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View Full Version : Aftermarket First-gen F-Body A-arm Geometries



MyFriendScott
06-17-2011, 04:48 AM
I'm not sure if I'm saying this the right way, but I noticed that none of the aftermarket manufacturers of A-arms list their product's suspension geometry improvements over stock. Product descriptions list the materials used, and benefits of using their product, such as additional header clearance, less weight, or less shimming for caster/camber over stock. But not one manufacturer makes any comparison over stock A-arms to caster/camber/toe improvements. Why is this?

Surely each manufacturer has done internal testing of their A-arm product, but it seems they're trying to justify the $400-$700 range based on materials used in construction and how strong the lower mounting surface is when a coil-over is used (as an example). Isn't the primary purpose of this product to improve steering angles?

In some ways, I feel the wool is being pulled over our eyes. Manufacturers saw a demand, created a product, but forgot to advertise the actual improvements to steering angles compared to a stock part. I'd like to challenge the manufacturers to include these improvements in their product descriptions. I read the thread about steering angles when using tall upper/lower ball joints, but again, this was performed by a private individual, not the manufacturer.

Manufacturers of A-arms, please share with us how your product improves steering angles/geometries over a factory A-arm. Cam manufacturers share their HP/torque curves, cylinder head and air filter manufacturers share flow characteristics, tire manufacturers share traction characteristics. Getting the point yet? All these products were designed to meet or improve upon a factory design, and their primary purpose is tested and results used in advertising to show improvements or differentiation from other aftermarket manufacturers of the same part. I'm feeling a bit jipped that this isn't the case with aftermarket A-arm products. If your A-arm wasn't designed to address improved geometry, then be transparent and say so. What are you hiding?

And yes, I am in the market for a set of uppers/lowers with coil overs, so I've been looking at products, and will buy when I can compare apples to apples.

Proforged
06-17-2011, 06:36 AM
If an aftermarket control arm is using a stock upper ball joint and a stock spindle, then the dynamic camber is exactly the same as stock. The only way to change the camber curve is by effectively changing the spindle height / virtual ball joint pivot, which can be accomplished with a taller spindle, a taller ball joint, or redrilling the UCA mounts (Guldstrand mod, which can be done with stock or aftermarket upper arms). Some uppers are shorter to add more negative static camber, and some uppers and lowers have a modified ball joint position to add caster (improved high speed stability).

To my knowledge, you have only a few options for control arms that improve the dynamic camber (i.e. improved camber curve):

Hotchkis Upper Arms with optional Tall Ball Joints: http://www.hotchkis.net/tall_upper_balljoint_af_body.html
Pro-Touring F-Body Upper Arms with optional Tall Ball Joints: http://www.pro-touringf-body.com/control_arms.html
SC&C Street Comp Package: http://scandc.com/new/node/28
Any stock or aftermarket arm and order the tall ball joints separately: https://www.pro-touring.com/showthread.php?52891-Power-Performance-Motorsports-tall-ball-joints-for-1st-gen-Camaro-Chevelle

Sorry if I missed any.

silver69camaro
06-17-2011, 07:00 AM
I can see this being a good thing and a bad thing for the manufacturer and the customer. It's good because it gives the customer more information, and if understood correctly, that's a good thing.

But, there is alot of people out there that have no idea what those numbers mean. Take bumpsteer for instance:
Company A has a system (say, UCA, LCA and spindle) that advertises .015" toe-in at 1" of bump. Company B has zero.

Which one would most people buy? Probably Company B's system, because most people believe that less bumpsteer is better. But what the customer doesn't know that the particular vehicle the system was designed for makes good use of the toe-in during bump, as this helps keep the vehicle straight during braking, which may make Company A's product better. See my point? The numbers can be published, but you may not know why the company arrived at those numbers. Was it from careful design iterations, or just because that's where the packaging forced it to be?

So it's not a easy situation for anybody. We have no problem sharing details about our suspension, but you have to ask first - and that's what I would try with other manfacturers.

Proforged
06-17-2011, 08:45 AM
I agree with Matt 100%.

For most customers, the important information won't be exactly what the specs are - bump steer, camber, caster, etc - the important information will be whether or not these are changed from factory specs AT ALL.

There isn't much of a benefit to installing a tubular upper or lower control arm that is just a stronger (heavier) version of the factory arm. The benefit comes from modifying the geometry (if it's done in the correct way). The easiest way for the customer to tell if an arm is using stock geometry (specifically camber gain) is to ask if it uses a taller ball joint or taller spindle. If it doesn't, then it is effectively the same as stock.

