So I had some Alston subframes welded onto my car a while ago. I was looking around and really wishing I had gone with something that would offer a bit more rigidity (maybe some 3-point ones such as UMI, SLP, KBDD, etc). Is it a bad idea to remove the already welded sfc's? I did a quick search and from what I gathered, I am risking damage to the frame of the car. If that is the case then I will leave it as it is.

ps. I don't mind if the current subframes are ruined, but it would be nice if I could get them off and not hurt them, so I could possibly re-sell them.

 

depending on how well they are welded on there you should be able to get them off with just a dremel and some cutting disk. they should come off without hurting either your car or the subframes, but i dont know for sure.

 

I had mine removed, and nothing happened to my car. I had the Kenny Brown double diamonds. I had a guy I knew grind all the welds off. Took him quite a while (couple of hours), mostly due to the fact that they were welded on quite well

If you are going to remove them, find a friend with a lift to get the car up in the air, and get a good grinder (a real grinder, not a dremel). If the welds are good, it's tougher than you think. I attempted it with my pneumatic cutoff wheel, and it was like using a plastic knife to cut a diamond.

Most importantly, take your time and do it right...

 

The guy who welded them in actually did a very good job, so this may not be so easy.

So it is probably a bad idea to put the car up on ramps/jackstands and take an air grinder to them myself?

I guess my next question is if it would be worth the hassle of removing these 2-point sfc's and replacing them with 3-point sfc's. Now I'm thinking probably not.

 

The problem with the air grinder is unless you have a HUGE compressor, the damn tank has to fill up every 30 seconds because the air grinder drains it so quickly. That and the discs they come with will get eaten up quite fast.

I'm not sure it's totally worth the hassle to swap SFC's. Considering you'll probably have to end up paying someone to remove them (to remove them correctly so you can resell them), paying someone to put the new ones on, and buying the new 3-points, you'll be out some serious coin when it's all said and done.

 

A lot of RR/AX guys don't use SFC's anyway, and some are not in favor of them. For the purpose 2 point should be more than adequate...

 

A lot of reasoning for AX guys not using SFC's is that it bumps you allllll the way up to a class called Street Modified (under SCCA Solo II rules), even if you have nothing else done to the car. Cars that run in SM are generally gutted, lightweight (close to 2600lbs.), non-streetable, and well, fast, and they cost more than most of us make in a year. It's hardly a place to try to compete on a national level with your F-body when they start their life as 3500lb+ cars...

And that was the reason I had mine removed. I dropped down a few classes and actually have a competitive car now.

Sorry for the story, but I figured I'd shed some light on why AX'ers aren't fond of them. It's not that they don't help, it's just the way the rules are set.

 

I'm looking to get into road racing, and I'm searching for any way of improving the car's handling, which is why I had thought of this. I think you're right TXAgZ28, it may not be worth the hassle. I'm just going to keep the 2-points for now and spend the money elsewhere.

 

From a handling standpoint, I think you're gonna find simple things like the right shocks and springs are going to get you more bang for your buck than fooling with swapping SFC's.

 

Not to hijack, but what differences did you notice once you removed them? I was looking into removing mine because I didn't like how they increased impact harshness. But I decided not to because the guy who welded mine on also did an excellent job and cutting through those welds would have been a bear ...

 

Mine are welded on REAL well for the fact that I want em to stay.....for now on. I also agree that 2 points are just fine for most apps. I would say that the 3s are cool and probably are needed once the rwhp goes north of 500, especially drag racing.

 

Didn't notice much difference at the time. I had some pretty stiff springs and Koni's on the car, so the car felt just as stiff as it did with the SFC's on there.

 

Then you need to look towards the suspension for improving handling foremost. For my open tracking experiences, my track car has about 505 rwhp and the chassis is more than adequately stiff for the purpose. I know this from using strain gauges and telemetry with gathering lap times and not by the placebo effects that are gathered from the booty dyno, especially when many around here use either the factory buckets or some sort of "street upgraded" buckets. Both of my F-bodies are T-tops as well (track car now converted to a "solid" top using aluminium alloy panel).

Depending on sanction and/or track rules, you'll need some sort of roll cage when going road racing (performance driving or wheel-to-wheel). The roll cage will be much more effective for chassis stiffening than the 2-point SFC's and not to forget to other safety gear that shouldn't be neglected as well.

AFA removing the SFC's, that's a decision you'll need to make for what you think they are worth. Over maybe two years, I have carefully installed and removed three sets from my daily driver, however i didn't really want to go to too much trouble to save any of them, so i sacrificed what ever SFC's to the cutting wheel and plasma cutter (so I didn't have to have too much fall over my head.) SLP's while being really beefy are indeed the roughest to remove if they're welded in according to their directions. Two points are useful for basically extending the jacking points, so when you need to raise the car to change tyres, you won't need to be so careful when selecting the jacking point. That's really what they're worth when running stiff springs combined with proper valving.

 

So if I am understanding you correctly, the sfc's only improve rigidity because the stock spring/shock combo is so poor? In other words, they are unnecessary when the rest of the suspension is set up and matched properly?

Good to know, I am going to leave them where they are for now, and start looking at good shock/spring combos. Later on in the future I may try and remove them to see if they were just adding weight to the car (they are not lightweight, I bet they weigh close to 30 lbs). Thanks for all the info, guys!

