Sam Strano

iTrader: (41)

Ok, first you must realize that you are comparing different cars. 3rd gens are a LOT, LOT more flexible than a 4th gen is. The 3rd gen was designed not a whole lot later than the good 'ol Fairmount/Mustang Fox bodies. Reagan was early in his first term (very early). I too have had 3rd gens, and they acutally do see big benefits from STB's (of course they actually have struts), and SFC's (just not as new a design). The 4th gen is a product of the '90's, and designed to have the top taken off to boot.

On the 3rd gen you did two things that would have make body impacts worse. The first was lowering the car and with Pro-kits on 3rd gens, the spring rates didn't do up to compensate, same rates, just lower which meant you slammed onto the bumpstops more often and harder. The second was teaming them up with KYB shocks which just do not deal with sharp impacts as well as the more premium shocks from Koni and Bilstein.

When you say the car is fine on smooth pavement and not confindence inspiring when uneven... that is showing you the suspension, not the chassis.

Suspensions and chassis are NOT the same thing. They can work together, or against the others, but are not interchangeable parts. And your suspension works a lot harder and more often than you uni-body flexes.

Again, when comparing the 3rd to the 4th gen you have to look at all the parameters. While front spring rates are different, the actual wheel rate isn't. A 3rd gen spring HAS to be stiffer because of it's location and has a LOT more leverage acting on it. The 4th gen setup is a better riding design, which is a large reason they used it but not much is due to rates. The chassis of the 4th gen is likely stiffer than the 3rd gen even with SFC's. But I think the main difference is the relatively poor spring/shocks combo you had on the old car. And we can make the 4th gen a LOT better handling very easily. I'd see what shocks it has, change them, and add at least a big front bar... and I mean 35mm. I don't really mess with 32's anymore. Maybe a bit larger rear bar, but that would be TBD.

Sam Strano

iTrader: (41)

Sure I do... to stiffen the chassis for extreme use.

You say you've seen 4th gens with 100, 200k miles develop cracks from "normal" use. I buy that. However, floorpan crack have, in my experience, stemmed from body mounted torque arms, which I'm betting most all those cars run. And I bet a lot of them drag race often and have a lot of power and stick. Those things will twist a body, and are damn good reasons to have SFC's. On the other hand I have a couple customers with over 200k miles on their 4th gens with no issues like that at all and do not have SFC's. Actually one car is a stiffer 1LE and has 350k miles. And it just broke the OEM k-member, but the chassis it fine. And the owner had reported some rattles, 90% of which when away when some $5-10 of change was pulled out of the car. BTW, this is a car that has been autocrossed(trophies at the Solo2 Nationals), drag raced (13.41 @ 106) and open tracked (Summit Point, I think maybe VIR) and driven to and from her job since the day it was new.

And lets not forget this thread wasn't started by someone asking what to do in an instance like heavy drag use.

SFC's are not, at all, BAD things. They are simply mis-used. They have their place and are effective for their jobs. However all you need to do is read the signatures of those with opinions. What you'll find is pretty clear cut. Those with a properly tuned shock package don't really find the SFC's to be the world beating idea those that have crappy shocks do. You can draw a lot of detail from reading what isn't posted as much as what is.

Sam Strano

iTrader: (41)

As for the gentleman with the cop-car. You are a canidate for SFC's. 145k of beating (which is what cops do to cruisers) isn't exactly normal use, and banging down bad roads and/medians will obviously be a lot harder on things than any regular use.

However, you said yourself the chassis seems tight. Pretty amazing considering the beating. Sure a creak here and there will pop up, and SFC's might very well stop that by adding some rigidity back (toward what it used to have pre-beatdown).

However, I agree that better dampers would make a much better handling car, with or without the SFC's. Most folks call a car that is very stable, hunkered down and doesn't wander or bob around a solid car. Those are all shock items first and foremost.

Again, in his case SFC's would be a good idea (and we can talk about which ones if you'd like) because of the uncommonly hard life his car has had and we'd like to try and get some lost rigidity back.

To the person asking about the shocks with a 1.75" drop. The only thing truly capable in off the shelf form of damping something springs that leave that short a stroke are Koni's. Bilstein's can be tuned to do it, but aren't off the shelf then (still less money).

Cop Car

iTrader: (14)

i know decarbons and stock springs are the best for road course handling, but i daily drive it and im very happy with the way it handles, i just want to make sure that my car dosent get squeaky or loose. from what im hearing i dont really need to worry about it.

one last thing, what is a monocoque, and how would i get it checked?

Sam Strano

iTrader: (41)

After 145k miles, how much looser do you think the car is going to get? Let's look at this pratically now, it's not a spring chicken and hasn't had a easy life. Do you really think it'll get so much worse at this point? No.

Add the SFC's if you are determined too.

Foxxtron

iTrader: (1)

As you know, our cars aren't a full frame chassis. It is a unit-body chassis, otherwise known as a monocoque.

EDIT: To get it checked, you'll need to find a body shop that has some method of measuring the overall geometry between different points on the chassis.

irocstang

anyone have any pics of the umi boxed sfcs on a thirdgen camaro. Any body buy em and install them and have an opinion about them? Anybody know where to find this kinda info on this message board?

jam01

i installed 3 point's. i reasoned it couldnt hurt. i currently own 3 third gens along with my 02 ss. i havent put sfc's on them yet i know they flex more because my 83 z had some cracks in the body, its non t top.i was assuming the 4th gens were just as bad. the only other mods are rr lwr cntrln arms and panhard bar. so far im happy with the way it handles, but i would like some stiifer shocks.

