unknown swerving

Elandan2 · August 01, 2021, 04:28 PM

According to the Dodge Parts Catalog, the M300,400 & 500 from 1975-77 use the same drag link, Dodge part # 4026505 which crosses to Moog DS881. The simplest way to tell is measure the drag link center to center and compare that to the specs.
https://www.finditparts.com/products/400546/moog-ds881?sctx=eyJzIjoiIDA4MDA2NjE0NjAxMCAgICAgICAgICAgICAgICAiLCJzb3VyY2Ui%0AOiJzZWFyY2hwYWdlIiwicHJvZHVjdF9pZCI6NDAwNTQ2LCJyZXN1bHRfY291%0AbnQiOjEsInJlc3VsdF9pZHgiOjB9%0A&ga_list=Search%20Results%20v2

Oz · August 01, 2021, 05:08 PM

Excellent, Rick!

shilohako · August 01, 2021, 09:59 PM

I have movement at steering column above gearbox, does that mean new (not remanufactured) gearbox needs adjusting. I took video but i cant get it to post. movement isnt below gearbox. it was this way before but new gearbox didnt change anything.
what am I missing???

shilohako · August 01, 2021, 10:27 PM

here is where i grabbed

Elandan2 · August 02, 2021, 08:18 AM

Is the movement between the "pot coupling" and the shaft above it? Although I've never had it apart, there is a bearing of some sort inside that coupling that allows the column to tilt. I wonder if the problem is in that area? I can't imagine that the lower input shaft is still available but looking at the drawing in the parts catalog, it appears to be possible to disassemble the coupling.

shilohako · August 02, 2021, 11:32 AM

I grab the pot coupling (im not sure what it does) but it moves above and below the coupling

shilohako · August 02, 2021, 04:38 PM

I have been looking up all day trying to find a pot coupling, but am having no luck. Even the dealer said I cant look things up that far back. Probably dont want to is the reason. I am going to pull off column later when I get home and see if top of gearbox moves or not. is there other moving parts above gearbox???

Elandan2 · August 03, 2021, 07:43 AM

The pot coupling is clamped directly to the input shaft on the steering box. There should be no play there. The coupling allows the steering column shaft to move laterally but shouldn't have any play radially. I think you will find they are made of "unobtainium" but looking at the diagram in the parts manual it appears that the coupling can be disassembled. Once apart, you may be able to repair or rebuild it. The other option would be to eliminate the coupling but then the tilt feature of the column would be gone as well.

shilohako · August 03, 2021, 08:34 AM

ok if i rebuild or eliminate pot but top of gearbox still moves did i get anywhere? does a new gearbox need to be adjusted?

Elandan2 · August 03, 2021, 06:55 PM

I guess the question is, is the pot coupling moving on the input shaft, or is the input shaft moving without moving the pitman arm? When you said that the garage found a steering box with no play, I assumed that meant that there was no (or little) play between the input and output shafts on the steering box. Maybe the best thing to do would be to disconnect the pot coupling from the input shaft and test it for yourself.

shilohako · August 05, 2021, 11:01 PM

ok not sure if I did it right, but I played with adjustments. pot seemed ok. I could move side adjusting screw in and out all the way and it had no affect on looseness. So then I tapped on the top adjustment and it barely moved but the play is gone. No idea if it is fixed or not. I do still have some small movement but I think it it more tie rod drag link stuff.

Elandan2 · August 06, 2021, 09:09 AM

Great!! Sounds like you've got most of it fixed.

Oz · August 06, 2021, 04:52 PM

Let us know how it goes

72Superior · February 01, 2022, 01:57 PM

Hello I have a 1972 M300 chassis and just went through a similar situation. Mine would grab the rugs in the road and wonder around at any speeds above 50 . I put new radial tires on which helped . I completely inspected the front end and it was all in good condition. I had my wife go into the rv and start moving steering wheel back and forth , what I found was the bracket that holds the steering box to the frame was slightly loose . I tightened all the hardware and took her for a spin , the wandering is gone !! Worth checking yours .

Sasquatch · February 05, 2022, 08:18 PM

I fought this on a M500, 1976 for years. The old Dodge chassis' were nicknamed "wiggle wagons" for a reason. Now you need to ask yourself how much you love the rig and want to keep it long term, because you can be going deep on this one.

You did an alignment and a steering box, so you can rule those two out.
Tires. How old are they and are they fully up to proper pressure?
With the age, it is a good idea, if not manditory idea to pack your front wheel bearings and replace the king pins. Just do it. It has sat for years on those pins and bushings.
Tie rod ends. Are they fully greased and tight?
If all the above has been properly addressed, then proceed below...
Leaf springs and bushings. If the busings in the springs are shot, it can sway left to right.
Rear leaf springs, the same applies and will directly affect your steering.

Do not add any aftermarket stabilizers, air bags, etc., until all the rest is addressed. Once the suspension and steering components are all 100%, here is what I did to get mine to steer straight and true:
Added more castor to the alignment. I think it is at 6 degrees. Some improvement
Upgraded to 225/75/19.5 tires. Big improvement
Bilstein shocks. No steering imprvement, but the ride was better.
Air bags on all four corners. Huge improvement

Oz · February 06, 2022, 12:32 PM

I did the same with mine except for the tire size change and castor. It was like a whole new, enjoyable driving experience!