Cool suspension upgrade-New product coming. What ya think? - Page 3 - Vintage Mustang Forums

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post #31 of 66 (permalink) Old 09-07-2016, 09:15 PM
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Tracy, no disrespect but the issue I see has really nothing to do with how much the rods ends can work at. It has to do with the fixed mounting points. Off hand I do not know the actual length of the control arm from the rod end to ball joint or the other two for that matter. But what we do know is that the length of the control arm is fixed. The length between the LCA mount and the strut rod mount of the frame is fixed. We also know the angle is fixed where the strut rod is welded to the control arm. Lets call call the point where the control arm bolts to the frame A. We'll call the ball joint B and the strut rod frame location C. So that makes the lower control arm AB, the lower control arm to the strut rod frame mount AC and the adjustable strut BC, So with the fixed know points plug in a constant for side AB and AC and alter the length of the strut BC. See how the angle at B changes as you adjust the length of the strut BC? That's not the ball joint, that's the welded connection. Or you could put in the fixed angle in and omit the length of one of the sides and see how it effects the AC when you alter the length of BC That's what I see.

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Tom

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Last edited by Huskinhano; 09-07-2016 at 09:26 PM.
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post #32 of 66 (permalink) Old 09-07-2016, 09:50 PM
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Originally Posted by Huskinhano View Post
Tracy, no disrespect but the issue I see has really nothing to do with how much the rods ends can work at. It has to do with the fixed mounting points. Off hand I do not know the actual length of the control arm from the rod end to ball joint or the other two for that matter. But what we do know is that the length of the control arm is fixed. The length between the LCA mount and the strut rod mount of the frame is fixed. We also know the angle is fixed where the strut rod is welded to the control arm. Lets call call the point where the control arm bolts to the frame A. We'll call the ball joint B and the strut rod frame location C. So that makes the lower control arm AB, the lower control arm to the strut rod frame mount AC and the adjustable strut BC, So with the fixed know points plug in a constant for side AB and AC and alter the length of the strut BC. See how the angle at B changes as you adjust the length of the strut BC? That's not the ball joint, that's the welded connection. That's what I see.

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No angles EVER change! The shape of the triangle formed by drawing straight lines between the centerlines of the mounting points and the ball joint is static. It doesn't change....unless you smash into a brick wall at speed (or adjust the length of the strut rod). What DOES change is the relationship between the frame and the centerlines of the mounting points on the control arm and the spindle, in a manner that can be geometrically calculated just like the motion of a spindle in a short/long arm set-up, and that's what the rod ends and the ball stud on the ball joint accommodate.

Last edited by Woodchuck; 09-07-2016 at 09:53 PM.
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post #33 of 66 (permalink) Old 09-07-2016, 10:56 PM
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Originally Posted by Huskinhano View Post
Tracy, no disrespect but the issue I see has really nothing to do with how much the rods ends can work at. It has to do with the fixed mounting points. Off hand I do not know the actual length of the control arm from the rod end to ball joint or the other two for that matter. But what we do know is that the length of the control arm is fixed. The length between the LCA mount and the strut rod mount of the frame is fixed. We also know the angle is fixed where the strut rod is welded to the control arm. Lets call call the point where the control arm bolts to the frame A. We'll call the ball joint B and the strut rod frame location C. So that makes the lower control arm AB, the lower control arm to the strut rod frame mount AC and the adjustable strut BC, So with the fixed know points plug in a constant for side AB and AC and alter the length of the strut BC. See how the angle at B changes as you adjust the length of the strut BC? That's not the ball joint, that's the welded connection. Or you could put in the fixed angle in and omit the length of one of the sides and see how it effects the AC when you alter the length of BC That's what I see.

