89_RS

Fair enough I'll admit I read and quoted wrong the accuracy of the level. As to whether or not a laser is more accurate than a bubble, I stand by what I say: the bubble is more accurate than the laser.

If you know how to use a bubble level, you will be more accurate than a laser. Problem is most people don't know how to double level, refine level, or most other basic surveying techniques that are meant to get you down to the accuracy or resolution of the instrument. They just want something that they know the tolerance of and can see where its pointing.

However, I think we can all agree that beyond 1/16" in accuracy is overkill for our cars.

injdinjn

As with any measuring instrument its accuracy depends on its quality of construction and how it is calibrated.
With a laser level the good ones are +/- 1/16" in 100ft so in 10 feet theory they would be 10x more accurate in 10 ft. One issue with a laser level is the thickness of the beam.
With a compensating optical level again well was it built and for what applications. A David White inst is fine for laying out patios and sidewalks.
My level is calibrated to 0.005' in 300ft. First order optical levels have the same accuracy but come with a micrometer adjustment for fine sighting.
ANY optical level is subject to eye parallax.
Electronic levels eliminate eye parallax but the rod has to be in very good focus to read the bar code rod.
Then there is the error by not having your measuring rod perfectly plumb. If its tilted out of plumb then your reading is wrong.

But as said earlier, on a 3rd gen who cares for less than 1/4 inch.

As for Pablos sag, you need the factory manual to determine the difference in points near the ends of the frame or unibody and somewhere near the middle under the B piller.

89_RS

What kind of level is it? Thats on par with Leica optical auto levels and Sokkia power levels.

Guest

FOr the accuracy of consistincy of the laser level I listed? I will sayu again it is dead nuts accurate for the application.

Fact: Whenever I set the scales using this level and baseline setup the SUpetruck chassis to 52.4% creoss weight....THEN... I transported the entire rack and scale setup to another location and used the laser to again setup the rack and scale system and THEN set the untuched car upon it the scales ALWAYS registered 52.4%. That laser is dead nuts accurate for this intended use- that task was performed probably 560 times and was always perfect.

You have to know how to use the laser level- Key note is to always use the front self leveling pointer and rest it on a platform that you can rotate it 360* with the front pointer reading- Do NOT use the front readings and then the side readings together in the same perimeter gauging - this is where the accuracy deficiancy lays.

Gumby

Aren't the tripod ones self lelving using the bubble system inside???

89_RS

I'm not sure. I know that on the outside, you get it close to being level using the level bubbles on the outside of the level, whether its a level vial or a bullseye bubble. I know that Spectra uses prisms suspend from the inside of the instrument to get a true plumb and auto compensator's to refine the leveling down to +/- 1/16". Not sure how the off the shelf hardware store ones do it though.

injdinjn

Ni2

Gumby

The trip pod ones are pricy pricy pricy fancy stuff, why I still don't have one.

Reminds me of the water filled compus everyone had in their car back in the day. It self levels to give an accurate heading.

JamesC

iTrader: (5)

The above from post #88.

JamesC

89_RS

Seeing as how there are quiet a few guys here who know a thing or two about levels, maybe we could put our heads together and come up with an accurate home made level. It would still be a first order magnitude level, but I'm betting there's a few MacGuyver tricks out there to make a decent level for not much money.

I'm thinking it would be an optical level based on something like a BB gun scope. It wouldn't be too hard to make a tribrach out of some plate and 3 machine screws and a tripod out of some 2x4's.

Guest

Why go to all that expense and headache? Just go to Home Depot, buy a 5 gallon bucket, some clear 3/8" tubing, and make a water level. It will be every bit as accurate as the bubble level or laser level. Tape the tubing to a piece of wood, put it on your first point (jackstand, preferably the high one), mark it at the bottom of the meniscus, and raise all the others to that same height.

injdinjn

Most optical levels do not focus under 5-10 feet.

For leveling a car a water level would be the most accurate.

If you looked at a optical level and tripod you would see why building your own is a waste of time

Dante93GTZ

iTrader: (5)

Got my MAC's on Friday and did a quick test fit just now. I noticed that with stock exhaust this style doesn't seem to work. Can anyone else verify this? It looks like the passenger side SFC will not clear the exhaust where it routes under the passenger side floorpan.