MyFriendScott
06-17-2011, 10:03 AM
So this is good stuff. When I started my search for replacement A-arms, I was under the impression that these products alone (without taller B/J's) tried to improve upon stock geometry, at least in static camber through a shorter upper, or better caster designed into either the upper or lower arm. The truth and the facts are finally coming into alignment :P for me. If a manufacturer's design does change the static setting in any way, it would be nice to have this listed in the product description.

As for releasing information that consumers could potentially be confused on, I hear your argument, but think it is the manufacturer's duty to understand their target market and represent the data in a way which those consumers would understand. I don't buy it that the data would lead to more confusion than understanding. Flat panel TV screen manufacturers talk in terms of progressive scan, interlacing, and GHz; their target market understands what these terms mean and can use them to compare product offerings. Those who don't understand ask for help or expert opinion. Relative terms or percentages over stock could be used instead of absolutes. For example, if a lower A-arm was designed to give more static caster than a stock lower, then it could be said the product improves static caster by 25%. I'm not asking for gobs of raw data, but I would like to know if your product is in fact a shorter distance from the pivot point on the frame than factory and why you think that's an advantage over stock. I don't mind calling and asking as long as someone is willing to have this discussion with me without an agreement from me to buy first.

Matt, I do realize that many of your customers are very accomplished racers, and as such, they are very well educated in the area of suspension geometry. I wouldn't think Art Morrison is worried about confusing these buyers. Zack's comment that there isn't much benefit to a tubular upper or lower without a taller ball joint is very enlightening and reinforces MrSuspension's comment about using taller ball joints or spindles to affect geometry.

Perhaps I am (was) the only one with the impression that installing a set of tubular uppers/lowers improved geometries all by themselves. I'm not the smartest guy in the room. So now I can begin my research over again, comparing these products based on qualities other than improving on stock geometry. I've already printed out a few versions of the Gulstrand template as it seems this is an inevitable modification for the goals I've set on my build.

silver69camaro
06-17-2011, 12:12 PM
That's a good analogy about a brand new TV and all it's features and how that relates to the customer. With suspensions though, it's not that cut-and-dry. If you compare two TVs, one will have X and Y features and the other one will not, let's say. Suspensions have much more grey area, some will have more camber gain and the other will have a little less. Does it have less because the engineer (or whoever) decided to add more antidive and therefore had to lengthen the FVSA to make that happen? Why did he do that? What data did he have to support that? How much anti-dive do YOU think it should have? There is no right answer. When you have limitations on any metric of suspension design, it will become a give-and-take design approach. If you want more of one property, you'll have to give up something else. If you want to decrease bumpsteer, you'll have to move the engine back - stuff like that.

Part of where I come from is that we make entirely new suspensions instead of optimizing stock desings within stock packaging limits. I totally get your point on say, a LCA. If it's longer, say how much - and tell me what that does and why I should buy it. If we're talking about, say our bolt-on Chassis for a Chevelle with a start-from-scratch IFS design, that gets complicated.

DarkoNova
06-17-2011, 04:34 PM
Perhaps I am (was) the only one with the impression that installing a set of tubular uppers/lowers improved geometries all by themselves.

No, I was also under the assumption that aftermarket arms improved caster (and even camber, according to some arms' manufacturing claims) all by themselves.

This is kind of surprising to find that without changing the spindle height, it's impossible to change caster/camber, IMO.

killer69
06-18-2011, 11:25 AM
No, I was also under the assumption that aftermarket arms improved caster (and even camber, according to some arms' manufacturing claims) all by themselves.

This is kind of surprising to find that without changing the spindle height, it's impossible to change caster/camber, IMO.

you are correct sort of , some brands (sorry cant say which ones) do say the uca/lca will improve camber gain. like stated above unless the ball joint pin is taller there there is NO camber improvement. Caster is able to be improved when designing the arms, either by moving the upper ball joint back, or the lower forward or a combimation of both..
The BEST camber improvement that can be made is with a taller spindle, second is to lower the inner mount on the UCA ( guildstrand mod) on the A & G bodies it is not very practical to do this mod. and third is a taller ball joint.

