Has anyone recorded roll center heights for modified stock suspensions as well as the aftermarket suspensions. It's interesting especially with the aftermarket suspensions that none of the advertising explains what the benefits may be. Making an informed decision is important when spending thousands on mods. Roll center, camber curves, caster curves and toe changes are important specs when choosing what is best for your application.

You'd think the aftermarket people would be able to easily provide that info, they already have all the dimensions and theoretically already did the math.

However, I suspect that with very few exceptions, most aftermarket "performance" suspensions, MII based, it's hype not performance they are selling.

I plotted out my stock suspension years ago, but that's it.

Most folks aren't that into the info. They are much more impressed by results and don't really care to get that detailed in the means.
That siad, if you spent a year in R&D developing a product, do you really want your trade info out to the public? Does KFC post their recipe for extra crispy chicken on the web? The formula for Mountain Dew? Chryslers Encryption Software to write to newer ECU's?
I've worked on a couple RMS cars and test for products from other companies and run the numbers. I could fix all of them, but I wouldn't tell them for free.
The only company that has done the homework and got it right- Hotchkis.

Reverse engineering the data is not hard, unlike the recipe for KFC or your other examples. Fixing it isn't hard either, well not at the design stage, who knows how hard a retrofit would be.

I think XV probably got it right too, have you tested any of their stuff?

http://www.onedirt.com/tech-stories/susp...ar-roll-center/


Years ago a buddy of mine made the transition from autox to road racing. He had to totally re-think his chassis approach. He was going to run a 69 MG roadster. I remember him setting up everything in his shop to make the calculations

Some one reverse engineering a product is always a possibility, and someone could do the same with my examples, if they have the inclination or talent. But if they have the ability to reverse engineer it, then they probably could have designed it themselves. And a copy of the product through jigging would be pretty obvious.

As to XV, Only their old Level 1 stuff and their current run of chassis "stiffening" products. Wasn't impressed with either.

I've plotted my Challenger out in its current configuration and played around with varying size control arms, spindles, and other attachments to see the changes. I've got all the roll center static and dynamic points along with camber, caster, and toe curves. Somewhere I still have all the older ones I did when I was running brand C and F cars as well.

I've never bothered to do anything with aftermarket set ups because I've not considered buying them and am not concerned with how they compare. Not only that, but I'd suspect they won't readily share this info with most of us, even if asked. I'd certainly suspect they all have it since they need these data points to formulate their set ups.

While I'm sure there are a small % of drivers who want some very detailed specs of their systems and will seek to further improve them beyond what they received, I believe the vast majority only care that they have something "modern" and "better" because they don't believe that something 40 years old is superior to something made in the last decade.Currently, there are only 4 ways to suspend a car, coil, leaf, torsion, and air, and all we can do is modify the geometry imparted on those four methods.

I purchase DSE products for shop work for many cars we've done. The specs for their systems are right on their site...

Does DSE even make mopar specific stuff, I couldn't find a listing.

I do see a bunch of specs though.

DSE doesn't make Mopar specific stuff at this point. Their charger at sema used gm based parts

I know DSE doesnt make mopar parts but that's not point.

Point is I was hoping to see what they had for us so I could look it over and compare, but it's not applicable.

I hear NASA makes some awesomely scienced out stuff too, but it's also not applicable.

I've prodded for some of this information from manufactures over the years and never seem to get anywhere. I would like to see the specified improvements quantified. If nothing else it'd show me someone, somewhere was doing some kinematic analysis and not just shooting from the hip or looking at just one or two variables.

"Reduced bump-steer!"

...ok, cool. How much are we talking? 0.001"? Or 0.100"?

So how bad is .100" ?

Is that over 3" of rebound or jounce? 0.100" is less than 1/8".

1/8 of movement/turning of the spindle is a lot at the tie rod end, probably 3/8" of movement of the tire back and forth...that is more than I would like to get in my b-body

I think the point was that the claims of improvement are not specified and there is no way to find out short of buying, installing and testing on your own.

I also strongly suspect that there is way too much before/after claims made with the before being a wore out unrebuilt 50 year old factory installed suspension against a new aftermarket one. Well duh there will be an improvement.

Reminds me of an aftermarket cylinder head manufacturer we all know that claimed in magazine ads years ago a large HP increase over factory heads.

In the fine print you found out that the factory heads were stock 305 heads and they were tested on a 350. No [censored] the aftermarket head was an improvement on a 350, you were choking it with the 305 heads. Technically, and probably legally, a factual claim but not accurate. But at least they put it in the fine print. Same can't be said about a lot of aftermarket manufacturers.

1/8" of movement is a lot at 3 inches of compression?

Think about what is going on a 3" of compression....low speed high G corner... The spindle will be at a high turning angle and straight line bump steer doesn't apply much.

The two measuring points on my commonly used bump steer gauge are 16.5" apart. A typical tire is 26".



I showed my results shown below with a guy that crew chiefs K&N Pro Series championship cars and full time designs and builds his own multi track championship cars. 1/8" of bump with the same style gauge I used at 3" is still good and he said don't mess with it. He did say 1/16" would be very good. Of course we're talking cars set up for handling. Not Drag cars.

Getting .001" at jounce AND rebound at 3" is nearly impossible. That's not reality if you've ever did this or did it regularly.

Correct, that is what I was going after. Thinking at all into the numbers I posted is a waste of effort, they were completely arbitrary.

I'm sure there is a slim number for those that are actually interested in the details. The primary mode of marketing I see is pretty far dumbed down, something along the lines of, "We race our car. Look, it's fast! Yours can be fast too! Buy -our name- parts!"

Some of these numbers you may not want your competitors all knowing, if you are a suspension component manufacturer. A fine line I'm sure. I suppose it comes back to making the case as a reputable manufacturer and showing what development goes into the car, like XV tried to do. Hotchkis tries to show theirs through their Challenger, the volume of builds they do, the number of vehicles they support, etc.

I dunno, seems to me they could take a stock vehicle, by stock I mean rebuilt to factory stock not a worn out vehicle, test it. Then install their stuff and retest WITH the same tires and rims as the before. Bumpsteer, ackerman, skid pad, G's and maybe braking distances could easily be gotten and not give any proprietary information away, which wouldn't be proprietary long anyway, it can be reverse engineered for the price of buying one setup.

Or one could use an existing known performer, Tom's Valiant comes to mind, and use it to test the new setup in a before/after comparison. Probably a reason some don't do it.

How much wheel travel do you have with your set up?