No "Return to Center" Steering Woes
 

Ok, I’m really getting frustrated trying to get my truck to return to center after a turn. I’ve done the “caster mod” documented many times on this site, moving my LCAs about 3/4” forward. Still no good. Today I finished installing new CPP UCAs that are supposed to provide 5 degrees of extra caster but still no good. The only thing that I can think of to do is put skinnier tires on the front. Right now, I’m running 275/60/15 tires all of the way around. Has anyone solved this problem while running wider tires? Here is what I’m working with:

1964 C-10, 350/TH350
1977 C-10 Spindles
Stock LCA with caster mod
New CPP 73-87 power steering box
Suspension is stock height

Re: No "Return to Center" Steering Woes
 

I was immediately thinking about offset and width of tires while reading your post.
If a set of stock rims n tires are handy put them on and go for a drive for comparison.

easy things first, play with front tire pressure up and down.
What is the toe set to? Try adding more?

If you can, try a drive with power steering belt off, any better ? Maybe you can change pulleys or add a regulator to reduce pressure at the box, get back more steering feedback

Re: No "Return to Center" Steering Woes
 

Thanks for the reply. Wheels are 15x8 with 4” offset. Stock wheels were 6 lug and now I’m running 5 lug. Toe in at 1/8”. Camber is 0 degrees. I did try upping tire pressure from 44 to 48 psi, no change. Has serpentine setup so can’t remove belt.

Re: No "Return to Center" Steering Woes
 

Saw your other post as well on this. Understand you do not want to spend extra money on checking alignment. But regardless of the mods that you have done, if you do not know the actual caster you have with what you have done. IMHO you are chasing a ghost.

Re: No "Return to Center" Steering Woes
 

I would agree w/Richard here. You need to know what your Caster setting/s are for effective advice.

Re: No "Return to Center" Steering Woes
 

I’m running 15 degrees.

Re: No "Return to Center" Steering Woes
 

If that is measured, great information. Think your steering should be very twitchy. My 2wd 94 only has less than 2 degrees caster with the 5" lift I put on. Steering is a bit lazy, but returns to center no problem. Have custom made upper arms to install to get caster back, just have not installed. See later model spindles were mentioned. What are rest of steering components that connect to them? Center link, end links? Reason I mention is this post here https://67-72chevytrucks.com/vboard/...d.php?t=853016 Maybe check other components.

Re: No "Return to Center" Steering Woes
 

I would question that number. Why is it so aggressive vs the OE specs range?

This era of trucks (63-87) suspension typically called for 2-3 POS degrees Caster w/most never reaching the 3° mark. Aftermarket parts & some clever tweaks to the stock stuff can boost the Caster number to yield a more aggressive 5-7 POS degrees.

To surpass double of that range = scrutinizing things & figuring out how that number/range was achieved.

Re: No "Return to Center" Steering Woes
 

Did a 3/4" LCA shift forward plus the 5 degrees added from CPP UCA. I'm pretty confident in this measurement. Driver camber is -0.3 degrees and Passenger camber is -0.1 degrees. Toe-in at 3/32".

I'm not purposely trying to be that aggressive on caster, just trying to figure out why no return to center.

Re: No "Return to Center" Steering Woes
 

Yes, I've read that that much caster can affect high speed stability, I've only driven around about 45-50mph testing out the return to center.

Re: No "Return to Center" Steering Woes
 

I understand you didn't intentionally target the +15° Caster. For me, the question would be what issue/s would/could that amount of Caster cause? Too much of a 'good thing' logic.
Is that additional Caster impacting the effects of the steering axis/geometry side of things cycling L-to-R @ the lower speeds associated when making turns (where the steering is expected to return to center vs changing lanes type of turn)?

Personally, since you forked over the $$ for those CPP arms, I'd put the lower control arms back where they're supposed to be. Get the alignment closer to the aggressive limit for Caster (+7° is aggressive) & see if there's a difference.

Re: No "Return to Center" Steering Woes
 

I agree with your logic, the only caveat being that I started with Stock Upper and Lower control arms(let's say it might have been 3 degrees of caster) and it was no good. Then I moved the LCAs forward 3/4"(let's say I had 8 degrees of caster total) and it was no good. Then I added the CPP UCAs(let's say I have 13-15 degrees of caster total) and still no good. That being said, I would like to return the LCAs back to their original positions. Do you feel like adding additional Camber would help any? More Toe?

Re: No "Return to Center" Steering Woes
 

Spindles, Rotors, Calipers and tie rod ends are 1977, everything else is 1964.

Re: No "Return to Center" Steering Woes
 

This could be mechanical, not alignment.