We are currently working on the G body platform, and the stock geometry is Horid!! there is no room to drop the UCA inner mount, so the Best improvement that can be made is the AFX Tall spindle, which is taller than the stock spindle and raises the roll center by almost 4 inches. the ackerman and bump steer are also improved altho still not the "BEST" it is all you can do and still have a bolt on design, the other option is to call Matt and order a complete chassis.
Like matt said it is ALWAYS a game of compromises, especially when you don't know the finished ride height. like with the Morrison chassis they know the finished ride height, with a bolt on system yuo dont, and you can only design the parts to be optomized at one ride height either side of that and everything starts to change.

MrQuick
06-18-2011, 10:28 PM
well....nvrm

Proforged
06-20-2011, 06:07 AM
The BEST camber improvement that can be made is with a taller spindle, second is to lower the inner mount on the UCA ( guildstrand mod) on the A & G bodies it is not very practical to do this mod. and third is a taller ball joint.

Blake,

Definitely agree with you that the best option is an AFX tall spindle if it within your budget!

Some things to consider about the Guldstrand mod vs. Tall Ball Joints:

1. The G-Mod is free, which is great, but it's also more or less irreversible.
2. The G-Mod restricts droops travel.
3. Tall Ball Joints are about $100/pair (uppers only, you don't use tall lowers on 1st Gen F-Bodies), which is $100 more than free, but it's also reversible.
4. If you have plans to eventually upgrade to a tall spindle but can't afford it now, Tall Ball Joints are a great short-term option. If you do the G-Mod, you can't use a tall spindle like the AFX spindle.

MyFriendScott
06-20-2011, 06:20 AM
I did another review, this time just capturing the steering geometry claims from the manufacturer only in the comparison. How each product claims to address caster and camber is my primary interest; materials, powder coating and colors, and other product features are left out of this analysis. All pricing was taken directly from the manufacturer's website so YMMV. I've listed the manufacturers in no particular order, and making no claims about winners or losers. I just wanted a reference table of A-arm manufacturers, their claims about geometry improvements, and price.

https://static1.pt-content.com/images/pt/2011/06/Screenshot-1.jpg

When reviewing the table, no one manufacturer has an upper and lower that addresses both caster and camber by design. This is neither good nor bad, I'm just stating the facts. Ridetech used the same wording on the upper and lower product descriptions when talking about caster and camber, so it may appear their uppers and lowers address both, but the product only seems to directly address camber by design (whatever "camber travel is recentered" means). Caster improvement still appears to be a manual process and not designed directly into the product.

BMR's A-arms don't claim to address camber or caster at all. If you want just a tubular A-arm replacement for the lowest price, BMR seems to be a good choice. SC&C also makes no claims about improving caster/camber by design but includes a tall upper ball joint to help improve suspension geometry.

Hotchkis is the only manufacturer that claims to have designed improvements in both caster and camber into their upper A-arm. They are also the most expensive uppers in the group.

DSE and Pro-Touring F-body are the only manufacturers that specifically claim to address caster in their lower A-arm product. No other A-arm that I researched, made any claims to improve caster or camber against a stock part.

So it seems, that if you don't plan on doing a G-mod on your 1st gen F-body, but you want replacement A-arms to help improve suspension characteristics, most of the listed manufacturers make claims to improve either caster or camber, but by how much is unknown. This is what I hope the manufacturers will work toward including in their part descriptions (I know, keep dreaming), otherwise I wouldn't bet on any of them to be any better than stock. Claims do not equal real world results so buyer beware.

Using a taller upper ball joint, or tall spindle, along with dialing in your preferred caster settings during an alignment might still be the best way to guarantee improvement over stock (versus accepting manufacturer claims). Those products with built-in caster may or may not be better for you depending on how much caster adjustment you desire.

If I missed a manufacturer in this comparison, it wasn't intentional. I used the icons on the right hand side of the forum pages to get the list of manufacturers with A-arm products.

killer69
06-20-2011, 09:46 AM
great comparison

bret
06-20-2011, 12:33 PM
Excellent questions and observations! First, I would like to clarify a couple of our terms...
1. Extra caster potential...we move the upper balljoint position back horizontally to allow you to run more positive caster without a huge stack of shims in the front control arm bolt. This extra caster will do a couple of things: increase straightline tracking stability, and increase your camber gain when turning.
2. Balljoint travel re- centered...our systems are designed to ride at a lower ride height than the oem version. If we did not recenter the balljoint position in the middle of it's travel at that new lower ride height, it could potentially exceed it's articulation capabilities and bind the balljoint pin against the balljoint housing. About the third time this happens you experience a catastrophic failure. Never pretty.

