super_kev

iTrader: (5)

No, way too much work, plus it makes the nose heavier, requires a custom driveshaft, etc.

I already have the Spohn unit, and I want to use it because it relocated the torque arm to the x-member. If you had looked at my drawing, you would see that I am doing it on both sides.

I was looking at that, and where the mount is welded it seems to leave room for only one of the two V notches for the pipes to go through on the other side of the transmission. You would have to built a Y to go under the LS1/T56 (which eats ground clearance) for a single through the notched area since the other side would be taken up by the TQ mount. But I'll be looking at it again in detail to see if I can't work something out.

Who said he recommended it? It was my idea in the first place. I'm just bouncing around ideas to get some feedback.

The problem with this country is that it has way too many idiots who are willing to sue anyone so they don't have to take responsibility for their actions. You think I would sue people just for what they said? I'm the one who's doing the modification here. I may be a Joe Blow (no offense taken), but I do have some common sense and can somewhat visualize what the subframe is doing and where the loads are. I personally think it's doable, and looking at the stock 3rd gen subframe, even seam welding that area would stiffen things up.

Well, since the car has been modified with a custom cage I built, custom SFCs, and seam welded, doing this isn't going to depreciate the value any further. If I had any plans to sell it in the future, I wouldn't be doing all this work.

MrDude_1

iTrader: (4)

how well did that seam welding work out for you?

im going to be under my car anyway when i put the SFCs on... i was thinking about going over some areas... like the subframe to floor points... any tips?

02NBMWS6

iTrader: (22)

Your ****** weird man...lol

MrDude_1

iTrader: (4)

hes also wrong... lol.
that "last page viewed" window, isnt exactly the most accurate way to time someone.

especially when they're like me and have multiple sessions (windows) open at a time.
and even more so when the board is spread out over several servers, like LS1tech is..

now im sure brains could make it accurate again, but he has other, more important things to do the board first....

11SECDWS6

iTrader: (3)

Thanks, that means alot coming from you

11SECDWS6

iTrader: (3)

Nope, but similar to brains I have much more important things to do than argue something so trivial.

You guys try to have a good day....

MrDude_1

iTrader: (4)

im having a great one.

super_kev

iTrader: (5)

All of you knock it off. Keep this on topic please...

I haven't driven the car since I've started all this work on it, so I couldn't tell you. Plus I installed the cage and SFCs at the same time. However, I believe it would make a big difference by itself, as the spot welds aren't as strong as a good MIG weld. I welded only the inside of the car from the firewall, along the sides, and the back to the end of the gas tank hump. I will probably be seam welding the subframe area near the firewall before I put the car on the road.

Clean the seams from the oil/tar sealer, and to make an even cleaner weld, grind the primer coating (gray) off before you start. I didn't do the latter until a ways down the road. I was a novice welder a year ago, and even though I had taken welding classes before, it didn't dawn on me that the gray I was seeing was primer and not bare metal. After all, I didn't have any problems getting spark, and at class we used only bare metal that gave spark, so I thought I was good to go. Now I know what I am doing, and I've gone back and checked my earlier welds to make sure they were ok. If you have more questions regarding seam welding, PM me.

Studytime

iTrader: (15)

So then what does it mean if Old SStroker left this thread before you did (i.e. He quit posting first)?

In the picture "looking rearward" the welds in the background look really good. The way everthing is laid out (as well as how this thread is laid out) it looks like you're going to be successful in getting this issue resolved. It is evident that a lot of care is being put in thus far.

That is one clean-looking third gen from the little bit that I can see.

Ben T.

joecar

Ok, I've been following along, hoping to learn a few things, and I do have a few comments about what was said (and I am trying to tread carefully in a few places...)...

it may not be professional, but if planned out carefully and done in a manner to allow repeatibility/consistency it would be effective and allow the right decisions to be made from the results (making it right)...

lol, us Joe's don't have a spare $20K or $20M to spend, and if we're going to wait to for that much money to fall into our lap we'd never build anything...!
Just because a person doesn't have the money nor the machinery does not mean they can't do it [right/correctly];

and you don't have to be a licensed and/or professional engineer to do something right or to have some sense about it (I'm not dissing you or any LPE's or PE's, I'm just making a statement);

I'd say super_kev has looked at his various options, and cutting/welding his subframes is one of them, and modifying the crossmember is another; he's obviously planned it out, feels confortable about it, showed he has a very good idea how to do it, and understands that loads/stresses have to be dealt with; I believe he'll do a good job of it; I'd love to see his pics when he's done.

(Mr Dude and SStroker, ...interesting digression on relocation bracket/LCA geometry... I'm reading/learning about geometries, wish I had some software to help me visualize suspension motion...)

