UCA Offset Bushing Install

[mgm1986]

I just read through a great post by @HWYCRZR on how to align at home, very helpful and informative! I would like to get a little clarification from those who have done it before I press new bushings in my Upper Control Arm.

Working on the drivers side, the bushings I removed were of the offset kind, with the thin rubber part closest to the frame on both front and rear bushings (pics attached). I understand this could have been done to help improve camber if the car was previously in an accident. Not sure of the history of the car so before I press the new offset bushings in the same way I thought I should ask for input.

Should I install the new bushings the same way, which is how the Moog installation instructions indicate for maximum camber? Or should I install them with the rear bushing in the opposite direction to assist in getting better caster adjustment?

I haven't used offset bushings before so any advice or input is appreciated.

Fun fact, these are Moog bushings that came in a Mevotech box from RockAuto...

 

[HWYCRZR]

My new bushings had a notch on each side of the flange which lined up horizontally. Which looks to be very close to how yours are lined up. I don’t recall if there were any other indexing points to only allow installation in one direction. I will look to see if I can find my disassembly pictures. You are correct the manual doesn’t indicate which direction to install. Mine are both the same direction with the bushing steel sleeve towards the engine and end of upper control arm.

 

[CBODY67]

In the GM world of things, the offset bushings are needed due to "crossmember flex" with time. I heard of this first on big block Chevelles, but actually apparently goes back to the 1955 Chevrolet cats. When I heard of this, I suspected "another flimsy GM design", but after considering the geometry of the situation, the LCA bushings sit at the top of "a tower" of sorts, where all of the forces which work to keep the wheels not perpendicular to the road surface happen. So some age-related deflection might happen. Hence the offset bushings.

Possibly installing them differently/staggered would increase or decrease the caster angles?

Enjoy!
CBODY67

 

[RemCharger]

More caster is almost always a good thing, but we don't know how the camber was before disassembly. Sadly.

 

[mgm1986]

More caster is almost always a good thing, but we don't know how the camber was before disassembly. Sadly.

This is a good point. It did have a bit of a pull and it liked to wander a bit down the highway. I don't know if that was due to bad alignment or worn parts.

So much information out there it is hard to say what the best thing is since she will be a cruiser not a race car.

Normally I would put it back as the instructions say but if there is a benefit to getting more positive caster in these big C-Bodies I'd like to know before I press the new bushings!

 

[413]

Why did you buy these offset bushings? What are you looking to gain?

If you want more caster then they way they were won't add any caster.

 

[mgm1986]

Why did you buy these offset bushings? What are you looking to gain?

If you want more caster then they way they were won't add any caster.

Another good question. The pictures above are of the bushings I removed so I bought the same ones to replace them. Understanding the way they were installed wont add caster.

Then I started reading how more caster can be a good thing on older cars and some suggestions came up that this could be done by installing the rear offset essentially backwards, with the hole being closer to the ball joint.

But I don't always trust videos I find and I like hearing from the experts here who have done it.

 

[HWYCRZR]

Edit . I was Wrong, the standard bushings based on my disassembly pictures were not offset. And after a closer look my new ones are not offset either. Replacement bushings can be offset for the upper control arm. At least for 67and 68. Not sure what year @mgm1986 has, but looks like his are offset.
I would be careful changing the position too much.
On the standard bushings I could easily get enough positive caster and could easily get the positive camber I needed. Now if you are running the front height lower than spec (very little torsion bar spring rate) and the back end jacked up then you may struggle to get enough positive caster with the original centered bushings.

Not the best picture, but the bushings look pretty centered.

 

[mgm1986]

Thank you, @HWYCRZR!

I'll reinstall them as they came out. I didn't realize the factory had offset bushings, learning new stuff all the time!

 

[CBODY67]

IF you staggered the UCA bushings to move the UCA ball joint rearward, for more caster, it might put the mounting bolts in a bit of a bind as the bolts would still be normal, but the center sleeves of the bushings would not be in a straight line any more. Which could put more flex into the rubber/urethane of the bushings, which might compromise their longevity. So both in the same orientation is best, to me.

The way the front end geometry of these cars is designed, the outer wheel (in a turn) cambers IN (negative camber) as the inside wheel cambers out (positive camber) so that as the body leans, the tires remain much more perpendicular to the road surface. In many cases, with the outer wheel still being a bit in negative camber territory. This keeps the tire sidewall much better braced against the turning forces for better handling capabilities and response. By comparison, a similar GM and Ford front suspension keeps the wheels perpendicular to the car chassis, as the body leans. Which puts the bulk of the cornering forces are the outer tread ribs rather than the full tread width. Which also means that a GM or Ford suspension will need BIG sway bars to keep things flat so the tires stay flat against the road. "More" caster is also needed, to better brace the outside wheel in a corner, too.

In some respects, I have pretty much determined that "max caster" is over-rated and really not needed on any car. It can be a Band-Aid fix to get the negative camber in the outside wheel in a corner, but with just 2*+ caster, it can lead to edge-wear on wider tire treads. I noticed this on a non-Chrysler car I have with P2256/70Rx15 Radial T/As on 15x7 factory wheels . . . in normal driving . . . on the front tires. Which can mean that wider treads and shorter sidewalls should be worse!

Even with .75*+ caster (the 1966 spec for power steering C-bodies), the steering has no issues returning to center from a turn on its own. New or now. +Caster is supposed to help straight line stability, but aerodynamics can play a big role too.