It's always important to remember that suspension SYSTEMS are meant to work in harmony with a known collection of parts. Either you know them or we know them. WE know that OUR parts work together correctly. We DONT know if they will interface properly if you choose a different spindle, steering arm, Balljoint, etc. They might...or they might not. The point is, use a complete system. All the manufacturers you have listed make fine products, although we all may reach our intended design criteria via different paths.

Pancakes are good. So is oatmeal. So is bourbon. Just not together.

dhutton
06-20-2011, 01:01 PM
Nice summary. You missed the SPC lower arm that SC&C sells. It has increased caster and some unique features for adjusting ride height.

killer69
06-20-2011, 03:36 PM
Excellent questions and observations! First, I would like to clarify a couple of our terms...
1. Extra caster potential...we move the upper balljoint position back horizontally to allow you to run more positive caster without a huge stack of shims in the front control arm bolt. This extra caster will do a couple of things: increase straightline tracking stability, and increase your camber gain when turning.
2. Balljoint travel re- centered...our systems are designed to ride at a lower ride height than the oem version. If we did not recenter the balljoint position in the middle of it's travel at that new lower ride height, it could potentially exceed it's articulation capabilities and bind the balljoint pin against the balljoint housing. About the third time this happens you experience a catastrophic failure. Never pretty.

It's always important to remember that suspension SYSTEMS are meant to work in harmony with a known collection of parts. Either you know them or we know them. WE know that OUR parts work together correctly. We DONT know if they will interface properly if you choose a different spindle, steering arm, Balljoint, etc. They might...or they might not. The point is, use a complete system. All the manufacturers you have listed make fine products, although we all may reach our intended design criteria via different paths.

Pancakes are good. So is oatmeal. So is bourbon. Just not together.

Couldn't agree more Bret, I would think most of the maunfacturers would adjust the ball joint angles to compansate for the lower rde height, i know we do.
only thing i have to disagree with you on is the fact that you say Bourbon is Good!! lol

DarkoNova
06-20-2011, 06:47 PM
Pancakes are good. So is oatmeal. So is bourbon. Just not together.

ESPECIALLY together!

MyFriendScott
06-21-2011, 04:54 AM
Nice summary. You missed the SPC lower arm that SC&C sells. It has increased caster and some unique features for adjusting ride height.

Thanks. I've updated the table to include SPC's products. As an update, SPC joins DSE and Pro-touring F-body now as manufacturers that claim to directly address caster in their lower A-arm design. Actually, SPC is now the only manufacturer I've been able to find that provides a value for how much their arm changes a factory setting.

j-rho
06-21-2011, 10:22 AM
The SPC adjustable upper arms are the only off-the-shelf suspension part I'm using on my whole car. Mainly, because they're adjustable.

Would be nice if somebody offered a similarly adjustable LCA, including a threaded spring perch for standard diameter springs. Might have to locate the adjusters outboard of the spring cup to keep the spring itself from sitting at weird angles, which would/could make the arm a bit more expensive to design and manufacture.

killer69
06-21-2011, 11:41 AM
i would be curious to know what adjustments you are planning on making with the SPC UCA?

MyFriendScott
06-21-2011, 11:48 AM
Table updated again to include the Alston Chassisworks A-arms. In reviewing their A-arms, I think they are missing an opportunity to provide a better description of their product.


Would be nice if somebody offered a similarly adjustable LCA, including a threaded spring perch for standard diameter springs. Might have to locate the adjusters outboard of the spring cup to keep the spring itself from sitting at weird angles, which would/could make the arm a bit more expensive to design and manufacture.

I'm going to guess and say that you don't see adjustable LCA's because of the tensile and compression forces applied to the LCA compared to the UCA. A threaded stud as part of the LCA design, could be a very weak point of failure.

A few of the LCA's offered, do have adjustable or rotating spring cups to allow ride height adjustment and/or to account for springs that have been cut. I did note that in the table.

Nessumsar
06-21-2011, 01:36 PM
I'm going to guess and say that you don't see adjustable LCA's because of the tensile and compression forces applied to the LCA compared to the UCA. A threaded stud as part of the LCA design, could be a very weak point of failure.

