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Ok, so the strut rod ties the lower control arm to the front chassis. I get that.
And adjusting the length of the strut rod changes the vertical line through the
upper and lower ball joints of the spindle. But how does this help stabilize the
geometry under hard braking? It seems to me that the momentum of the
chassis would tend to push the upper control arm forward. Why would
the lower need stabilization?

This may tie in to a behavior I noticed before I tore down the front end. Under
braking, like on the highway before taking an offramp, the front end would
wander from side to side, as if the steering suddenly became loose (looser).
Is it possible that the old worn bushings on the strut rods were having an
effect on the handling under braking? (More likely it was the combination of
old worn bushings throughout the front end).




Rich
'67 C-code 'vert (Dees67)
'69 GT FB (project car)
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Just look at the play in the spindle movement when you have the strut rod out(as opposed to a one installed with new bushings), there is nothing to keep lower control arm stiff.Kind of like that multiplied effect, a little bit of play on one end can lead to alot of movement on the other.Historical trivia: If you ever watch the Bullitt movie, when McQueen stops after the gas station explosion by sliding sideways over a curb, you will really see a messed up wheel,control arm and strut rod.

1967 S code GT Deluxe Coupe 65B
1966 Convertible 76B 289 4 speed
1964 Fairlane 500 2DR HT-the new project
1986 Jeep Cherokee 4X4 the "beater"
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I replied to this post under your "bent" thread.

Black primer 66 coupe, bench seat, 68 302-2V, C-4, 3.55 TSD
879 posts as "66 bench-coupe" on old VMF
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Hi, I chased a similar problem in my 67 coupe the car was hit pretty hard and when they put it back together they used non 67 parts well that threw everything off the car wandered like you described but it did it on every bump. after I rebuilt the frontend and had it aligned twice it still did itthe front end shops were trying to tell me the frame was bent but I had put it on a frame rack before I bought it and it was within 1/16" I finally found a old snapon frontend gauge in a yard sale and figured I had nothing to lose by adjusting it well when I pulled the struts forward to where the specs called for the thing drove like new. they never bothered to adjust this at the two shops the car was in. if the lower control arm is behind the upper it will not drive right when you turn the wheel it actually moves the bottom of the tire so it pulls that way.
John
 

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I fthe lower control arm is behind then that is negative caster, in front is positive. Negative caster is better for handling at higher speeds and positive caster is better for handling at slower speeds. Most cars for the street come with some positive caster.

Black primer 66 coupe, bench seat, 68 302-2V, C-4, 3.55 TSD
879 posts as "66 bench-coupe" on old VMF
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Upper A arm limits the for and aft movement of the balljoint by anchoring it with the two UCA bushings so it can only swing up or down. The LCA only has one bushing letting it move up, down, fore and aft. By triangulating it with the strut rod limits fore and aft movements.

Rubber bushing compress under braking and cornering and make the car feel loose. Harder bushings or spherical rod end will "stabilize" suspension movements .

It's positive caster that make the car more stable at high speed but feel heavy a low speeds. Less caster makes steering eaiser but less stable at speeds.

The adjustment of the strut rods shouldn't have anything to do with braking, it's the soft bushing that deflect under braking that have an ill effect on handeling.

67 coupe 289 auto
 

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You're right. I had it backwards. Sorry for any confusion.

Black primer 66 coupe, bench seat, 68 302-2V, C-4, 3.55 TSD
879 posts as "66 bench-coupe" on old VMF
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Is heim-joint same as uniball used in British car talk?

Door handle first when cornering
 
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