SPL adjustable LCA and tension rod install

[Biggsy]

Another reason to learn how to do your own alignments at home. One of the most satisfying things I’ve ever learned to do.

It’s on my to do list for 2024. But with the cost of some of the equipment, I could buy 3-4 alignments. At the end of the day I need to stop being lazy lol.

if I had $6k fall in my lap I would take the easy way and get the professional hub stands with laser precision and leveling plates lol.

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[JAJ]

I've seen those DYI kits that they sell but I don't have a lift so I have no way to get under the car with all the wheels loaded. Conceivably I could raise it with my quick jack and then lower onto some race ramp blocks but seems like the precision would probably not be there.

Here's an idea of how you could do your own:

https://www.mustang6g.com/forums/threads/track-alignment-setting.162531/post-3484610

As @galaxy said, once you've done your own, going to a shop loses a lot of its luster.

The setup in @Tomster's post probably costs less than an shop alignment and it's shockingly precise.

 

[WItoTX]

Agree with the others, if you have the time and interest, diy is the way to go. I use stacks of wood cribs, and put a plastic bag between the wood and tires. Then disconnect the battery and bounce the suspension, and measure from there, using fishing line, a magnetic level, and a metal ruler.

The first time sucks, but it gets much faster after that.

Good luck with the alignment shop, I hope everything goes smoothly!

 

[matthewr87]

Yeah I'll see what happens at this place. For those of you that do your own alignments which way do you turn the steering rod to increase toe out?

 

[JAJ]

Yeah I'll see what happens at this place. For those of you that do your own alignments which way do you turn the steering rod to increase toe out?

The steering tie rod is in front of the center of the axle, so you want to turn it so the front of the tire is pushed out to reduce toe-in/increase toe-out.

Looking toward the inside face of the wheel from under the car (on either side), looking along the tie rod toward the rod-end, hold the rod end and turn the tie-rod anti-clockwise to push the rod-end away from you.

Remember to take the spring clip off the rubber boot at the steering module end of the tie rod before you turn it, and put it back when you're done.

 

[matthewr87]

The steering tie rod is in front of the center of the axle, so you want to turn it so the front of the tire is pushed out to reduce toe-in/increase toe-out.

Looking toward the inside face of the wheel from under the car (on either side), looking along the tie rod toward the rod-end, hold the rod end and turn the tie-rod anti-clockwise to push the rod-end away from you.

Remember to take the spring clip off the rubber boot at the steering module end of the tie rod before you turn it, and put it back when you're done.

Okay thank you. Another question for the alignment experts here. I swapped out the LCAs and tension arms for the SPL variant. I tried to match the lengths of each to the OEM measurements. I did not touch the toe at all. However, after install I have a crazy amount of toe in. What could be causing this? I need to rectify before I can drive to an alignment shop because none in the immediate area want to touch my car. Thank you in advance.

 

[galaxy]

My guess would be you didn’t get lengths and such as close as you think you did. I’m not super familiar with the adjustments on those arms, but very very tiny adjustments make significant changes in toe. And with those arms, that’s a lot of moving parts. Things are going to be off.

 

[Biggsy]

others can correct me if I’m wrong but I’m sure you changed the roll center which leads to a change in camber/toe

 

[matthewr87]

others can correct me if I’m wrong but I’m sure you changed the roll center which leads to a change in camber/toe

So in theory I didn't use any of the spacers between the bearing and the knuckle which, according to the SPL instructions, is supposed to keep the roll center the same as OEM. But it is definitely possible that is just an approximation and that the roll center did change.

 

[Biggsy]

So in theory I didn't use any of the spacers between the bearing and the knuckle which, according to the SPL instructions, is supposed to keep the roll center the same as OEM. But it is definitely possible that is just an approximation and that the roll center did change.

Then I’m stumped too lol. Questions that need answers

 

[matthewr87]

Then I’m stumped too lol. Questions that need answers

I think the most likely explanation is that my measurements are off between the OEM and the SPL arms. But what I can't understand is what combination of changes in LCA and tension arm length would lead to an increased toe in.

Btw Precision Auto refused to work on my car and all the other places in the area have drive on lifts that my car probably won't clear. So I need to get the car into driveable shape myself so that I can make it to GR.

 

[Biggsy]

I think the most likely explanation is that my measurements are off between the OEM and the SPL arms. But what I can't understand is what combination of changes in LCA and tension arm length would lead to an increased toe in.

Btw Precision Auto refused to work on my car and all the other places in the area have drive on lifts that my car probably won't clear. So I need to get the car into driveable shape myself so that I can make it to GR.

wow. I didn’t think places would refuse like that especially when it comes to alignment. I guess the quick thing to do is get a set or make a set of toe plates at a minimum to get it to GR. Bring all instructions with you. They will definitely listen to you and will work with you to get it aligned how you want.