I don't see any problems with making an adjustable LCA. Using a heim joint (or something similar) in place of the existing bushings would allow for enough adjustability, given the arm is designed with this in mind; and it wouldn't be any less strong.

j-rho
06-21-2011, 03:43 PM
The problem with lengthening the arm inboard of the spring mount point, is you put the base of a spring at a funny angle in relation to the upper spring perch.

There are ways of providing adjustability outboard of the spring seat, it just isn't as simple as threaded heims. The Porsche 996 GT3 does this from the factory with a 2-piece LCA, where you can insert varying-width shims between the two pieces, to alter LCA length. Caster is a bit trickier (in the GT3's case the longitudinal location is handled by a separate link with its own adjustment) but there are ways to do it, with machined blocks with varying amount of longitudinal offset built in.

MyFriendScott
06-21-2011, 07:34 PM
Ah ha! Going back as far as 2006 and the sticky discussion about "what do sub frame connectors really do...", the following comment was made on post #70 by SN65


It is interesting to me that no one publishes any test data on their structural modifications. Everyone and their brother (or sister) makes a subframe connector, but no one publishes any data on what the actual improvements may, or may not, be.

When dealing with a group of car fanatics who will pay thousands and thousands of dollars to improve performance in any way shape or form, you would think that testing and publishing the data on chassis modifications would be a no brainer.

This is exactly what I'm talking about--the marketing-speak, limited to non-existent data provided to support claims about improvements over a stock design or performance. I've recently gotten back into hot rodding, car crafting, call it what you will, but is this the state of things now? Are we all grown up with money to blow, willing to pay for products that only claim to function better than stock, but use no supporting data to prove it? I'm not trying to shake up the industry, I'm just trying to be a well-informed buyer before I spend my hard-earned money. And I'm trying to understand why it is I should buy this part instead of that one. Maybe I stand alone, but I can just as easily find other things to spend $500 on, than a car part that I can't point to a data point and say, "See, this is why I replaced the factory part with it."

I think it's coming down to an understanding now that without a taller upper ball joint or spindle, or the G-mod, no aftermarket A-arm is going to make ANY improvements over stock on dynamic camber. All the A-arms can do is change camber and caster static values. So is gaining a degree of caster at ride height really worth $500+? Is having a rotating spring cup in a LCA worth $650+? Personally, I don't need the weight savings that tubular A-arms give, additional tire clearance for 275's up front, or 8 degrees of caster, so it's clearer to me that a set of tall spindles is more effective and equal to, or less than the price of a pair of UCA's and LCA's. Pozzi's discussion on the Power Performance tall upper ball joints showed improvements over stock dynamic geometries, and these are what, $50 ea? And of course, the G-mod is still....free.

Hey, if I'm way off here and not getting something, please let me know, otherwise the A-arms are getting crossed off my Christmas list.

killer69
06-21-2011, 08:30 PM
Ah ha! Going back as far as 2006 and the sticky discussion about "what do sub frame connectors really do...", the following comment was made on post #70 by SN65



This is exactly what I'm talking about--the marketing-speak, limited to non-existent data provided to support claims about improvements over a stock design or performance. I've recently gotten back into hot rodding, car crafting, call it what you will, but is this the state of things now? Are we all grown up with money to blow, willing to pay for products that only claim to function better than stock, but use no supporting data to prove it? I'm not trying to shake up the industry, I'm just trying to be a well-informed buyer before I spend my hard-earned money. And I'm trying to understand why it is I should buy this part instead of that one. Maybe I stand alone, but I can just as easily find other things to spend $500 on, than a car part that I can't point to a data point and say, "See, this is why I replaced the factory part with it."

I think it's coming down to an understanding now that without a taller upper ball joint or spindle, or the G-mod, no aftermarket A-arm is going to make ANY improvements over stock on dynamic camber. All the A-arms can do is change camber and caster static values. So is gaining a degree of caster at ride height really worth $500+? Is having a rotating spring cup in a LCA worth $650+? Personally, I don't need the weight savings that tubular A-arms give, additional tire clearance for 275's up front, or 8 degrees of caster, so it's clearer to me that a set of tall spindles is more effective and equal to, or less than the price of a pair of UCA's and LCA's. Pozzi's discussion on the Power Performance tall upper ball joints showed improvements over stock dynamic geometries, and these are what, $50 ea? And of course, the G-mod is still....free.

