Steering Dampers 101
08-24-2005, 03:03 PM
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Le Mans Master
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Steering Dampers 101
The C2 and C3 Corvettes with manual steering had a steering damper up until around 1968. Then for engineering and/or cost reduction reasons, it was determined that it was no longer required. I would guess that one or two Corvette durability vehicles were driven the equivalent of 100,000 miles and deemed acceptable for steering and handling performance before they decided that they could remove it.
Now, the basic Corvette chassis didn't really change from 1963 through the late 1970s or 80s. So what changed from 1968 to 1969 that might have allowed the damper to be removed? Well probably nothing major. Possibly tire changes? Maybe something changed back in the middle or late 60s but removing the damper was never investigated at that time.
Steering dampers were used on many manual steering vehicles throughout the years.
What about power steering? Well, steering wheel or road wheel fight can be experienced with power steering as well. Even though the hydraulics in the power steering circuit typically does a pretty good job of damping.
The General Motors Milford Proving Ground has a Ride & Handling Loop that has some washboard indentations right on the inside edge of high speed right and left hand turns. By driving on the washboard areas at various speeds, you could sometimes hit it just right and the front wheels and steering wheel would start to frantically oscillate. It was called wheel fight.
It was determined that during wheel fight the rack piston inside the power gear would be forced back and forth by the oscillation of the tie rods. The motion of the rack piston would cause pressure pulses to be back driven into the pressure side of the gear valve. It was found that if a one way check valve was installed in the pressure port of the gear, the wheel fight could be greatly reduced. For power steering vehicles, Saginaw Steering Gear developed a pressure port check valve.
Point of information: The pressure port on Saginaw gears is always the inboard port - the larger of the two gear ports. The low pressure return line port is always the one closest to the gear input shaft.
If you look into the pressure port of many Saginaw power steering gears, you might find a small metal plate that seems to block the very center of the port. Old Saginaw power gears (up until 1980) used a 45 degree flare seat to seal the hose ends to the gear. On some gears there was a little metal plate that is pushed upward by a small spring and sits on the underside of the brass flare seat.
On power gears built from 1980 and later, the gear ports were designed as metric o-ring. In the pressure port, you might find a metal capsule. There will be a small plate in that capsule that is spring loaded upward (similar to the flare port.) The 1998 through 2004 Jeep Grand Cherokee power gear has this type of incapsulated check valve.
The small metal plates are easily unseated by the flow of power steering oil from the pump into the gear. So they really don't add much back pressure. However, any pressure pulses that try make the rack piston move are immediately counteracted by the plate which moves back and blocks any flow back through the pressure port.
I believe that some Saginaw rack and pinion gears also have a check valve capsule in the pressure port.
Jim Shea
Now, the basic Corvette chassis didn't really change from 1963 through the late 1970s or 80s. So what changed from 1968 to 1969 that might have allowed the damper to be removed? Well probably nothing major. Possibly tire changes? Maybe something changed back in the middle or late 60s but removing the damper was never investigated at that time.
Steering dampers were used on many manual steering vehicles throughout the years.
What about power steering? Well, steering wheel or road wheel fight can be experienced with power steering as well. Even though the hydraulics in the power steering circuit typically does a pretty good job of damping.
The General Motors Milford Proving Ground has a Ride & Handling Loop that has some washboard indentations right on the inside edge of high speed right and left hand turns. By driving on the washboard areas at various speeds, you could sometimes hit it just right and the front wheels and steering wheel would start to frantically oscillate. It was called wheel fight.
It was determined that during wheel fight the rack piston inside the power gear would be forced back and forth by the oscillation of the tie rods. The motion of the rack piston would cause pressure pulses to be back driven into the pressure side of the gear valve. It was found that if a one way check valve was installed in the pressure port of the gear, the wheel fight could be greatly reduced. For power steering vehicles, Saginaw Steering Gear developed a pressure port check valve.
Point of information: The pressure port on Saginaw gears is always the inboard port - the larger of the two gear ports. The low pressure return line port is always the one closest to the gear input shaft.
If you look into the pressure port of many Saginaw power steering gears, you might find a small metal plate that seems to block the very center of the port. Old Saginaw power gears (up until 1980) used a 45 degree flare seat to seal the hose ends to the gear. On some gears there was a little metal plate that is pushed upward by a small spring and sits on the underside of the brass flare seat.
On power gears built from 1980 and later, the gear ports were designed as metric o-ring. In the pressure port, you might find a metal capsule. There will be a small plate in that capsule that is spring loaded upward (similar to the flare port.) The 1998 through 2004 Jeep Grand Cherokee power gear has this type of incapsulated check valve.
