Won’t drive straight, wandering, darting

[alabamafrog]

I got new tires on old purple last week and now she rides great but I can’t keep her going straight. I’m constantly having to fight the steering wheel to keep her between the lines and when going around curves she is very unstable feeling. I adjusted the steering box screw but that didn’t help. I took her for an alignment today and they said everything was tight and the alignment was good. They could not find anything wrong.

The tires are 305/70/16 Nitto Terra Grapplers class E 65 psi max. I have tried 65 psi, 60 psi, and 55 psi with no noticeable difference. My old tires were 315/75/16 buckshot mudders and they road like crap but drove straight as could be. I figured down sizing from 315 to 305 and upsizing from class D to E would make the truck more stable when towing heavy but now it is dangerous to drive even empty.
Any ideas????

[joeniel]

I think Nittos are just bad luck lol. I had 285s out on last week and now I have the worst vibration in the world. Mechanic says its a driveline issue (will find out tomorro for sure), started right after i got tires on.

[icysmooth]

If you're getting a shake in the wheel in turns,it's probably the steering stabilizer/s,if not,I'd try another shop,you shouldn't have that when all parts are tight and aligned.

[alabamafrog]

No shake in the wheel at all, everything is smooth as silk besides the darting.
The truck did not come factory with a stabilizer but I did add one to it several years ago. I guess I could remove it to rule it out. That was the only suggestion the front-end guy had.

[icysmooth]

Well,I don't think removing it will help,because it keeps it from darting.
Does it do it on a smooth road as well with no dips or bumps?
Only reason I ask is I had same problem years ago and come to find out the shop's alignment machine was wrong,(it was towed out ),took it to another shop and never drove so nice when they were done with it.
Just something to consider.

[alabamafrog]

It does it even on a glassy smooth road, it does really pull, its more like it is just hard to find the center, I have to keep working it back and forth to keep it straight. I may try a different alignment shop, I also think the steering box may have too much play or wear.

[robthebuilder]

I've been having kinda the same problem, the steering just feels loose to me. Funny, I just got some Nitto terra grapplers too, but stock size. Seems like the steering wheel just has some slop in it, but I haven't tried to adjust the box yet. Maybe it is the tires, or maybe our trucks are starting to drive like old turds.

[icysmooth]

Yeah,sure sounds like alignment,don't know how many miles you've put on the new tires,can you see any cutting on the treads yet?
My steering box is getting sloppy,but still drives good and straight,one of these days i'll replace it.
Btw-what model JD's on the trailer?

[chvyrkr]

If your front end is in fact solid as the shop said it was, then I think you're probably right about the steering box.

[alabamafrog]

It should be pretty good, I replaced all 4 ball joints and all of the steering linkages and joints at around 150,000 miles, basically everything except the steering box.

I can turn the wheel about nearly 2” before the tires move in each direction. When I tighten the steering box screw I still have the play but the wheel sticks and has to be turned back to straight by hand instead of the tires caster turning it back for you.
With the old tires there was no problem at all, I could drive with my knee at 80 mph. Now with the new tires I have to use both hands and can’t even eat my Mc double!


Tractors;
1947 A
1948 A
1951 MT
1956 60
2000 4700
Tractor pics http://s273.photobucket.com/albums/j...frog/Tractors/