 

[JAJ]

Okay thank you. Another question for the alignment experts here. I swapped out the LCAs and tension arms for the SPL variant. I tried to match the lengths of each to the OEM measurements. I did not touch the toe at all. However, after install I have a crazy amount of toe in. What could be causing this? I need to rectify before I can drive to an alignment shop because none in the immediate area want to touch my car. Thank you in advance.

It sounds like your matching the arm lengths was off by a very small amount, but in the confined quarters where the geometry it set, an error of 1 mm can change things a lot.

At this point, have you measured the toe-in? It's not hard - requires a measuring tape, a couple of jack stands, some string and a small steel rule that measures in mm (mm are more convenient than inches).

Step 1: Park the car in a level area and make sure the steering wheel is centered.

Step 2: Place jack stands ahead of the car at the left side, one about a foot ahead of the front bumper, one about a foot behind the rear bumper, far enough from the side of the car so you have a clear line of sight from one to the other. Set the tops of the stands roughly at the height of the wheel centers.

Step 3: Tie a piece of string to the top of the front stand and run it to the top of the rear stand. Put a weight on it and let it hang so it's straight and moderately tight - a straight line.

Step 4: Measure out to the string from the centerline of the front bumper - maybe on the license plate - a piece of tape with a pencil mark at the car's center is handy.

Step 5: Measure again at the rear. Move the rear stand until the distance to the string from the center of the rear bumper is the same as the distance from the center of the front bumper. Check both front and rear to make sure they're identical - changing one can affect the other as you adjust.

Step 6: Once the string is straight and parallel to the centerline of the car, measure in from the string to the forward edge of the front wheel and then measure in again at the rear edge of the front wheel. The difference between the two measures is the "toe" and it should be zero (for now). If the front of the rim is further from the string than the rear, then you have toe-in.

Now do it again on the right side.

I'm saying all this because knowing what the toe is might help us figure out how to get it fixed enough that you can make it to the shop you're going to take it to. The measuring method above isn't perfect, but it'll identify how bad the situation is.

 

[matthewr87]

It sounds like your matching the arm lengths was off by a very small amount, but in the confined quarters where the geometry it set, an error of 1 mm can change things a lot.

At this point, have you measured the toe-in? It's not hard - requires a measuring tape, a couple of jack stands, some string and a small steel rule that measures in mm (mm are more convenient than inches).

Step 1: Park the car in a level area and make sure the steering wheel is centered.

Step 2: Place jack stands ahead of the car at the left side, one about a foot ahead of the front bumper, one about a foot behind the rear bumper, far enough from the side of the car so you have a clear line of sight from one to the other. Set the tops of the stands roughly at the height of the wheel centers.

Step 3: Tie a piece of string to the top of the front stand and run it to the top of the rear stand. Put a weight on it and let it hang so it's straight and moderately tight - a straight line.

Step 4: Measure out to the string from the centerline of the front bumper - maybe on the license plate - a piece of tape with a pencil mark at the car's center is handy.

Step 5: Measure again at the rear. Move the rear stand until the distance to the string from the center of the rear bumper is the same as the distance from the center of the front bumper. Check both front and rear to make sure they're identical - changing one can affect the other as you adjust.

Step 6: Once the string is straight and parallel to the centerline of the car, measure in from the string to the forward edge of the front wheel and then measure in again at the rear edge of the front wheel. The difference between the two measures is the "toe" and it should be zero (for now). If the front of the rim is further from the string than the rear, then you have toe-in.

Now do it again on the right side.

I'm saying all this because knowing what the toe is might help us figure out how to get it fixed enough that you can make it to the shop you're going to take it to. The measuring method above isn't perfect, but it'll identify how bad the situation is.

Okay thank you. I'll do this tomorrow and report back. But I have a feeling the toe in is going to be pretty bad. I can see it just by eye.

I'm wondering if making the LCAs longer than stock would pivot the back of the knuckle outward (because of where the LCA attaches relative to the pivot point) and cause the increased toe in. Perhaps that is the simple explanation and I just need to wind out the steering tie rod a bit (or decrease the length of the LCA).

 

[JAJ]

Okay thank you. I'll do this tomorrow and report back. But I have a feeling the toe in is going to be pretty bad. I can see it just by eye.

I'm wondering if making the LCAs longer than stock would pivot the back of the knuckle outward (because of where the LCA attaches relative to the pivot point) and cause the increased toe in. Perhaps that is the simple explanation and I just need to wind out the steering tie rod a bit (or decrease the length of the LCA).

Yes, if the LCA connects to the knuckle behind the centerline of the strut, then it'll rotate the knuckle toward toe-in if it's too long.

I'd be inclined to shorten the LCA a bit to straighten out the wheel. The steering tie rod is at the length that works for the OEM parts, so leave it alone and fix the toe problem by adjusting the new parts.

Once you know how far you have to re-angle the wheel, you can probably get fairly close by putting the car in the air and doing some measurements from a marked point under the car out to the brake rotor or the wheel edges as you adjust the arm. It only has to be good enough to get the car to the shop.

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