Hey, if I'm way off here and not getting something, please let me know, otherwise the A-arms are getting crossed off my Christmas list.

i think also you are missing some or the other benifits, Delrin bushings, stronger tubing, better materials, non 40 year old steel, adjustable steering stops, better quality control. it is like saying that i am not going to spend any money on better sway bar bushings, when ill bet if you did you would notice an improvement, even tho you didn't change any geomery. or even the sway bar.

if your not going to put 275 up front or run 8 deg of caster ( which is too much by the way) then you don't need tall spindles either? you can cross them off your list as well.

Can a really well prepared car with OEM components perform well? YEA but the car shown on the first page is a RACECAR, that has had hundreds of hours of testing and prep and modifying.
Ask David Possi how many hours he has working on the stock front sub frame in OneLapCamaro?

i will just guess..........300. and they use tubular control arms?? and i know it has been through at least 4 different variations.
one lap was over 5 seconds slower (that is with 2 very competant drivers i am not bashing either or the car just stating facts)than my Nova at RTTC and it has 150-200 more HP.

j-rho
06-21-2011, 09:02 PM
I think it's coming down to an understanding now that without a taller upper ball joint or spindle, or the G-mod, no aftermarket A-arm is going to make ANY improvements over stock on dynamic camber. All the A-arms can do is change camber and caster static values. That's not exactly true - an upper arm with a shorter length, will increase dynamic camber gain once it's above parallel.

DarkoNova
06-22-2011, 03:33 PM
i think also you are missing some or the other benifits, Delrin bushings, stronger tubing, better materials, non 40 year old steel, adjustable steering stops, better quality control.

I'll be the devil's advocate here, I guess. Why would "stronger tubing, better materials, non 40 year old steel, adjustable steering stops, and better quality control" even make a difference if the arms are in good condition? Assuming there's no flex in your stock arms, the only thing I'd bother with is Delrin bushings. Other than that, it really does seem like aftermarket arms, at least lower arms, are unnecessary.

Also, not to nitpick, but stronger tubing, better materials, non 40 year old steel, and better quality control basically all mean the same thing. Sounds a bit like padding the list of benefits. ;)

killer69
06-22-2011, 07:24 PM
I'll be the devil's advocate here, I guess. Why would "stronger tubing, better materials, non 40 year old steel, adjustable steering stops, and better quality control" even make a difference if the arms are in good condition? Assuming there's no flex in your stock arms, the only thing I'd bother with is Delrin bushings. Other than that, it really does seem like aftermarket arms, at least lower arms, are unnecessary.

Also, not to nitpick, but stronger tubing, better materials, non 40 year old steel, and better quality control basically all mean the same thing. Sounds a bit like padding the list of benefits. ;)

"IF THE ARMS ARE I GOOD CONDITION"
how will you know if there is flex in your old arms? are they bent? twisted?
i guess you can save 500.00 bucks then??? it's up to you.
we could take the customers factory arms and test them and if they don't flex and arn't 30% rusted away and the ball joint mounting isn't distorted due to being change 10 times, then replace the bushings, and ball joints, again, weld on some adjustable steering stops sandblast and powdercoat them and ship them back??? probably only cost ........... 500.00 i guess at some point you have to decide if new parts are worth paying for??

Rod
06-22-2011, 09:39 PM
lets see if any of this helps, its all just seat of the pants over the last year of tuning my camaro from its restored stock configuration, and after each change and some SCCA events along with some goodguys peanut tracks thrown in and Daily driving here is what I have noticed

1, Hotchkis TVS kit = stiffer better riding car, corners better than stock, but still wanders on the freeway, pushes around corners lightly(removed rear sway bar no push after)
2, AGR 12:1 = box smoother steering response, little less wander
3, Global west upper arms = faster turn in into corners
4, tall upper ball joint = less bump steer, not as noticeable on small tracks, better on large tracks and freeway
5, DSE lower control arms = less tracking sensitivity, almost no bump steer, smoother corner exiting under acceleration

also after the AGR addition hotckis sub frame connectors and global west solid frame bushings were added and the entire car felt tighter (more road feel) than before under normal use

