Suspension and Chassis Questions about your suspension? Need chassis advice?

For those with lowered cars and LCA relocation brackets...

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Old Jul 12, 2005 | 11:37 PM
  #1  
92RSB4C's Avatar
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From: Friendswood(Houston),Texas,USA
For those with lowered cars and LCA relocation brackets...

What angle on the LCA gave you the best performance?
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Old Jul 13, 2005 | 12:05 AM
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From: Roscoe, IL
Car: 1991 Trans Am
Engine: LQ4
Transmission: T-56
Axle/Gears: 3.70
how lowered is the car? idealy you want the lca to be parallel to the ground
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Old Jul 13, 2005 | 03:04 AM
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92RSB4C's Avatar
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From: Friendswood(Houston),Texas,USA
1-1/2" is how much it is lowered. Any pros/cons to slight angle changes?
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Old Jul 13, 2005 | 07:55 AM
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From: Charleston, SC
Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
if its lowered enough that the axle half of the LCA is higher then the chasis side, then get the relocation brackets... 99% of lowered cars just need the upper hole of the brackets... only really slammed cars need the bottom hole to even them out.
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Old Jul 13, 2005 | 08:48 PM
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From: Southern Maryland
Car: 91 Z28
Engine: L98
Transmission: built 700R4
Axle/Gears: 3.42
I have sportlines and was told by umi performace (relocation bracket manufacturer) to use the lowest hole.
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Old Jul 14, 2005 | 08:51 AM
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Mongoose's Avatar
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From: Monroe,NC
Car: 90 Formula
Engine: 305
Transmission: 700R4
Axle/Gears: 9 bolt/3.27
I have the Sportlines and I use the bottom mounting hole. These really made a difference in how the car felt at speed. Before the car's rear felt like it was trembling,after it was rock solid and traction was much improved. I've never tried the upper position since I was pleased with the lower.
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Old Jul 14, 2005 | 02:43 PM
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From: Southern Maryland
Car: 91 Z28
Engine: L98
Transmission: built 700R4
Axle/Gears: 3.42
I had really bad wheel hop before installing the relocation brackest olso, now it's no more
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Old Jul 14, 2005 | 04:01 PM
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From: Dale City, VA
Car: 91 GTA and 85 IROC
Engine: 355
Transmission: gear jammer
Axle/Gears: 4.11
What about for drag use? Any downside to using the bottom hole? Could you get less traction by going to far?
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Old Jul 14, 2005 | 06:58 PM
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From: Boscobel, Wisconsin
Car: 1987 Iroc-Z
Engine: 355
Transmission: 700r4 w/ about 7500 miles on rebuild
where are the different places to get LCA relocation brackets? i know Spohn sells them for $65.. what are some other manufacturers and their prices?
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Old Jul 14, 2005 | 07:42 PM
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From: Woodland Hills, CA USA
Car: Yes...
Engine: Last time I checked...
Transmission: See "Engine"...
Global West ($98.99) and BMR ($79.99 for weld-in. $119.99 for bolt-in.)
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Old Jul 14, 2005 | 09:20 PM
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From: Boscobel, Wisconsin
Car: 1987 Iroc-Z
Engine: 355
Transmission: 700r4 w/ about 7500 miles on rebuild
hmm... go Spohn... lol
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Old Jul 15, 2005 | 05:35 AM
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From: Southern Maryland
Car: 91 Z28
Engine: L98
Transmission: built 700R4
Axle/Gears: 3.42
umiperformance.com
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Old Jul 15, 2005 | 07:52 AM
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From: Dale City, VA
Car: 91 GTA and 85 IROC
Engine: 355
Transmission: gear jammer
Axle/Gears: 4.11
Originally posted by BretD 88GTA
Global West ($98.99) and BMR ($79.99 for weld-in. $119.99 for bolt-in.)
that's insane. do they give you **** lube w/ that a$$ raping?
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Old Jul 15, 2005 | 08:37 AM
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From: Charleston, SC
Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by Free Bird
What about for drag use? Any downside to using the bottom hole? Could you get less traction by going to far?
two downsides..

one, if its too extreme, you could shove the wheels down really hard on the launch, and have them "spring back" and unload about 10-15 feet out of the hole.... it'll feel like a good hook, followed by a spin/breaking loose

two, if its too far off, when you hit the brakes at the end of the track, the rears will want to lift off the ground, so they just slide and your braking distance increases.



