LCA Relocation Bracket Geometry
05-12-2014, 02:05 PM
#1
3rd Gear Member
Thread Starter
Join Date: Jan 2010
Location: Louisiana
Posts: 738
LCA Relocation Bracket Geometry
I've been riding on steeda sports forever now, never did any relocation brackets for my LCA's. Figured since I've changed so much else I may as well do that too.
What is the geometry I am looking for? Does the LCA need to be parallel to the ground when the car is level and on the ground?
I've looked at all the relocation brackets. They are nice, but I have a 4-axis waterjet and plenty of steel so I'd rather spend $20 cutting them out and bending them as opposed to $150 on so premade stuff that won't be as beefy as what I make.
Also, do I need to drain the rear end of fluid before I weld the relocation brackets in? I've never done any welding on a rear end, only TIG welding on unibodies. Gonna MIG the brackets in place.
What is the geometry I am looking for? Does the LCA need to be parallel to the ground when the car is level and on the ground?
I've looked at all the relocation brackets. They are nice, but I have a 4-axis waterjet and plenty of steel so I'd rather spend $20 cutting them out and bending them as opposed to $150 on so premade stuff that won't be as beefy as what I make.
Also, do I need to drain the rear end of fluid before I weld the relocation brackets in? I've never done any welding on a rear end, only TIG welding on unibodies. Gonna MIG the brackets in place.
05-13-2014, 05:54 AM
#2
3rd Gear Member
Join Date: Sep 2011
Location: DE
Posts: 546
Yes, ideally you want the LCA to be parallel to the ground. Maybe even upward at a slight angle from the axle to the body. I bought the whiteline relo brackets and I couldn't believe how thick the steel was. Overall, I was very impressed by them. This set is only $100 at AM, not $150 like you said.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
05-13-2014, 01:34 PM
#3
3rd Gear Member
Thread Starter
Join Date: Jan 2010
Location: Louisiana
Posts: 738
Yes, ideally you want the LCA to be parallel to the ground. Maybe even upward at a slight angle from the axle to the body. I bought the whiteline relo brackets and I couldn't believe how thick the steel was. Overall, I was very impressed by them. This set is only $100 at AM, not $150 like you said.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
I am also pretty sure your whiteline relocation brackets aren't chromoly and are just carbon steel. I'm almost positive.
I plan to use 1/4" thick carbon on the outside with a spacer to make up for the thickness of the original mounting location. Kind of like the BMR ones but way beefier.
05-15-2014, 06:12 AM
#4
3rd Gear Member
Join Date: Sep 2011
Location: DE
Posts: 546
Yeah, I may have been mistaken about the whiteline material. Most of their control arms are chromoly and I thought the brackets were too.
Either way, I don't see the need to make either of these brackets beefier. They have been tested on track and drag cars. The brackets are specifically designed for their purpose. I don't think engineers and racers would skimp on something so important.
For welding on the axle tube, yes you should drain the fluid.
Either way, I don't see the need to make either of these brackets beefier. They have been tested on track and drag cars. The brackets are specifically designed for their purpose. I don't think engineers and racers would skimp on something so important.
For welding on the axle tube, yes you should drain the fluid.
05-15-2014, 06:16 AM
#5
4th Gear Member
Join Date: Mar 2012
Location: Texas
Posts: 1,044
Whiteline rules
Yes, ideally you want the LCA to be parallel to the ground. Maybe even upward at a slight angle from the axle to the body. I bought the whiteline relo brackets and I couldn't believe how thick the steel was. Overall, I was very impressed by them. This set is only $100 at AM, not $150 like you said.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
Personally I would recommend buying those and saving your time and efforts for other fabricating projects. Do you know what gauge steel you will be using? You will need something substantial to match the strength characteristics of the Chromoly 4130 used in the Whiteline brackets. Finally, the whiteline brackets can be welded in place, but this would only be needed for serious HP applications.
05-15-2014, 06:54 AM
#6
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
A street/strip car can run with LCA inclination going uphill toward the chassis as long as the street driving does not include hard cornering. Here, you want to increase anti-squat, and most folks interested in this kind of setup don't (shouldn't) drive the corners hard enough to make axle roll steer become critical.
For autocross, road course open tracking, and "canyon running", you don't want a setting anywhere near that aggressive. Level to slightly uphill toward the axle will make the axle steer easier to deal with. Axle roll steer is more important than anti-squat here.
Don't forget that the car settles a fraction of an inch when you get in. In a car that has already been lowered this will tend to increase both the anti-squat and the understeer effect from axle steer.
Anti-squat and axle steer can be calculated for any LCA adjustment position that either exists in an available product or that you want to try out in a DIY-fabbed version. . . . If you knew what you wanted in those parameters you'd be able to determine what adjustment position(s) you'd need to have.
