Instant Center adjustment...NOT for drag racing
12-30-2009, 08:32 AM
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Instant Center adjustment...NOT for drag racing here is the car setup:
full weight 99z28
manual trans
stock 10bolt, 3.42 gears
stock torque arm (for now)
Koni SA
BMR lowering springs ~1.25"
non-adj LCA (poly/rubber)
LCA relocation brackets
poly torque arm bushing
BMR torque arm relocation bracket
(sfc, phb and sway bars but i don't think they really affect what i'm asking)
i just got the TA bracket for christmas and installed it last nite. spent some time searching/reading trying to figure out the ins and outs of adjusting the Instant Center (can be done with the bracket). however all the information seems to pertain to drag racing, not to mention between the confusing descriptions and faulty information...i can't make heads or tails out of it.
SO...
how does Instant Center pertain to a lowered car, built for spirited street driving and canyon carving?
things i'm still not sure of due to confusing info:
1- on the TA relocation bracket...raising the mounting point does what?
2- for cornering which is better, short or longer IC?
3- assuming everything else is stock, how does lowering the rear affect IC?
4- in drag racing, in reference to tweaking IC, i hear about adjustments that plant the tires quickly, but then "unload" them fast. what does "unload" them do/mean? this is more curiosity, not sure it plays much into canyon carving.
i obviously have several means by which to adjust IC...both with the 2 mounting holes for the LCA-brackets and the TA-bracket.
what really brought this about is that i installed the TA mount in what i'm pretty sure is the stock location...but it is putting the bottom edge of my TA very close to my 3" true dual exhaust. THAT got me wondering what affect...possitive or negative...i would get from raising the mounting bracket one notch. i think that would give me the clearance i need.
but will it adversely affect handling? will it make the car lauch better (not a huge concern)?
as with everyone....i would LOVE to have a car that cuts corners like its on rails AND plants the tires at stop lights.
i realize this is almost impossible...as one does not lend itself to the other.
but hey...i can dream right?
full weight 99z28
manual trans
stock 10bolt, 3.42 gears
stock torque arm (for now)
Koni SA
BMR lowering springs ~1.25"
non-adj LCA (poly/rubber)
LCA relocation brackets
poly torque arm bushing
BMR torque arm relocation bracket
(sfc, phb and sway bars but i don't think they really affect what i'm asking)
i just got the TA bracket for christmas and installed it last nite. spent some time searching/reading trying to figure out the ins and outs of adjusting the Instant Center (can be done with the bracket). however all the information seems to pertain to drag racing, not to mention between the confusing descriptions and faulty information...i can't make heads or tails out of it.
SO...
how does Instant Center pertain to a lowered car, built for spirited street driving and canyon carving?
things i'm still not sure of due to confusing info:
1- on the TA relocation bracket...raising the mounting point does what?
2- for cornering which is better, short or longer IC?
3- assuming everything else is stock, how does lowering the rear affect IC?
4- in drag racing, in reference to tweaking IC, i hear about adjustments that plant the tires quickly, but then "unload" them fast. what does "unload" them do/mean? this is more curiosity, not sure it plays much into canyon carving.
i obviously have several means by which to adjust IC...both with the 2 mounting holes for the LCA-brackets and the TA-bracket.
what really brought this about is that i installed the TA mount in what i'm pretty sure is the stock location...but it is putting the bottom edge of my TA very close to my 3" true dual exhaust. THAT got me wondering what affect...possitive or negative...i would get from raising the mounting bracket one notch. i think that would give me the clearance i need.
but will it adversely affect handling? will it make the car lauch better (not a huge concern)?
as with everyone....i would LOVE to have a car that cuts corners like its on rails AND plants the tires at stop lights.
i realize this is almost impossible...as one does not lend itself to the other.but hey...i can dream right?
12-30-2009, 08:24 PM
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seriously...nobody knows??
come on BMR guys...where you at? Madman??
stewing this in my brain today i thought of this:
- LCA relocation brackets help shorten IC...thus planting the tires better.
- raising the mounting point on the TA bracket lengthens IC
do they negate each other?
i know i sure don't have any wheel hop!!! she spins and spins in 1st gear at WOT
come on BMR guys...where you at? Madman??
stewing this in my brain today i thought of this:
- LCA relocation brackets help shorten IC...thus planting the tires better.
