LCA Drop / Anti-Roll Ball Joints - Ford Mustang Forums : Corral.net Mustang Forum
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post #1 of 12 Old 09-05-2019, 05:40 PM Thread Starter
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LCA Drop / Anti-Roll Ball Joints

I am going to need a set of of these to help correct the angle of my lower control arms on my 2003 GT with MM coilovers and MM LCA's.

I have found three brands and they all seem to only provide 1/2" of drop:
Steeda X2 P/N 555-8101
SR Performance (American Muscle) P/N 398125
Proforged P/N 101-10432

FWIW, the Steeda X2 are $40-$45 more than the other two.

Does anyone know of any others that offer more than 1/2" of improvement?

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post #2 of 12 Old 09-06-2019, 12:00 AM
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X2 ball joints are 0.70" taller than stock SN95 ball joints.

It is unlikely that you will find a taller ball joint out there than that. The reason is that the chances of the ball joint stud increase greatly, the taller it is. The greater the distance from the spindle boss down to the ball joint cup, the less side load is required to break the stud.

Early S197 extended length ball joint studs break fairly easily on track. In 2011, Ford changed to a larger ball joint stud to fix this problem even on the stock nonextended length stud.

Remember that you must install a bumpsteer kit and bumpsteer the car, when using extended length ball joints. If you don't, the car will handle much worse than with stock studs.


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post #3 of 12 Old 09-06-2019, 12:31 AM Thread Starter
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Makes sense.

I have the bumpsteer tie rod ends from MM installed already. I installed the MM LCA's (forward offset) without changing out the supplied standard ball joints. I know that I could solve this the "right" way with a MM k-member. Two probems for me with that solution: 1) cost! with the required add-ons, this is over $700. 2) I already have the forward offset LCA's. With the MM K-member, the forward location gets moved forward 1.5". Looking at my positioning compared to the images on the MM website with my current ride height of 26.5", I think the tires would be pretty close to the front side of the wheel arch? https://www.maximummotorsports.com/M...tang-P393.aspx I am running a P255/40ZR-17 now. I'll be going to 18's and a little taller tire. Will I have clearance issues?
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post #4 of 12 Old 09-06-2019, 02:46 AM
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You would have to trim part of the bumper cover inside the wheel well and cut of the lump in the plastic fender liner on the driver's side, but other than that, there would be no clearance issues.

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post #5 of 12 Old 09-06-2019, 12:50 PM Thread Starter
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Hmmm. OK.

With my current set up, I already have 5.6* of caster. That is with the MM C/C plates pulled back as far as possible (to minimum). What would the caster look like with the MM K and my forward offset LCA's? How much caster is too much? I don't street drive this car much but I do drive it to and from the track.
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post #6 of 12 Old 09-06-2019, 01:08 PM
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With the MM k-member and MM forward offset FCAs, you would then have a minimum caster of 7.4 degrees. The c/c plates can be reconfigured to reduce this back to 5.6 degrees. How to do this is not covered in the installation instructions. Optimum caster is between 6 and 6.5 degrees for most performance use with these spindles.

You would have to convert to a bolt through style bumpsteer kit with the MMTR-5.

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post #7 of 12 Old 09-06-2019, 01:28 PM Thread Starter
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Why the need to convert to bolt through?
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post #8 of 12 Old 09-06-2019, 01:48 PM
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Read the article below.

https://www.maximummotorsports.com/G...r-Problem.aspx

If you are changing the height of one end of the FCA by 0.75", then you need to also change the height of the inner or outer tie rod by 0.75" to keep the FCA and tie rod parallel to each other. This is the safe adjustment limit of tapered stud style bumpsteer kit.

https://www.maximummotorsports.com/A...tCenter_LG.jpg

The MM k-member changes the height of the inner pivots of the FCA by 1" or 2", this therefore requires a bolt through bumpsteer kit as these have a greater range of safe adjustment.

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post #9 of 12 Old 09-06-2019, 02:15 PM Thread Starter
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I had read that article before. It is a good call back for refreshing my understanding of bumpsteer. I already own a MM bumpsteer gauge so I am able to make the measurements.