Old SStroker

LOL! FWIW, I tend to read/respond during lunch break or coffee break time. Every once in a while I take a pause to work. Must be nice to have lots of free time.

Yeah, when I was in the OEM auto business (PC), we spent lots of money on testing rigs, but some folks did extra-curricular vehicle building/modifying and the more arcane methods were used. Results were very similar...within a few %.

FWIW, you can get actual torsional and bending rates as well as comparative rates.

For zoomies, look at truck pull headers. As you know, better performance than 8 stacks.

super-kev, you are definitely NOT a Joe Blow. I'd like to see you car sometime.

ProdriveMS

I can help with some advice on seam welding if you want. Before I graduated college I worked as a fabricator for the Subaru rally team and part of the shell prep was to seam weld the entire shell. Weld 1 inch long beads about 1 inch to 2 inches apart. Dont put a continuous bead on the seam as it will put too much heat into the shell without adding much in rigidity. The normal practice is to weld a bead in one corner of the car, move to another corner put a bead down, then move to another. This prevents putting too much heat into one local area. In the UK, the WRC cars are welded while bolted down to a jig to prevent them from moving. Afterwards, the suspension points are checked on a CMM. In the US though, we didn't have that luxury, so we made every effort possible to prevent warping the shell.

After seam welding, grind down the welds. Any weld sticking up above the sheet metal adds no rigidity and is dead weight. You can remove about half the weight you added with welds by grinding them flush with the sheet metal.

If this is going to be a track car and you want to strip some of the rubberized undercoating off, there's a nice trick for that as well. We get a bottle of liquid nitrogen. You can pick one up at a welding store that supplies gasses. You'll also need about 6' of the steel hose which they carry as well. Freeze the undercoating for a few seconds, then chip it off with a hammer. You'll be left with pretty sheet metal and a pile of hardened undercoating on the floor that can be easily swept up with a broom. It's quicker, cleaner, and much easier than heating the stuff up with a torch and scrapping.

Al

MrDude_1

iTrader: (4)

well, this isnt strickly a track car... but it is a convertible, with big power, so anything to stiffen it, helps.

that is a great idea to try with the undercoating.... i think im going to try that... i dont have any nitrogen, or any empty bottles to have it filled... but i do have some nitrous left over.. that sprays nice and cold too... costs more, but i already have it availible....
i need to get that undercoating off to weld on the SFCs.

so just a bunch of 1" long beads.. heh, i can do that.

TT632

iTrader: (3)

Interesting topic. Being a former Test Engineer for GM and a Japanese OEM(forgive me) it's easy to see the areas in these vehicles that could use improvement (There's a lot of compromise between groups when developing these cars). thats why there are the abundance of venders making parts to make our car's "better". Many of these after market companies wouldn't know Modal Anaysis from an Finite Elements model, but they make parts we all use. Point being, experienced fabricators can easily achieve stiffer and more robust structures than what is built into them from the factory. On the other hand, a novice could be cutting into a structural member and Jeopardize the integrity of the vehicle being modified. Looks to me like the methods employed above would work well if correctly fab'd and welded. While everyone may not have quality test equipment, basic methods suggested above can be very practical in verifying vehicle stiffness changes.

DRVETTE

I had a 3rd gen before my present car, and i did exactlly the same thing, and reinforced the area which i cut out, and i had a 4" exhaust pass thru that area, it wasnt a thru design, like a hole as much as a clearance cut. It will work especially if your suporting the surronding area with sub frame connectors. It worked on my car and i went down to 8.8s at 150. with no twisting of the body. Just a thought.

super_kev

iTrader: (5)

Thanks for the input, but I will stick to the pass through design that I'm thinking about, as it will be stronger than a notch. However, I will have to wait until summer rolls around before I start working on it.

ibanez7

iTrader: (7)

with a notch cut/material removal or a through hole cut:

I would guarantee, that if I modeled the structure in a 3D modeling program (solidworks) and did a FEA (finite element analysis) (cosmoworks) using pressure, force and load, you would see the subframe connectors failing FOS (factor of safety).


My suggestions for rigidness, yes use a through hole cut on the subframe. Then weld a tube (larger then the exhaust pipe) inside the Subframe from side of the cut to the other.

Create a sheetmetal channel (sleave, u-shape etc..), drill matching through holes, through the channel. Then line up the channel over the subframe, aligning the through holes to be concentric and weld. For extra support maybe weld up a gusset between the floor of the car and the subframe and or subframe sleave.

MrDude_1

iTrader: (4)

i know for a fact that the entire car, stock, fails a modern computer test.

3rdgens were the first GM car to go thru the complete computer design process, with the goal of using the computer to tell them how little they needed...
its not a very strong chassis... for what its made of, its stiff... but its not made of much. lol.