- raising the mounting point on the TA bracket lengthens IC
do they negate each other?
i know i sure don't have any wheel hop!!! she spins and spins in 1st gear at WOT
12-30-2009, 10:29 PM
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My guess is you won't get a ton of answers about this stuff here. But it does interest me too. What's this TA bracket and its adjustment all about? What bracket did you get? I thought there was just relo braces to get the TA off the tranny. I didn't know there was one that had more adjustments to it.
I'm a noob to all this instant center stuff, but I try to learn when I get free time. I'm guessing you won't get a end-all be-all answer on if a lower instant center is just plain better for handling. That's pretty vague of a question. I'm pretty sure your IC will effect different things like corner entry, corner exit, and other stuff.
I'm going to experiment with a few things this year. I run in spectator drags which is a form of short oval track racing. So I need my car to turn left all the time. I'm considering putting in a PHB relocation bracket. Not the ones that UMI or BMR have.. this one I'm talking about has several holes. I'm going to see how well putting my PHB in the lower holes effects cornering. Also, I may try out the short torque arm. Since I don't need to do any serious braking, I might get it to see how well the short arm helps me plant during the launch and hopefully throttling out of corner exit. My biggest problem recently has been keeping the rear under control during corner entry and exit. I've spun my wheels and or spun out a few times lately. Neither of which will help me beat the toughest drivers there.
I'm a noob to all this instant center stuff, but I try to learn when I get free time. I'm guessing you won't get a end-all be-all answer on if a lower instant center is just plain better for handling. That's pretty vague of a question. I'm pretty sure your IC will effect different things like corner entry, corner exit, and other stuff.
I'm going to experiment with a few things this year. I run in spectator drags which is a form of short oval track racing. So I need my car to turn left all the time. I'm considering putting in a PHB relocation bracket. Not the ones that UMI or BMR have.. this one I'm talking about has several holes. I'm going to see how well putting my PHB in the lower holes effects cornering. Also, I may try out the short torque arm. Since I don't need to do any serious braking, I might get it to see how well the short arm helps me plant during the launch and hopefully throttling out of corner exit. My biggest problem recently has been keeping the rear under control during corner entry and exit. I've spun my wheels and or spun out a few times lately. Neither of which will help me beat the toughest drivers there.
12-30-2009, 11:57 PM
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I have read the following and I am still not sure, I suggest the OP read
good luck ,Johnny
https://ls1tech.com/forums/drag-raci...on-launch.html
good luck ,Johnny
https://ls1tech.com/forums/drag-raci...on-launch.html
12-31-2009, 06:57 AM
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i've read that thread...it is more about pinion angle...not instant center.
but i did read this, in reference to moving the front of the TA up or down on the adjustable bracket:
HOWEVER, moving the front mount of the torque arm up or down SHOULD change the pinion angle too.
but i did read this, in reference to moving the front of the TA up or down on the adjustable bracket:
HOWEVER, moving the front mount of the torque arm up or down SHOULD change the pinion angle too.
Last edited by teke184; 12-31-2009 at 07:18 AM.
12-31-2009, 07:31 AM
#6
here is the car setup:
full weight 99z28
manual trans
stock 10bolt, 3.42 gears
stock torque arm (for now)
Koni SA
BMR lowering springs ~1.25"
non-adj LCA (poly/rubber)
LCA relocation brackets
poly torque arm bushing
BMR torque arm relocation bracket
(sfc, phb and sway bars but i don't think they really affect what i'm asking)
i just got the TA bracket for christmas and installed it last nite. spent some time searching/reading trying to figure out the ins and outs of adjusting the Instant Center (can be done with the bracket). however all the information seems to pertain to drag racing, not to mention between the confusing descriptions and faulty information...i can't make heads or tails out of it.
SO...
how does Instant Center pertain to a lowered car, built for spirited street driving and canyon carving?
things i'm still not sure of due to confusing info:
1- on the TA relocation bracket...raising the mounting point does what?
2- for cornering which is better, short or longer IC?
3- assuming everything else is stock, how does lowering the rear affect IC?
