The Stovebolt Site Forums The Shop Area Driveline caster

The caster on a 53 chevy p/u with bias tires is 2 deg. So running radial how much more caster do i need, I have been told that a total of 4 deg is about right. Has anyone done this? Any input would help. 53 3100 root

Increasing caster will also increase turning effort, as the wheel tries to lift the vehicle as it's turned away from straight ahead- - - -more caster, more lift. Try 3 degrees as a good starting point with radials, and only go to 4 or more if the vehicle tries to wander when driving straight ahead. Be sure the "center point" adjustment on the worm and sector gear is correct before tinkering with the caster.
Jerry

I did not change the caster after changing to LT radials.
I notice no problems - just easier steering and better tracking at all speeds.

I had to play with the PSI - achieving a balance between steering-ease and minimizing "wandering".

I've had the same experience as Tim on my '50, 3604. After
rebuilding the front end, new king pins/bushings, tie rod/drag
link ends, steering box and installing Cooper Radials I used
the stock caster shims and I don't have any steering problems.
It turns easy, one handed if she's rolling a bit, and it does
not wonder.
I've posted this video before, it's nothing to fancy and it
has real lousy sound because its a cheap ten year old Kodak
Easy Share camera mounted rigidly to the seat back, but you
can see how easy she steers, especially in the beginning
when I pull out of the driveway and how straight it tracks
at speeds up to 65mph.

Denny Graham
Sandwich, IL

Denny, I would have said you were wrong untill I saw that video. Very Nice!

I changed to 4° shims after replaceing king pins, front springs, shackles, bushings, shocks, tires, tie rod and drag link, and adjusting the steering box. I was still not happy with it, but the 4° shims did help.

Last week I replaced the steering box with an extra I rebuilt and, as it turns out, that was the problem.

After watching your video, I'm thinking about changing to 2° or 3° shims.

I've mentioned this before, but it sometimes is overlooked. Please keep in mind your truck was designed to use the same diameter tires (and wheels naturally) front and back. If your front tires are a smaller diameter than your back tires, your caster measurement will be reduced. If you've had your front axle bent to lower it or you're doing anything to lower your front axle relative to your back axle, everything changes. There are no real rules on caster...you have to experiment a bit to see what works best, but 4 degrees could be a bit on the high side in my opinion. What Jerry said about having to lift the truck with more caster is right on target and important.

Caster (simply put) places the load point ahead of the contact point of the tire at the road. This causes the wheels to track straight and to return after turning. Correct tire pressure is important. Not using tires which are greatly too wide is also important. A tire greatly wider than the suspension was designed for changes the scrub radius and this isn't adjustable.

Finally too much caster can cause problems aside from making the truck hard to steer. It can increase shimmy and make bumps and road shocks more dramatic. It will cause kingpin parts to wear out more rapidly. It isn't usually a problem with straight axles, but if you have unequal caster, it will cause your truck to pull toward the side with the lower caster. Negative caster will cause: wandering, tendency to bump steer, instability and can give you that sort of "Jeep Wobble" that is nearly impossible to control until you bring the truck to a stop.
Jon

Thanks for the input, I think I'll leave it at 2deg. Denny the video was great. 53 3100 root

One trick on individually-adjustable front suspension is to run approximately 1/2 degree less caster on the driver's side wheel, such as Rt. +3 degrees, Lt. +2 1/2 degrees. This causes the vehicle to lead slightly to the left, to "climb" the drainage crown of the road. The result is a vehicle that tends to track straight ahead, even on roads that are made to drain rainwater by putting in a slight slope toward the shoulder.
Jerry

Jon G, I don't want to say you're wrong, but in my case the 4° caster shims helped out a lot with the handling of my truck. If it made it harder to steer, I didn't notice.

The 2° shims were designed for the original bias ply tires and it's generally axcepted that you need a bit more caster with radials.

Also, 60+ year old springs de-arch a bit, reduceing caster. I had 2° shims, but my caster was 1° positive.

So with 4° shims I'm running about 3° positive.

Please re-read my note. I said 4 degrees could be on the high side in my opinion. I also said there were no rules and you had to experiment a bit to see what works best.

Now at this point I'm a little confused. Didn't you say you replaced all your front end components including your springs with new or rebuilt? And then you needed 4 degrees after doing all that until you replaced the steering box? How are you measuring the angle? Front end machine or other method?
Jon

Jon, you ARE confused. Re-read MY post, I never once said my springs were "new" or "rebuilt" in either of my posts.

Also, I am running 3° not 4.

Don't put words in my mouth and then try to call me out.