lower control arm shims

[tbirdsfly]

local shop did a ftr end rebuild for me. Now i canot get my pos caster set. Are there shims that go ,on the rear lower control arm bushing? If I can move the lower arm forward with arm rear bushing shim ,then the pos caster can be set. The book specs that the 2 top alinment shim locations should not be mord than XXX differnt. can some one post or send me a pick of the location for the lower arn bushing shims ? any views of the lower arm /bolts/bushings/shims /ect would be great. I want to move the lower control arm forward to increase pos caster. Less shims in frt and more on rear + more pos caster. top ball joint back-bottom ball joint forward =pos caster.

Learned my lesson next time take pics and stamp parts
thanks

[simplyconnected]

Yes, there are a number of shims (3054) on the lower control arms. They go between the bushing and crossmember. Normally, we butt the lower control arm against the #2 crossmember and shim the #1 crossmember. If your frame was moved, the shims may be swapped from one side to the other. In some years the shims are square and other years they are round. It doesn't matter though, they both do the same thing.



BTW, these shims are there to take up any space DIFFERENCE between variations in sheet metal stampings. I don't understand how your guy could have installed the lower arms without using spacers. Good to see someone who understands caster. - Dave

[9310alloy]

Shims

Shim location towards the front on my 1960 Bird. Like Dave said.. You do not want the A arm to slide around on lower pivots. The shims were there to stop that and yes the location of A arm will affect castor and the best way to gain castor is the lower A arm location. How the lower bushings were pressed in A arm will affect shims & A arm location between cross members. Just a note do not tighten any pivots until chassis is settled in with its normal weight & ride height.
Mike

[simplyconnected]

I agree with 9310alloy, and I'm glad he mentioned the very important fact that these bushing bolts MUST be tightened only when the front end is sitting at 'normal stance'. At Ford, a guy in a pit would have tightened the bolts while the wheels are resting on a moving flat-top conveyor. You can do it by resting the front wheels on ramps while the rear end is level on jack stands. That should allow enough room to crawl under the front and tighten the bolts to set the bushings.

Nothing turns on the bolt, so I refrain from calling it a 'pivot bolt' because it is not. If you look at the bushing, the inner sleeve has teeth that dig in when tightened. So, all rotation is done in the urethane but there is a 'range of motion' that must not be exceeded or the urethane will tear prematurely. If you tighten while the front wheels hang, you're setting the 'center of rotation' wrong.

So, why shims? Why not just make the tolerances closer?
Understand that sheet metal thickness and alloy is all over the map. Ford buys steel from different companies and from different countries. I have seen a coil of steel change thickness right in the middle of the coil. For outer skins, we constantly adjust press 'shut height' to compensate, all day long. Different alloys produce different 'spring-back', so when a part is formed in a die the variation from one 'float of steel' to another can be profound. We use 'go' and 'no-go' gauges that show acceptable tolerances.

Lower and upper control arms are pressed in dies at over 500 per HOUR. During the day, we go through many coils of steel and we hold consistency as close as possible. Then, we press-in bushings that also have tolerances. The answer is to use shims in this 'stack' of errors. - Dave

[OX1]

Not that you wouldn't want lower control arm
placement even from side to side, for castor
purposes (not that you could ever find out
if they are or not without a frame machine).

But is there a reason you can't even up castor
from the upper shims?

[simplyconnected]

...But is there a reason you can't even up castor from the upper shims?

Even with what, the rear axle? Again, there are tolerances (even in the rear springs and their center pins) and YES, the upper shaft commonly has an un-even number of shim thickness from left to right to adjust camber.

Sometimes the tolerances are too far out to properly shim the top. So... a small adjustment from the lower arm will move the ball joint fore or aft. Those shims are 1/16" which is a lot in terms of 'front end alignment'. Most lazy shops won't bother with the lower arm shims for a simple front end alignment because now, they have a suspension spring to deal with. I have heard so-called mechanics say the alignment is 'impossible', which is BS. Ford builds a lot of adjustment into their suspension. - Dave

[c4clewis]

Make sure you get those shims in AND the bolts TIGHTENED!!! I went through several wheels because a shop never tightened them. I couldn't figure out what what causing the wheels to break, yes literally break. Without the shims in and tightened, every time you hit a bump it can change the alignment.

[OX1]

he shims were there to stop that and yes the location of A arm will affect castor and the best way to gain castor is the lower A arm location.

Just for kicks.