The small metal plates are easily unseated by the flow of power steering oil from the pump into the gear. So they really don't add much back pressure. However, any pressure pulses that try make the rack piston move are immediately counteracted by the plate which moves back and blocks any flow back through the pressure port.
I believe that some Saginaw rack and pinion gears also have a check valve capsule in the pressure port.
Jim Shea
08-24-2005, 03:25 PM
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Melting Slicks
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Jim,
It has been my experience that any vehicle running larger tires needs a steering dampener. It is almost impossible to drive a jeep without them. I have owned seven and everyone of them had them ans some failed and it is scary to have those big tires shaking wildly, trying to steer and slow down enough to get it under control. It shakes the same as if the king pins are worn out.
Bernie
It has been my experience that any vehicle running larger tires needs a steering dampener. It is almost impossible to drive a jeep without them. I have owned seven and everyone of them had them ans some failed and it is scary to have those big tires shaking wildly, trying to steer and slow down enough to get it under control. It shakes the same as if the king pins are worn out.
Bernie
08-24-2005, 03:46 PM
#3
Team Owner
HAHA...you ai'nt kidding a bit there Bernie, that damn wheel fought it way outta my hands for the most part, no matter how hard I gripped it, that damn thing just shook so badly....
obviously the suspension hit some sort of harmonic freq there that it wanted to vibrate at, and them tires had a LOT of weight to take controll with....for sure...
still can't figger out just why it was fine for 60k miles or so, then all of a sudden.....
GENE
obviously the suspension hit some sort of harmonic freq there that it wanted to vibrate at, and them tires had a LOT of weight to take controll with....for sure...
still can't figger out just why it was fine for 60k miles or so, then all of a sudden.....
GENE
08-24-2005, 04:04 PM
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Originally Posted by BerniesVette
It has been my experience that any vehicle running larger tires needs a steering dampener. It is almost impossible to drive a jeep without them....
08-24-2005, 05:20 PM
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Originally Posted by BerniesVette
It shakes the same as if the king pins are worn out.
Sorry for being the thread's weak link, but I presume that a damper would be located where the control valve is between the box and center link? Where was it on the earlier vettes?
08-24-2005, 06:35 PM
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Chris,
No worn parts. I believe that you see steering dampeners on 4WD vehicles for several reasons: big tires and wheels, heavier spindles, brakes and steering parts and a suspinsion that travels much father on 4WDs. I've never seen a dampener on a sports car but can't say that it would hurt to have one on a vette. I know that the system that is one the C3's leave a little (or lot) to be desired. But I don't think that the Classic Chevy steering mod would require one. You could always try it without and then with to see if there is any difference in the feel. It would be interesting to try.
Bernie
No worn parts. I believe that you see steering dampeners on 4WD vehicles for several reasons: big tires and wheels, heavier spindles, brakes and steering parts and a suspinsion that travels much father on 4WDs. I've never seen a dampener on a sports car but can't say that it would hurt to have one on a vette. I know that the system that is one the C3's leave a little (or lot) to be desired. But I don't think that the Classic Chevy steering mod would require one. You could always try it without and then with to see if there is any difference in the feel. It would be interesting to try.
Bernie
08-24-2005, 07:46 PM
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Drifting
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St. Jude Donor '05
Just let your front tires be a little bit out of alignment and see the shake it creates. This is because there is no stabilizer to prevent it from happening.
As for Dampener 101, Jim,I see that you describe a check valve to allow pressure to disapate and relieve generated pressures, but no steering dampener shock mentioned. If it had a steering shock dampener installed it would not have gotten to the steering box in the first place. A check valve is post occurrence and does nothing to prevent the issue from happening. So we have to have severe occilation to create the condition the valve is supposed to alleviate.
In case no one read the earlier post the Jeep that this 808 box
came from has a factory steering shock dampener. Why does it have one if they are of no value and the 808 box has the magic valve to cure the problem?
And no we are not covering up worn front suspensions or bent frames. Listen to Gene and believe us that when the right conditions occur you won't have to have anyone explain WTF happened to you, if you survive. If you don't understand what it does or how it works how can you argue the point? jim
As for Dampener 101, Jim,I see that you describe a check valve to allow pressure to disapate and relieve generated pressures, but no steering dampener shock mentioned. If it had a steering shock dampener installed it would not have gotten to the steering box in the first place. A check valve is post occurrence and does nothing to prevent the issue from happening. So we have to have severe occilation to create the condition the valve is supposed to alleviate.