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How is the welding of the LCA mount and the strut rod mount of the frame being bolted as Street or Track and others do it different?
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post #34 of 66 (permalink) Old 09-07-2016, 11:04 PM
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How is the welding of the LCA mount and the strut rod mount of the frame being bolted as Street or Track and others do it different?
Read post #27

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post #35 of 66 (permalink) Old 09-08-2016, 11:28 AM
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No angles EVER change!
Sure they do. Measure the 3 angles. Now, lengthen or shorten the strut rod tube. What are the angles now? They've changed. Not an issue IF there was a pivot at the strut rod/LCA intersection like the slotted holes in our strut rod plate but there isn't. This will cause bind.
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post #36 of 66 (permalink) Old 09-08-2016, 12:19 PM
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I have early TCP strut rods on my '66 Shelby which I drag race. They have a similar "yoke" style front attachment. The amount of front end travel my car is more than the rod end /yoke can handle and it is constantly loosening the jam nut on the rod end. I am thinking about "clocking" the yokes to gain some clearance at maximum front end lift or limiting upward travel to stop this from happening.

I also see GT289's concern. "IF" the strut rod length is adjusted , there would be a slight angle change at the fixed point where the tube attached to the control arm.


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post #37 of 66 (permalink) Old 09-08-2016, 04:56 PM
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Sure they do. Measure the 3 angles. Now, lengthen or shorten the strut rod tube. What are the angles now? They've changed. Not an issue IF there was a pivot at the strut rod/LCA intersection like the slotted holes in our strut rod plate but there isn't. This will cause bind.
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post #38 of 66 (permalink) Old 09-08-2016, 08:06 PM
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Originally Posted by Huskinhano View Post
Read post #27
Got it. Just went out to look at my SoT strut rods and note the control arm end is slotted.
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post #39 of 66 (permalink) Old 09-08-2016, 09:24 PM
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I've been thinking about what you guys said about binding. Last night I sat under the car looking at for a while. I'm sitting in my office at work today and I had a visual epiphany. I think I see it now. Up to this point probably have not had to adjust it enough to have it become an issue. I'll have to get under the car this weekend and shorten and lengthen the strut rod and watch what happens.
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post #40 of 66 (permalink) Old 09-08-2016, 10:01 PM
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Originally Posted by Shaun View Post
Sure they do. Measure the 3 angles. Now, lengthen or shorten the strut rod tube. What are the angles now? They've changed. Not an issue IF there was a pivot at the strut rod/LCA intersection like the slotted holes in our strut rod plate but there isn't. This will cause bind.
There's a few factors in play here.

First, using the "triangle example", you have to use the following points to establish the triangle...
-a. The lower ball joint.
-b. The OUTER race of the control arm spherical bearing.
-c. The OUTER race of the strut rod spherical bearing.

The angles formed at "b" and "c" ONLY change when the strut rod is moved to adjust caster. In use its length is fixed and the angles remain static.

During compression and extension of the suspension, as the lower control arm swings up and down, the above triangle is static. The angles don't change. What DOES change is the angle of offset between the inner and outer races of the spherical bearings.

Since the leg formed by the strut rod to ball joint is considerably longer than the leg formed by the control arm mount to ball joint, the movement at the strut rod mount is much less than at the control arm mount.

As the control arm moves up or down from a neutral position, and since the strut rod leg length is fixed, the control arm, at the ball joint, is pulled forward and the spherical bearing at the control arm frame mount twists clockwise (down) and counter-clockwise (up). Because the forward leg, the strut rod, is mounted at a different angle than the control arm, the spherical bearing primarily rotates, but there is a slight twist as well, since this leg is longer than the other.

If there was a rod end at the point where the strut rod mounts to the control arm there would be no need for one at the strut rod frame mount, a simple clevis would be all that is needed.

What's the difference, and why do I like Tracy's solution better?

If the rod end was placed at the strut rod to control arm joint, rotational force (torque) placed on the spindle by the wheel, tire and brake assembly must primarily be handled by the upper control arm mounting point as there is more freedom for the control arm to move downward at the strut rod rod end and twist at the control arm frame mount rod end. Replacing THIS joint with a bushing would help, but now there would be binding when adjusting the length of the strut rod and as the strut rod to control arm joint swings through an invisible arc.