The lower A-arm is installed @ 19 degrees from frame rail.
So for every .125 inch shim, you get .12 inches of movement
directly front to back (obviously depends on which end you put shim).

The upper A-arm rotates approximately 2 degrees for every .125
inch shim you install in only one spot where the alignment shims go.
That translates into about .25 inch movement of upper ball joint, forward
or aft, again depends on which spot you put shim.

Upper to lower ball joint pivot points are 10.5 inches apart,
so for every .125 inch shim (upper or lower)

Lower A-arm will change castor .75 degrees, while upper A-arm
will change castor about double, or 1.5 degrees.

[simplyconnected]

From the factory, location of the shims is NON-negotiable. ALL lower 'A' arms are butted against the #2 crossmember (which also holds engine mounts) and any excess bushing space is shimmed in the #1 crossmember, which is the front or first crossmember.

The number of shims or the thickness of shims may vary. There are NO two car bodys that are identical because they are made of sheet metal and welded together. The welding process makes metal move as well, so we use welding fixtures for better consistency. Nothing here is perfect, so we use shims to make it perfect.

c4clewis, I'm sorry your bolts were never tightened and you suffered loss as a result. I would go back to the so-called 'mechanic' who was paid to do a good job, but released your car before the bolts were securely tightened. That is a safety issue caused by wanton negligence because any reasonable person knows to tighten suspension bolts before releasing the car. Thank God you're still around. - Dave

[OX1]

That makes sense as that # 2 crossmember looks to be made
of more exacting tolerance, having to able to align motor
correctly and appears to be made out of a single tube, vs
the #1, which seems like several pieces welded together.

Lucky for me, I put drivers side together and could only fit
one shim, which I put @ the #1 (not for any reason
whatsever). Just happened that I put that pin through the
#1 crossmember last and it was easier to hold shim with
opposite end of A-arm already supported.

From the factory, location of the shims is NON-negotiable. ALL lower 'A' arms are butted against the #2 crossmember (which also holds engine mounts) and any excess bushing space is shimmed in the #1 crossmember, which is the front or first crossmember.

The number of shims or the thickness of shims may vary. There are NO two car bodys that are identical because they are made of sheet metal and welded together. The welding process makes metal move as well, so we use welding fixtures for better consistency. Nothing here is perfect, so we use shims to make it perfect.

c4clewis, I'm sorry your bolts were never tightened and you suffered loss as a result. I would go back to the so-called 'mechanic' who was paid to do a good job, but released your car before the bolts were securely tightened. That is a safety issue caused by wanton negligence because any reasonable person knows to tighten suspension bolts before releasing the car. Thank God you're still around. - Dave

[simplyconnected]

I urge everyone to follow the Shop Manual. These are not my ideas. The same techniques held true in many prior years with all Ford car lines. - Dave

[tbirdsfly]

Shim location towards the front on my 1960 Bird. Like Dave said.. You do not want the A arm to slide around on lower pivots. The shims were there to stop that and yes the location of A arm will affect castor and the best way to gain castor is the lower A arm location. How the lower bushings were pressed in A arm will affect shims & A arm location between cross members. Just a note do not tighten any pivots until chassis is settled in with its normal weight & ride height.
Mike

great pic now i am ready to get to work.... Question can you post a pick of the rear ? and how do i move the arm? dose the entire assembley have to be revoved ? 1 -12 pack or 2?

[simplyconnected]

I urge everyone to follow the Shop Manual. These are not my ideas. The same techniques held true in many prior years with all Ford car lines. - Dave

great pic now i am ready to get to work.... Question can you post a pick of the rear ? and how do i move the arm? dose the entire assembley have to be revoved ? 1 -12 pack or 2?

Suspension work is bull-work and it appears you didn't read my post. The springs store enough energy to hold up the front of your vehicle.
If you have problems following the Shop Manual, hire this work out and have it done by an experienced mechanic. This is potentially very dangerous work. - Dave

[9310alloy]

Follow Repair Manual

Please read the factory repair manual... per Dave's instructions. Ford recommended shims to the front on the lower A arm. You need to remove coil spring first. If you are not experienced with this procedure you need to follow instructions exactly... For Your Own Safety.... You than can see if any shims need to be added / subtracted. No for or aft movement of the lower A arm when fit between cross members. You want to be able to move the arm up / down with minimal resistance. Remember Ford installed shims to the front. Do not torque down bolts until car is loaded & at normal ride height.

[Yukon60]

Excellent info, thx all.