A few things
First, if customer service is based on forum activity, consider this forabodiesonly, forbbodiesonly, forebodiesonly, bigblockdart, moparts, lat-g, pro-touring, dodgecoronet, cuda-challenger, protouringmopar, yellowbullet, facebook-personal, facebook-rms, twitter, instagram, google+, mymopar, moparstyle, linkedin, and on and on, with more popping up every day. Add in a jillion emails and phone calls and I think youd agree that maintaining a presence on forums is impossible. Facebook messaging and regular email are two methods to reach me anytime Im not asleep if you have a problem, I think thats pretty good customer service. In addition, there are three topics that almost always devolve into a fire storm cylinder head air flow numbers, manifold or ported vacuum advance, and front suspension geometry. Getting into these battles is unproductive and time consuming when, in the end, it usually yields nothing for all involved.
Someone mentioned Pro spindles are much lighter. This is false.
Wilwood Pro, RMS, and stock MII spindles are all the same, a squeak over 8lbs each.
Instant center and roll center are both raised by a taller upper pivot, not lowered as I read here somewhere.
As the stance goes up, so does the roll center. Raising the upper pivot point only raises the RC further. This creates a geometric roll resistance, but leads to unpredictable jacking in a corner, which can be unsettling. Far better to keep the RC low and use sway bars to control roll resistance. In theory, behavior changes as the RC goes above and below ground, because the effect of the pendulum changes direction - RC left above ground becomes RC right below ground. But even in professional racing its debatable how much is gained or lost by this. In hobby racing and street cars its barely worth mentioning, but it is fun to think about.
Changing the upper pivot point does in fact change bumpsteer geometry. Bumpsteer has nothing to do with the lower arm and the tie rod being parallel. The reason unequal length IFS has bumpsteer is because it causes the spindle to travel in an elliptical pattern, while the tie rod swings in a perfect radius. Changing any pivot point will change the shape of the elliptical pattern, which requires changing the position of the tie rod on the arc to maintain minimum bumpsteer in the useable range. Not changing it will create a completely different bump curve. Caster settings also change the bump curve, so a bump curve is designed at a particular caster angle, any other caster angle and the curve also changes. Even 1/16 height change in the pivot can change the bump curve, but it is minor and if the bump curve is really good, those small changes will still be well inside the acceptable range. But if the curve is questionable to start with, small changes can move the curve into the red.
As for a chart, image attached. This was measured at 6 degrees caster. For reference, second image is ½ raised upper, all else the same. Probably just fine, but definitely increased and definitely different.
Last thing about bumpsteer far too much attention is paid to bumpsteer and not nearly enough attention to other matters. If you have a drag car one that really is only for drag racing and nothing else, bumpsteer is as far as you need to worry about. But for the other 99.9% of the cars on the planet, If you have 15 rims and big fat BFGs, you can easily stand ½ of bumpsteer without even noticing the tires flex so much it makes no difference. While its best to have nice angles for everything, even the OEMs typically have well over ¼ of bumpsteer my 06 SRT8 Charger has .375 total bumpsteer even with Nitto Invos on 20s you cant tell and nobody questions how these newer cars handle. But on aftermarket suspension bumpsteer is all the rage, yet no one ever seems to wonder where the RC is, or what the ackerman error is, even though they are far more important items to consider in a street car with spirited cornering.
By cranking up preload on a coil over, you change nothing. Preload only serves to require more weight before the shock begins to compress which means it wont compress as far with full weight on it, which is just another way to say it raises the ride height. The effective spring rate, and ride quality remains unchanged.
Having a level lower control arm is also an old wives tale. It's an easy way to minimize bumpsteer and other problems in a suspension that isn't quite right. But if it IS right, the arm angle doesn't matter much within reason. As for camber gain, you only need to have X amount, there are a number of ways to achieve it, so the combined arm angles merely need to satisfy your gain requirements, not necessarily be at a particular angle. But because the arm angles also dictate a number of other functions, you often have to settle on the best balance between them. Getting too perfect with one angle may have a detrimental affect on another, and even though the numbers are perfect for one aspect, the suspension may have some quirky behavior because of some other aspect thats too far out. Shorter control arms also cause excessive angle changes and too much track width change, which also can cause mysterious behavior. Theres no set number as to what is too short, merely the shorter they get the more likely a problem will arise, so its best to keep them as long as physically possible.
Speaking of track width, like wheel alignment, its measured at ride height, not with the wheels hanging down. And depending on the needs, there are a bunch of brake kits. Baer brakes all have about 58.5 on an A-body RMS kit, as do the smaller Wilwoods with a zero offset. 13 and 14 Wilwood are all basically 60, and I also use smaller Wilwood kits with this 60 track for certain wheel requirements. I prefer the 60 versions on my own stuff, as its cheaper to get 18 wheels with a higher offset. There are plenty of cheap brake kits out there using basic auto parts, some have custom hubs that usually run zero offset, while others use a Ford Granada rotor which is +0.25. Prior to 2007, I used a wider track width to accommodate air ride because of demand that the system fit either air or coils. By late 07 I discontinued air ride and moved the track in. I ended up shortening the arms on a number of those earlier ones to the later specs if they called me about it. Theres no way to help someone I dont know about, so if they prefer to just complain on the internet theres not much I can do. So stories of too wide of a track have been inaccurate for 8 years now. Maybe by the time I retire those stories will fade away.
And while Im not saying anyone else is wrong, Ill tell you that modifying spindles is not easy or cheap, and neither is making custom adjustable tie rod ends. Disallowing 15x7 or 8 rims is also a big pain. If there was a way to use stock items with a front rack, while maintaining proper geometry and stock engine height, I would do it in a heartbeat. But all of that is not possible in a Mopar. Chevys have the engine higher above the suspension and slightly further back, allowing a higher rack height under the oil pan. Mopars do not. And raising the engine is out of the question. Most customers I have already need 3 or 4 hoods because the engines are so tall, if the engine was higher than stock these guys would need cartoonishly tall scoops. Some guys have regular engines under a stock hood, but most are not.
If it was for my own car just for fun it might be possible to skimp on the geometry to allow some other things, but when people pay thousands, they expect it to be right on the money for a particular use and they expect me to stand behind it. Some customers are running standing mile at well over 200mph, others are stunt drivers that need to make repeatable maneuvers without wasting expensive camera time. Others yet are road racing in France or Poland or some other far away place. These people will not stand for compromises of any kind and many of them want the data to back it up before theyll order. So if I use a more complicated method to make something, its for good reason.
In the end though, people will make what they like and others will buy what they like so I dont really push trying to convince people. You have to buy what makes you happy. It is just a hobby after all.
IMHO