In case no one read the earlier post the Jeep that this 808 box
came from has a factory steering shock dampener. Why does it have one if they are of no value and the 808 box has the magic valve to cure the problem?
And no we are not covering up worn front suspensions or bent frames. Listen to Gene and believe us that when the right conditions occur you won't have to have anyone explain WTF happened to you, if you survive. If you don't understand what it does or how it works how can you argue the point? jim
Last edited by PROSOUTH; 08-24-2005 at 09:48 PM.
08-25-2005, 02:18 AM
#9
Team Owner
Pro, one thing I can say is that in ~40 years of daily driving, that has been the ONLY vechicle that ever exhibited the problem, some of these machines at various stages were so worn out it's a wonder the wheels stayed on the car, and I"m not kidding either...but never hit that harmonic thing...
I think my '60 vette had kingpins in it, and it was fine that a way....
whole long list of Dodge 3/4 ton work vans...'73, 75, 89, 85, and they all never had any problems shoot this '85 here now pushing 300k miles....never had that problem....can't figger it...
GENE
I think my '60 vette had kingpins in it, and it was fine that a way....
whole long list of Dodge 3/4 ton work vans...'73, 75, 89, 85, and they all never had any problems shoot this '85 here now pushing 300k miles....never had that problem....can't figger it...
GENE
08-25-2005, 08:07 AM
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Jack 71,
The steering damper is usually located right where you see the power steering assist cylinder. The damper is just a glorified shock absorber. It attaches to the frame and to the relay rod.
The steering damper is usually located right where you see the power steering assist cylinder. The damper is just a glorified shock absorber. It attaches to the frame and to the relay rod.
08-25-2005, 08:15 AM
#11
Team Owner
Originally Posted by Jim Shea
Jack 71,
The steering damper is usually located right where you see the power steering assist cylinder. The damper is just a glorified shock absorber. It attaches to the frame and to the relay rod.
The steering damper is usually located right where you see the power steering assist cylinder. The damper is just a glorified shock absorber. It attaches to the frame and to the relay rod.
GENE
08-25-2005, 08:19 AM
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My experience with the steering dampener leads me to believe that off road vehicles with big tires, heavy suspensions systems with long travel and solid front axles are the primary users. They work well for what they do and more and more off road kits include them. I have never seen them used on cars, but that isn't to say they would make them steer better. Most auto houses sell them as a bolt-on. There is a definate need for them and I wouldn't have a 4WD without one.
Bernie
Bernie
08-25-2005, 09:06 AM
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St. Jude Donor '05
Well, it's apparent I am in the minority here supporting the use of a steering shock dampner. So I guess you guys are all going to tell me I need to sell the set of Bilstien shocks I have because I won't be needing them for the Vette. I mean look, if I have all new parts and my frame ain't bent I shouldn't need any other suspension shock absorbers either should I? :BS
jim
jim
08-25-2005, 09:38 AM
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Jim,
I don't think anyone said not to use a steering dampner. I can tell you for a fact if I had a vehicle that the front wheels start to shimy on me, after checking components for wear, I would definately use a dampner to settle it down. I haven't owned a new vehicle since 1994 so I don't know how the new ones are equipped but I know that there is an after market for them so that tells me people are using them. And I wouldn't hesitate to put it on anything I drive.
Bernie
I don't think anyone said not to use a steering dampner. I can tell you for a fact if I had a vehicle that the front wheels start to shimy on me, after checking components for wear, I would definately use a dampner to settle it down. I haven't owned a new vehicle since 1994 so I don't know how the new ones are equipped but I know that there is an after market for them so that tells me people are using them. And I wouldn't hesitate to put it on anything I drive.
Bernie
08-25-2005, 10:13 AM
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St. Jude Donor '05
Sorry guys it must be this 
HEAT!
I'm not trying to say that everyone needs one, just that they have a purpose and I feel that a Corvette with 9 1/2" wheels and 17x255 or larger front tire needs to be stabilized or dampened before reaching the steering box. There are rotational frequencies that cause vibration and need to be dampened and road conditions that in conjunction with the oversize tires warrant the use of one.
I guess I need to call Bilstien and see it they have a stabilizer to match my other shocks.
I'm going to use one. 
Hey, I do things different than most people. I'm not really a follower of norm. I guess my steering stabilizer will be another oddity to go with my SSM lift bar on the rear. lol jim
HEAT!I'm not trying to say that everyone needs one, just that they have a purpose and I feel that a Corvette with 9 1/2" wheels and 17x255 or larger front tire needs to be stabilized or dampened before reaching the steering box. There are rotational frequencies that cause vibration and need to be dampened and road conditions that in conjunction with the oversize tires warrant the use of one.
