QUOTE (Racer Chris @ Mar 23 2006, 04:12 AM)

[QUOTE=Porcharu,Mar 23 2006, 03:15 AM] [QUOTE=Here's an example of the tubular brace I like. [/QUOTE] What happens in a wreck - say a bad one where the rear of the car gets all wadded up. Looks like that bar might end up in your back. I like the idea of the tube for stiffening, but I have been thinking about this potential proplem for a while. [/QUOTE] I whacked the left rear corner of my race car at 100mph against an armco barrier. I never lifted. The pickup ear folded around the end of the tube reinforcement. The firewall is quite strong along the bottom edge where it is welded to the floorpan and there is a second layer a couple inches forther forward. There's no danger of injury from that tube.

That's good to hear. Not good that you crashed tho.

Seam welding is "welding the seams" (between the spot welds). This may help a tad in some highly stressed areas, but only if the original engineering was really bad. It's really popular in the Civic crowd, but I think it's mostly way too much work for way too little gain.

QUOTE (SirAndy @ Mar 23 2006, 09:27 AM)

if you come to the breakfast on sat. i'll let you test-sit my car. the door-brace actually makes it EASIER to get in/out of the car ... Andy

Sir Andy,

When you install a cage like the one in your photo, does it not obstruct both the engine lid release knob and the front truck release knob? Pic's? How do you get around this issue?

Thanks,

Andys

QUOTE (andys @ Mar 23 2006, 01:46 PM)

When you install a cage like the one in your photo, does it not obstruct both the engine lid release knob and the front truck release knob? Pic's? How do you get around this issue?

engine lid knob is fine, it clears the cage ...
front hood knob has to be turned 90 deg. and shaved on top. no big deal really ...

Andy

I don't have any good pictures of the welding done on my car.....this one is prolly best. The factory welding(to use the term loosly) in this area is gawd awful. I had to spend hours grinding out the cold lap & porosity....amongst other flaws.

I also welded around the perimiter of the ear & ground it shooth. The same with the arch at the wheel well.....after grinding the ends of the lap even....then ground that smooth. On both of these areas, there were spot welds that blew out the edge of the material. IIRC, most of the rest was more seal welding than anything that would add much strengh.....tho I could be wrong.

Unibodies are designed to be assembled using the quickest method that *will suffice*. As to wheather this is the strongest method is for you to decide. This thing sure as hell wasn't designed to cope with what I'm doing to it.

QUOTE

I think it's mostly way too much work for way too little gain.

Not sure I can agree with that. Porsche factory racecars have come seam welded for years. From the 72RS lightweight to the 2003 GT3RS that we own have welded seams. I havent seen a 997 GT3 yet so I cant comment on them, but i tend to think that Porsche will continue this practice.

QUOTE (SirAndy @ Mar 23 2006, 03:29 PM)

QUOTE (andys @ Mar 23 2006, 01:46 PM) When you install a cage like the one in your photo, does it not obstruct both the engine lid release knob and the front truck release knob? Pic's? How do you get around this issue? engine lid knob is fine, it clears the cage ... front hood knob has to be turned 90 deg. and shaved on top. no big deal really ... Andy

Doesn't the roll bar sit directly in front of the engine lid release? Can you explain? I'm probably going to mock up a cage with PVC pipe, but don't see how I'll be able to pull the knob.

Andys

Just drill another hole and weld another bong 1 inch over...

No biggie.

QUOTE (andys @ Mar 23 2006, 11:22 PM)

Doesn't the roll bar sit directly in front of the engine lid release? Can you explain? I'm probably going to mock up a cage with PVC pipe, but don't see how I'll be able to pull the knob. Andys

Andy,
If you are careful positioning the tube where it welds to the rocker there is room for the handle to be pulled. The roll cage tube should be outboard of the lid release centerline. It may be necessary to shorten the handle 1/4" or so and tap the hole a little deeper. It's close.

Re: the dog-ear tube braces
What's the "desired" OD of the tubing? Wall thickness? (.120 or .095)

Guess it sort of depends on how much stress you think is going on there, but I've run across pics of guys doing semi-tube frames that looks like they're using 1.75" OD, & the pic on this thread looks ...1"(?)

Curious to the consensus of what's "needed" & what's overkill.

Sorry...
I tried to bite my tongue but couldn't make it...

so jumping in here.
I think seam welding IS a Ton of work, yes for only small gain... but come on.. in racing gain is gain.
- How much money do people spend on 5 hp in racing?
- How much money do people spend on weight in racing?
every little thing helps!

