LCA Relocation Brackets
10/17/07, 11:42 AM
#1
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LCA Relocation Brackets
Ok here is my question, i just bought some LCA brackets but no LCAs and i wanted to know since i do not have a lowered car would it still be ok for me to bolt the LCA to the lowest setting or the one under the original mount?
10/17/07, 11:59 AM
#2
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I'd call BMR or whichever company you bought them from and ask. I got the BMR relos and I'll be installing them with stock arms but my car is lowered. Even then BMR recommended using the top hole as the lower hole is more for drag strip only situations.
10/17/07, 06:59 PM
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If you are not lowered I doubt you will derive any benifit. Its meant to correct the instant center location. Raising too much is just as bad as having it too low.
10/17/07, 07:45 PM
#4
Even without being lowered, my LCAs angled down towards the front of the car, and I was getting way too much squat on the launch. Anti-squat brackets helped a lot.
10/17/07, 08:53 PM
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Well if they are angled down out of the wraper, then there may be something to gain, but not necessarly jumping to the bottom hole of the bracket. If the rear instant center gets too high and short, you 'could' end up with the CG ahead of its point of action, at which time you start over anti squat (rear of the car starts to raise). Weight transfer only changes in that the car CG does. All depends on the geometry of the 3 link set up.
My stock ride height measures 1/4" down at the front. Maybe 3/8" to 1/2" with me in it. So going to the bottom hole is a very drastic adjustment considering the car is at stock ride height. With the stock LCAs though, he may have no choice but to use the bottom hole, in which case to balance things out IMO the UCA relo frame bracket should be considered as well.
My stock ride height measures 1/4" down at the front. Maybe 3/8" to 1/2" with me in it. So going to the bottom hole is a very drastic adjustment considering the car is at stock ride height. With the stock LCAs though, he may have no choice but to use the bottom hole, in which case to balance things out IMO the UCA relo frame bracket should be considered as well.
10/17/07, 09:30 PM
#6
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well i have the BMR brackets and i do not know if i will be installing them just yet. Should i just wait till i get the rest of the lowering done to install these, plus i was not really going to install them till i could get my billet BMR LCAs so it could complete the anti-wheel hop kit.
10/17/07, 09:45 PM
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Based on my thoughts above, if the stock LCA will fit in the second hole up, go for it. If you have to go to the bottom with stock LCA and ride height, then consider the UCA relocation bracket as well, just so you don't over kill the instant center correction.
When you lower the car an 1" or so, the bottom hole for the LCA 'may' be better.
You can only tell by launching the car and capture it on video and see how much the amount of squat changes. The change in feel will be pretty subjective. 60' times may show the real difference.
When you lower the car an 1" or so, the bottom hole for the LCA 'may' be better.
You can only tell by launching the car and capture it on video and see how much the amount of squat changes. The change in feel will be pretty subjective. 60' times may show the real difference.
10/17/07, 09:50 PM
#8
What he said
Id use the next hole down if your stock height.stock arms...next one down is too severe...chances are you will have binding in driveshaft/rearend...lots of chatter on a hard launch...a bad thing!
10/17/07, 09:58 PM
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Hi RedDragon,
For best road handling you want the LCA's to be mounted so they are parallel to the ground with the car sitting on the ground. For drag strip use you need to do some testing and see what gives you the best 60' times. For an automatic car you can set the LCA's to hit the tires harder than a manual car. If you have a stock ride height car I suggest that you leave it alone until you have lowered the car. When you do install your LCA relocation brackets and set them in whatever hole is closest to parallel to the ground. For a more drag oriented car I suggest that the arms are level or pointing downhill looking front to back given the option. this improves off the line grip, the farther you move the LCA's down the harder the power will hit the tires on launch. For a road or handling oriented car you want the LCA's to be pointing straight back or slightly up hill if you have to choose. This setting improves the car's rear axle steering behavior when driving fast in the corners by reducing roll oversteer and makes the car more stable handling.
HTH!
10/17/07, 10:47 PM
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Hi RedDragon,
For best road handling you want the LCA's to be mounted so they are parallel to the ground with the car sitting on the ground. For drag strip use you need to do some testing and see what gives you the best 60' times. For an automatic car you can set the LCA's to hit the tires harder than a manual car. If you have a stock ride height car I suggest that you leave it alone until you have lowered the car. When you do install your LCA relocation brackets and set them in whatever hole is closest to parallel to the ground. For a more drag oriented car I suggest that the arms are level or pointing downhill looking front to back given the option. this improves off the line grip, the farther you move the LCA's down the harder the power will hit the tires on launch. For a road or handling oriented car you want the LCA's to be pointing straight back or slightly up hill if you have to choose. This setting improves the car's rear axle steering behavior when driving fast in the corners by reducing roll oversteer and makes the car more stable handling.