TBART70
06-24-2011, 06:21 AM
Not that I know how to drive a race car or autocross to the limit, but even for the street which my car is. I felt that having better quality than stock would make a noticeable difference in the way the car drove. I have had my 70 Camaro for 23 years, about 15 years ago I lowered it, put in urethane bushings, better shocks, lower profile tires and aligned it to the best street specs I could get with stock stuff. It really made difference in the way it rode and drove, it made it more fun to drive. I have used the SPC stuff on a Chevelle, I don't like the adjustable uppers, I think it caused more issues than good when I tried to align it, although I haven't touched it since. I purchased the whole Speedtech front suspension coilover conversion for my 70 Camaro recently, wow how nice is the quality of the parts. It will be a long time before my car is done so I can't say how it will perform. ( I'm not worried ). But just seeing the difference in quality compared to stock is amazing. I was using an aftermarket chassis (never drove it) that I modified and came to the grim realization of the lack of quality in this particular setup ( including all of my own fabrication ). There is something to be said for proper R&D and a engineer behind the parts. The stock stuff is fine if you don't want to or can't spend the money, but there is a difference in it, will I ever find the limit of my car if I had stock stuff, no way dude. I felt that if I was going to do this build I would try to get good stuff now. You can always upgrade later. You don't have to do it all, just some small changes make them so much better to drive. You can buy new stock stuff and upgrade them or upgrade stock, but by the time yo are done with blasting, coating, labor and parts I can see the cost being up there, maybe not exactly as high but close.

MyFriendScott
06-27-2011, 05:16 AM
I appreciate the seat-o-the-pants feedback. I don't doubt that with lots of other suspension changes, comes better than stock handling. What I'm after however is the actual suspension geometry differences (be it static or dynamic) between an aftermarket tubular A-arm compared to stock. There are other improvements versus a stamped A-arm that aftermarket arms provide, I am aware, but that wasn't the focus of my interest.

Put very simply, the question was, "What are the design differences in camber and caster on an aftermarket arm compared to factory?" After collecting each vendor's description, it was clear that only one vendor actually listed the difference in numerical value. The rest did not list any differences. Why is this important?

Before I started this thread, ask yourself if you were under the impression that aftermarket A-arms improved suspension geometry in some way. Now, based on the descriptions given by all but one of the A-arm manufacturers, by how much do the arms actually improve on these geometries? It's a crap shoot. So either you're going to spend your money buying an A-arm for the other benefits listed by the vendor, or you're gambling with your money that what you end up with matches your belief. And most of us don't have a setup to measure before/after suspension geometry anyway, so we may all remain happily ignorant of any changes at all and several hundred dollars poorer.

Marcus SC&C
06-27-2011, 10:08 AM
MFS, nice thread. There`s a lot to cover here but the basics are pretty simple. Like the guys said already A arms are capable of allowing different amounts of static alignment and they can be tweaked to allow for better travel without binding at lowered ride heights etc. You can`t make major geometry changes with them, any of them, because the pickup points of the suspension define the geometry. A arms don`t define the pickup points, the pickup points define the A arms. The A arms just connect them together, so while they play a very important role (try driving your car without them!) it is a *supporting role* to the pickup points lead role.
Still the better companys try to gain every edge possible. The SPC UCA for example take the lead from many modern cars and do away with shims. Larger adj. range and less compromises at a lower price point, I think they`re just about a no brainer. The SPC lowers were the first line of arms with improved geometry for wheel/tire fitment at high + caster settings. You can call that added caster if you like but with SPC UCAs we can get all we want and more without having to alter the lowers so it was really done more for improved clearance. We built adjustable ride height into them because it was always a big issue and traditionally you needed coil overs or air suspension to easily adjust the ride height. Now folks can do it with conventional coil springs.
Moving the pickup points is where we can really make some BIG gains in these cars (where the stock geometry is often totally backward). This is truly re-engineering the car not just tuning a poorly engineered system.
A few updates to your chart (nicely done BTW). You listed SC&C UCAs but at that price point it would be a StreetComp Stage 1 tall ball joint package with UCAs not just A arms alone. We also offer a Stage 1-Plus, 2 and 2-Plus all based on tall and X-tall ball joints. The 2 and 2-Plus also include bumpsteer correcting tall tie rod ends. These are all high end CNC machined,
modular ball joints not just taller versions of OE ball joints. We were the first company in the industry to apply tall ball joints to muscle cars for geometry correction. The rest are following our lead. I`m not bragging, just sayin... :)
Honestly although the chart is a cool idea you`ll find that all of the better arms do more of less the same thing, help the car achieve a better static alignment and better fittment at lowered ride heights. Some will be formatted differently to work with the geometry of taller spindles / ball joints. There`s just not much more they *can* do. It`s simple nuts and bolt geometry, any marketing to the contrary is just marketing. Mark SC&C

