2nd gen f-body aftermarket sub frames

[a73formula]

I read somewhere that these are out now for the 2nd gens with the rack and pinion steering and they lower the car 2"s but I can't find the article. Does anyone know who is making these and possibly have a link or # to reach them.

Thanks

[TLWiltman]

Martz chassis has one
Lateral-Dynamics is working on one
You'll probably get more info using the search function
Good Luck

[a73formula]

thanks

[Skip Fix]

One of the Pontiac guys got one that used Corvette A arms, not sure if it used rack. Trev is his name. Pretty slick 77/8 black TA . Was in High Performance Pontiac a few months ago. I'll see if I can dig up who made his.

[Skip Fix]

Here's a thread on it.

http://forums.performanceyears.com/forums/showthread.php?t=401701&highlight=subframe

[Mean 69]

You might wish to think twice about a replacement front frame and suspension, or at least wait a short while before you make the final decision. We (Lateral Dynamics) are developing a kit that should really transform the performance behaviors of the second gen's, utilizing the stock frame.

The general consensus is that the second gen suspension is "good" in stock form and that all you need to do is add some good springs, shocks, and a decent sway bar. Not necessarily the case, these changes in themselves will have a really big positive impact, but some small geometry changes really wake things up for these cars. Unfortunately, due to the configuration of some of the stock components, it's really difficult to do so.

We are in the process of building prototype parts for this application, including tubular control arms that allow changes to the fundamental geometry, as well as being FAR superior pieces overall to the stock or currently available aftermarket offerings, and other necessary pieces. The setups will use todays really good steering box systems rather than a rack and pinion approach due packaging issues with trying to get the rack in the correct position. If you haven't driven a car with a performance power steering box arrangement, don't scoff, they are really terrific these days and you wouldn't know the difference between the feel of them relative to a rack in most cases. We have very high expectations for this setup, so high in fact, that on my own 70 Camaro project car that is well into the build cycle, we changed plans to use the stock modified frame rather than to complete the completely custom unit that is also currently under development.

For you techie types, the specifics of the second gen geometry that are being addressed are primarily camber issues, caster issues, and perhaps most importantly, roll center migration. In the stock form, the roll center moves laterally far too much for our preferences. By altering the position of some pivot points, slightly, this aspect is greatly improved dynamically. In addition, the ever popular "negative camber gain" on the stock suspension is not nearly as aggressive as it needs to be to make today's tires perform at their potential, the same changes to the pivot point locations, as as well as some static design changes to the geometry of the upper control arms dramatically improve this aspect of the behavior. That's not all by any means, but these are perhaps the two most important areas we addressed.

Thanks,
Mark

[Skip Fix]

Mark if you can get more caster WITH more negative camber that would be great. About 3+ caster and 1.5 neg camber is all I could get when autocrossing with roadrace slicks.

700lb/in front springs, 1 1/4" front factory bar, good WS6 non variable ratio steering box. Factory rear springs 5/8" rear bar. My car was pretty neutral then and no brake dive/unload rear tires in a corner like softer springs in the front and bigger bar did.

[Mean 69]

Both of those will be no problem with the setup. But, we feel pretty confident that you'll be able to run a bit less static camber and still get the same stick in the turns with the other modifications we are making to geometry. Once we get the prototypes fitted up and insure there are no unforseen clearance issues, I plan on posting the differences in the geometry via a WinGEO suspension model overview. It should be very nice.

Thanks for the input, the specifics you posted seem very much in line with what we are thinking as well (spring rate, sway bar, etc).

Coil-overs, anyone?
Mark

[TLWiltman]

Mark,
Are you still planning on clearing a 295-315 tire with the stock frame?

For specifics, my thought is along the same line as skipfix.
-750# front springs (or equivalent wheel rate w/coil-overs)
-matches with about a 225# rear spring
-3-piece splined sway bar (in a commonly used spline and length. I think 37" is standard for a front-steer car.)
-Adjustable steering stops?

All I have time to think of now... work beckons. I still need to get up to Calsbad to see the goods. Next Thurs/Fri are about as good of a chance as I'll get (Going back to Wa on the 25th)

[Slow Ride]

You might wish to think twice about a replacement front frame and suspension, or at least wait a short while before you make the final decision. We (Lateral Dynamics) are developing a kit that should really transform the performance behaviors of the second gen's, utilizing the stock frame.

The general consensus is that the second gen suspension is "good" in stock form and that all you need to do is add some good springs, shocks, and a decent sway bar. Not necessarily the case, these changes in themselves will have a really big positive impact, but some small geometry changes really wake things up for these cars. Unfortunately, due to the configuration of some of the stock components, it's really difficult to do so.

We are in the process of building prototype parts for this application, including tubular control arms that allow changes to the fundamental geometry, as well as being FAR superior pieces overall to the stock or currently available aftermarket offerings, and other necessary pieces. The setups will use todays really good steering box systems rather than a rack and pinion approach due packaging issues with trying to get the rack in the correct position. If you haven't driven a car with a performance power steering box arrangement, don't scoff, they are really terrific these days and you wouldn't know the difference between the feel of them relative to a rack in most cases. We have very high expectations for this setup, so high in fact, that on my own 70 Camaro project car that is well into the build cycle, we changed plans to use the stock modified frame rather than to complete the completely custom unit that is also currently under development.