The quality is nice but after looking again at the Alstons, I think I'd rather have those than the MACs. Maybe I'll sell em and get the Alstons afterall. The MACs are nice, but its basically bent tube with a flat plate on them to attach to the subframe. They don't have that nice taper like the Alstons do.

Gumby

Id agree, Alstons look like something out of a pro race shop.
Well formed bent tube on a pro $$$$$$ machine.

Not a back yard, grab some square stock min work or tools needed to make it.

Pablo

iTrader: (1)

Actually, in pure bending, square stock is better. Tubes are only better in torsion or where you want the same flexural modulus in every direction. Henceforth, nascar chassis elements are box and the roll cages are round. You don't know what direction an impact is coming from which is why a roll cage is round tube. An SFC is undergoing minimal amounts of torsion. Look under any serious truck chassis and you will find a box section chassis. The taller the better.

turbosbox

Why such concern over "leveling" ?
Are your springs all perfectly equal in spring-rates? Weight all perfectly balanced on each corner?
Lots of interesting talk on precision leveling, but for street subframe connectors it is a total waste of time.
If your suspension is already loaded and the alignment set to that, all the goal is for the SFC's is to try to keep that somewhat managed by strengthening the frame so it doesn't twist that out of whack during hard acceleration or turns.
Someone mentioned dynamic leveling? but using static methods...
We might as well determine dynamic centers of gravity in determining how to weld up the SFC's.

Edit: other reasons of course to install SFC's include eliminate rattles and body sags causing cracks and bad door closing etc...

spurgeon76

The Alston's come as a bolt in but you can have them welded up.

Guest

Look at the frame as a spring. If you were to place one wheel on a 4" block, there would be additional stress in the chassis starting at that location. Then you weld in your SFC's. Now take out the block. This really is not any different than preloading a chassis with slapper bars or via the sway bar links or chassis mount location, wedge in the spring, etc. You've put a different spring rate into the car, permanently... and better yet into something that was not only not designed as a spring but does a terrible job of being one. If you think the addition of those SFC's is going to minimize flex on a preloaded chassis... well... its not going to do that very well. Its a couple inches of steel tubing, not a W12x210 I beam (that'd be something in a large building). So what happens if you do that is every time you load and unload that wheel, its going to act a lot different than the other 3. Thats why leveling was brought up. The only real argument one could make is how close is close enough? There is not much symmetry to the chassis either, so making an assumption that a level chassis with a thirdgen and welding in SFC's is going to provide the same amount of resistance to deflection at each of the 4 corners is only going to get you into trouble if you want to consider microscopic effects like these.

turbosbox

Um, yes, I would expect SFC's to minimize body flex, or why put them on? Decorations to add ballast? Show pieces for cruise night? Exhaust protectors for speed bumps? Jack points?
I realize the need to have the car sitting level before installing them, like not in a twisted configuration, but this thread is a carryover from others on the same topic, and some points have gotten lost.

Guest

This is a typical veiw from 99.99% of the world that do not understand the complexities of chassis dynamics and never will to the extent it takes to know why this is important to level the vehicle. THIS is why we are having this dicussion. Your soring rates are NOT all the same not even side to side. You would be amazed to see how much factory springs varry when you put them on a spring rate tester. THEN there are so many other factors that are way to many for me to start listing.

Just start with a level frame and then you are starting with a perfect canvas. Otherwise? so much for best performance- people on race tracks always think the other guy is cheating because they have exactly the same parts visually...but not technically. My famous quote once again," Its not just what you have, its how you set it"

Dean

KiLLJ0Y

iTrader: (1)

bump from the dead..

simple question, how is the ground clearance on the alstons/MAC's? anyone take any side pictures? my car is low, i dont want to be scraping the crap out of them

Gumby

IM fine with Alstons n 225/60/15 hair smaller then stock.

Guest

Resurrect to say that until finding this, I too would've never considered combining different SFCs under one car. Maybe a chart of which brands work together, as a sticky?
Looks to me like I can do Spohn + Alston? Or did I misunderstand?

zenish

never mind

white1991rs

I insisted that the suspension had to be loaded when I had these installed and the guy doing it like refused to try another method to lift it and welded them in with no weight on the wheels and at first I was really upset but the car drives absolutely fine I dont think its an issue.