TheBandit
06-27-2011, 11:04 AM
Marcus, your website/e-shopping is tough to navigate. Can you point out how your arms (lowers I assume?) allow for adjusting ride height with conventional coil springs? Is this via spacers or is it like an AFCO/Landrum threaded adjuster? Maybe a link to your product would be helpful - I just can't find it navigating the site lists.

bret
06-27-2011, 12:12 PM
Marcus has written an EXCELLENT book on How to Make Your Musclecar Handle. There is a section that addresses this very subject very nicely. I highly recommend it. Its on Amazon and his website. It could easily be a roadmap for those who want to modify their own suspensions at little or no cost to affect significant performance gains.

Now, why do manufacturers make tubular control arms? Simple...most people do not want to do the level of research, developemnt, and testing neccessary to acheive these kinds of performance gains. That is why they pay us to do it. The same principle applies to me buying crate engines...I'm not an engine guy...or a transmission guy. However, I throroughly applaud those who are, and support any efforts for a hotrodder to dig into why something works [or doesn't] instead of just bolting stuff on. Those guys make better customers.
So, why not publish some detailed dimensions and alignment data? No reason really. In print, real esteate is very precious and this level of data would confuse and scare MOST customers. [obviously not this crowd!] On the web however, no reason to not publish this. I will try to dig some of this stuff out of our engineering notes and see what might be relevant.

Good thread!

dhutton
06-27-2011, 03:19 PM
Marcus, your website/e-shopping is tough to navigate. Can you point out how your arms (lowers I assume?) allow for adjusting ride height with conventional coil springs? Is this via spacers or is it like an AFCO/Landrum threaded adjuster? Maybe a link to your product would be helpful - I just can't find it navigating the site lists.

Spacers.

Marcus SC&C
06-28-2011, 07:22 AM
Clint, there`s an article on setting ride height with SPC lower A arms right on top of our homepage or if you click on SPC and scroll to the LCAs or just type in "SPC lower arms" in the search box it will take you right them. Click on the video and you can see how the shims work. It`s super simple and really effective. We tried threaded seats but it`s too hard to get at them and changes are much harder to quantify. With the shim set up 1/4" spacer equals 1/2" of ride height, two of those equals 1" etc. so all you have to do it measure, decide how much you want to change it and put the right number of spacers in, once and done, instead of fiddling with threaded adjusters all day.

Bret, thanks for the kind words. It means a lot coming from you! I believe good companys with sound engineering don`t have to use marketing smoke and mirrors to sell their products. The purpose of the book was to give people a solid understanding of the basics,the issues that some of the cars have and the tools to make well informed decisions on how to fix those issues and tune them for best performance. I was totally shocked at how many companys flat refused to be in the book because they didn`t want anyone to take a hard look at the design of their products! Mark SC&C

bret
06-28-2011, 12:14 PM
Clint, there`s an article on setting ride height with SPC lower A arms right on top of our homepage or if you click on SPC and scroll to the LCAs or just type in "SPC lower arms" in the search box it will take you right them. Click on the video and you can see how the shims work. It`s super simple and really effective. We tried threaded seats but it`s too hard to get at them and changes are much harder to quantify. With the shim set up 1/4" spacer equals 1/2" of ride height, two of those equals 1" etc. so all you have to do it measure, decide how much you want to change it and put the right number of spacers in, once and done, instead of fiddling with threaded adjusters all day.

Bret, thanks for the kind words. It means a lot coming from you! I believe good companys with sound engineering don`t have to use marketing smoke and mirrors to sell their products. The purpose of the book was to give people a solid understanding of the basics,the issues that some of the cars have and the tools to make well informed decisions on how to fix those issues and tune them for best performance. I was totally shocked at how many companys flat refused to be in the book because they didn`t want anyone to take a hard look at the design of their products! Mark SC&C

Its just the truth on my end...I liked the book so much I bought all my sales guys a copy. No one has done a better job of explaining this stuff in plain english. My only suggested revision for the next edition might be to include some of our new shocks:):):)

Ishmael
06-28-2011, 07:03 PM
Good thread. Thanks.

MyFriendScott
12-09-2011, 07:20 AM
I've updated the table of manufacturers and claims for 1st gen control arms. The latest control arm info added covers "SRD Parts".

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