What's new
CK5
Register an account today to become a member! Once signed in, you'll be able to participate on this site by adding your own topics and posts, as well as connect with other members.

Twitchy as hell after hydro assist

True I did finally change my fush and moved it for the 52s. But I only used 6.75 shackels and my springs are basically in the same place as before about 3/4 inch from the frame at ride height so no caster changes least big ones. But if I did change caster it would be leaning back more right? Such would move the axis making it less twitchy. Ie a chopper vs a bmx bike. This definitely is not DW. I had that bad before but the new preload adjusting steering arms and bronze upper bushings cleared that up
 
When you said it was speed related I automatically thought higher RPM related....as RPMs rise it gets worse kind of thing. Didn't think about gearing and speed specifically.

Did you change out your steering shaft for a more rigid version? Sloppy steering at slower speeds isnt as noticable as when you are going faster. I would think the same would be true for stiffer steering and not being use to having it that stiff. Just a thought.
 
What hole do you have the drag link in on the crossover arm. If it's not in the end of the crossover arm that would make it twitchy at speed. I'm running a 1.75" ram on mine and at speed it isn't twitchy at all. It self centers and drives like it should. :dunno:
 
My steering has always been stiff and tight. So that isnt new. My draglink is 7in from the kingpin on my steering arm.

You kinda have to drive it to feel what it is doing. but the best way i can describe is there is a small amount of side to side play in the wheel as is expected. as soon as you start to move the wheel the steering turns quite a bit. Its like it has a super ratio.

Or it feels like my wheels are straight up and down like this |
when they should feel setup like this \

yeah its not like it actually "Gets worse" at higher speed. It is just more dramatic at high speed since a small change in the wheels is much more noticable.
 
Couple of thoughts here. A smaller cylinder will respond faster than a larger one. But, you seem to be using the most common size, so I suspect that is a dead end.

The bigger the holes and lines, the faster the fluid can flow, which will make the cylinder respond better, but due to the nature of the system, you can't really get too much volume.
Not enough is a problem, the control valve in the steering sector supposed to control how much is sent, not the lines.

The whole setup hinges on the steering sector. Think about how it works. As you are driving straight, the spool valve is closed, sending no fluid to either the ram or the regular steering assist part.
When you start to turn the steering wheel, it tries to turn the pitman arm through a spring hooked to the spool valve.
If the arm moves, the spool valve stays centered and no fluid flows.

Of course, unless the arm is unhooked from the steering, it is not going to move. When you continue to turn the wheel, the stalled arm moves the valve against the spring tension, and the fluid flows adding assist.
If the assist is not enough, the valve moves farther and more fluid flows.

As the arm moves, catching up to the input, the valve centers and the fluid stops. The arm "chases" the input.

Now, what this means, is that the output arm is the feedback sensor for the whole system.
The steering box does not know or care what the hydraulic cylinder is doing. It only cares about what the output shaft is doing.

If you disconnected the pitman arm from the steering, and put a load on it, the cylinder would move to the end of its travel and stay there under pressure until the arm was centered in respect to the spool valve.

Which means, any slop between the old steering arm and the steering is going to cause the cylinder to over react.
It sounds to me like the cylinder is pushing part of the steering faster than the arm is moving.

Or, there is damage in the steering box that is causing the spool valve to float and not react to the output like it should.

I hope all that made sense, my leg is hurting and it takes my mind off it when I do the whole logical chain of events thing, plus I am running on too little sleep.
 
NorCal_Chris said:
It doesnt seem to be rpm related. Just speed related. The faster i go the twitchier it is. I tapped my box in the usual chevy spot near the casting line up top, and on the bottom near the the factory plug. Think it needs to be bled more? I mean the power is there but my fluid is a little frotthy. It has no issues low speed or sitting still turns nice and smooth
Click to expand...

You still have air in the system. Get the front wheels off the ground and start the engine and then cycle the wheels lock to lock about 20 times but FIRST do yourself a HUGE favor and with the engine running crack the lines loose at the ram (one at a time) because I had air trapped in my system and that was the only way I got rid of it instantly. :thumb:
 
You still have air in the system
Click to expand...

Good point. Air in the system would have the same effect as the output arm and the cylinder not tracking together.
Air would cause them to move at different rates and loads.

The primary thing about hydraulics is that it acts like a solid bar. The fluid is not compressible. If you move enough fluid into a cylinder to move it one inch, then it will move that one inch as soon as the fluid arrives.

With air in it, the cylinder might not move until the pressure builds up enough to overcome the load, and then it might move farther than you expect as the air uncompresses because you put in more fluid to compress the air than you would have normally.

Which would fool the steering box by causing uncommanded movement.
 
Im at 1/8 toe in.

I will try bleeding it more today and will try your trick Scott.

