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Ol'fogasaurus black buggy
Posted: Tue Oct 02, 2007 10:49 am
I am starting to work on my other buggy again and have run into a fit problem with the body and pan. The body is sitting on the pan and you can see some of the gap between the body and the pan (both sides are about the same fit wise). A lot, but not all, of the problem is in the rear of the pan where the rear cross piece comes in. The two outside ends are sitting high with keeps the body from sitting correct.
When I put the pan halves on, I had a lot of hand fitting to do plus I didn't have any help holding things in place when I trimmed and tacked. I have over two hours of hammer and dolly work, per side, just to get the pan halves close enough to tack in place (these are the thin pan halves and all the ones I have seen are pretty sad stampings). On the driver' side, the channel on the rear cross piece did not sit fully on the casting that comes from the rear torsion housing. (see below)
You can also see that I didn't notice that the stiffening flange was long and hit the bottom of the casting which was part of the problem. The gap here is about .125. Question: can the casting on the rear torsion tube be heated and bent? Can the end of the casting be cut and welded (welding is what I am most curious about). This piece is part of the area where the donuts for the torsion bars sit. The drop of 1/8th of an inch will make a difference in the fit between the body and the pan, but not all of it. Heating and bending would be nice but cutting and dropping the piece would be better, fit wise.
I know I could also heat the pan where the contact is made and force the pan down on the casting or I could grind away the problem area, both are alternatives but I still think I may need to be sure of the cutting and welding option.
As a side note; I also have to pinch-in the last three or four inches of the pan, about .30, in to meet the body contour enough to install the last bolt. If not done the bolt hole will be in the radius of the body and the bolt head will more than just ride the radius.
The body is made of Carbon fiber/mat. Question: How hard is it to work with fixing glass and mat problems when the body is carbon mat? I would appreciate any help in this direction too. If you look at the upper right corner is the last picture you can see some of the mat though the gel coat. Also, the welding it not mine!
As a side bar:
You can see how bad the pan half stampings are with the wrinkles all around the rear foot well. Of all the (thin) pan halves I have seen are about the same quality. Definitely, if I have brain fade and attempt to do it again I wills spend the extra $$$ and get the thicker pan halves.
Posted: Tue Oct 02, 2007 3:34 pm
I dont have any real input for the problems your running into. But damn looks good so far! I love fiberglass buggies!
Posted: Tue Oct 02, 2007 4:27 pm
What's carbon mat, that looks like regular fiberglass?
Posted: Tue Oct 02, 2007 4:46 pm
I've always had problems welding castings. Not sure what it is exactly- the alloy of the average casting or a property of the casting itself (like heat-induced latent stress), but I usually run into a lot of cracking in the cast part after welding. Only way around it seems to be pre and post heating as much of the piece as possible- even then, I wouldn't suggest it for structural pieces.
Glass is a breeze, ignoring the noxious fumes and dust. It should sand easily and accept new fiber/epoxy fairly readily (do the same prep as for painting metal- sand, dust, repeat). I'm a lot better at welding than I am at fiberglass, hopefully someone will chime in with more experience. Oh yeah- alwayssss wear a resperator (I like the full face mask) and some serious chemcial gloves- you'll be happy you did.
Posted: Tue Oct 02, 2007 7:40 pm
Thanks guys. I did talk to a local buggy guy who thought that some pre-heating of the casting was necessary priot to welding. People cut the top off the shock mounts and weld to the top but I haven't seen anything about welding around the bottom of the casting where things are in some tension. I don't think there is a lot of loading here but it is causing some probems. Why the shape of the contour is different witht his buggy doesn't necessarly make sense. The little hook shaped piece seems to be the major part of the fit problem.
I am still curious about the strenght of the carbon fiber cloth as compaired to normal fiberglass cloth. Also, how will the marrage of glass cloth and carbon fiber cloth match up. Not much glassing has to be done (I think) but where the problem is in the rear of the buggy. I think I need to do some doubling on the fenders but not sure yet.
Posted: Fri Oct 05, 2007 6:27 pm
More information and a question.
After finally getting a hold of a friend of mine who is a welder, I asked him about welding and bending cast steel. He told me that heating and bending the casting would probably not work and that the material would break. Casting material is not necessarily the same as material you use for forming.