Thank you for going down this path with me. Lots to consider. The costs keep adding up to make the k-member work with the forward offset LCA's.

I have ordered a set of X2's and I'll see how much improvement I can get with those and raising the ride height some.

If this doesn't end up satisfying me, I think the best cost option is to go k-member and scrap the forward offset LCA's for some standard offset.
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post #10 of 12 Old 09-06-2019, 02:35 PM Thread Starter
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Geting a little off track from my original post...

Having quickly skimmed through that article again, I am left wondering: Is it a fair statement to say that the angle of the LCA is not as important as long as the bumpsteer is corrected?

From the article:
"Now, you won't find any suspension design book claiming the tie-rod must be parallel to the ground to achieve minimum bumpsteer. Looking at only one side of the suspension, at stock ride height the tie-rod usually appears parallel to the ground because the lower front control arm is parallel to the ground. That's usually a design goal, as having the lower front control arm parallel to the ground minimizes sideways tire scrub with suspension movement. To meet various other design goals, the control arm may appear to be parallel to the ground, but with careful measurement it's often very slightly off."

I not super familiar with "tire scrub" but isn't some of that effect controlled or maybe even irrelevant if running lots of camber?

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post #11 of 12 Old 09-06-2019, 05:39 PM
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There is a particular order that parameters should be adjusted when designing a suspension.

Bumpsteer optimization is one of the last.

Assuming that the FCAs are parallel to the ground at ride height, on a Fox/SN95 Mustang that will mean that the FCA and tie rod are nearly parallel to each other. You can see this from the requirements outlined in the bumpsteer sketch from my previous post. If a Mustang spindle had the tie rod mounted 6" higher on it, than it does, then the tie rod and FCA would not be nearly parallel to have minimum bumpsteer. The fact that they are so close to the same height, is why they are nearly parallel to each other.

Scrub in this case, is when the tire moves in a direction at 90 degrees to its normal axis of rotation. If the FCA is 14" long and is parallel to the ground at ride height, and the suspension goes into 10" of bump travel, then the tire is going to scrub inwards 4". (14"-(14^2-10^2)^0.5)). The same happens if the suspension moves into 4" of droop travel. I've used a huge amount of travel for the length of the FCA to illustrate the numbers easily. The point is that because the FCA has a finite length, when the suspension moves up and down, the tire has to move sideways. The longer the FCA is or the less the vertical suspension movement, the less distance the tire will scrub side to side.

Why is this a problem? Because in reality, the tire does not move side to side when the suspension scrubs. The tire is in contact with the ground through the rubber. What actually happens is that the sprung mass of the car is being accelerated side to side. This is bad because this uses up cornering grip that the tire has. When the car hits a bump in the corner, the sprung mass has to move from side to side. This causes the front tire to start sliding earlier. Once the front tire starts sliding, it does not stop. Because dynamic cf is less than static cf.

The result of this is that when the suspension is adjusted so that the FCA is parallel to the ground at ride height, the tire will have the minimum possible scrubbing from side to side, for that length FCA. If you look at an offroad race vehicle, they go to great lengths to make the control arms as long as possible to avoid scrubbing. Frequently the FCA pivot axis nearly touch each other in the middle of the vehicle.

https://www.speednik.com/wp-content/...-in-action.jpg

Note that the above truck appears to have optimal bumpsteer geometry. The tie rods have roughly the same angle between the upper and lower front control arms. In other works, if you extend a line through the UCA, tie rod and LCA, they will all meet at one point on the other side of the truck, the IC.
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post #12 of 12 Old 09-06-2019, 06:35 PM Thread Starter
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Thank you. I have been doing a lot of reading and looking at a lot YouTube vids on the various suspension set up elements today. It can get pretty complicated trying to digest it all at once. However, I am getting a lot better understanding of why the negative slope my control arms have as they sit now is bad and how important that angle needs to be in relationship to the center of gravity (roll center) and the instant center of the car.

Thanks for all of your insight. Let me work on the immediate issue of getting the control arms at least as close to level with the immediate cost effective solution available. Hopefully, with the X2's I wont have to jack the car up like a 4x4. I have spent a load of money (lots of it with MM) trying to get this set up right. I hate going backward and spending even more but it is what it is...
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