For you techie types, the specifics of the second gen geometry that are being addressed are primarily camber issues, caster issues, and perhaps most importantly, roll center migration. In the stock form, the roll center moves laterally far too much for our preferences. By altering the position of some pivot points, slightly, this aspect is greatly improved dynamically. In addition, the ever popular "negative camber gain" on the stock suspension is not nearly as aggressive as it needs to be to make today's tires perform at their potential, the same changes to the pivot point locations, as as well as some static design changes to the geometry of the upper control arms dramatically improve this aspect of the behavior. That's not all by any means, but these are perhaps the two most important areas we addressed.

Thanks,
Mark

Will this new "system" also work on the 4th gen x-body?

[Mean 69]

Hey Tad,

My sincere apologies for not having been available, I'm not keeping very "standard" hours these days, and I really hope that this changes for the better soon.

I don't think it will be practical to run the really-really big front meats, just the "really" big ones: 275's are likely to be the practical limit. No question, we will experiment with fitment and trade offs, but today, I'm really thinking 275's. This is a departure from the original plan for the car as some might note, as is the decision to run a modified stock front frame, but I really like what I see from the engineering we have done in the last few weeks. It all started with a very nice customer car, on a relative budget, and has really sparked some nice creativity on our end.

On the other notes, the coil-overs will have very close to the same motion ratio as the same setup. Not ideal, we'd like to move things around, but in the interest of packaging the setup and not requiring making structural cuts to the frame, we're not deviating much on this one. In fact, our intention is to make the setup very modular, so a customer can buy certain pieces, apply to the car, and then upgrade at a later date to other pieces. In particular for the coil-over conversion kit, this means that if you already have a set of our "standard" lower control arms, you won't need to replace them to go to the improved coil-shock setup. And so on.

Sway bar will be unique, it'll have the same flair as the splined unit, but we have some "better" ideas for it. Light, effective, adjustable, and terribly sexy. Still in the works, but I am confident that it'll knock socks off.

Adjustable steering stops are standard, and a damn good idea.

Just another note on the spring and sway bar rates: in general, we are more of a "softer spring, stiffer sway bar" type of approach, within practical bounds of course. I want to make this distinction as it applies to our proposed setup to make people think for a second. In most cases, the answer to improved handling is largely dependent upon stiffer springs, etc. Why? Because the fundamental suspension geometry is usually bad (as in the case of our beloved Muscle Cars, originally designed around bias ply tires, it didn't matter back then), so limiting the amount of travel keeps you closer to the "sweet spot," if there is one. If you change the fundamentals of the suspension, the sweet spot gets far larger if done properly, and it's less disadvantageous to allow the car to bump/roll, etc. In other words, realtively larger roll angles don't cause the tires to get nearly as upset as they usually would, for instance. Hard one to put into words....

Folks, thanks for the interest, and please, we love input. Now is the time to let us know what your concerns are for this application! Feedback, please, always welcome.

Mark

[TLWiltman]

Mark,
No sweat on the scheduling... I know all about non-standard hours (5:30p-5:30a. 7 days a week on my end).

I'm pretty curious to see what kind of tire sizes would fit given some "judicious" steering stop adjustment (for a "track-only" type of adjustment. Say... 15-20* steering lock as opposed to stock)

Penske coil-overs, perhaps?
Sway bars... I'm interested
Adjustable steering stops... I have a feeling those will come in very handy
I thought a 750# spring was considered a soft spring:jump: . I am pickin' up what your puttin' down, though.

concerns... Kind of centers around the full-floater rearend (and the lug-centric 5x5 wheels to match) and being able to have the same style of wheel on both ends (I fear that a 5x5 front hub may be easier said than done). Then comes the brakes, etc...

I'll probably come up with more. Brain is officially mush now

[Skip Fix]

I'm not an engineer om suspension I just knwo drivign hard into a turn AND braking softer springs allow the rear to unload (brake dive)and unless you have ABS the rear brakes lock or you turn the prop valve down enough not to and you could have more brake in the rear the other times. I know you can change the dive characterisitcs with A arm mount angles also.

When I used a thicker rear bar it would pick up the inside rear tire in a tight turn (or my angled driveway) so I dropped back to ta samller one. I know Guldstrand likes stiffer rear springs and NO rear bar, but it never worked for my driving.

On my 79 Camaro with an specific offset front I could fit a 10" wide(tread) 24.5 diameter 16"wheel roadrace slick. Limiting factor for that size wheel was the tie rod end and the inner fenderwell-it had none. try mounting those stiff wall short profile suckers!

For those of you that have never use roadrace slicks you can purchase 1/2 tread depth for pretty cheap from John Berget. They are a kick, talk about some lateral Gs!! Makes autocross compounds feel like regular tires.

[TLWiltman]

Folks, thanks for the interest, and please, we love input. Now is the time to let us know what your concerns are for this application! Feedback, please, always welcome.

Mark
Mark, you have a PM

[Mean 69]

Mark, you have a PM

Crap, I just noticed this today. I suck....
M