When I mentioned that I was told I might want to heat the metal before welding he said that I would probably want to heat it up after welding to get rid of stress caused by the welding. If this is true, and once he mentioned it I seem to remember that this is a true statement, how hot do I post heat the metal? What about cooling the area off? Do I let it cool naturally or do I cool it rapidly?
Is this information stuff that should be bunched in with the welding stuff?
Thanks a head of time.
Posted: Fri Oct 05, 2007 6:48 pm
I agree cast cannot be bent. As for welding I have never actually learned the correct procedure but have gotten advise and tried it. I was told (and did) to get the metal glowing hot before welding. I arc welded it with a rod made for cast. As with most materials, a slow cool down is the way to go.
Posted: Fri Oct 05, 2007 7:31 pm
Trying to weld a casting is a b*&%^$! Welds never have held for me longer than a few months if that. As others have stated cast can't be bent either. Could you grind off the area that you need removed and leave it be, or does it need to be readjusted so to say?
The Wild Kids
Posted: Fri Oct 05, 2007 10:04 pm
I thought I mentioned that grinding down the cast supports was an option at the start of this string but I couldn't find it on the original post. I must have removed the sentences during my spell checking and editing of the post prior to sending it to Leather for posting (thanks again for the support Leather).
It is really hard to get in the area where the supports and the pan halves are and the pan halves are not that flexible. From what I am hearing, maybe the grinding away of material on the casting is only real option.
I hope there is more input on this question. I think there is some good information coming out of this discussion. Maybe this information should be in a sticky or something like that.
The graphite mat (the mat is black) is a thin weave and is very light. I think is supposed to be stronger than regular F/G mat (at least that is what I think I was told. I used to target shoot with a bow and ended up using Graphlex arrows. Lighter that XX75, stronger than wood. I had fewer problems with it "tailing" than I did with the other type of shafts I tried. The Graphlex arrows held up well when coming in contact with the target frames and obstructions such as clipping trees in the shoots.). It is too bad I couldn't get something up there to give a sense of the small dimensions of the weave. You can get F/G weave this small too.
Posted: Sat Oct 06, 2007 12:08 am
Guys at work welded some cast the other day.
1 heat it red hot with torch
2 mig weld
3 keep it as hot as you can for as long as you can(they put the part in a bucket of floor dry and left it overnight it was still to hot to touch next day)
If it cools too fast it will crack the cast right next to the weld
Posted: Sat Oct 06, 2007 3:59 am
Can you take a pic of the C/F mat i work with them in the Navy and may be able to tell u what u have . from the pic you have up the it looks like a chop gun was used and the mat is a repair.
Posted: Sat Oct 06, 2007 6:55 am
I have welded a lot of cast...it's time consuming to do it correctly...but can be done. There are a couple ways to weld cast...and both will work.
One is with preheating and one is without. I personally prefer the pre-heat method...be it can't always be done.
For preheating...heat the cast to between 700 and 800 degrees...you can go a little higher...but don't get too close to 1400 or you will have a problem. When up to temp...weld a very short bead (an inch or less) and then peen the weld...let it cool a little, preheat again, short bead, peen, repeat until you are done. When done...try to let it cool as slow as you can (sand would be perfect...but anything to keep it from cooling too fast will be an improvement. Oh...I always use an arc welder for this...on a low setting (can't get too hot) with a "Ferroweld" electrode made by Lincoln.
If you are going to do it cold...it will still need a little preheat...you just do not want to get it so hot that you can't hold your hand on it....Run a very short bead...peen the bead and then wait until it cools off completely...and repeat until done.
Posted: Sun Oct 07, 2007 4:58 pm
Is the whole torsion housing cast steel not just the end pieces? Reason for asking is that I could cut the tangs that supports the pan off then make and weld a new support in place. It looks like I have to drop the rear corners up to (about) a quarter of an inch, maybe more.
Still looking at my options.
Thanks for all the help and opinions so far.
Posted: Mon Oct 08, 2007 11:40 am
I think I have figured out what to do. I was given the key to the answer over a year ago when I was building my lift. So now I have to see if that answer is usable with a body mount stiffening tube under the pan's outer flange.
Thanks for all the help and input.
Posted: Mon Oct 08, 2007 2:58 pm
Lee, isn't this the same setup you were putting the V6 into? I'm corfused, looks like you stripped it all down?
What are your plans now?