that didn't use Saginaw pumps or gears) I could never feel the change in effort from those Japanese droop flow pumps.
Jim
Are you familiar with the Heidt's Adjustable Power Steering Valve?
From what I understand of it, you set the adjuster **** until you get the "road feel" you want at speed which allows the fluid to override spring tension within the unit and bleed off back to the return line. This is from their website...
Turning the **** counterclockwise takes pressure off a spring that holds the needle in the orifice. At idle and at very low pump speeds and pressure, the needle stays firmly entrenched in the orifice to maintain full power assist. Full assist makes it easier to negotiate parking lots at slow speeds. When the pump speeds up and creates more line pressure, the pressurized fluid pushes the needle up and bleeds off a specific amount of fluid and pressure into the return line, and subsequently back to the reservoir. Turning the **** out more takes yet more pressure off the spring, therefore bypassing more line pressure and consequently reducing the power assist at speed.
Last edited by saudivette; 10-16-2006 at 12:36 AM.
10-16-2006, 07:59 AM
#17
Le Mans Master
Member Since: Jul 2000
Location: Saginaw Michigan
Posts: 6,001
Likes: 0
Received 98 Likes
on
81 Posts
I am not familiar with the Heidt valve. From the description this is what I think happens.
The pump doesn't know what is happening downstream outside the pump. It just displaces a certain quantity of fluid for each revolution of the pump. The quantity is preset by the discharge fitting and the flow control valve inside the pump. A set quantity of fluid goes out the discharge fitting, the rest gets recirculated back inside the pump.
It doesn't make much difference how much backpressure is created outside the pump, the pump keeps trying to push a fixed amount of fluid out the discharge fitting. The Heidt valve is diverting a portion of that flow back to the pump, however, in order to do that, it is creating backpressure that the pump has to fight. (Twisting the control **** on the valve.) Increasing the backpressure that the pump has to work against increases fluid temperature.
The principle behind a EVO valve is that a needle and seat inside the valve is electronically regulated. It controls the actual output of the pump and the amount of fluid that is recirculated inside the pump. This does not have much affect on fluid temperature.
So the affect upon the rotary valve inside the steering gear is the same (i.e. reduced flow to the gear valve, reduced valve response, increased apparent steering effort). The affect upon the pump is much different, increased system backpressure and increased fluid temperature because of the external diverter valve.
Now it is true that you can now add an external cooler to the system. But you are now chasing your tail. The more backpressure the higher the steering fluid temperature; the larger the cooler required.
Just my 2 cents.
Jim
The pump doesn't know what is happening downstream outside the pump. It just displaces a certain quantity of fluid for each revolution of the pump. The quantity is preset by the discharge fitting and the flow control valve inside the pump. A set quantity of fluid goes out the discharge fitting, the rest gets recirculated back inside the pump.
It doesn't make much difference how much backpressure is created outside the pump, the pump keeps trying to push a fixed amount of fluid out the discharge fitting. The Heidt valve is diverting a portion of that flow back to the pump, however, in order to do that, it is creating backpressure that the pump has to fight. (Twisting the control **** on the valve.) Increasing the backpressure that the pump has to work against increases fluid temperature.
The principle behind a EVO valve is that a needle and seat inside the valve is electronically regulated. It controls the actual output of the pump and the amount of fluid that is recirculated inside the pump. This does not have much affect on fluid temperature.
So the affect upon the rotary valve inside the steering gear is the same (i.e. reduced flow to the gear valve, reduced valve response, increased apparent steering effort). The affect upon the pump is much different, increased system backpressure and increased fluid temperature because of the external diverter valve.
Now it is true that you can now add an external cooler to the system. But you are now chasing your tail. The more backpressure the higher the steering fluid temperature; the larger the cooler required.
Just my 2 cents.
Jim
Last edited by Jim Shea; 10-16-2006 at 08:01 AM.
10-16-2006, 02:16 PM
#18
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by Jim Shea
I am not familiar with the Heidt valve. From the description this is what I think happens.
The pump doesn't know what is happening downstream outside the pump. It just displaces a certain quantity of fluid for each revolution of the pump. The quantity is preset by the discharge fitting and the flow control valve inside the pump. A set quantity of fluid goes out the discharge fitting, the rest gets recirculated back inside the pump.
It doesn't make much difference how much backpressure is created outside the pump, the pump keeps trying to push a fixed amount of fluid out the discharge fitting. The Heidt valve is diverting a portion of that flow back to the pump, however, in order to do that, it is creating backpressure that the pump has to fight. (Twisting the control **** on the valve.) Increasing the backpressure that the pump has to work against increases fluid temperature...