A binding balljoint, tie rod, idler arm, steering column/joint or
A badly setup steering box; setup too tight or a bad PS valve or
Something installed wrong giving bad geometry as suggested a couple posts up

even if all this stuff is new I'd do some checking

Re: No "Return to Center" Steering Woes
 

I'm wondering if there's an issue w/binding somewhere within the steering itself? How well do the TRE angles look? Seems there could possibly be an impact there (especially for a lowered truck) but possibly something to verify on a stock height set-up as well. What about binding @ the BJ pivots?

For testing, jack the front up & block both sides up (under the a-arms) w/the tires barely off the ground. This would replicate weight on the suspension w/o having the resistance of the vehicles weight on the ground/road impacting things. Cycle the steering by turning L-to-R & see how the wheels pivot @ the spindle? How is the resistance @ the steering wheel when turning each way? Is it consistent for both directions?

Disconnect the TRE's & repeat the testing again @ the hub. Rotate each side back & forth L-to-R & feel for possible binding @ the BJ's (I've heard of more than one vehicle w/new parts causing issue). Eliminate this stuff as a possibility.

I request my trucks to be set up @ static NEG .5° Camber w/as much Caster as possible w/o impacting that Camber target. I like the impact it has on grip in corners. I rely on others doing the alignment (@ commercial places of business) so I've never had the ability to thoroughly ID full Caster/Camber results through the range of travel.

While there's no confusing them as a Vette, both of my lowered HD trucks ('99/OBS 3/4-ton CC SWB & Squarebody CC Dually) using the above alignment target specs handle much better vs their stock height/stock alignment specs in comparison & this is w/both still usng steel 6" wide front wheels/narrow tires. Both feel planted w/o much (any?) understeer & steering return to center + input feel is nice/consistent.

Re: No "Return to Center" Steering Woes
 

Here are some pics of my setup

Re: No "Return to Center" Steering Woes
 

A few more. I have jacked up the wheels and turned wheel lock to lock without any binding or significant resistance. Removing TRE and checking BJ stiffness is a good idea.

Re: No "Return to Center" Steering Woes
 

Are you testing for binding from the steering wheel or at the tires?

With it jacked up and motor running does the steering stay where you put it or creep? (bad PS valve)

If you have a place where you can do it safely you might try doing some downhill motor off turns, see if it wants to center without PS.


When you upgraded to the PS box, how did you align the box on the 64 frame? Did you use a spacer or put a bump in the frame?
Is the steering arm on new box in same geometry as the old one was?
Did you replace the idler arm/ redrill it's mounts?
Is the center link horizontal relative to frame? is it parallel to a line through the ball joints?
Any chance you have a bent spindle, steering or control arm?

Re: No "Return to Center" Steering Woes
 

Steering box was mounted using REZ Engineering Kit with locating plate.
Box is lined up as original
Idler arm is '64, located in original position
I don't believe anything is bent.

I checked for binding at the steering wheel, motor not running

Re: No "Return to Center" Steering Woes
 

I'm not familiar with it, does the REZ kit include a spacer so the box clears the frame? Do they say anything about adjusting idler arm?


FWIW:
I have a 64 frame under a '52. I converted to PS last winter with an early 80s suburban box. I DIY'd it but layed out redrilling the frame so the end of the steering arm was in matching spot and the box remained in alignment. About 1/8 spacer, ground the casting seam off box plus some clearance into the frame to clear the bump.
I did not change my idler to the newer, longer style. My center link is slightly off level. I'm switching to disks and newer control arms this spring and will address the idler at the same time.

It rode and turned OK, drove it all summer and into fall. There IS a tendency to hold a gradual sweeping turn and not return to center. It did not bother me, knowing I had further plans for this winter. I run 225 front tires. The alignment is tape measure and level done in my not very flat driveway. Camber about right, 1/16 toe and very little caster maybe a degree. But I don't put a lot of faith in the accuracy of those numbers. I might have some play in a CA bushing, I hear a clunk but can't find any movement. Truck does have some noises to it.

The 80s 'burban PS box plus an unknown origin pump provides a lot of steering assist. Like park with one finger easy to steer. It could use less so there was more feedback.



I'd check all your components for binding under load and pay some attention to geometry of the steering gear. Are you confident in your alignment shop?

Re: No "Return to Center" Steering Woes
 

Yes the kit spaces the box the correct distance from the frame.

Re: No "Return to Center" Steering Woes
 

Can we see a picture of the shim stacks on the upper control arms?

And can you post the alignment print out after the alignment?

When you did the Caster Mod how far from the end of the lower shaft did you drill the the new index hole?