There's been a lot of questions lately about LCA relocation brackets, so instead of answering the same question ten times I thought I'd explain everything carefully and then leave it here for all to read, and so I can link back to it when it comes up in the future. So here goes:
LCA Angle. There has been a lot of discussion about how adjustable LCAs let you change your pinion angle. But what about LCA relocation brackets? What do they do? LCA brackets attach to your rear axle, at the rearmost end of the LCA. They have multiple different bolt holes that you can choose between, allowing you to choose what the angle of your LCAs is.
The LCA angle is important becasue of what the LCAs do. The main job of the LCA is to transfer the force from your rear axle to the body of the car. They are literally what pushes your car forward when you accelerate. (The UCA contributes too, but to a lesser extent). The LCAs have a pivot at each end. This means that they cannot apply a torque or "twisting" force. They can only apply force in a straight line, along their length. You could not, for example, use an LCA as a wrench. But you could push against something with it.
When an 05+ Mustang rolls out the door at Ford's plant, the car is configured so the LCAs are basically paralell with the ground. They are horizontal. Thus, when the axle starts to push forward, the LCAs push along their length--horizontal--and they push the car straight forward. Makes sense, right?
So what happens if you change this angle? The most common case of this is if the car is lowered. When you lower the car you lower the car's body. But, the rear axle stays put. This has the effect of lowering the front of the LCA. Instead of being horizontal, the LCAs are now lower in the front and higher in the rear. When you accelerate, the LCAs push in a straight line, just as they aways do. But now the straight line is angled downwards at the body connection of the LCA. This means that MOST of the force from the wheels is still pointing forward, but a portion of it is actively pushing the body of the car down towards the ground. Newton taught us that every action has an equal an opposite reaction. And it's this reaction that's bad. The reaction to the body being pressed down, is that the rear axle is being pressed UP. This force actively lifts the tires off the pavement....as if you had a big helium balloon tied to your axle. The harder you accelerate, the more your axle gets lifted up...and that costs you traction. A car that is lowered without LCA relocation brackets has LESS traction under acceleration than a stock-height car becasue of this! The angled LCA also causes a rougher ride.
How can we fix that? LCA relocation brackets let you change the position of the rearmost end of the LCA. By switching them to a lower mounting postion, we can restore the OEM horizontal configuration on a lowered car. That means you can have your car lowered, but without suffering the ill effects I just described.
But we can also change things to our advantage. If we lower the rear end of the LCA even more, so now it's lower in the rear than at the front, we get a similar situaton to what I described above...but backwards. Now, the force from the rear axle is pushing up on the body. The reaction force pushes DOWN on the axle, planting it to the pavement. In this case the harder you accelerate, the more the tires are pressed onto the road...providing more traction. This is excellent for drag racing, and this kind of adjustment is key on all successful drag race vehicles. This is why all serious drag race cars run a multi-link rear suspension or ladder bars (if the rules allow it), becasue it enables better traction at launch.
Thus, using LCA relocation brackets lets you correct your LCA angle if you lower the car. They also give you the option of running an even more agressive setting (lowered or not) which will enhance your traction at launch.
Note that running the LCA at an angle (any angle, good or bad) will result in slightly ride harshness on rough roads.
CHURCHHHH!!!!! Preach on Rev CrazyAl. Maybe if a mod drops in they could make this a stick for the handling section.
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Black 06 GT 5-Speed premium IUP JLT CAI/EVO tune, borla,FRPP 4.10s, Trutrac, Steeda, Eibach, Tokico, CHE, Centerforce, Findaza, Spydershaft, two bad feet in the cockpit, to be continued...
Posts: 787
Joined: 4/6/2005 From: LI, NY Status: offline
Awesome write up CrazyAl, as usual your willingness to share your suspension knowledge benefits us all.
I hope you don't mind, I compiled the 2 posts you wrote about adjusting Pinion angles and this one on LCA relocation brackets and combined then into a single article and posted it on my web site listing you as the author. Here is the link to it: http://www.cherod.com/mustang/HowTo/LCA%20_adj.htm
If you don't mind, I'll try to redraw the diagrams using an illustration tool and repost the article. If you have other information you'd like to share, I'd be glad to help you write it up, illustrate it and post it on the website.
Thanks again for sharing your knowledge and experience.
..and you are welcome to post that information on your website. And please do "fix" the drawings. Those are my lazy beer-influenced sketches, so there is plenty of room for improvement!
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Black 2006 GT Coupe Dynatech LT headers & X; Borla catback C&L CAI; 93 oct tune Full BMR, Spohn & Steeda suspension D-Specs; Alum driveshaft Second Skin Audio damping; Infinity spkrs; Goodyear Eagle F1 255F/295R - FR500 wheels
Crazy Al, I have learned a ton from you on this site and I dont even know you. Thanks for taking the time to do this stuff, it give the novice more confidence to work on their own ride!
That was so beautiful it brought a tear to my eye....