And I have the Hotchkis SFC's does anyone know if any of these inner ones aren't compatible for some reason?

rusty vango

isn't that the whole point?? to adequately tie the subframes together?? why hasn't anyone made a set that combines both designs?? why do we have to buy TWO different sets just to get it right??

myroc86

Most of the time if you want it done right you have to build it yourself...

Flip 2

iTrader: (1)

Saw this when it originally went up, but was getting deep into a LS1 installation.
Like the OP says, the difference is amazing. Definitely worth doing, adding inner connectors (Alston's for me) to outers you already have…OR… putting both on. I already had some custom outers done years ago. They made a big difference, but were clearly not enough with a move to New England, and it's challenging roads.
Warning to LSX types- the Alston's require some work to the Hawk's transmission mount. Both want to be in the same place, so a bit of fitting is needed. WORTH the effort.

IROCZman15

iTrader: (25)

gotta say guys. I had the inner alstons bolted in and they worked for a little while... at the time i had minimal welding skills and no drive-on "loaded chassis" lift so i took it to a local race shop, they reccomended a full S&W subframe kit. after learning about it, i was all in. i ended up selling the alston inner bars to ed-pontiac.


very happy with this subframe setup:

posts of the frame start at my #4 post
https://www.thirdgen.org/forums/susp...rame-into.html

or view it on my dumb-*** website:

http://www.freewebs.com/iroczman15/workdonein2009.htm

since then the underside has been completley stripped down to metal, undercoated as well as the rear .
of course im not putting down a ton of horsepower, but this kind of frame that ties into rockers, has a driveshaft loop, and an integrated tq-arm has been incredible for the past 4 years.

just wanted to put it out there for curious fbody wrenchers

IROCZman15

iTrader: (25)

ALSO. JUST IN CASE PEOPLE WANTED TO SEE PHOTOS OF THE s&w KIT "ISOLATED" HERE IS A LINK TO PHOTOS I TOOK WHEN I WAS SANDING DOWN THE UNDERSIDE OF THE CAR AND LEAVING THE FRAME INTACT, IT SHOWS THE CONTOURS AND PARTS OF THE FRAME SETUP MUCH BETTER

http://www.freewebs.com/iroczman15/workdonein2010.htm

Gumby

Gonna bump this, as im gonna take this route myself now and rally make things solid, might even tie the two in spots...

cept BMR is funny, same price on website and ebay, cept ebay is free shipping, website is not. with ebay fees n paypal, they lose money, direct website sale you make more, so you charge shipping there??? would of ordered them tonight if the website didn't want $45 shipping.

Gumby

How did ya get the LCA bolts out? even cut the head off, wouldn't turn, won't pound out, tempted to drill them out, but my luck the sleeve will start to spin 90% done....

GOATS2QUICK

iTrader: (5)

bigger hammer.

91ls1t56

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I had the Alston inners and the Spohn crossmember. As stated above they want to occupy the same spot and the crossmember dose not want you to have exhaust so this is what ended up happening.

SirReveller

iTrader: (4)

Gonna bump this up again to the Trump era: when ya get the BMRs (to combine w the Alstons) is it SFC008 or 009? With Hooker 2055s + MF catback in my case.

This would seem to indicate 009s but I recall the 008 seemed to fit shorties too(?) and be the more traditional design like the UMI sfc?

BMR offers two versions for different exhaust combinations. Part Number SFC008 is designed for cars with full length headers and exhaust systems that run inside the frame rails. Part Number SFC009 is designed for cars equipped with the OE manifolds or shorty headers with OE exhaust or OE type exhaust that runs on the passenger side, outboard the subframe.

Flip 2

iTrader: (1)

SFC008
The tail of the squib mentions the OE type exhaust- seems to include the outer passenger side routing. Such an exhaust setup will not work with a LS motor installed. Long tubes or no, the exhaust wants to run down the center of the car. That would seem to indicate 008. I bet the 009 just makes a bunch of space accommodations you will not need to worry about.

SirReveller

iTrader: (4)

Excellent- exactly what I suspected. 008s it is. Ty Flip.

SirReveller

iTrader: (4)

Thought I'd just note as an FYI that the shipped weight on BMR's invoice is 37.0lbs.

UPS has the Alstons at 21.0 lbs.

91Z-28-350

Sorry, going to necro this thread again - anyone have pics of both the Heidts and BMRs installed? F@*king Photobucket ruined yet another thread it seems.