Boat Like Steering Issues

OK so I have a 69 CJ 5 That steered great at high speeds with the original Dana 27 frong axle. I recently rebuilt a 1972 Dana 30 and swapped it in place of the original axle. I also installed the disc brakes from a 1979 CJ. After test driving it I found out the jeep now acts like a boat when steering at 45+ miles per hour. It takes constant steering to keep it in one lane... I took it to a front end shop to have them check it out and they told me I had 3 degrees of caster with 2 degree shims. They told me my Toe In was "in spec" They were concerned about the Saginaw power steering box I had installed previously. I replaced the power steering box with a newly rebuild Red Head Steering box and installed 6 degree shims which I assume is giving me 7 degrees of caster based on the previous measurement. After a test drive the steering is better but not good. HELP!!! what can my issue be? The ball studs seemed fine when I installed the knuckles. The tie rod ends are new. The Steering box is new.

 

Checked the rear end? Shackle bushings, U-bolts, center pins, etc.? Cracked frame or spring shackle mount?

 

No and I will but there wasn't an issue there before with the Dana 27 so i'm assuming it has to do with the new installation

 

Wheel bearings? And Dont quote me but I think..a 72 would have been drums originally and there may be a spindle difference.

 

do you have one of these on steering gear box
Warrior Products 895 Steering Box Brace for 71-75 Jeep® CJ-5
I am thinking frame flex . have someone look a box while you move steering wheel left to right

 

The spindle is the same... Wheel bearings are new and torqued to spec...

 

There is a little flex in the frame but only when you max out the post

 

Post some pictures of your steering setup...........Saginaw gear boxes have several ratios...........something that is darting around on the freeway in a short wheelbase vehicle may have a problem with a quick ratio gear box.....or was the input shaft centered in it's Left to Right travel before the Pittman arm was installed?.................... But there are many things that can effect the steering geometry ......worn suspension bushings, rear axle out of alignment with the front, Bump steer, shocks, tires , air pressure just to name a few.......

 

My D30 did the exact same thing. I have a D30 build in the fabrication forum. Lots of great info from members here. After getting new shims I am at 5 degrees positive. That made a huge difference. I also messed with toe in for days. It is pretty much dead on at 1/8 inch. Oddly enough after a day of moderately 4 wheeling it is great now.
D30 Upgrade

 

The "new" Red Head saginaw steering box is maybe a slower ratio that the one you were using previously. Is the pitman arm on the new steering box the same length as the previous box?
Also, the length of the steering arms (steering pivot to tie rod hole) from the D27 to the D30 could be differnt lengths. And closely related, the tie rod from the pitman arm to the knuckle on the D27 problably connected via tie rod end vs it now likely attaches to its own hole outboard of the one piece rod between the knuckles on the D30, making a slower ratio.
The effective lengths of the steering arm (knuckle) determines how "quick or slow" the steering is. Boat like steering comes from a slow steering ratio. Caster angle determines how easily the front wheels return to (and stay) centered straight ahead.
-Donny

 

I was typing some of what Donny just beat me to about 1-hole vs 2-hole ratios, so... delete...

One other thing that jumps out at me is - don't assume anything when it comes to actual caster measurements. Get your hands on some sort of an angle measuring tool and see what you have at the knuckle.

And not to insult your intelligence; I just have to ask. The shims are in the correct direction? The pinion should look like it is almost pointing down at the ground (vs. up toward the transfer case) with 7° of caster.

 

I picked up an angle tool at Harbor Freight for cheap.

 

Thanks for everyone's reply's so far. Yes the shims are in correctly. The Knuckle to knuckle rod is the one that came with the D 30 and was adjusted by the front end shop who also measured the actual caster.

 

If the front end shop put your Jeep on the alignment machine, they should have a printout. You could ask for it. Everyone that gets an alignment should get the printout - they paid for it. That will tell you both the front and rear axle geometry.