HTH!
For best road handling you want the LCA's to be mounted so they are parallel to the ground with the car sitting on the ground. For drag strip use you need to do some testing and see what gives you the best 60' times. For an automatic car you can set the LCA's to hit the tires harder than a manual car. If you have a stock ride height car I suggest that you leave it alone until you have lowered the car. When you do install your LCA relocation brackets and set them in whatever hole is closest to parallel to the ground. For a more drag oriented car I suggest that the arms are level or pointing downhill looking front to back given the option. this improves off the line grip, the farther you move the LCA's down the harder the power will hit the tires on launch. For a road or handling oriented car you want the LCA's to be pointing straight back or slightly up hill if you have to choose. This setting improves the car's rear axle steering behavior when driving fast in the corners by reducing roll oversteer and makes the car more stable handling.
HTH!
10/17/07, 11:27 PM
#11
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Pretty much, generally speaking setting the LCA's lower on the axle end for drag racing can help increase tire bite on launch but you can over-do it and initally transfer too much weight too fast leaving hard only to get too much wheel spin once you leave if you don't have enough power to keep the rear end loaded. So you have to experiment with the position of the LCA's, tire pressure and shock damping.
For road racing you want the LCA's as level as possible but if you have to choose between lower at the axle than the front LCA mount or higher than the axle end, you want to choose to set the LCA's higher on the axle side. This is not ideal though which is why the Steeda LCA relocation brackets are a better design, more adjustment holes closer together means you have a much better chance to hit the right location for your application or use!
Does this clarify what I said for you? If not just ask!
HTH!
10/17/07, 11:41 PM
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When you launch the car at the track, a bunch of things are happening, all in a VERY short time frame. As the axle rotates the tires forward, the axle housing rotates the opposite direction, pulling against the UCA, and pushing against the LCAs, which actually apply the force to the chassis and move the car forward. So far, all is good. With too little anti-squat dialled in, for example, where the chassis mount of the LCA is lower than the axle mount, the initial acceleration is re-directed into dumping the body downward in the rear, and lifting it in the front, and too much weight transferance occurs. At that point, the suspension is incredibly heavily loaded, and as the springs rebound, will unload violently, and get you into wheel hop, with the tires bouncing up off the pavement and spinning. This is bad.
At the other end of the spectrum, with too much anti-squat (the chassis mount of the LCA is significantly higher than the axle side) you can acutally get NEGATIVE weight transferrance, and with no weight on the rear axle to help plant the tires, they go up in smoke. In this case, the LCA is pushing upwards against the chassis, causing it to lift, and taking the weight off the rear. This is also bad.
Somewhere in the middle is the sweet spot. When the LCA is roughly paralell to the ground (and therefore the mount points are roughly paralell), you will get the minimum amount of weight transferrance necessary to plant the tires properly. No energy is wasted moving the chassis around, the tires don't spin, and you're off like a rocket. This is good.
There is an art to tuning a chassis, just like tuning an engine. The right combination of parts, and the right setup (proper corner weighting, the right damper valving, the right tire pressures, the right spring rates, the right instant-center location, launched at the right RPM with the right clutch feed-rate) will give you the maximum amount of acceleration, in much the same way that the right fuel and spark curves will give you the most power possible from that engine combo.
There are dramatic differences between drag suspension setup and road-course setup, but the common focus is on suspension component rigidity. The stock UCA and LCA parts are simple, stamped steel bits with very soft bushings. If you change those out for HD pieces with good stiff bushings, AND DO NOTHING ELSE, you will see a solid increase in your launch energy. Now, if you take the good components, and tune them properly to your particular car, you will see another order of magnitude in terms of launch energy conservation.
My car, for example, is set up for corner carving. I use lowering springs, HD swaybars, adjustable UCA and LCA, LCA relocation brackets, bump-steer tie-rod ends, and adjustable shocks. When I launch in a straight line, the car BARELY squats, and launches hard. If all I was worried about was straight-line, then I would dump the front swaybar alltogether, as it effectively prevents the front end from rising, hampering my weight transferance, and reducing the available traction. However, when I hit that first corner, whoa up the car from 90+MPH down to 50 or so and crank the wheel to the left, that same reduced weight transferance keeps enough weight on the back tires to allow the brakes to function at a high level, and the heavy swaybars control the amount of weight being transfered to the right side of the car, and as a result, I can make it around the corner, tracking flat under power. When I bring the car back to center at the corner exit, the same heavy swaybars keep the car neutral, without rolling back over, and as a result, I can carry more speed out of the corner and accelerate heavier, sooner.
