Your opinion on chassis build up.

SON240sx Automotive
1

I have a week off for the holidays and during this time I plan on seem welding my project car before I put it on the rotisary so I can work on the under carage.

I am just looking for opinions on what seems you would weld and how you would go about it. I am a profesional welder and I will be useing a top of the line welding machine.

I know what I am doing but am curiouse to here other peoples ways.

Also I am thinking about useing expanding foam in the frame rails rocker pannels etc. What foam do they use and where can I get some? I have not yet researched this but I thought I would just ask.

2

use mono foam. itll work just fine, just make sure u drill a few holes in case u put too much in ive seen that shit bend a locker door right out , as for the seam welding chris, i dunno , i would assume along every seam u can… the more the better, are u actually using a seam welder or are u going to use a mig and weld the seams ?

3

I spent a while deciding what route I’d take on this myself and tried just picking out certian seams say but then once I really thought about it, if your going to do it, might as well do every seam.

I myself kept a 2.50’’ gap between welds

4

the most important thing is going to be putting a tarp over the faster cars in the garage so that you dont do any damage to things of actual value.

BLAAAAAAAAAAAAAAAAAARG

5

Its only faster for the time being because I made it that way and mine does not have an engine…but we will see who is faster when its done.

6

yes, eagerly awaiting 2010… lol

7

Alot of ppl have different theorys behind seem welding. One thing to keep in mind is to make sure all seem sealer is gone because it contaiminates the welds. If i were you i would just do the engine bay and firewall and fill the front frame rails and rockers with foam. Check out club4ag and try doing a search. There are numerous write ups on seem welding!! Many people avoid doing the back of the car , but like i said everyone does it differently. I recommend checking out club4ag.com it doesn;t hurt to read more up on it. They also recommend types of foams. It takes a very long time i am sure u know! Goodluck

8

weldning in any form equals heat put into the unibody… which means stress and twists, heated adhesives and melted anti corrosion coatings on the inside of everything from B pillars to tower joints…

I’ve explained the modern ways to do this a few times already, read the back posts, or not, your choice. I just don’t want others to assume this ‘seam-ing’ method is the ONLY way to do it… like it was back in ~ 1965…

9

Ian man , chris is asking for opnions, please do explain and share some knowledge, he didnt ask if there were back posts about the topic, he asked for what people think, chris isnt one of the shit tlkling hardcore wannbes ur used to posting in response to and hes not a noob, u have a wealth of knowledge on alot of stuff, so just for once , seeing as how its christmas be nice please

10

I assume this is going to be a track only vehicle?

11

LOL, I thought I was being , at very least, mild.

But thier are whole back posts on this subject that has allot more info in it that I can probably put down in one post.

However a short synopsis of my ‘thoughts’, which do not equate to the be all to end all, just ’ my opinions, based on modern technologies and what I’ve experinced with these products over the last 2 decades.

Foam, easy to use when prepped properly, the ‘mono foam’ is a poor mans version of ureathane foam, the mono does not create an even cellular system which tends to get denser as it approaches the surfaces it’s being pressed agianst. Large bubbles can be found in the mono product. Stenght is no where near the same flexural and torsional effects are drastically reduced with the Ureathane, which are not found in the mono foams… however, it’s better then nothing, but I don’t reccomend it.

Automotive adhesives are best used on a two clean metal surfaces where large overlaps or joints are located. this usually applies to ’ floor’ of the cabin both front and rear also where main subframe panels join. This saves you from pouring heat into these joints where it cando the most damage. The right adhesive ( as thier are MANY out there now for differnt jobs ), in the right place will work better then a seam weld as during warm and cold cycles there is an ammount of give as metal contracts and expands. This maintains the original idea behind the spot welding and OEM joint adhesives.

Rivets… are VASTLY under rated we build whole aircraft shells with it, the wings we build that take up to 56-58,000 lbs of loading these are 100% riveted…the only welding in most wings is on a fuel tank… everything else is riveted together. Rivets are not the Can. Tire ‘po’ rivets… but proper industrial/aircraft rivets. Sized peoperly with the right washers backing them. These are used where ever you have a flanged joints, where multiple panels meet. most common and sayest ones to recongnize aer on the uinbody front frame forks, body side door openings and the D spar or rocker flange where the under body, Upright and curved elements of your D spar all meet… placing a rivet ever 3" or eqidistant between the OEM spot welds will increase the rigidity by an amazing ammount. You just need to make sure that you are using the right rivets for that depth of material.

Lastly you need to balance out the ammount of stiffenig you do to the frame… tightening up one point will just move those forces down to the weakest point in the frame… if you work on the whole midsection of the vehicle and get it rock solid then both the rear and front of the car are now going to be stressed that more and having to deal with more loading. Same with the reverse, you focus on the fore and aft section of the uni body… the cabin area will be taking up all the loading … balance, is the key don’t over do it one area.

12

If you choose to go with rivets, see if you can get a hold of a pneumatic riveter. Putting in a hundred or so rivets with a hand held pop-riveter isn’t a lot of fun.

As BAS pointed out, stiffening one area could change the loadpath to creatre problems in other areas, so, I would weld/rivet as many of the seams as feasible.

13

Thanks for your post’s guy’s. I will not be useing rivets, not that I don’t think that they will work but I don’t like dilling holes in my chassis. I m going to use the mg welder to seam weld the car. Remember though that the car is completely stripped and I have acces all the seams including the all the sams underneath the car as it will be on a rotisary.

This is not a rush project iether it is not a big deal to me if I only do 4 stich welds a day spreading them out evenly front to back left to right and then go back the next day and do another 4. This will keep the sheet metal from obsorbing to much heat and warping. I also know a few techniques on how o keep the weld temp down. I have been doing this for around 6 years now.

Thanks for your opinions and feel free to coment on how I am going about this.

14

Also a powered tool will give you a consistent load on each rivet. Hand tools tend to modulate depending on how your holding the tool and what kind of angle your at…