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Discussion Starter · #1 ·
I'm almost done with my power steering install/suspension rebuild. The power steering system works very well and I'm very happy with it. /forums/images/icons/smile.gif.

I've done an alignment with information gleened from the VMF with decent results except for caster. The car tracks well, but doesn't want to fully come back to center on it's own. I have to turn it back the last 1/4 - 1/2 turn (quick ratio box.) It seems even on both sides. Do I need more positive camber? Is there something else I'm missing? I don't think it has anything to do with the power steering system, but I want to be sure.

These numbers are as close as I can measure with my primative tools (measure tape, straight edge, etc.)
Toe in = 1/8"
Camber = -1*
Caster = ? I've added a 1/8" and a 1/16" shim to the front bolts of both upper control arms. In theory this should give me 3* positive caster, but I'm not betting on it.

Edit: I have also done the Shelby mod.

Advice & Opinion greatly appreciated.
 

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I have the same problem. I removed the PS on my 66 too. I too set the toe in for 1/8" ( sameway, tape) I didn't touch anything else or check anything else for that matter. Last Saturday night, I asked Dinosawnj the same thing, he fealt it's an aligment issue. Otherwise, mine drive fine too.

I'm not too concerned at the moment because I want to lower the upper arms and will need to re-do everything. BTW, I thought caster was set by the front struts, not shims? GM cars you have to set the caster that way.
 

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Discussion Starter · #3 ·
I've never had a classic Mustang with P/S, so I wasn't sure if there was some sort of self centering mechanism in the power steering system itself (I don't think there is.)

I do know that the caster is adjusted with shims on a '66, the strut rods are torqued to spec and are not adjustable.
I did the Shelby mod also.

Did you get any answers from Dinosawnj yet?
 

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Self centering, I can't swear to it but I think the idler arm is different for PS cars, I've heard that it has resistance in the bushing to return to center.

I saw Bob Saturday night at Whiskey Cafe'. I really did persue it since I'm going to take my front end apart to lower the arms. I'd suggest PMing Bob or any of the other opentrackers such as Art, opntracker or roadracer. BTW, Bob is in the back row on the right with the blue shirt and his lovely wife, Anna with the black shirt.

We were going to take the picture in a different spot....but I realized there would have been a Nash Metropolitan in the background. So we turned around and used Bob's 66. We couldn't have that on the VFM, could we, *LOL*
 

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Try more positive caster. See below for explanation. Bob.

Caster
When you turn the steering wheel, the front wheels respond by turning on a pivot attached to the suspension system. Caster is the angle of this steering pivot, measured in degrees, when viewed from the side of the vehicle. If the top of the pivot is leaning toward the rear of the car, then the caster is positive, if it is leaning toward the front, it is negative. If the caster is out of adjustment, it can cause problems in straight line tracking. If the caster is different from side to side, the vehicle will pull to the side with the less positive caster. If the caster is equal but too negative, the steering will be light and the vehicle will wander and be difficult to keep in a straight line. If the caster is equal but too positive, the steering will be heavy and the steering wheel may kick when you hit a bump. Caster has little affect on tire wear. The best way to visualize caster is to picture a shopping cart caster. The pivot of this type of caster, while not at an angle, intersects the ground ahead of the wheel contact patch. When the wheel is behind the pivot at the point where it contacts the ground, it is in positive caster. Picture yourself trying to push the cart and keep the wheel ahead of the pivot. The wheel will continually try to turn from straight ahead. That is what happens when a car has the caster set too far negative. Like camber, on many front-wheel-drive vehicles, caster is not adjustable. If the caster is out on these cars, it indicates that something is worn or bent, possibly from an accident, and must be repaired or replaced.