In terms of suspension, it's nigh-on impossible to serve both masters well. It's been my experience that the road-course cars are slow out of the box at the strip, and the drag cars are nearly undrivable in the twisties at speed.
All the real suspension tuning is done in spring rates, damper valving, and corner weighting, and the difference between a handling and acceleration tuning is huge...
10/18/07, 12:13 AM
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Almost, but not quite... All this talk about "instant center," "anti-squat," and "percentage rise" all relates to describing the behaviour of the rear suspension under acceleration and deceleration... I don't remember where I heard this description, but it's a lot like pushing on a refrigerator. If you push at the top (too little anti-squat), it won't move forward, but will tip over. If you push at the bottom (too much anti-squat), you won't budge it, because your feet can't get traction. But, there is a sweet spot, somewhere in the middle that will give you maximum movement with minimum applied force. Tuning the rear suspension is trying to find that sweet spot.
When you launch the car at the track, a bunch of things are happening, all in a VERY short time frame. As the axle rotates the tires forward, the axle housing rotates the opposite direction, pulling against the UCA, and pushing against the LCAs, which actually apply the force to the chassis and move the car forward. So far, all is good. With too little anti-squat dialled in, for example, where the chassis mount of the LCA is lower than the axle mount, the initial acceleration is re-directed into dumping the body downward in the rear, and lifting it in the front, and too much weight transferance occurs. At that point, the suspension is incredibly heavily loaded, and as the springs rebound, will unload violently, and get you into wheel hop, with the tires bouncing up off the pavement and spinning. This is bad.
At the other end of the spectrum, with too much anti-squat (the chassis mount of the LCA is significantly higher than the axle side) you can acutally get NEGATIVE weight transferrance, and with no weight on the rear axle to help plant the tires, they go up in smoke. In this case, the LCA is pushing upwards against the chassis, causing it to lift, and taking the weight off the rear. This is also bad.
Somewhere in the middle is the sweet spot. When the LCA is roughly paralell to the ground (and therefore the mount points are roughly paralell), you will get the minimum amount of weight transferrance necessary to plant the tires properly. No energy is wasted moving the chassis around, the tires don't spin, and you're off like a rocket. This is good.
There is an art to tuning a chassis, just like tuning an engine. The right combination of parts, and the right setup (proper corner weighting, the right damper valving, the right tire pressures, the right spring rates, the right instant-center location, launched at the right RPM with the right clutch feed-rate) will give you the maximum amount of acceleration, in much the same way that the right fuel and spark curves will give you the most power possible from that engine combo.
There are dramatic differences between drag suspension setup and road-course setup, but the common focus is on suspension component rigidity. The stock UCA and LCA parts are simple, stamped steel bits with very soft bushings. If you change those out for HD pieces with good stiff bushings, AND DO NOTHING ELSE, you will see a solid increase in your launch energy. Now, if you take the good components, and tune them properly to your particular car, you will see another order of magnitude in terms of launch energy conservation.
My car, for example, is set up for corner carving. I use lowering springs, HD swaybars, adjustable UCA and LCA, LCA relocation brackets, bump-steer tie-rod ends, and adjustable shocks. When I launch in a straight line, the car BARELY squats, and launches hard. If all I was worried about was straight-line, then I would dump the front swaybar alltogether, as it effectively prevents the front end from rising, hampering my weight transferance, and reducing the available traction. However, when I hit that first corner, whoa up the car from 90+MPH down to 50 or so and crank the wheel to the left, that same reduced weight transferance keeps enough weight on the back tires to allow the brakes to function at a high level, and the heavy swaybars control the amount of weight being transfered to the right side of the car, and as a result, I can make it around the corner, tracking flat under power. When I bring the car back to center at the corner exit, the same heavy swaybars keep the car neutral, without rolling back over, and as a result, I can carry more speed out of the corner and accelerate heavier, sooner.
In terms of suspension, it's nigh-on impossible to serve both masters well. It's been my experience that the road-course cars are slow out of the box at the strip, and the drag cars are nearly undrivable in the twisties at speed.
All the real suspension tuning is done in spring rates, damper valving, and corner weighting, and the difference between a handling and acceleration tuning is huge...
When you launch the car at the track, a bunch of things are happening, all in a VERY short time frame. As the axle rotates the tires forward, the axle housing rotates the opposite direction, pulling against the UCA, and pushing against the LCAs, which actually apply the force to the chassis and move the car forward. So far, all is good. With too little anti-squat dialled in, for example, where the chassis mount of the LCA is lower than the axle mount, the initial acceleration is re-directed into dumping the body downward in the rear, and lifting it in the front, and too much weight transferance occurs. At that point, the suspension is incredibly heavily loaded, and as the springs rebound, will unload violently, and get you into wheel hop, with the tires bouncing up off the pavement and spinning. This is bad.