a third smaller side effect is that the farther from level they are, less efficent the LCAs can be at transmmitting movement... but honestly, ive never seen that shown in a timeslip... moving them effects too much else to quantify that....
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Old Jul 15, 2005 | 12:20 PM
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From: Dale City, VA
Car: 91 GTA and 85 IROC
Engine: 355
Transmission: gear jammer
Axle/Gears: 4.11
That's good information to have. thanks.
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Old Jul 19, 2005 | 01:23 AM
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From: DC Metro Area
Car: 87TA 87Form 71Mach1 93FleetWB 04Cum
Originally posted by MrDude_1
one, if its too extreme, you could shove the wheels down really hard on the launch, and have them "spring back" and unload about 10-15 feet out of the hole.... it'll feel like a good hook, followed by a spin/breaking loose
Damnit, I wish I could find the video of my WS6 doing that… it seems like no one really believes it could happen, but I’ve come to the conclusion that 99% of people can’t really feel what the car is doing off the line. If they feel a hard hit that is all they need to “know” that they are working.

two, if its too far off, when you hit the brakes at the end of the track, the rears will want to lift off the ground, so they just slide and your braking distance increases.
why would that happen?

a third smaller side effect is that the farther from level they are, less efficent the LCAs can be at transmmitting movement... but honestly, ive never seen that shown in a timeslip... moving them effects too much else to quantify that....
well, more accurately, you don’t get as much weight transfer because the back can rise violently enough to prevent some of it. Really, on sticky tires it would probably be easier to tune this with adjustable shocks then LCA pivot points.

Another disadvantage is that they cause roll oversteer (on corner entry) and exit understeer which is exactly the opposite of what most people expect and what is generally fast.

My $.02:
- for road race/autox and most street use, you really want the backs of the LCA’s slightly higher then the front to give the best characteristics with turns
- compromise street/handling/dragstrip – perpendicular to the ground or _slightly_ down on the axle side. This is where you want to be if you run drag radials or street radials at the dragstrip
- on real drag tires (soft sidewalls, slicks, cheater slicks…) you want to adjust the axle end downward as your sidewalls get softer. At some point you’ll actually reach a point where you’ll actually only need the rear springs to support the car before it starts moving and under power the antisquat action of the rear suspension will actually be able to hold the back end of the car up.
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Old Jul 19, 2005 | 07:32 AM
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From: Lowell, MA
Car: 91 Formula, 95 GT
Engine: 5.7, 5.0
Transmission: T5, T5
Axle/Gears: 3.42:1, ???
Originally posted by 83 Crossfire TA
perpendicular to the ground or _slightly_ down on the axle side.
you really meant parallel
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Old Jul 19, 2005 | 08:12 AM
  #18  
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From: Charleston, SC
Car: 91 Camaro Vert
Engine: 02 LS1, HX40
Transmission: 2002 LS1 M6
Originally posted by 83 Crossfire TA


why would that happen?

same reason they move going forward..
when you hit the brakes, they're pulling backwards relitive to the chassis, and that makes the wheel want to go up....


im still not sure about why myself... you would think the wheel going up would let the car down, and lessen the nose pitching down, but it really just lets the rear end skid easier..
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Old Jul 19, 2005 | 09:12 AM
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From: Portland, OR www.cascadecrew.org
Car: 1990 Camaro RS
Engine: Juiced 5.0 TBI - 300rwhp
Transmission: T5
Axle/Gears: 3.42 Eaton Posi, 10 Bolt
Originally posted by MrDude_1
im still not sure about why myself... you would think the wheel going up would let the car down, and lessen the nose pitching down, but it really just lets the rear end skid easier..
Because the wieght transfer is already forward, initial the torquing from the brakes, and the anti-squat will cause the rear end to lift. The LS1 cars have tons of problem with brake hop due to the better front/rear brakes they have. It all has to do with how much the front grabs, and how good the brakes are. If you have ever seen a photo of a Porsche with the tail end in the air, you will see just how much weight transfer there can be under very fast decell.

Its a really hard thing to explain in text of course, I can visualize it, and feel it though.
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