JD 620 Steering catch issue

[offroad23]

Had to pull the radiator out of the 620 and to get it out we had to remove the power steering worm housing assembly (item #31) from the tractor. Got everything put back together and now there is a catch in the steering just right of center. Will be going along fine and then all of a sudden it will catch and not want to steer at all. Eventually your able to overcome the catch and all is well again for a while. All we did was remove the four bolts that attach housing to the steering pedestal and remove the steel power steering lines. I did remove the housing last night to look at it and it appears the worm gear is not engaging with the steering gear very well. Only thing I can think of is that the paper shim item #32 was falling apart so I replaced it with another one that I thought was similar thickness that we had. How do I verify what I need for this shim? What do I need to look at here to fix the issue?

 

[wore out]

Had to pull the radiator out of the 620 and to get it out we had to remove the power steering worm housing assembly (item #31) from the tractor. Got everything put back together and now there is a catch in the steering just right of center. Will be going along fine and then all of a sudden it will catch and not want to steer at all. Eventually your able to overcome the catch and all is well again for a while. All we did was remove the four bolts that attach housing to the steering pedestal and remove the steel power steering lines. I did remove the housing last night to look at it and it appears the worm gear is not engaging with the steering gear very well. Only thing I can think of is that the paper shim item #32 was falling apart so I replaced it with another one that I thought was similar thickness that we had. How do I verify what I need for this shim? What do I need to look at here to fix the issue?

View attachment 64311

There's many things that can cause the steering to "hang up", but let's start with what you had apart. Below is the instructions for shimming the steering worm assembly to the steering pedestal.

So you want to GENTLY turn the steering wheel back and forth a small amount to get a "feel" of the gear lash. If you put much force to turning the wheel there will be motion in the spring-loaded cam that operates the steering valve and you will get a false sense that there is backlash in the worm and sector itself.

 

[offroad23]

If there is to much backlash does that mean more or less shims for the worm assembly to steering assembly?

 

[wore out]

If there is to much backlash does that mean more or less shims for the worm assembly to steering assembly?

More shims/thicker "shim pack" would = MORE backlash.

If too much backlash, remove shims to make a thinner shim pack.

 

[offroad23]

More shims/thicker "shim pack" would = MORE backlash.

If too much backlash, remove shims to make a thinner shim pack.

Thank you, I had a very thin shim and a thicker one in there installed together when I took it apart last night. Reassembled it with just the thinnest shim and hopefully get a chance to test it later today.

 

[offroad23]

Still catches, backlash less than 3/4". Turns great to right, but any time going back past center slowly to left catches. Guess I will pull it off again.

 

[Rich Duane]

To work on any of the 2 cylinder power steering you will need service manual SM2050

 

[offroad23]

To work on any of the 2 cylinder power steering you will need service manual SM2050

Have a manual on order.

 

[wore out]

Have a manual on order.

As I wrote in my first reply ''There's many things that can cause the steering to 'hang up' ''

Are you sure it worked well before you removed the "worm unit"?

I have seen the bolts break that hold the moveable vane to the steering shaft, causing the vane to jam in it's cylinder.

Wear and damage to the "cam" inside the steering worm can cause it, as well.

 

[offroad23]

As I wrote in my first reply ''There's many things that can cause the steering to 'hang up' ''

Are you sure it worked well before you removed the "worm unit"?

I have seen the bolts break that hold the moveable vane to the steering shaft, causing the vane to jam in it's cylinder.

Wear and damage to the "cam" inside the steering worm can cause it, as well.

Only odd thing I ever recall with the steering was when tractor was sitting in place and was idling it would want to turn to the steering to the left at times, didn't do it all the time, but sometimes.

 

[offroad23]

Got the manual yesterday and started tearing things down. Here is what the internals look like.

 

[Fixingfarmer]

 

[offroad23]

View attachment 65403

Apparently something happened at one point, wonder if that is where my catch is coming in. Was wondering if I can weld/build it up and smooth it back out.

 

[Fixingfarmer]

Apparently something happened at one point, wonder if that is where my catch is coming in. Was wondering if I can weld/build it up and smooth it back out.

Or sanded down...is there a chunk of it floating around where that goes?

 

[wore out]

View attachment 65403

The cam or ramp appears to be worn, as well. As to the chipped area, the only time the pin would normally move that far is when it is steered manually with the engine "off" or if the steering wheel is held HARD at the end of rotation after the wheels have reached the end of their travel in the full RH turn direction

 

[620 John]

If it's the cams that are causing the catching I wish you luck with trying to get them smoothed out. Mine catches just like what you're describing. I had mine apart a few times trying to get the cams to operate smoothly and couldn't get it right. I'd suggest putting the cams back together on the worm gear but don't install the worm gear and manually turn the cams in both directions with a pliers. You might find the catch by operating the cams.

 

[offroad23]

Can I just smooth the cams back out? Should I try to fill in the broken spot or should I replace worm gear? I haven't found broken chunk in anything yet.

 

[wore out]

Can I just smooth the cams back out? Should I try to fill in the broken spot or should I replace worm gear? I haven't found broken chunk in anything yet.

Besides being "smooth" the profile of the cam needs to be "as new" to cause a correct and even motion that shifts the spool in the steering valve fore and aft and centers it when no steering assist is needed.

It MAY also be worth checking on the condition of the housing, vanes, seals, and bolts down in the "vane motor" as well as checking for debris that has settled down there. If the vane motor sticks the result will be a lot of manual input to the worm and sector as the operator gets rough with the steering wheel trying to force the system to move by brute force.

 

[offroad23]

I am still struggling with this, the issue seems to be in the steering valve or worm gear and cams. The way it is currently acting is that the valve is stuck between positions because one started tractor can not be steered right or left and the steering valve starts getting very warm. Shut the tractor off and it can be manually steered right or left. Jacked the front end up and it can easily be turned left to right manually. Appreciate any insight into cams/pins and steering valve setup/adjustment. I have a manual but things are not clear enough for me to figure out yet. Hoping someone can give some pointers. Thanks in advance.

 

[ET]

Is your 620 a black dash late model?