You shouldn't have to weld directly to the axle tubes, just short beads to the OE brackets. If you take your time, let things cool between running each bead, and maybe keep a wet rag handy I think you could get away without draining the diff. On the other hand, if there's any chance that the diff fluid is getting near time to be changed, this would be a great opportunity to do so.
Norm
Last edited by Norm Peterson; 05-15-2014 at 06:56 AM.
05-15-2014, 12:17 PM
#7
3rd Gear Member
Thread Starter
Join Date: Jan 2010
Location: Louisiana
Posts: 738
This should be based on how you're going to use the car.
A street/strip car can run with LCA inclination going uphill toward the chassis as long as the street driving does not include hard cornering. Here, you want to increase anti-squat, and most folks interested in this kind of setup don't (shouldn't) drive the corners hard enough to make axle roll steer become critical.
For autocross, road course open tracking, and "canyon running", you don't want a setting anywhere near that aggressive. Level to slightly uphill toward the axle will make the axle steer easier to deal with. Axle roll steer is more important than anti-squat here.
Don't forget that the car settles a fraction of an inch when you get in. In a car that has already been lowered this will tend to increase both the anti-squat and the understeer effect from axle steer.
Anti-squat and axle steer can be calculated for any LCA adjustment position that either exists in an available product or that you want to try out in a DIY-fabbed version. . . . If you knew what you wanted in those parameters you'd be able to determine what adjustment position(s) you'd need to have.
You shouldn't have to weld directly to the axle tubes, just short beads to the OE brackets. If you take your time, let things cool between running each bead, and maybe keep a wet rag handy I think you could get away without draining the diff. On the other hand, if there's any chance that the diff fluid is getting near time to be changed, this would be a great opportunity to do so.
Norm
A street/strip car can run with LCA inclination going uphill toward the chassis as long as the street driving does not include hard cornering. Here, you want to increase anti-squat, and most folks interested in this kind of setup don't (shouldn't) drive the corners hard enough to make axle roll steer become critical.
For autocross, road course open tracking, and "canyon running", you don't want a setting anywhere near that aggressive. Level to slightly uphill toward the axle will make the axle steer easier to deal with. Axle roll steer is more important than anti-squat here.
Don't forget that the car settles a fraction of an inch when you get in. In a car that has already been lowered this will tend to increase both the anti-squat and the understeer effect from axle steer.
Anti-squat and axle steer can be calculated for any LCA adjustment position that either exists in an available product or that you want to try out in a DIY-fabbed version. . . . If you knew what you wanted in those parameters you'd be able to determine what adjustment position(s) you'd need to have.
You shouldn't have to weld directly to the axle tubes, just short beads to the OE brackets. If you take your time, let things cool between running each bead, and maybe keep a wet rag handy I think you could get away without draining the diff. On the other hand, if there's any chance that the diff fluid is getting near time to be changed, this would be a great opportunity to do so.
Norm
05-15-2014, 06:17 PM
#10
6th Gear Member
Join Date: Feb 2007
Location: state of confusion
Posts: 7,635
With that information, right now your axle roll steer is somewhere around 9.5%, which is rather high compared to stock (a little under 3%, which is a pretty good place to be for a wide variety of driving situations). I'm guessing your LCA inclination is about 6° uphill toward the axle vs about 2° uphill toward the axle as OE. Those figures are with a 185 lb driver aboard.
Relocating the axle side LCA pivot downward something like 1.1" to maybe 1.25" will get you back to the OE amount of axle steer (around 3%, with LCA inclinations 2° or so uphill toward the axle). In your case, at a little more than 1.5" down, the axle steer starts going "loose", which can be good for autocross if maybe not so good in other situations, such as where the road might turn at the same time it crests a small rise. Fortunately, the effect is pretty mild as long as you don't drop the axle side pivot heights too much more than the car is lowered. Twice as much as the car lowering would be a lot and way too much for your purposes. At 40% more (about 1.75"), maybe not . . . but you'd have to drive it to find out for sure, as the numbers alone can't tell you what you'll be happy with.
Norm
Relocating the axle side LCA pivot downward something like 1.1" to maybe 1.25" will get you back to the OE amount of axle steer (around 3%, with LCA inclinations 2° or so uphill toward the axle). In your case, at a little more than 1.5" down, the axle steer starts going "loose", which can be good for autocross if maybe not so good in other situations, such as where the road might turn at the same time it crests a small rise. Fortunately, the effect is pretty mild as long as you don't drop the axle side pivot heights too much more than the car is lowered. Twice as much as the car lowering would be a lot and way too much for your purposes. At 40% more (about 1.75"), maybe not . . . but you'd have to drive it to find out for sure, as the numbers alone can't tell you what you'll be happy with.
Norm
Last edited by Norm Peterson; 05-15-2014 at 06:23 PM.