 

Only unecessary for the vibration purposes for what many use them for around here. Since a lot of drag racers need very soft valvings and soft springs for the quickest weight transfer possible, that's why many resort to SFC's for that purpose. Also, the dedicated drag racers perform launches with some high rpms, using sticky tyres, and sometimes launching with the "catching air" effect (which raises the front end of the vehicle off of the ground, then "slams" it back down, all while shooting straight down the quarter mile). If you're road racing, I highly doubt you will use a suspension designed like this (different type of sticky tyres as well).

FWIW, several of the members around here who are also over at FRRAX have discovered how SFC's don't do what many placebo testimonies claim they do. Once again, not uncessary, just uncessary for what many are trying to achieve with regards to better handling and braking. Plus, there are too many generalisations about this car in general with regards to the whole SFC issue. There is way too much pliance in the suspension parts to allow you to "feel" minute chassis flex. If there was enough to feel, you'd see the hood misaligning, windows popping out of their seals, doors becoming grossly misaligned only over a few thousands miles.

And one more thing... the NVH qualities apparent to the cabin occupants and the torsional rigidity are indeed two seperate matters. Once again for torsional rigidity, some pretty sophisticated instrumentation combined with consistent testing is the method for determining torsional rigidity. Many of the so called "quieting effects" are mostly placebo.

As I mentioned before, you can leave them there for a while and and see what happens. They're already there, so removing them will cost time and possibly money that you could use right now to spend on much more effective items to resolve your handling issues.

 

I don't mean to hi-jack this thread, but I'm very interested. I have 3-pt SLP bolt on SFCs. My car is a DD that sees open track events at my local 1.8 mile road course. I put them on to make it stiffer in part, but my main goal was to keep the car tighter in terms of quality. My hope was this would counter act the race track beatings.

However, I feel like it has negitively impacted ride. It seems harsher. Is this placebo effect, or does it realy make it harsher?

Does it realy do much to keep the car nicer (tighter, less squeaks and rattles, etc)? I originally thaught that anything stiffening would be a good thing (and a roll cage is outa the question for me)...but I'm kinda thinking the hardtop camaro may be stiff enough as is.

I'm considering removing them. Would welding them down instead help with my intended goals any?

What do you guys think?

 

My long winded 2 cents on this matter:

What you're feeling is what I felt as well with all of the types I have installed, so this isn't being imagined. Now, what makes these effects placebo is the fact that since you are feeling something (NVH being effected for better or worse), one or more persons think it must be doing what they're thinking (stiffening chassis is a result of what they're feeling), but the reality is that the "feelings" aren't a result of what they're detecting with their booty dyno (more accurate instruments such as strain gauges and consistent testing over the floorpan and crumple zones yield nothing, compared to the change in NVH detected by the SOTP). In short, the regular human senses a driver has is no instrument to be used when detecting such things from a finite point. An exception would be a result that is extremely obvious (hoods, panels, doors, windows all coming apart). Kind of see what I mean?

Now, if it were me, and the SFC's were bolted on, you perform something that you can come to a decision to whether or not you have use for them. Go to that same track, and perform some laps with the SFC's installed, record your times, then do some more laps without them while recording their times as well. Bear in mind that all other parameters need to be ceteris parabis (everything else held constant, type of tyres with equal wear, tyre pressures, alignment settings, spring rates, damper valvings, sway bars, corner weights, fuel weights, etc.). Also, it helps for your bushings, ball joints, mounts, spherical bearings, and other similar items to be in top notch or good working condition as well. If you feel that the SFC's yielded better times with them installed, then you could keep them, or if you feel the SFC's were dead weight that increases your times, then you can remove them if you wish. The ultimate decision is yours, however this is just some input of what I did in order to make a decision to shed some dead weight and some light on the truth behind their purpose.

I also pose another question that should be asked as well, "If it's already strong enough for what's being used, how much more money spent and weight added is really needed?"

 

To be honest, I don't think the diff is significant enough to be measured in my lap times (partly because I am not consistant enough). My goal was to keep the car more of its low mile self and less like a beat racecar. I was hoping its benifit would be to keep the car from twisting up under my track sessions. I was also hoping for better ride quality as the suspension could better "do its work" with a more rigid chassis.

Any thaughts on those issues?

 

I was hoping that the creases on my quarter panels wouldn't get worse. The one thing my "booty dyno" told me beyond a shadow of a doubt was that my ride quality got worse. I ended up pretty much correcting that by getting Bilsteins and running soft tires ("touring" up front and DR's in the back). Needless to say, my handling became worse because of the tires.

 

Even though the chassis is a set of springs of sorts, so are all chassis, and it's not necessarily due to it being a monocoque or a tubular frame. Many of the professional "prototype" chassis's are monocoques, and even the hyperexotic carbon fibre chassis's are monocoques as well.

Just to let you know, my street vehicle is the one that had SFC's at several intervals over it's 150K miles. I bought the car used at around 32K. My 94 V6 was eventually converted into a track vehicle that has used engines ranging from 400rwhp to now 505rwhp and it's never had SFCs, and only received a roll cage about 20K ago. Both cars use at least 13 spherical bearings in their suspension parts (track vehicle being 15, since I use double rod ended trailing arms). They are both rattle free. Heck, I've even had some who have SFC's and STB's who didn't know what my street car had and noticed that it's free from the noises they have, yet I beat my street car like a car should be driven (on an AX course that is).

Just more info to relay.