4- in drag racing, in reference to tweaking IC, i hear about adjustments that plant the tires quickly, but then "unload" them fast. what does "unload" them do/mean? this is more curiosity, not sure it plays much into canyon carving.
i obviously have several means by which to adjust IC...both with the 2 mounting holes for the LCA-brackets and the TA-bracket.
what really brought this about is that i installed the TA mount in what i'm pretty sure is the stock location...but it is putting the bottom edge of my TA very close to my 3" true dual exhaust. THAT got me wondering what affect...possitive or negative...i would get from raising the mounting bracket one notch. i think that would give me the clearance i need.
but will it adversely affect handling? will it make the car lauch better (not a huge concern)?
as with everyone....i would LOVE to have a car that cuts corners like its on rails AND plants the tires at stop lights.
i realize this is almost impossible...as one does not lend itself to the other.
but hey...i can dream right?
full weight 99z28
manual trans
stock 10bolt, 3.42 gears
stock torque arm (for now)
Koni SA
BMR lowering springs ~1.25"
non-adj LCA (poly/rubber)
LCA relocation brackets
poly torque arm bushing
BMR torque arm relocation bracket
(sfc, phb and sway bars but i don't think they really affect what i'm asking)
i just got the TA bracket for christmas and installed it last nite. spent some time searching/reading trying to figure out the ins and outs of adjusting the Instant Center (can be done with the bracket). however all the information seems to pertain to drag racing, not to mention between the confusing descriptions and faulty information...i can't make heads or tails out of it.
SO...
how does Instant Center pertain to a lowered car, built for spirited street driving and canyon carving?
things i'm still not sure of due to confusing info:
1- on the TA relocation bracket...raising the mounting point does what?
2- for cornering which is better, short or longer IC?
3- assuming everything else is stock, how does lowering the rear affect IC?
4- in drag racing, in reference to tweaking IC, i hear about adjustments that plant the tires quickly, but then "unload" them fast. what does "unload" them do/mean? this is more curiosity, not sure it plays much into canyon carving.
i obviously have several means by which to adjust IC...both with the 2 mounting holes for the LCA-brackets and the TA-bracket.
what really brought this about is that i installed the TA mount in what i'm pretty sure is the stock location...but it is putting the bottom edge of my TA very close to my 3" true dual exhaust. THAT got me wondering what affect...possitive or negative...i would get from raising the mounting bracket one notch. i think that would give me the clearance i need.
but will it adversely affect handling? will it make the car lauch better (not a huge concern)?
as with everyone....i would LOVE to have a car that cuts corners like its on rails AND plants the tires at stop lights.
i realize this is almost impossible...as one does not lend itself to the other.but hey...i can dream right?
When you adjust the setting up or down on the relocation cross member (the second set of holes from the bottom is stock. And adjust the torque arm up in the front will put the arm more center to the intersecting point therefore allowing weight to transfer faster.
And when cornering a lot of Auto X and road race guys go with a full length arm eliminates a lot of brake issues so you have better control into the corners.
When the rear end is lowered it puts your lower control arms in the wrong direction (pointing up in the rear) and moves the instance center to the front of the vehicle which is not what you want. Which this is where you lower control arm relocation brackets come in by allowing you to readjust the control arm to the correct angle.
And when you hear about suspension loading and unloading that means when the weight transfers it loads the suspension therefore planting the rear tires. And if the vehicle unloads it will make the vehicle have traction issues and allow you to put the power to the ground.
I hope this could help you and if you have any other questions feel free to ask or call. I will be in the office until 4:30 EST and if by chance you are still confused it will be easier to explain over the phone.
Thanks
Brad
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01-05-2010, 04:04 AM
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Is the instant centre that is in question be the one regarding the fore and aft ends of the vehicle with regards to acceleration and braking and not the one with regards to the suspension and/or axles of each end? It appears to be since there's mention of a torque arm.
With that mentioned as well as making good use of acceleration and braking for a corner carver, I do wonder has anyone in this thread tried a decoupled torque arm?
Yeah, I know I haven't really answered the OP's question, however if anyone would like to read about this, try looking over at www.frrax.com and look for the threads pertaining to it. They also have a link to the sponsor who manufactures one.
I actually designed my own based upon the information in the Herb Adams' "Chassis Engineering" book. Not really as good as the one mentioned at FRRAX, but it helped me resolve the instant centre problems with regards to acceleration and braking.
With that mentioned as well as making good use of acceleration and braking for a corner carver, I do wonder has anyone in this thread tried a decoupled torque arm?
Yeah, I know I haven't really answered the OP's question, however if anyone would like to read about this, try looking over at www.frrax.com and look for the threads pertaining to it. They also have a link to the sponsor who manufactures one.
I actually designed my own based upon the information in the Herb Adams' "Chassis Engineering" book. Not really as good as the one mentioned at FRRAX, but it helped me resolve the instant centre problems with regards to acceleration and braking.