I'm sure tube framing every weak point would produce bigger gain, but its heavier and not always legal.

We spent 2 years prepping our chassis
and then 6 months assembling it.
my thread shows all of the assembly, but doesn't show the 2 years of seam welding and chassis work that went into it......

We seam welded a bunch of it.
here are a few shots:

Inside of the same:

Brant, Thanks! I was working on that area last night..

PITA to weld... I couldnt get my welder configured right..

Andrew

QUOTE (TimT @ Mar 23 2006, 05:50 PM)

QUOTE I think it's mostly way too much work for way too little gain. Not sure I can agree with that. Porsche factory racecars have come seam welded for years. From the 72RS lightweight to the 2003 GT3RS that we own have welded seams. I havent seen a 997 GT3 yet so I cant comment on them, but i tend to think that Porsche will continue this practice.

you better believe it.

the 997gt3 is a piece of art and is seamwelded throughout.

QUOTE (Andyrew @ Mar 24 2006, 09:28 AM)

Brant, Thanks! I was working on that area last night.. PITA to weld... I couldnt get my welder configured right.. Andrew

something tells me if you are having trouble "configuring" your welder, you're not the person to be seam welding that car.

go find a professional. if you cant afford it a) get a job, B ) learn to weld, c) give up the advantage.

Do it , Andrew.
Some of your passes are gonna look like hammered shit initially.....but that's why they make grinders. Just concentrate on your puddle & the movement required to tie the metal together.....setting the heat & feed takes some fooling around, but once you're close, you'll see it.

You're gonna have to do some overhead and that's where it gets tough. Make sure you have some leathers to keep the hot stuff off your pink body.....most of the time. The smell of burning hair and sound of sizzling flesh is all just part of the fun......a couple months later, you'll laugh about it.

QUOTE (MattR @ Mar 24 2006, 02:01 PM)

QUOTE (Andyrew @ Mar 24 2006, 09:28 AM) Brant, Thanks! I was working on that area last night.. PITA to weld... I couldnt get my welder configured right.. Andrew something tells me if you are having trouble "configuring" your welder, you're not the person to be seam welding that car. go find a professional. if you cant afford it a) get a job, B ) learn to weld, c) give up the advantage.

Thanks mister!


I think I'll stick with JP's advice.

Here, let me post some pics of some of my welds..

Its a new welder, and I just got more gas, its possible they gave me the wrong stuff. I had a tough time getting it setup right for some of my other stuff, only had the welder a little bit.

I can weld just fine thank you matt. Given that the welder is setup propperly...

My problem was dirty surface area and the fact that welding on 1/4 inch of metal, upside down, trying to set the temp and speed of the welder is a little difficult.

Andrew

Heres some shots of my crappy welding.

Back of the rear fender.. Not as structural as ahead of it. Figured it was a good place to test.

yummy! goober welds!

man, you got MattR'd!


have some fun. a grinder is all you need.....

more

Get it dialed in a little... and figure I'll try a little piece.

Smore

Close up of my only line I did.
Rest were done by tacks so I could grind them off if I wanted.

more welds

My trouble area..

Couldnt get a clean weld, burnted a little through, played with the settings, Metal felt a lot thinner than the rest.. Sparks would rest on my glove and burn my hand, and hit my shirt, and splatter over my mask... Upside down.. arm fully extended.. Gave up... lol

have you thought about grinding the area you wish to weld first?

Yes.. I used a wire wheel.



heres my long kit welds.

Finally my setup.

sometimes I use a MAP torch or propane torch to burn off the paint before I weld...

then a stiff wire hand brush to clean up the area.

followed by primer after the weld.
(In fact I did ever single seam with POR-15 on the orange car)

brant

QUOTE (Andyrew @ Mar 24 2006, 03:37 PM)

Yes.. I used a wire wheel. heres my long kit welds.

Were those done with a spot welding machine?

Matt, no... I did them myself with the same mig pictured.


Brant, Good tip. I know doing the longs I would have to use a screwdriver to scratch up the paint with, then it would take a second to burn the paint and then I was good..
I'll use that for the rest of my work. The wire wheel couldnt get all the paint, and it took forever.

How did you take the seam sealer off? wire wheel or burned it?

Wire wheel took forever on the tower pictured.

QUOTE (Andyrew @ Mar 24 2006, 02:44 PM)

I can weld just fine thank you matt. Given that the welder is setup propperly...

A little modesty goes a long way.