IF the car is aligned with the rocker panels parallel to the road surface, caster will be "as presented". If the rear end of the car is raised (added-arch rear springs or air shocks), effective caster will head toward negative values. Same if the front ride height is lowered. If the rear springs are "flattened" with additional loads in the trunk, effective caster will be increased. Zero caster is when the line drawn through the upper and lower ball joints hits the road at a 90* angle. If the line is angled in front of the lower ball joint, that is positive caster. Which relates to the upper ball joint being moved rearward.

Y'all have a nice weekend!
CBODY67

 

[413]

Standard bushings are offset for the upper control arm. At least for 67and 68.

No, I must disagree with this statement on the factory uses offset bushings. Never heard that one before, but I'm willing to learn. Do you have any proof to back this up?

How could we learn this yes or no? How about the factory service manual as a qualified source? 1967 Polara Monaco manual does not say anything about offset bushings or the correct direction to install them. And if the bushings were offset it would be very important to install them in the proper direction. Why don't they address this?

Photos are of the 1967 Polara/Monaco service manual page 2-10

Rockauto shows "original design standard bushings" and offset for more camber.

 

[CBODY67]

As it now seems that all aftermarket UCA bushings are "offset" from all vendors, IF such an offset is not needed or desired, might the offset be vertical rather than horizontal? Which THEN would speculate if the thick part should be at the top or bottom?

Happy weekend!
CBODY67

 

[413]

Aftermarket bushings are centered just like factory.

Many brands offer offset bushings. If you don't know why you are buying them or which way to install them, then just use the stock stuff.

Like @CBODY67 said earlier, .75 positive caster and the steering wheel returns, car drives just fine.

A car that has alignment settings off or one bad part and the car can drive terrible. Don't need the trick of the week parts, just get back to basics.

 

[mgm1986]

Aftermarket bushings are centered just like factory.

Many brands offer offset bushings. If you don't know why you are buying them or which way to install them, then just use the stock stuff.

Like @CBODY67 said earlier, .75 positive caster and the steering wheel returns, car drives just fine.

A car that has alignment settings off or one bad part and the car can drive terrible. Don't need the trick of the week parts, just get back to basics.

I agree and I am unsure why the ones I removed where offset. Since I have the offset ones to go back in I am going to install them as I found it as I have no baseline alignment numbers to work from.

As you pointed out, they do offer the standard stock, no offset, on RockAuto so if I go for an alignment and they gripe I will find out what they want.

I am not a mechanic nor do I have any idea what I am doing. I just like doing it and between the shop manual and this forum I am fumbling my way through it.

 

[mgm1986]

Here is one example of why I was interested in learning more about adjusting Caster, but I have no idea if I NEED to do this so I am NOT going to do it. I am going to install these as they were removed with both arrows pointing to the ball joint.

But some folks on the A-Body and B-Body forum have done it with them pointing in different directions to adjust Caster.

Moog offset bushing install question.

Offset upper control arm bushing question??

The attached is from one of those threads, to illustrate.

 

[HWYCRZR]

Let me go back and look at my pictures from my original. Which I know weren’t changed and I will go back and find the moog p/n I ordered. Mine are installed so is difficult to tell and the eccentric washer could be giving me an optical illusion. I guess it has been almost 10 years since I installed them (or more). You are correct on the manual being vague and no mention of offset direction, which in most other situations they state if there’s a certain direction.

 

[Big_John]

I am unsure why the ones I removed where offset.

As I understand it, the offset bushings were made for cars where there isn't enough adjustment left to bring the alignment into spec.

So, basically for a car that's had some front end/and or frame damage.

Do you think the car has ever been crashed and repaired?

 

[Just Carbs]

The offset bushings "generally" allow for increased positive caster without going to an excess negative camber condition.

Mopar says .75 p caster for late 60s with belted or bias tires of the day, and 3.5 p caster for late 80s rwd with radials. Lots of people that know something about Mopar say 60's and 70s Mopar need 3.5 p caster with radial tires.
And yet Mercedes says a whopping ---- "9 p caster"----- for their mid 80s sedans. And yes, that works astonishingly well for them. I have 300D and 300SD.

But it all revolves around how you want your car to behave and on what roads, what crown, what wind, and at what speed.

The 60s and 70s Mopar's self-center pretty good with their 7-degree included (non-adjustable) king pin angle, so a lot of p caster may not be needed around town or on the interstate.

At the end of the day, the only way to get the car to suit your preference is to start trying different number combos, keep good notes, and tailor it to your liking. But you won't realize this until you actually do it.

You need a caster/camber gauge like this one, if you don't already have one. And turn plates.

 

[CBODY67]

That particular gauge and turn plates is what our local Chrysler dealer had. Clips onto the end of the spindle, so it is as accurate as it can be.

ONLY thing is that it worked just fine for normal wheel cover or hub cap cars. NOT so well for Magnum 500 wheeled cars. They usually got the spare out and installed it on each front wheel. For the Class II 16-alor W23s, they'd have to unbolt the center cap.

CBODY67

 

[Boydsdodge]

Here is one example of why I was interested in learning more about adjusting Caster, but I have no idea if I NEED to do this so I am NOT going to do it. I am going to install these as they were removed with both arrows pointing to the ball joint.

But some folks on the A-Body and B-Body forum have done it with them pointing in different directions to adjust Caster.

Moog offset bushing install question.

Offset upper control arm bushing question??

The attached is from one of those threads, to illustrate.

View attachment 716140

I use the offset bushings to gain some extra caster, as described in the Mopar Action artical above.