Caster Mod for pre 73

[hewittca]

I'm bringing back this thread because I have now test driven my truck and I am not entirely happy with how it steers. Just to refresh, I moved my lower arms forward 3/4" and have a manual steering box. Before the caster mod, the steering was definitely firm at low speed but manageable. Now, with the mod, low speed turning is noticeably firmer. It is quite difficult to make a right hand turn out of my driveway without going into the opposite lane. Return to center may be marginally better, but it didn't really stand out as an improvement to me. At speed, I will say that the truck does track nice and straight with virtually no needed input in the wheel to keep it that way. If I need to steer more than 45 degrees on the wheel, however, the steering starts to get really heavy and almost unresponsive. After the first drive I was already planning out a power steering swap. In the meantime, I am wondering if it's worth it to back out some of my caster either through shims or redrilling a new index hole at 1/2".

One other thing I noticed while driving is that my springs are rubbing the front edge of the cavity where they reside in the crossmember. This is due to the bottom of the spring moving forward 3/4" with the arm. Did anyone else have this problem, and if so what did you do to resolve it?

[cab4word67]

Originally Posted by hewittca

I'm bringing back this thread because I have now test driven my truck and I am not entirely happy with how it steers. Just to refresh, I moved my lower arms forward 3/4" and have a manual steering box. Before the caster mod, the steering was definitely firm at low speed but manageable. Now, with the mod, low speed turning is noticeably firmer. It is quite difficult to make a right hand turn out of my driveway without going into the opposite lane. Return to center may be marginally better, but it didn't really stand out as an improvement to me. At speed, I will say that the truck does track nice and straight with virtually no needed input in the wheel to keep it that way. If I need to steer more than 45 degrees on the wheel, however, the steering starts to get really heavy and almost unresponsive. After the first drive I was already planning out a power steering swap. In the meantime, I am wondering if it's worth it to back out some of my caster either through shims or redrilling a new index hole at 1/2".

One other thing I noticed while driving is that my springs are rubbing the front edge of the cavity where they reside in the crossmember. This is due to the bottom of the spring moving forward 3/4" with the arm. Did anyone else have this problem, and if so what did you do to resolve it?

I did 5/8" mod and had 4" drop springs and 2.5" droup spindles. I love the way it drives but I also have a 3 turn loc-loc PS box

[itsnotbroken]

Hi guys,

"cab4word" asked if I'm sure I moved the contraol arms forward. Yes, I moved them forward. But I double checked the new hole & it's .825" to the rear, NOT .750" as I planned. It is a mistake, but .075" is not enough to make this large caster error.

"theastronaut" - The arms are on the same side they have been on for the last 35 years, BUT, that doesnt mean I put them back on the right side when I repainted them for this project.

That 22 degrees I had yesterday is not accurate. I was just sticking a level on the spindle to get a rough idea. The lower ball joint boss is a lot thicker so it really affects the angle.

I made up a shim for the top ball joint boss so that the digital level sits exactly the same distance from the CENTER of the ball joint shafts. The correct caster angle is 15.5 Degrees (through the center of the ball joint shafts)

Also, the truck was not perfectly leveled yet. The rear was a lot lower than the front. As of today the truck frame is dead level sitting on 6 jackstands & a bunch of shims.

I also read a few other racing forums & checked the caster using the "turn the wheels 20 degrees both directions then do some math" method. These measurements were within .5 degree of the digital level on the ball joints. Close enough to know I'm semi accurate. Close enough to rough this in.

But 15 degrees caster is still about twice what I'm looking for.

I'm going to put the lower shaft back in the original hole & see where the caster was before I started. (why didnt I measure before I started?)

[SCOTI]

Originally Posted by itsnotbroken

Hi guys,

"cab4word" asked if I'm sure I moved the contraol arms forward. Yes, I moved them forward. But I double checked the new hole & it's .825" to the rear, NOT .750" as I planned. It is a mistake, but .075" is not enough to make this large caster error.

"theastronaut" - The arms are on the same side they have been on for the last 35 years, BUT, that doesnt mean I put them back on the right side when I repainted them for this project.

That 22 degrees I had yesterday is not accurate. I was just sticking a level on the spindle to get a rough idea. The lower ball joint boss is a lot thicker so it really affects the angle.

I made up a shim for the top ball joint boss so that the digital level sits exactly the same distance from the CENTER of the ball joint shafts. The correct caster angle is 15.5 Degrees (through the center of the ball joint shafts)

Also, the truck was not perfectly leveled yet. The rear was a lot lower than the front. As of today the truck frame is dead level sitting on 6 jackstands & a bunch of shims.

I also read a few other racing forums & checked the caster using the "turn the wheels 20 degrees both directions then do some math" method. These measurements were within .5 degree of the digital level on the ball joints. Close enough to know I'm semi accurate. Close enough to rough this in.

But 15 degrees caster is still about twice what I'm looking for.

I'm going to put the lower shaft back in the original hole & see where the caster was before I started. (why didnt I measure before I started?)

Post a pic/pics of the a-arms. Images help sort things out.