With the spherical bearing placed at the frame mount of the strut rod, the strut rod, itself, becomes a solid portion of the control arm assembly and the torsion force place on the spindle is spread all the way down the strut rod to the frame mount as well as by the upper control arm.
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post #41 of 66 (permalink) Old 09-08-2016, 11:38 PM
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I hear ya woodchuck. If someone thinks about it on the surface, the 67 and later Mustangs have adjustable strut rods and a fixed angle between the strut rod and the lower control arm, but that's about all I can say about that right now because I think a rat or squirrel just carried my keys away that I had stashed in the bushes while I was on a run and I can't find them anywhere!! ??
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post #42 of 66 (permalink) Old 09-08-2016, 11:42 PM
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I'll find out this weekend when I crawl under the car and start changing the length of the strut rod by a lot more to see what happens
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post #43 of 66 (permalink) Old 09-10-2016, 06:44 AM
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Originally Posted by Woodchuck View Post
There's a few factors in play here.

First, using the "triangle example", you have to use the following points to establish the triangle...
-a. The lower ball joint.
-b. The OUTER race of the control arm spherical bearing.
-c. The OUTER race of the strut rod spherical bearing.

The angles formed at "b" and "c" ONLY change when the strut rod is moved to adjust caster. In use its length is fixed and the angles remain static.

During compression and extension of the suspension, as the lower control arm swings up and down, the above triangle is static. The angles don't change. What DOES change is the angle of offset between the inner and outer races of the spherical bearings.

Since the leg formed by the strut rod to ball joint is considerably longer than the leg formed by the control arm mount to ball joint, the movement at the strut rod mount is much less than at the control arm mount.

As the control arm moves up or down from a neutral position, and since the strut rod leg length is fixed, the control arm, at the ball joint, is pulled forward and the spherical bearing at the control arm frame mount twists clockwise (down) and counter-clockwise (up). Because the forward leg, the strut rod, is mounted at a different angle than the control arm, the spherical bearing primarily rotates, but there is a slight twist as well, since this leg is longer than the other.

If there was a rod end at the point where the strut rod mounts to the control arm there would be no need for one at the strut rod frame mount, a simple clevis would be all that is needed.

What's the difference, and why do I like Tracy's solution better?

If the rod end was placed at the strut rod to control arm joint, rotational force (torque) placed on the spindle by the wheel, tire and brake assembly must primarily be handled by the upper control arm mounting point as there is more freedom for the control arm to move downward at the strut rod rod end and twist at the control arm frame mount rod end. Replacing THIS joint with a bushing would help, but now there would be binding when adjusting the length of the strut rod and as the strut rod to control arm joint swings through an invisible arc.

With the spherical bearing placed at the frame mount of the strut rod, the strut rod, itself, becomes a solid portion of the control arm assembly and the torsion force place on the spindle is spread all the way down the strut rod to the frame mount as well as by the upper control arm.
The angle at the ball joint changes also when you change the length of the strut rod, your 'a' angle. This is the only one of concern as the other points have bearings with misalignment built in. How much it changes and how much it binds the threads in the tube for how many degrees of caster, I dunno.
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post #44 of 66 (permalink) Old 09-10-2016, 10:57 AM
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I I think a rat or squirrel just carried my keys away that I had stashed in the bushes while I was on a run and I can't find them anywhere!! ??
I HATE when that happens!

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post #45 of 66 (permalink) Old 09-10-2016, 10:57 PM
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The angle at the ball joint changes also when you change the length of the strut rod, your 'a' angle. This is the only one of concern as the other points have bearings with misalignment built in. How much it changes and how much it binds the threads in the tube for how many degrees of caster, I dunno.
I think we're talking about different triangles.

If you draw a triangle that intersects the mounting bolts of the spherical bearings and the ball-stud of the ball joint then, yes, all 3 of those angles change. That's why there are spherical bearings in the 2 places where the control arm mounts to the frame.

There WOULD be an issue with binding if ordinary roller bearings or bushings installed because they would prevent the control arm, at the ball joint, from moving forward or backward. That's why the OEM control arm/strut rod binds when the strut rod is lengthed or shortened (pulling the control arm forward or back) or when the control arm moves up and down (binding at the strut rod to frame mount....the purpose for the rubber bushings). The installation of spherical bearings at the control arm mount and strut rod frame mount eliminates the binding.
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