Need more neg Camber / Pos Castor '66 2+2 - Vintage Mustang Forums

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post #1 of 45 (permalink) Old 11-18-2012, 04:09 PM Thread Starter
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Need more neg Camber / Pos Castor '66 2+2

Redid my front end last winter and without any shims I am at 1 degree neg Camber and 1/2 degree pos Castor. If I add shims to increase castor the Camber goes positive. So, I have been considering moving the pivot point on my LCA inboard. According to my calculations .2 inches of movement on either end of the spindle equals 1 degree of camber. I have also heard that many in the vintage race circuit shorten their UCAs covertly to get better geometry which would also fix my issue. I would like to get to 2 degrees neg camber and 5 degrees pos castor. Not that I would use it all but would like to be able to get there. Probably will settle at 1 degree neg camber and 4 to 5 degrees pos castor for Autocross and occasional track days. THe car is driven on the street quite a bit.

Questions:

1) has anyone else done this calculation and do these numbers jive? e.g. for every .2 inches I move the LCA pivot inboard, I get one degree of neg camber which could be traded for castor.

2) has anyone shortened their UCA - What does that do for the front end geometry. Obvously I would get more negative camber as the suspension compresses. Are there any down sides? How much did you shorten it? I heard 1/2 inch.

I am also thinking that a shorter UCA will give me more tire to fender clearance which wouldn't hurt if I decide to go lower on my stance.

3) One last thing I heard recently is that people are repositioning their spring perch an inch outboard. Seems to me that would equate to increased spring rate and shock response. Why did you do it and were you happy with the result.

4) How much Castor can adjustable struts add? I have heard it's just for fine tuning or can you add several degrees?

A few things: I can't use adjustment kits for the LCA because I have a cross bar that picks up the pivot bolts on the LCA. I'm too cheap to buy after market tublar UCA/LCA peices and I Love to weld and am looking for a winter project.

Thanks,

M

Last edited by dobrostang; 11-18-2012 at 04:17 PM.
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post #2 of 45 (permalink) Old 11-18-2012, 05:45 PM
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Have you considered the shelby drop mod?

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post #3 of 45 (permalink) Old 11-18-2012, 06:30 PM
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I did body work for years. Most times if you can't get it aligned there's something bent. I didn't realize how big of an unnoticed issue this was with old stang's till I started hanging out here. It appears as these cars age the weight of the engine starts to push the frame rails wider. Some times when this happens the top of the shock towers get stucked inward. People seem to fix the shock tower issue with a mote carlo bar and not worry so much as to why it was so tight getting in. They assume because there's a singel brace under the engine everything is fine there. I read one thread where the person was redoing the frame rails and found the cross brace now didn't bolt up and thought they did something wrong. So start by measuring the distance accross the frame rails. They may be to far appart pushing your lower arms outward.
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post #4 of 45 (permalink) Old 11-18-2012, 11:48 PM
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Quote:
Originally Posted by dobrostang View Post
Redid my front end last winter and without any shims I am at 1 degree neg Camber and 1/2 degree pos Castor. If I add shims to increase castor the Camber goes positive. So, I have been considering moving the pivot point on my LCA inboard. According to my calculations .2 inches of movement on either end of the spindle equals 1 degree of camber. I have also heard that many in the vintage race circuit shorten their UCAs covertly to get better geometry which would also fix my issue. I would like to get to 2 degrees neg camber and 5 degrees pos castor. Not that I would use it all but would like to be able to get there. Probably will settle at 1 degree neg camber and 4 to 5 degrees pos castor for Autocross and occasional track days. THe car is driven on the street quite a bit.

Questions:

1) has anyone else done this calculation and do these numbers jive? e.g. for every .2 inches I move the LCA pivot inboard, I get one degree of neg camber which could be traded for castor.

2) has anyone shortened their UCA - What does that do for the front end geometry. Obvously I would get more negative camber as the suspension compresses. Are there any down sides? How much did you shorten it? I heard 1/2 inch.

I am also thinking that a shorter UCA will give me more tire to fender clearance which wouldn't hurt if I decide to go lower on my stance.

3) One last thing I heard recently is that people are repositioning their spring perch an inch outboard. Seems to me that would equate to increased spring rate and shock response. Why did you do it and were you happy with the result.

4) How much Castor can adjustable struts add? I have heard it's just for fine tuning or can you add several degrees?