I see why you an alpha clash so often... its like watching two positive poles of a magnet being throw at eachother really fast. At first you repel but one of you will eventually flip and you'll be inseperable (except one of you will be face down).

I never said I was GOOD at welding, I just said I could do it..

Geez matt, You PMSing today? cus all I hear is bitch bitch bitch...

QUOTE

eventually flip and you'll be inseperable

Just like you and aaron? Aw, how cute.. But im taken.. sorry

QUOTE (Andyrew @ Mar 24 2006, 04:38 PM)

Finally my setup.

Which Lincoln are you using?

135

one's on ebay..

http://cgi.ebay.com/LINCOLN-SP-135T-sp-135...1QQcmdZViewItem

If I were to do it again, I'd get the plus. my school has the plus, makes a much better connection.. Makes me think mine is setup wrong..

QUOTE (Andyrew @ Mar 24 2006, 05:02 PM)

QUOTE eventually flip and you'll be inseperable Just like you and aaron? Aw, how cute.. But im taken.. sorry

hey! i got no dog in this fight.....

leave me outta this...

i think its cool youre going for chassis rigidity.

have you given any thought to warpage? ala... weld and then move on to a different area. ive read people have warped their chassis' by laying continous bead after bead.....

Yup, My mind is all on shrinkage...

Thats why I only laid one bead.. and I generally moved from one side, back to another.. let it cool down a bit. "stitch" welding... one stitch at a time

You want the surfaces *clean*....no paint or other guck
in the weld area....real clean. On that overhead, grind the pinch seam down so both sections of metal are the same height & CLEAN. You gotta get your face up close to that joint to keep right on that parting line & I ran it down hand.
I never found shrinkage to be an issue....just laid it on.

This was a similar seam, but 3 sections of metal & almost flat.

Grinders are gud.

But bondo is better.

Did you have trouble keeping the wire on the seam as well?

You seam welded, ground it down, and welded it again? Explain to me what you did with that sail pannel.. Thats my next weld project..

As I said, there are 3 layers of sheet metal there.
I had to do about 3-5 inches at a time as the spotwelds holding it together are.....disappeared.
After the "fin" is ground down just a bit proud of the flat surface, you're faced with metal, gap, metal, gap, metal.
Naturally when you have a deal like that , blow thrus are a problem.....but just keep doing a wash pass and seal em' up.

On that lower pinch seam, I ground as described, welded, (Yes, a hell of a time keeping on the parting line.....get close. & brace on your other hand....even when it's on fire) then came back and smoothed things out with various grinding instruments. An angle grinder for the big globs, then a sanding disc and/or rice cake on a die grinder to make things pretty (kinda). You don't wanna leave sharp edges or joggles....stress points crack....or start em'. Smooth is gud.
IMO, that arch is a high stress area on the car.

another idea would be to take your grinder (you should have one for a welding job like this) and grind at an angle on the flange that sticks out where the two pieces are laid together. In metal shop this is a trick we used for flange welds.

This is how the body is normally "welded" together. Spots welds on a flange that's painted over. Very little surface area to weld on, you're going to get gobs of weld material where it rolls down, cools and puddles into large globs. More difficult than it has to be, plus you have a small target to aim for to keep the 2 pieces together.

Hummm.....gud idea. Where were ya when I was doing this?

I'm not much of a welder (varying results) but cleaning to bare metal, like JP mentioned is a MUST

If you don't your results will suck no matter what...

The paint and other crap that's still there will contaminate your weld. Your weld will sputter like mad and you get lousy penetration ( = bad weld)

Wirebrush on an electric drill works perfectly fine, but yes, you'll have to put some elbow grease into it... no pain, no gain

seam sealer comes off best with the wirewheel too

if your weld sucks, just grind it down and have at it again...

But if you use your angle grinder and do about a 60º angle going through both pieces, you can get more surface area to weld on. Afterwards you're going to grind it to the appropriate shape so this will not matter. You are achieving the same goal (seam welding) but doing it cleaner to begin with. Just don't be a doof and cut yourself on your freshly-made lap weld area.

PS: It's always easier to lap weld two pieces together than flange weld...

Nice sketch, but I visualized it.
The long side opposite your gun would prolly be consumed....a gud thing.....but you don't have to go overhead...just kinda angle the gun upward some......which I really like. Some fussing would be in order.....isn't there always?

I drew pictures because not everyone can clearly visualize what I was saying

Thanks a ton bondo!!!

That really helps. I will hence forth do this.

And prep my area better..