Flawless02SS

iTrader: (9)

Go 3pt, or go back home.............

FUN LS1

There are occasions where SFC's, especially 3-Points) may be useful:

1) People who have Torque Arms connected to the floor pan (3_point SFCs take the stress/load instead of the Floor pan)

2) Convertibles

I fall into both categories. I'll also be adding a 6-pt roll cage eventually, and that should really help body stiffness as much protect the occupants...

99ssleeper

iTrader: (98)

I bought 3 point for a few reasons.

I plan to run a relocated torque arm and having it connect to the SFCs is, IMO, the proper way to set them up. It will be noisier, but I like to drag race and this is the optimal set up for me. It's a dumb idea to put that much stress on the tailshaft of the trans...but it would be fine for everyday driving. Also, relocating the TA helps to optimize the IC of the rear suspension which is a critical setup for a drag car (which this one has a good chance of becoming).

My car has ttops. Nobody can tell me the structure is as stiff as a hardtop model with the two extra braces above the side windows. I believe a 3 point welded to the chassis will keep everything above it from twisting. There is a reason a lot of the 4th gens get the dimples on top of the quarter panels from racing. I have driven a hardtop and I have driven a convertible. The way they felt were miles apart and they both had the same suspension (decarbons, prokit, ss anti roll bars...so, not great by any means).

Last, I want to be able to put a jack under the SFC and lift one side of the car up. It's such a paint to try and get under the kmember or around the muffler on a lowered car.

To me, it's worth a few hunderd bucks to have them done. They will do nothing for how the car handles...that is not the job of the subframe connector. But, I believe they will help to reinforce the chassis and provinde a good place for the TA mount and to jack the car up.

Foxxtron

iTrader: (1)

You are right about a T-top vehicle not being as stiff, however it will not be stiffened greatly by adding a tiny amount (SFC's are a really small improvemment with the lower chassis, but not the upper part, mostly improves chassis stiffness with extreme acceleration and braking, but no real proof with lateral loads found in hard cornering, pretty much an elaboration of what you stated). I discovered that the hard way then discovered that a solid retrofit panel directly to the T-top area solved the problem, and the way I designed mine can still be removable without having to modify the T-top area.

As far as the dimples, I have never gotten those and if you search for my most recent posts, you can see that I have driven the car very hard for most of it's near 150K miles (current milage, other posts will relfect somewhat less). If you think, that SFC's can solve them, I have seen those with SFC's (3-points) that still have them, regardless of them heavily drag racing, and they put them on when they bought their F-bodies brand new. Many will despise me stating this, but I would like to reintroduce that statement from some of the AX and RRer's here that where the majority of 2 and 3 point SFC's mount, they are far away from the dimple areas of the quarter panels, plus the quarter panels are pretty much constructed like the engine bay firewalls, so much more reinforcement is necessary (to the point of being expensive, invasive, and labour intensive).

FSUNole17

iTrader: (18)

Foxtonn or sam, would running a crossmember mounted TA be a good reason to run 3pt subframes? if it takes stress off the floor pan then thats reason enough for me, handling improvements or not

Sam Strano

iTrader: (41)

That'd be a damn good reason. And BTW, highly recommended because you need to do whatever you can to brace the floorpan since it's not built or intended to take those torque arm loads!

GMmexican

iTrader: (7)

coudlnt you just make your own SFC's? the metal isnt that expensive?.........only problem i see is getting them to fit properly.

z_speedfreak

iTrader: (3)

boy reading this thread was a big eye opener. I've ben holding out on doing donuts in my 4th gen until I get a set of SFC's and my reason is that this is my third ttop'd chevy and from my expierence doing donuts have made the ttops not seal as well, my last 3rd gen i was especialy hard on before selling it, the ttops always had a slow & slight leak to them but after busting donuts and other manuvers the leak grew and spread to the drivers side aswell and I also ended up cracking the paint along the rear quarters below the (B?)-pillars so I've just ben really weary of twisting my Z up. but now, im going to go do some nasty donuts .....as soon as spring is here

Foxxtron

iTrader: (1)

Bear in mind that on 3rd Gens, both SFC's and STB's are definitely a must. My experience with 3rd Gen chassis flex was visual, as again, it's impossible to detect with the ol' "butt-o-metre."

B.W.

iTrader: (3)

This thread really is an eye opener. I guess I can hold off on the SFC's unless I get a body mount TA or something. I was going to order a UMI STB and some SFC's in a few months, I still hear the STB can really help with handling though. My car is a hardtop too. I will only be around 450rwhp this summer, so I think I'll dump the money instead into some springs and shocks.

Foxxtron

iTrader: (1)

When you state "body mount", I assume "floor mount", and in that case, you'd be unwise to install a torque arm that is mounted to the floor pan without using a 3-point SFC. If you will be installing a floor mounted TA, then definitely install it with a 3-point SFC as this is definitely needed since the stress is no longer on the on the transmission, which is a robust area for a torque arm.

s346k

iTrader: (4)

would a stalled automatic car cutting between 1.5-1.7 60' times benefit from a 3 pt. sub-frame?

i'm asking because i just bought a set and installed them today. and i honestly don't see how i could NOT benefit from adding these to the car. when these cars launch fairly hard they yank ONE of the front tires, implying that the body is twisting...wouldn't 3 pt. SFCs help combat this problem?