A few things: I can't use adjustment kits for the LCA because I have a cross bar that picks up the pivot bolts on the LCA. I'm too cheap to buy after market tublar UCA/LCA peices and I Love to weld and am looking for a winter project.

Thanks,

M
I've got just a little experience with this stuff, so I'll take a crack at it.

1) Your numbers are pretty close, BTW. There is some benefit to moving the
LCA inner pivot further in. Usually this is accompanied with a longer lower arm.
You also mention at the bottom of your post that your lower arm pivot bolts
are picking up the #2 bolt-in crossmember, ala the Boss 302 Chassis Manual.
Gonna be tough to move your arms in.....
See #4 below for a good way around this.

2) "I have also heard that many in the vintage race circuit shorten their UCAs
covertly to get better geometry"..... Really? Those cheaters! We used to do
those trick UCA's all the time under the guise of "strengthening" them.
I can neither confirm nor deny how much shorter but a shorter arm, lowered about
1 3/8" works awfully well. The car "rolls" negative. It generates a negative camber
curve in other words. Because at ride height this modified suspension is already
past the closest point of approach in its arc, tire to fender clearance is improved.

3) Ohhh, more clandestine stuff. When you move the spring perch location on the
upper arm, you fool with the motion ratio. This has a direct effect on the wheel
rate. So yes, there are some nice benefits to changing this. ANYTHING that
improves tire compliance with the road will be an improvement. A roller spring
perch you might also find to be a good upgrade. Making the spring more
effective is a good thing.

4) You might be able to squeeze 5 degrees pos caster with some of the adjustable
strut rods out there. I've got some massaged '67 units on my GT that'll do 4 degrees.
Because the tire gets closer to the front of the fender lip, you may have do a little
work up there as well.

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post #5 of 45 (permalink) Old 11-18-2012, 11:50 PM
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Hmmm....I don't have much to add here except point out I run -2.5 (for sure) and +3.5 castor (pretty sure but I honestly never paid much attention...was most concerned about getting those 245 40 17 on the front) on my 65 with stock location moog lowers, shelby drop, and opentracker's relocated ball joint uppers that I could run the 1.75 drop with but didn't and heim joint struts.

Nick
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Last edited by dodgestang; 11-18-2012 at 11:53 PM.
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post #6 of 45 (permalink) Old 11-18-2012, 11:58 PM
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If you shorten the uppers "slightly" you don't have to drop the arms so far and
don't have to run anywhere near as much static negative camber.

Personally, I hate those factory upper arms but that's just me. Seen too
many failed units over the last 30 years.

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Attached Images
File Type: jpg broken upper arm.jpg (96.2 KB, 141 views)

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post #7 of 45 (permalink) Old 11-19-2012, 12:33 PM
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So dropping the UCA 1 3/8" (rather than the shelby drop 1/2") will improve it pretty dramatically? Do you do this manually or is there a kit to drop the UCA that much?

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post #8 of 45 (permalink) Old 11-19-2012, 04:14 PM
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The original numbers Klaus Arning came up with actually had the
number at slightly over 1" down.
However, what has come to be called the Shelby drop has always
had you drilling 1" down because anything over 1" really works the
ball joint in a stock upper arm. It will break. It's just a matter of
when it will break.

At the very least you need to attend to the BJ angle if you want
to drop below 1"..... and you really should shorten the arm while you're
messing with the BJ angle......you know, as long as you're in there anyhow.
And strengthen the arm too. They're pretty sad for actual performance
use. (yeah I know CS raced on them- what else is new?)

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post #9 of 45 (permalink) Old 11-19-2012, 07:51 PM Thread Starter
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Quote:
Originally Posted by GT289 View Post
I've got just a little experience with this stuff, so I'll take a crack at it.

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1991-1995
I was hoping you would! Thanks for the responses.

To fill in the blanks, I have montecarlo and export braces (20 years) plus the custom lower brace. Roller perches, big block springs (0.685), roller (like a Heim joint) conversion on LCA. Arning drop 1", red konis. 3 kids, other hobbies and SHMBO of course. So I just don't have the $$$ for tubular A arms. If I did have the money, I'd probably replace the rear springs first anyway.

Since I did the conversion on the LCA last winter, It would be easy to lengthen the LCA also.

I have heard that you need a negative wedge kit if you go more than 1" lower on the drop. Thanks for the photo of the broken UCA, now I know where to beef it up.

