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Adding rigidity while restoring rusted metal


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Hi all! 
 

I thought some of you might like to see

the the reinforcement I’m working on to rebuild my rusted out rocker. I have the “slip on” rocker cover for asthetics, but the inside will be home made. 
 

I have prepared a vertical rib (14 gauge) which will go down the centerline of the rocker and serve as the surface for jacking the car, and where both the floor pan and slip-on rocker will weld to. Between the inner axial rib and inner rocker, I have welded in additional ribbing to resist shear (20 gauge). I will add additional 20 gauge ribbing between the axial rib and the outer rocker. 
 

Just an engineer geeking out. I’m sure there is a lighter, more efficient design but I’m having fun. 

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It is good you have the time and skill to do that!  One thing I have done on two of my 240Z cars is having beefing up the frame rails.  I do not mean the kits that are out there like the Bad Dog parts but instead more heavy duty boxed frame.  The first 240Z we did we welded a heavy gauge U shaped on the inside and underside matted together to form a true boxed frame.  That worked good but a lot of work and you had to take out all of the interior.  The next version on the second 240Z an already boxed heavy gauge metal was welded just to the underside.  This work was done by Dando's Automotive in Fremont, CA.  Both of these worked great as the cars are so much stiffer and stronger.  It actually saved my life see this post.  

You might consider also doing this as I think it is a great way to improve a street car for stiffness as well as safety without needing that extensive of a roll bar setup.  I am building a more crazy street car that already has a 9 point cage which I plan on doing this same frame rail upgrade.  My Red Z without any roll bars to me is about as stiff as my Z with a 9 point cage which is pretty cool...

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Hey thanks for the reply! I didn’t think anyone was interested 😂. I will look into what you did! 
smart to add the weight as low as you can. Moving the CG down by even half an inch will be noticeable when you corner hard. 
 

This is a race car so any additional rigidity without increasing weight is a win. You can use really thin metal (20 gauge) when under shear stress, so you don’t have to add a ton of weight if you are strategic about how you add it. Most of the rigidity I am adding is in the service of replacing rust, so the added time isn’t too bad when there isn’t much salvageable metal to start with.

 

also, my full race cage is holding the whole body together while I geeked out on the rocker. Without the cage or carefully choosing how you suspend the weight of the car, you could twist the frame and have a permanent body warp. I have seen some people temporarily weld bracing while rebuilding frame rails. 
 

here are some more pics and vids of my progress this weekend. I have only been welding for four months so it ain’t the prettiest thing. 

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Posted (edited)

Replacing passenger toe panel. Needed to reinforce the area just ahead of the passenger front vertical door Pilar, so I can cut out my rusted frame rail and tie rod box. I’m happy with the results :) 

 

needed this done so I can confidently finish the brake line and fuel line in the tunnel, since it passes the frame rail. Anyone else feel like one thing lead to another... to another... and soon enough it’s 6 months? 

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Edited by AydinZ71
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Since the previous owner made the mistake of terminating the role cage tot he wheel well (and not the strut tower), I’m working on bridging across. I thought by using the wheel well skin as part of the bridge, I could use less metal overall. 

 

I think it needs a verticals flange too, since the tunnel will have tremendous force upwards. 

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5 hours ago, jhm said:

Aydin, I think you're like me (and many others here)....once I get going with the welder, I just don't want to stop!!  :-)

 


haha! Thanks :) Yeah I mean, I kinda do want to stop and start driving, but I’m obsessive and little things here and there keep bugging me. 🤷🏽‍♂️. My neighbor calls me a “perfectionist”, and I think I’m starting to see why...

 

I put a vertical bridge/gusset/rib across from the tower to the roll cage. 1086E98D-8FB9-4BA7-9DA5-0C5AB6DC8FDC.jpeg.e3a7bcf371e50383e79dd3e6dc2b6a0f.jpeg

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Speaking with Greg Ira a few weeks ago, one of things he would have done differently with the orange car he competes with is more stitch welding and bracing. Not for ridgidity, he said he had plenty of that. Rather, he felt the unibody had been cracking and tearing over time. I must have taken that to heart a little too much 😂

 

a part of the concern is making sure I don’t have to go back and add metal in the future. Once she is all epoxied up, pencils down! 

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8 minutes ago, 260DET said:

I'm liking what has been done here and the thought process involved. Keep going.

 

What was done to my sills/rockers was to simply run some square tube underneath against the pinch weld flange and weld it in place. Makes jacking easy too anywhere along it.


hey I really appreciate that! Thank you 🙏 

If my rockers were not gutted, I probably would done the same thing as you. I think I got a little carried away. Lol still, she is moving along 

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Posted (edited)

Passenger firewall complete. Also installed the floor pan subframe so I have something to template against as I add back more steel. The smoke is just weld-through primer offgasing from heat. Wear a respirator!

 

@Invincibleextremes gave me two tips that really helped. Turn up the heat on the welder, and don’t grind the welds down flush. I did see some stress cracks in areas I had welded down completly, and subsequently needed to hammer. Unless it’s in the body panels, I don’t see a need to make a flush, seamless metal surface. The added bead height acts as a thickened edge, and helps add rigidity. Especially since I’m using 20-gauge in most places that only need to resist shear force. 

Edited by AydinZ71
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On 3/12/2021 at 5:47 PM, AydinZ71 said:


hey I really appreciate that! Thank you 🙏 

If my rockers were not gutted, I probably would done the same thing as you. I think I got a little carried away. Lol still, she is moving along 

 

What you have done is better, it's added very little extra weight while adding considerable strength where needed.

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I used 14 gauge for the bottom flange since it is often used as a lift point. In addition to welding all four sides, I included plug welds along the length so it is attached to the tube as well. 
 

one disadvantage of the OEM resistance spot welding is that inaccessible steel surfaces can not be tied together. You end up with a handful of layers laying on top of each other, with only the edges fused. By tying each surface that is nearby, it will act as one ridged body with much less flex 

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I want to start putting stuff back on the car (finally), starting with the fuel cell. To do that I needed to brace the rear skirt, and add some diffuser mounting tabs when I was at it. The fuel cell is much smaller than the Original gas tank and spare tire well. There is a s lots of room for a tremendous Eddy current to be generated behind the skirt, causing it to flap in the wind and act like a wind catch. 
 

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