Positive caster improves straight line tracking because the caster line (the line drawn through the steering pivot when viewed from the side) intersects the ground ahead of the contact patch of the tire. Just like a shopping cart caster, the wheel is forced behind the pivot allowing the vehicle to track in a straight line.
If this is the case, then why did most cars have negative caster specs prior to 1975 ? There are a couple of reasons for this. In those days, people were looking for cars that steered as light as a feather, and cars back then were not equipped with radial tires. Non-radial tires had a tendency to distort at highway speed so that the contact patch moved back past the centerline of the tire (Picture a cartoon car speeding along, the tires are generally drawn as egg-shaped). The contact patch generally moves behind the caster line causing, in effect, a positive caster. This is why, when you put radial tires on this type of car, the car wanders from side to side and no longer tracks straight. To correct this condition, re-adjust the caster to positive and the car should steer like a new car.
 

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See my post above. I would say more positive caster, but if you have +3 already, that's alot. Since these cars are old and fatique has moved around all the relative points in the chassis, alignments can get tuff without more accurate guages. In this situation, theoretical calculations on degree differences may not be too accurate. If everything else is OK, I would have an alignment shop recheck. Then if say the machine says the car is square, but you have "0" caster, you can add shims by feel if the mechanic won't play with the shims.

Bob.
 

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Should be. The factory manual says the following:

The removal of shims at the front bolt or the installation of shimns at the rear bolt will cause the upper ball joint to move forward (positive)......A 1/32" change of shim thickness at either bolt will change the caster angle approximately 1/2 degree. The difference between the shim stack thickness at the two bolts should not exceed 1/6 "

I needed an adjustable strut rod to get both camber and caster where I wanted it. TCP makes the easiest bolt on strut rod.

Bob.
 

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Bob - You are the first VMFer I've seen admit to using adjustable strut rods to dial in more caster on a pre-67 car. In fact, I've been cautioned not to do so on my 66 by some here.

When I purchased my set of TCPs a couple of years ago, the ads typically touted them as being suitable for caster adjustment. Since then, the ads no longer say anything about alignment. That may be just a coincidence.

Anyway, I'd be interested in hearing more about your experiences with the TCP rods. My car has been "under construction for the last 2 1/2 years, so I have no idea if these rods will make alignment easier. I have combined the rods with a Pro Motorsports Vario-Centric Camber adjusting plate kit (uses eccentrics like a 67). Between the two, I am hoping to eliminate the shims altogether.

Sound reasonable to you?
 

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Correction to my earlier post: You are the 2nd person to say they used adjustable rods in this manner. I found an old PM from Opentracker that indicates he was using adjustable rods for alignment on his Cleveland-powered beast.

What I had been told by some was that it was impossible to correctly set all of the alignment parameters correctly when changing the frame-rail-to-control-arm angle on an early car.

This never made sense to me - because that angle changes (alot I would think) whenever a rubber-bushed car is pushed hard in a turn.

Even if the arm is not perfectly perpindicular to the frame rail, I would think that maintaining a nearly-constant angle (thru the use of less-compliant arm bushings and heim-jointed strut rods) would yield much better handling and steering.

Just curious about your experience, so I know what to expect.
 

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First thing to remember is that starting in 67, the strut rod is how Ford told you how to adjust caster. I also run the TCP strut rod, the ProMotor vario-camber kit with Global West upper and lower control arms.

Times and suspension geometery have changed alot since 66. We now upgrade to negative roll front suspensions and know that the "0" or negative caster Ford spec'd in the sixties causes alot of the light steering/wandering (that people pay alot for a TCP setup to get rid off - sorry, my rant for the month). With today's radial tires you can have +1 to+ 2 1/2 positive caster.

Doing an alignment right is serious work. If you only use just the strut rods to adjust caster, it probably isn't a good thing. If you have the right equipment (my buddy has turntables, Optical toe guages and camber/caster guages, and we still rack the car ocassionally to check all four wheels). I would ony use strings and a tape measure to do a race track repair or to get the car ready to drive to the alignment shop.
Bump steer is an issue with these cars when dropped )or more serious with the Granada downgrade (sorry for two rants in one month). This is why most discount alignment shops won't work or deviate from factory spec's if they will do the work). My car will handle comparable to an TCP manual rack equiped car.

Bob.
 
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