No seriously man...you should write a Mustang suspension booklet. Publish it and sell it for like $1000 because you got some great info...But seriously you have single handedly stopped my focus from getting more hp to pretty much doing the whole suspension before I spend another dime on hp......
Posts: 2147
Joined: 3/25/2006 From: Nor Cal Status: offline
quote:
ORIGINAL: odiaz
Awesome write up CrazyAl, as usual your willingness to share your suspension knowledge benefits us all.
I hope you don't mind, I compiled the 2 posts you wrote about adjusting Pinion angles and this one on LCA relocation brackets and combined then into a single article and posted it on my web site listing you as the author. Here is the link to it: http://www.cherod.com/mustang/HowTo/LCA%20_adj.htm
If you don't mind, I'll try to redraw the diagrams using an illustration tool and repost the article. If you have other information you'd like to share, I'd be glad to help you write it up, illustrate it and post it on the website.
Thanks again for sharing your knowledge and experience.
Great job on that write up and the redo on the drawings. I have saved this into my favorites for sure.
Great Job from both you and A.
Richard
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2006 GT-Borla Stingers, Eibach Pro Kit, Tokico D-Specs, MGW Billet, 20" Foose Nitrous w/BFG KDW Tires, CHE panhard bar & Support
hey Al....i just now got my adjustable LCA's and relocation brackets in......what type of shop do i need to go to to get these installed.....i called around and a shop said "yeah i believe we can do that" ....i went up to goodyear (knowing that even if they could do it i would pretty much be bending over in the process).....but they told me that they wont work on anything that has been lowered like mine has(eibach sportlines).....plus they said that they wouldnt be able to warranty the work because i already had the parts...i just want to make sure that it is all done properly. -Danny
I would look for a real speed shop, not a "chain" place like Firestone, Goodyear, Midas, etc. Find a shop that specializes on performance cars.
The LCAs are easy to install. You could do it yourself in less than an hour with some wrenches and a jack. As for the LCA brackets, those are a little more involved, and I highly suggest welding them in place. Unfortunatley that further limits who can do the work.
You also might ask around at places that do custom paint. Again, not a chain like Maaco, but a private auto paint & body shop. They will be able to weld in the LCA brackets for sure. If for some reason they can't or won't do the work, ask them who people go to for working on hot rods or classic cars. That will probably give you some leads.
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Black 2006 GT Coupe Dynatech LT headers & X; Borla catback C&L CAI; 93 oct tune Full BMR, Spohn & Steeda suspension D-Specs; Alum driveshaft Second Skin Audio damping; Infinity spkrs; Goodyear Eagle F1 255F/295R - FR500 wheels
I just bought the Spohn Upper and lower control arms. Do I need the relocation brackets as well or is that only to adjust the stock lower control arms? -Andrew
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Tokiko D-specs, 20" Black Foose Nitrous Wheels, Fays 2 Watts Link, Hurst Shifter, CHE K-Member Brace with Torque Limiters, CDC Brake Light Kit, Spoiler,and Black Billet Grille, Spohn Lower control arms with BMR relocation Brackets
Adjustable LCAs (or UCAs) allow you to adjust the length of the arm, which in turn changes your pinion angle.
The LCA relocation brackets allow you to adjust the angle of the arm, which is for the aforementioned suspension adjustment (instant center).
The two things are TOTALLY SEPERATE from each other.
If you lowered your car then you would ideally use BOTH. The adjustable control arms let you set your pinion angle correctly. The LCA relocation bracket fixes your LCA angle & instant center.
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Black 2006 GT Coupe Dynatech LT headers & X; Borla catback C&L CAI; 93 oct tune Full BMR, Spohn & Steeda suspension D-Specs; Alum driveshaft Second Skin Audio damping; Infinity spkrs; Goodyear Eagle F1 255F/295R - FR500 wheels
i realize this thread may be dead, but i'd like to try and revive it. i followed the instructions from CrazyAl and Spohn and BMR [the latter two sucking big donkey nuts] and now when i downshift from third to second and get the rpms up there, the back end wants to push out to the passenger side. and occasionally i've also got a "pop" that sounds like something shifting around. is that just the rod end torquing or something. as i said, aside from the perfect torque specs, i was very careful with the install and the pinion angle readjustment. could not torquing them exactly right cause these problems? it doesn't seem like it, but then again what do i know. ug. despite the fact that people say "a few hours and some wrenches" these projects take me 8-10 hours at least. didn't help that the BMR brackets were a few milimeters too narrow to get on and required some persuasion with a threaded rod and two nuts to push them apart enough to get the rod end in there.
I had some intstalled last week by a local speed shop and this weekend when I shifted hard 1-2 my rear kicked out to the drivers side. I have to call'em and see if an adjustment can help this as well.
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Tngstn 06GT-5 spd -Vortech HO S/C-Tuned by Realspeed Auto You can never have too much power, just not enough traction. 12.33 @ 112.3 - 1.71 60"
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LCA angle & LCA relocation brackets & you - 
