Boxed LCA's ????????
Thread Starter
Launching!
Joined: Oct 2002
Posts: 240
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From: Point Mugu, CA
Boxed LCA's ???????? I was reading somewhere (of course I forgot where), and saw a post talking about the fact that BMR boxed LCA's bind during autocross and hard cornering. I am going to lower my car with all BMR products (APHR, LCA reloc brackets, springs, and LCA's). I do more autocross stuff than drag racing due to the fact that there are no strips nearby for me, but there are plenty of autocross events. I would like to get into drag racing more when I move so which style of LCA should I go with. I don't need the adjustable ones, just something for the daily driver that occasionally autocrosses and maybe one day can get it to the strip for a few runs.
She is a 99 WS-6 A4 with Lid, 85mm MAF, MAF translator, LS6 intake manifold, Corsa cat-back, HPP3 for shift firmness, shift points, and rev limiter, ZO6 18x9.5 wheels, MSD 8.5mm wires, NGK TR55 plugs, and QTP LT's with dual QTEC's in the mail.
304rwhp and 321rwtq.
She is a 99 WS-6 A4 with Lid, 85mm MAF, MAF translator, LS6 intake manifold, Corsa cat-back, HPP3 for shift firmness, shift points, and rev limiter, ZO6 18x9.5 wheels, MSD 8.5mm wires, NGK TR55 plugs, and QTP LT's with dual QTEC's in the mail.
304rwhp and 321rwtq.
Re: Boxed LCA's ???????? The boxed LCA's do bind. Think of it this way, the front LCA mounting bolts are fastened to the car and don't move (at least for this conversation we'll consider them a fixed mounting point). The rear LCA mounting locations are mounted to the axle which is also a fixed mounting point (those bolts will always stay parallel and in a straight line with each other). If you set the body on jackstands and removed the springs and shocks from your car, the axle and rear tires will stay in a straight line (parallel to the body) and drop to the garage floor. Now, to simulate what happens when one wheel hits a pothole (or during a body roll situation, such as in a hard corner), put a jack under one side of the axle and lift one wheel. In a perfect world, only that wheel would move upwards and the other side would stay on the ground. With "rod end" style control arms, that is mostly what happens (the wheel on the ground "tilts" or changes camber and loses some contact patch, but it tries to stay planted). With boxed control arms and poly bushings, the bushing won't allow the axle mounting bolts to twist, and it won't let the frame bolts twist (relative to the control arm) and the boxed arms won't twist. So, now when we lift one wheel, both wheels will lift off the ground since there is no compliance in the bushings or the control arms (nothing that would allow the axle hoousing to rotate). This is not a desirable situation.
Boxed arms work quite well for some drivers in some situations, but anything they can do, a rod end can do better (the poly is a little quieter though, rod ends make some noise).
Sorry for the extremely long answer, but I hope that helps. Good luck.
Boxed arms work quite well for some drivers in some situations, but anything they can do, a rod end can do better (the poly is a little quieter though, rod ends make some noise).
Sorry for the extremely long answer, but I hope that helps. Good luck.
Thread Starter
Launching!
Joined: Oct 2002
Posts: 240
Likes: 0
From: Point Mugu, CA
Re: Boxed LCA's ???????? Thanks for the replies that helps a lot. The car as previously mentioned is a daily driver. I hate excess noises to come from the car, but I like to autocross it and as soon as I find a strip near me she is going to start going there too. So basically I think tubular LCA's are my best choice with the poly bushings vice the rod ends.