Now that I think about it, changing the angle of the BJ would be easy while I'm shortening the A arm...

Thanks,

M

Last edited by dobrostang; 11-19-2012 at 08:05 PM.
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post #10 of 45 (permalink) Old 11-19-2012, 10:03 PM
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So, with a 69, I would just need to measure an inch below the stock UCA mounting point, double, triple check the measurments..... and I should be good?

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post #11 of 45 (permalink) Old 11-19-2012, 10:35 PM
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can't believe nobody else caught this...
To INCRESE NEGITIVE CAMBER you move the LOWER control arm mount OUTBOARD.

I just noticed the OP third sentence above,if you move the inner pivot inboard you will increase POSITIVE camber.

Last edited by cyclone03; 11-19-2012 at 11:57 PM.
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post #12 of 45 (permalink) Old 11-19-2012, 10:45 PM
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That's a method as well!

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post #13 of 45 (permalink) Old 11-20-2012, 02:43 AM
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Quote:
Originally Posted by dobrostang View Post
I was hoping you would! Thanks for the responses.

I have heard that you need a negative wedge kit if you go more than 1" lower on the drop. Thanks for the photo of the broken UCA, now I know where to beef it up.

Now that I think about it, changing the angle of the BJ would be easy while I'm shortening the A arm...

Thanks,

M
Definitely don't try that negative wedge nonsense. It's a solution looking for a problem.
Mod the end of the arm itself instead.
AFA where the arms fail, the 4 bolt style is notorious at the BJ end, but the pivot shaft
end is a joke too. Seen a few where that screw-in gizmo (threaded cups) ripped
right out of the arm. Last one I saw like that was on a '67 390 coupe with really
low miles.....guy was 2 block from getting onto the freeway when it failed.

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post #14 of 45 (permalink) Old 11-20-2012, 02:48 AM
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Quote:
Originally Posted by cyclone03 View Post
can't believe nobody else caught this...
To INCRESE NEGITIVE CAMBER you move the LOWER control arm mount OUTBOARD.

I just noticed the OP third sentence above,if you move the inner pivot inboard you will increase POSITIVE camber.
Wasn't paying much attention. Original Poster can't move the lower arm in or out,
anyhow. He's locked it into place by tying it to the #2 bolt-in crossmember under
the engine. (Good mod too. That stock pickup point moves around a little bit, as hard
as that is to believe.... put a camera under there once on a track car years ago)

ex-Global West GM
1991-1995

As the drill sergeant said, "I taught you everything you know. I didn't teach you everything I know."

"Human beings, who are almost unique in having the ability to learn from the experience of others, are also remarkable for their apparent disinclination to do so."
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post #15 of 45 (permalink) Old 11-20-2012, 04:54 PM
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Quote:
Originally Posted by cyclone03 View Post
can't believe nobody else caught this...
To INCRESE NEGITIVE CAMBER you move the LOWER control arm mount OUTBOARD.

I just noticed the OP third sentence above,if you move the inner pivot inboard you will increase POSITIVE camber.
Not if the arm is longer. I thought the OP was referring to making the lower arm longer by moving the inboard mount further inboard. This changes the arc the lower arm follows robbing less negative camber gain as jounce progresses.

I dabbled with making my own front coilover suspension. I played with different scenarios. The scenario more or less mentioned in the original post seems to be a good way to go using stock parts. I have not put any of this to the ground so I cannot claim any results.

beyond the mods the OP did
aftermarket sway
stiffer springs
roller perch
bearing at the LCA inner pivot

My plans are to shorten the upper arm to 9.25" in length, stock is 9.625". I am using the Opentracker UCA roller kit to do this. Order extra sets of tubing to have just in case. Drop the arm either 1.25" or 1.125". Cut the ball joint end of the UCA to allow the angle to change, weld and brace it. Move the perch out up to 1". I have made my LCA inner mount adjustable height and length wise to make adjustments if I don't like it.

These changes, with the exception of the adjustable LCA inner, are pretty close to an aftermarket suspension kit. You can add a bit of caster when you weld in the UCA roller kit. I like these changes because you are out a couple of control arms if it doesn't work.

You need to be careful going to extremes on the side view swing arm, especially at full compression. This is most affected by lowering the UCA a bunch. It changes the rate of camber too quickly to adjust driving to.

Sense is not as common as you think.
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