Hopefully it is just air in the lines and this solves it
 
Fordum said:
Couple of thoughts here. A smaller cylinder will respond faster than a larger one. But, you seem to be using the most common size, so I suspect that is a dead end.

The bigger the holes and lines, the faster the fluid can flow, which will make the cylinder respond better, but due to the nature of the system, you can't really get too much volume.
Not enough is a problem, the control valve in the steering sector supposed to control how much is sent, not the lines.

The whole setup hinges on the steering sector. Think about how it works. As you are driving straight, the spool valve is closed, sending no fluid to either the ram or the regular steering assist part.
When you start to turn the steering wheel, it tries to turn the pitman arm through a spring hooked to the spool valve.
If the arm moves, the spool valve stays centered and no fluid flows.

Of course, unless the arm is unhooked from the steering, it is not going to move. When you continue to turn the wheel, the stalled arm moves the valve against the spring tension, and the fluid flows adding assist.
If the assist is not enough, the valve moves farther and more fluid flows.

As the arm moves, catching up to the input, the valve centers and the fluid stops. The arm "chases" the input.

Now, what this means, is that the output arm is the feedback sensor for the whole system.
The steering box does not know or care what the hydraulic cylinder is doing. It only cares about what the output shaft is doing.

If you disconnected the pitman arm from the steering, and put a load on it, the cylinder would move to the end of its travel and stay there under pressure until the arm was centered in respect to the spool valve.

Which means, any slop between the old steering arm and the steering is going to cause the cylinder to over react.
It sounds to me like the cylinder is pushing part of the steering faster than the arm is moving.

Or, there is damage in the steering box that is causing the spool valve to float and not react to the output like it should.

I hope all that made sense, my leg is hurting and it takes my mind off it when I do the whole logical chain of events thing, plus I am running on too little sleep.
Click to expand...

Good explaination.

Put the above together with the characteristics of Hydro fluid, and then frothy fluid, and it seems like the air in the system is either THE culprit or a good part of it.
 
I chased the same problem after I installed hydro assist on my Cummins swapped k30. With just a little steering input it would dart across lanes. Air was the culprit of my problems. Just keeping bleeding it and cycling the steering until the fluid isn't frothy and you should be fine.
 
kill me now.

Must have turned 100 times then cracked bottom lines. then 50 or so times. Let it sit a half our then just went at it again about 100 times. fluid still looks like it has tiny bubbles....

This is frustrating. I think i may take the ram off and cycle the steering with it floating there, maybe it will like that
 
NorCal_Chris said:
kill me now.

Must have turned 100 times then cracked bottom lines. then 50 or so times. Let it sit a half our then just went at it again about 100 times. fluid still looks like it has tiny bubbles....

This is frustrating. I think i may take the ram off and cycle the steering with it floating there, maybe it will like that
Click to expand...

That can help and holding the cylinder so the end of the cylinder that is emptying out is upward to help the air come up and out.
 
You may have done this, but I like to bench bleed the ram with the hoses connected before connecting them to the box. Basically, I use gravity to bleed everything I can and fill from the bottom of the hydraulic system up to the top. It's never taken me more than maybe 20 minutes to bleed the steering that way. The ram is probably the hardest part of the whole system to do because it is so far away from the main circulation.
 
I unhooked the ram and let it hang with the piston down turned a few times and bam! No more froth or bubbles. Took it for a spin and it is tons better. Return to center is still not really there but after driving for a few Mons I got used to it. Tracks like a dream and zero bumpsteer.

Thanks all of you for the help and suggestions . Now we know air can do all sorts of crazy Junk
 
I feel your pain about the turning. I blew the shear clip on my power steering hose on my F150 when I ran off the edge of the pavement trying to run over a rattlesnake one time.

Had to drive home almost 40 miles with 12.50/33s and no power steering.
After I replaced the pump and hose, it had some air.
Went down the the local civic auditorium on the city marina and started turning loops and figure 8s in the big parking lot.

About an acre of empty flat parking lot, so I was not paying too much attention to what was going on around me.
Getting a little dizzy in fact.

Never thought about the fact that this was in a very public place.`
I was not cutting doughnuts, or burning the tires, just nice big loops. Made one big swing, and suddenly my front end swung by three city police cars sitting side by side with their lights on..........

Fortunately, I knew a couple of them. And I was smart enough to not get out of the truck. I probably would have fallen down.
They had their dispatcher call the plant and talk to our mechanic, who verified what I was doing.

They left, but I heard one of them mutter typical J.
After I got the air out, I had to sit for a few minutes to let the world stop going around.
You keep driving in circles and 8s for a while and you will get very drunk feeling.
 
There's something to be said for putting the front diff on jackstands and running it lock to lock for a while. And keep the reservoir topped so it doesn't get another chug of air.


Sent from my Desire HD using Tapatalk
 
You must log in or register to reply here.

Latest Posts

Top Bottom