Frame mod: Improvement or just extra weight?

69427

69427

The Artist formerly known as Turbo84
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Mar 30, 2008
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Clinging to my guns and religion in KCMO.
Was looking at the ('69) frame today trying to see where I can add some stiffness to the front half of the wheelbase. The bend in the frame (under the side louver area, just ahead of the front body mount) looks like an area that could use reinforcement. Most every reinforcement I could think of had serious limitations due to interference with the under body area. So, the only area possibly left available was internal to the frame rail. I was entertaining the idea of cutting open the inner side of this bend, and inserting some 2 1/2 inch tubing (matching the bend arc), and welding it to the internal walls (and then welding the original frame panel back on). Some 3/16 wall tubing weighs about 3 pounds per foot, so the net weight increase would be about 3 1/2 pounds per side counting the tubing support gussets.
Make sense, or just a colossal waste of energy? ( I haven't tried actually bending this size tubing yet, either.)

I appreciate the feedback.
Mike
 
Why not weld a big gusset on the inside radius or a plate and box it up? You'll have 3 "walls" which will make it a good bit stiffer and it's probably lighter than what you want to do, and certainly a lot easier.
 
The (under) bodywork extends to about a half inch from the frame in much of that area. A decent gusset would only encompass about half of the arc. Without being able to put substantial material distance on each side of the bend "apex", it just doesn't appear to do much but add weight. Without the body panel intrusion, I would have put in gussets there, as the effort needed would have been minimal.
I've got other stuff amusing me at the moment, but unless I come up with a better idea in the near future, I might just go with the original idea.
 
It would be internal, similar in concept to the Speedway picture. But I was planning on using a tubular member inside to provide some torsional resistance also.
I did previously cut open the frame area above the differential crossmember (batwing) mounts and added an additional internal gusset to stiffen up the vertical "axis" area to try to reduce frame flex during rear wheel vertical loads.
 
Well, I haven't come up with any better ideas to stiffen up the front of the frame, so I'm going ahead with the internal bracing. The first bend by the front bodymount area is the first area I'm working on. The concept is simple, but the grinding and buffing to remove all the internal surface rust is slow and dirty.

IM000933.jpg

I tried to cut the access hole with a small cutting wheel, but it was taking forever, so I ended up using my plasma cutter. A ton faster. Haven't decided whether to reuse the pieces I cut out, or just make a pattern and use a new piece. Here's the tubing mocked up so I can get an idea of what the internal gussets between the frame rail and tubing will look like. I'll be putting in four braces in the four front frame bends. It certainly looks like it's going to be amusing trying to weld in there.

IM000935.jpg
 
I took some pictures of the frame section with the body on

I'll upload them in a bit
 
TheSkunkWorks said:
Twin_Turbo said:
Why not weld a big gusset on the inside radius or a plate and box it up? You'll have 3 "walls" which will make it a good bit stiffer and it's probably lighter than what you want to do, and certainly a lot easier.
Click to expand...

Guess I was MIA, but I think TT was referring to something like this...

Framegusseting.jpg
Click to expand...

I agreed with TT on the easier aspect. But as I noted in post#3, the lower bodywork impinges on the area needed for the gusset. As it is, I'm almost done with the left side, with internal tubing inside both bends, and it's gone a lot quicker and smoother than I would have guessed. It's one of the very few items on this frame modification that has not been a headache. LOL

IM000937.jpg
 
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Yellow73SB said:
Here's the pictures I took


101_1905.jpg
Click to expand...

The above picture shows one of the main issues when trying to add an external gusset to the frame. The floor and other aspects of the underbody restrict the amount of gusset possible without cutting up the floor. I don't think the short amount of frame arc accessible by the gusset would add significant improvement. Hence, my decision to add the material to the interior of the frame.

I appreciate your posting of the frame pictures.
Thanks,
Mike
 
TheSkunkWorks said:
Brings my thinking back around to an aft motor plate being something that could lend some stiffness by tying the front of the car together between the front and trans x-members.
Click to expand...

I'm most likely going to put one in when I put the 4 speed in

it's only .09 thick though

http://cgi.ebay.com/ebaymotors/Jegs...010QQitemZ200233453947QQrdZ1QQsspagenameZWD1V

I'm going to look around a bit for some other plate options

But If I ever run SVRA I don't think it's allowed

I'll just extend the rollcage tubing like this

DSC04046.jpg

He also has some plate over the frame on the outside, seems like a lot of extra weight though

DSC00881.jpg
 
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Got the left side done. Man, I'm sick of welding. I just don't have the patience to do this for hours on end.

IM000946.jpg

Got the right side opened up. I learned a few lessons on the left side, so I'm hoping the tubing installation in this side goes a lot quicker. The main time consuming aspects of all this is grinding and buffing the internal frame walls to get a clean weld surface, along with making patterns and cutting out the tubing mount gussets.

IM000949.jpg
 
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