I guess I need to call Bilstien and see it they have a stabilizer to match my other shocks.
I'm going to use one. Hey, I do things different than most people. I'm not really a follower of norm. I guess my steering stabilizer will be another oddity to go with my SSM lift bar on the rear. lol jim
08-25-2005, 10:44 AM
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Melting Slicks
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Jim,
From what I have seen on the forum, not one of us is normal! Each of us does things differently to suit our personality and pocketbook; not to mention our particular preference. If I were running bigger tires, I would have to consider the dampner; might anyway because I do know what it is like to have the steering shake out of control. Good luck with your mods!
Bernie
From what I have seen on the forum, not one of us is normal! Each of us does things differently to suit our personality and pocketbook; not to mention our particular preference. If I were running bigger tires, I would have to consider the dampner; might anyway because I do know what it is like to have the steering shake out of control. Good luck with your mods!
Bernie
08-25-2005, 01:07 PM
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I am talking about GM car divisions back in the middle 70s. Back then, you never knew if a vehicle with manual steering was going to require a linkage damper until a prototype was built and evaluated at the GM Proving Grounds. The car divisions hated to install a linkage damper because they were so expensive! But at the time, there was no formula or computer program that would predict that you needed one.
They also evaluated power steering vehicles and determined if they would require the pressure port check valve. That valve was quite inexpensive so they didn't throw a fit if they needed to include it.
I don't think that we ever needed a linkage damper on any production GM passenger car vehicle with power steering. But my memory could be flawed. It is possible that some trucks may have required one.
MRVette,
We always called it the intermediate rod. Others called it a relay rod. Drag link may have been a technical term for a special type of steering rod. I would have to get out one of my suspension and chassis books from somewhere in the house to look it up.
Jim
They also evaluated power steering vehicles and determined if they would require the pressure port check valve. That valve was quite inexpensive so they didn't throw a fit if they needed to include it.
I don't think that we ever needed a linkage damper on any production GM passenger car vehicle with power steering. But my memory could be flawed. It is possible that some trucks may have required one.
MRVette,
We always called it the intermediate rod. Others called it a relay rod. Drag link may have been a technical term for a special type of steering rod. I would have to get out one of my suspension and chassis books from somewhere in the house to look it up.
Jim
Last edited by Jim Shea; 08-25-2005 at 01:11 PM.
08-25-2005, 01:44 PM
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St. Jude Donor '05
Thanks for the information Jim, and my apologies for hi-jacking your thread.
I still think that as even you state they were tested and,
"The car divisions hated to install a linkage damper because they were so expensive!."
This also coincides with my earlier statement that a bean counter saved money removing them.
The point of passenger cars not needing them may again be true especially with the provision of a check valve, but the car I describe is not a passenger car and is especially not designed to use 7 inch rims and F-78 tires.
My '87 Jeep had a steering stabilizer from the factory and it was not large enough to control the 15 x 8" rims and 31x10.50 tires so I had to opt for a larger shock dampener. Oh yeah, this Jeep only had 10,000 miles on it when it was lifted and re-shod. Yes I know this changed the whole geometry, but it would have needed the same extra shock to dampen the extra large wheels and tires and this is the same theory I have tried to convey here.
As for GM not providing a steering stabilizer on a PS car, I can't place one either, but one thing for sure, the vibrations and influences on the Corvette front suspension were the same on a '68 Corvette because they were basically the same except for the power assist cylinder on one and the steering dampner on the manual steer car.
I still think that as even you state they were tested and,
"The car divisions hated to install a linkage damper because they were so expensive!."
This also coincides with my earlier statement that a bean counter saved money removing them.
The point of passenger cars not needing them may again be true especially with the provision of a check valve, but the car I describe is not a passenger car and is especially not designed to use 7 inch rims and F-78 tires.
My '87 Jeep had a steering stabilizer from the factory and it was not large enough to control the 15 x 8" rims and 31x10.50 tires so I had to opt for a larger shock dampener. Oh yeah, this Jeep only had 10,000 miles on it when it was lifted and re-shod. Yes I know this changed the whole geometry, but it would have needed the same extra shock to dampen the extra large wheels and tires and this is the same theory I have tried to convey here.
As for GM not providing a steering stabilizer on a PS car, I can't place one either, but one thing for sure, the vibrations and influences on the Corvette front suspension were the same on a '68 Corvette because they were basically the same except for the power assist cylinder on one and the steering dampner on the manual steer car.