The pump doesn't know what is happening downstream outside the pump. It just displaces a certain quantity of fluid for each revolution of the pump. The quantity is preset by the discharge fitting and the flow control valve inside the pump. A set quantity of fluid goes out the discharge fitting, the rest gets recirculated back inside the pump.
It doesn't make much difference how much backpressure is created outside the pump, the pump keeps trying to push a fixed amount of fluid out the discharge fitting. The Heidt valve is diverting a portion of that flow back to the pump, however, in order to do that, it is creating backpressure that the pump has to fight. (Twisting the control **** on the valve.) Increasing the backpressure that the pump has to work against increases fluid temperature...
There's a write up about it at their web page http://www.heidts.com/heifram1.htm
but to quote a bit of it...
Heidt's developed a small adjustable pressure bypass unit, which is installed in line between the rack/box and the pump. It bleeds pressure back to into the return side and lowers the line pressure to the rack or box. You can adjust it so the amount of power assist you end up with is comfortable for you... It's important to know that this is not a simple rigid needle and seat device. If it were, as the engine speed increased and the pump increased volume, the line pressure to the rack or box would increase... The unit works like a common air regulator where line pressure works against a spring-loaded piston. As soon as the line pressure exceeds the spring pressure, the valve opens and fluid is bypassed, keeping pressure constant at all times. It's because the pressure is not regulated by volume but by pressure that the speed of the pump does not affect line pressure to the rack or box and the power assist does not change with engine speed.
10-16-2006, 03:46 PM
#19
Melting Slicks
It makes sense that any type of valve or abstruction in the line will create backpressure, even if its a hair in the line it will create a theoretical backpressure so small you probably couldn't even measure it.
I think that even though the valve is diverting fluid back to the resoviour it is still creating a slight backpressure, more than if there was no valve and the fluid ran free. Your not reducing the output totaly to where the fluid has only one way out (steering box), the excess is diverted back to the resoviour so in my belief the backpressure is minimal. If your pump has a high output, more than the steering box can handle then you will already have backpressure. Its sounds like its very important to match the two gpm flows.
Now, at what point of backpressure do you install a cooler?
Personally I thought it was overkill unless you run it on the track but mismatching parts such as hydro & the jeep box with an aftermarket pump might warrant a cooler. Has anyone with this combination ever experienced problems with fluid temp?
I think that even though the valve is diverting fluid back to the resoviour it is still creating a slight backpressure, more than if there was no valve and the fluid ran free. Your not reducing the output totaly to where the fluid has only one way out (steering box), the excess is diverted back to the resoviour so in my belief the backpressure is minimal. If your pump has a high output, more than the steering box can handle then you will already have backpressure. Its sounds like its very important to match the two gpm flows.
Now, at what point of backpressure do you install a cooler?
Personally I thought it was overkill unless you run it on the track but mismatching parts such as hydro & the jeep box with an aftermarket pump might warrant a cooler. Has anyone with this combination ever experienced problems with fluid temp?
10-16-2006, 04:55 PM
#20
Melting Slicks
Member Since: May 2004
Location: Aussie expat in Saudi Arabia
Posts: 2,084
Likes: 0
Received 0 Likes
on
0 Posts
Originally Posted by 68 NJConv 454
...in my belief the backpressure is minimal. If your pump has a high output, more than the steering box can handle then you will already have backpressure...
Now, at what point of backpressure do you install a cooler?
Personally I thought it was overkill unless you run it on the track but mismatching parts such as hydro & the jeep box with an aftermarket pump might warrant a cooler. Has anyone with this combination ever experienced problems with fluid temp?
Now, at what point of backpressure do you install a cooler?
Personally I thought it was overkill unless you run it on the track but mismatching parts such as hydro & the jeep box with an aftermarket pump might warrant a cooler. Has anyone with this combination ever experienced problems with fluid temp?
I would have thought though, that the back pressure created by installing the Heidt's valve would be minimal to none because (purely my meandering thought process) the output flow isn't obstructed, you're just splitting it...
If the output pressure is say, 1000psi and that gives you no "road feel", you adjust it so that at 800psi the valve opens. Fluid is bled off back to the pump so that less fluid reaches the steering box - "heavying up" the steering. Output pressure would still be the same at the pump, because of engine RPM. How could diverting some fluid away at the valve create back pressure at the pump?
Or am I now