At the other end of the spectrum, with too much anti-squat (the chassis mount of the LCA is significantly higher than the axle side) you can acutally get NEGATIVE weight transferrance, and with no weight on the rear axle to help plant the tires, they go up in smoke. In this case, the LCA is pushing upwards against the chassis, causing it to lift, and taking the weight off the rear. This is also bad.
Somewhere in the middle is the sweet spot. When the LCA is roughly paralell to the ground (and therefore the mount points are roughly paralell), you will get the minimum amount of weight transferrance necessary to plant the tires properly. No energy is wasted moving the chassis around, the tires don't spin, and you're off like a rocket. This is good.
There is an art to tuning a chassis, just like tuning an engine. The right combination of parts, and the right setup (proper corner weighting, the right damper valving, the right tire pressures, the right spring rates, the right instant-center location, launched at the right RPM with the right clutch feed-rate) will give you the maximum amount of acceleration, in much the same way that the right fuel and spark curves will give you the most power possible from that engine combo.
There are dramatic differences between drag suspension setup and road-course setup, but the common focus is on suspension component rigidity. The stock UCA and LCA parts are simple, stamped steel bits with very soft bushings. If you change those out for HD pieces with good stiff bushings, AND DO NOTHING ELSE, you will see a solid increase in your launch energy. Now, if you take the good components, and tune them properly to your particular car, you will see another order of magnitude in terms of launch energy conservation.
My car, for example, is set up for corner carving. I use lowering springs, HD swaybars, adjustable UCA and LCA, LCA relocation brackets, bump-steer tie-rod ends, and adjustable shocks. When I launch in a straight line, the car BARELY squats, and launches hard. If all I was worried about was straight-line, then I would dump the front swaybar alltogether, as it effectively prevents the front end from rising, hampering my weight transferance, and reducing the available traction. However, when I hit that first corner, whoa up the car from 90+MPH down to 50 or so and crank the wheel to the left, that same reduced weight transferance keeps enough weight on the back tires to allow the brakes to function at a high level, and the heavy swaybars control the amount of weight being transfered to the right side of the car, and as a result, I can make it around the corner, tracking flat under power. When I bring the car back to center at the corner exit, the same heavy swaybars keep the car neutral, without rolling back over, and as a result, I can carry more speed out of the corner and accelerate heavier, sooner.
In terms of suspension, it's nigh-on impossible to serve both masters well. It's been my experience that the road-course cars are slow out of the box at the strip, and the drag cars are nearly undrivable in the twisties at speed.
All the real suspension tuning is done in spring rates, damper valving, and corner weighting, and the difference between a handling and acceleration tuning is huge...
Hi SoundGuyDave,
Well that was a good try but there are so many things you have wrong I can't even begin to correct them all.
Cheers!
10/18/07, 08:16 AM
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Hi Glenn,
They do different things, what have you already done to your suspension and what are you trying to achive? How do you use the car and what do you percieve as an issue with the suspension as it sits now?
Cheers!
10/18/07, 08:23 AM
#16
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With your car lowered 1.4 in. you probably should already have an adjustable UCA to correct pinion angle... the LCA relocation bracket will not correct that adjustment. But, a relo bracket does work well in conjunction with the lowering springs and adjustabel UCA. It allows you to balance the rear suspension geometry.
Bobby M.
10/18/07, 09:52 AM
#17
Well if they are angled down out of the wraper, then there may be something to gain, but not necessarly jumping to the bottom hole of the bracket. If the rear instant center gets too high and short, you 'could' end up with the CG ahead of its point of action, at which time you start transfering weight off the rear axle. All depends on the geometry of the 3 link set up.
10/18/07, 11:28 AM
#18
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well then i guess i will just wait till i get everything together, i am looking at this set up,
Tokico D-specs
Steeda swaybars with HD endlinks
BMR panhard bar and support
BMR mild drop springs
BMR Relocation brackets
BMR billet LCAs
BMR adjustable UCA and mount
still thinking on Steeda HD strut mounts or MM caster camber plates
Tokico D-specs
Steeda swaybars with HD endlinks
BMR panhard bar and support
BMR mild drop springs
BMR Relocation brackets
BMR billet LCAs
BMR adjustable UCA and mount
still thinking on Steeda HD strut mounts or MM caster camber plates
10/19/07, 01:23 PM
#19
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Heres pics of mine with 1.4'' drop! in the first pic you can see the J&M bracket levels the factory control arm. As others have said the reco brackets stop the hop but if you want to adjust the pinion angle you'll need the adjustable lower control arms! Since these photo's I have also installed J&M adjustable pan hard bar, J&M upper strut mount camber plates and a Steeda bump steer kit, what a difference these few mods make!!