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Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.


Race Car Fabrication There is a lot of cool fabriaction going on the race car industry, show us what you got.

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  #221  
Old 05-26-2015, 02:02 PM
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entropy entropy is offline
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Oh-geez I can understand the Disk... One lower and one cervical
Been a couple years on at this point, there were those days, thankfully not lately, where just breathing without pain a days goal...

Chassis looks amazing!

Take care

E
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Last edited by entropy; 05-26-2015 at 02:04 PM.
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  #222  
Old 06-02-2015, 07:19 AM
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Originally Posted by entropy View Post
Oh-geez I can understand the Disk... One lower and one cervical
Been a couple years on at this point, there were those days, thankfully not lately, where just breathing without pain a days goal...

Chassis looks amazing!

Take care

E
Thanks! The first few days of the disc episode were hell. Thanks to some pretty sharp physical therapists, I'm getting better without surgery.

Made a little more progress on some tin work. The front belly pan is all finished up:



I was pretty happy that I got all the lines to line up correctly on the two sections when everything came together. I can remember when I used to sweat bullets to make a shape like this come out close to the right width, let alone make two the same. Experience!

The other thing I did on these that I haven't done before was to lay out all the notches before bending so I could cut all the radii with punches and deburr when the panels were still flat. It definitely takes more time to lay out this way, but it saves a ton of time vs. cutting all the notches in the panels with hole saws or files after it's formed.

The other piece I made up was a little chin spoiler to finish off the front end. This is mostly cosmetic, but it should encourage air to go through the radiator instead of under the car.



I've decided on a "less is more" approach on the bodywork on this thing. Partially for maintenance (less stuff to get dinged up), plus if it's not there it can't weigh anything in the first place. I'm trying to make what is there really nice, though.
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  #223  
Old 07-06-2015, 10:06 AM
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I haven't updated this real recently because I've mainly been doing reassembly. Lots of sandblasting and painting all the bolt-on steel parts, shortening bolts, etc. Not much in the way of fabrication content.

I did manage to get the throttle linkage designed and built. This is a rising-rate (progressive) linkage that opens the butterflies about 30% in the first half of the pedal travel, and the remaining 70% in the last half. The reason for this is to help the driver get the car off the corner without a wing and on the hard tire we're required to run.

After settling in on a design, the first step was to make up the bell cranks. These are made out of 1/4" 6061 plate and use aircraft bell crank bearings for the center pivot. The two pieces are held together with solid rivets.



Then, I started at the engine and worked my way back to the loud pedal. Fortunately I was able to use an existing hole in the injection to attach the bell crank. The linkage rods are 3/8" x 0.049" wall 4130 tube, with 10-32 ends from Chassis Shop.



The bell crank closest to the pedal needed to be set off the chassis structure a bit to get the pivots in the right place. I made this bracket out of 3/8" tubing to do that. Digging my little Ridgid bender for this stuff!



The knee bone is connected to the...



I needed a bit of offset to get from the pedal to the bell crank. In order to not use up all the misalignment in the rod ends to do this, I put an S-bend in this link.



After getting it all together, the pedal hits the floor just as the butterflies are wide open, just as I had laid out in my spreadsheet. Yay math!

But...there was one thing I hadn't counted on. There is just enough compliance in the linkage that the progressive bell crank wanted to toggle over center at the very top of the travel (throttle closed). It's not a safety issue, but would be annoying as hell to feel that click in the pedal as you're trying to ease into the gas. In order to fix it, I added an up-stop on that bell crank:



With that sorted, I was able to add a return spring on the pedal. I used the KISS method here and just bent a couple of small hooks out of 3/16" mild steel rod.



This week's project is to get the fuel system plumbing all sorted...

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  #224  
Old 07-06-2015, 06:51 PM
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Regarding the following posts from October 2013:

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Originally Posted by TheBandit View Post
One last question here... can I drive it?
Quote:
Originally Posted by Graham08 View Post
Maybe...it seems like everyone that sees it asks that question! There's a line forming...gotta get it done first.
What's my current spot in line and are there any favors or particular variety of beverage I can offer to get moved up?
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  #225  
Old 07-06-2015, 09:06 PM
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Bell-cranks, offset, linkage......just awesome!
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  #226  
Old 07-07-2015, 08:02 AM
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Quote:
Originally Posted by TheBandit View Post
Regarding the following posts from October 2013:





What's my current spot in line and are there any favors or particular variety of beverage I can offer to get moved up?
Not sure. I think you need to demonstrate your driving prowess in your Nova before I give you a shot.

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Bell-cranks, offset, linkage......just awesome!
Thanks!
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  #227  
Old 07-07-2015, 11:26 AM
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Awesome stuff Graham!

And I call dibs after Clint! Of course, and against my better judgement for admitting this, it should be noted that three races ago ended in me barrel-rolling twice, soooo, yeah. The last two races have been accident free though!
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  #228  
Old 07-07-2015, 11:32 AM
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JaysinSpaceman JaysinSpaceman is offline
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I totally dig the bell crank system. The fact that you made it progressive is just over the top. I know at one point you said "Yeah math", what was the geometry or the formulas that 6th used to figure it out. Most of the time when I build bell cranks and linkages I have to make mock-ups to get everything right. Really it is mostly because I suck at math.

Everything looks great.

Thank,
Jaysin
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  #229  
Old 07-07-2015, 03:16 PM
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Originally Posted by JaysinSpaceman View Post
I totally dig the bell crank system. The fact that you made it progressive is just over the top. I know at one point you said "Yeah math", what was the geometry or the formulas that 6th used to figure it out. Most of the time when I build bell cranks and linkages I have to make mock-ups to get everything right. Really it is mostly because I suck at math.

Everything looks great.

Thank,
Jaysin
Thanks!

It will take a few minutes to sketch everything up that went in the spreadsheet I used, but it's reasonably simple trig. I simplified the calculations some (they don't account for the angles of the links, for example) to make it work in a spreadsheet, and it seemed to work out OK. Much better than what turns into hours of fiddling (for me anyways) to do with mockups.

If you PM me your email address, I can share the spreadsheet I used, but it definitely needs some explanation to go with it.
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  #230  
Old 07-07-2015, 04:33 PM
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Whoa you didn't account for the angles of the links?!? Your kinematics will fall apart and the thing will probably get stuck at 10% throttle on the final lap! Better start over :P
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  #231  
Old 07-08-2015, 07:32 AM
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Whoa you didn't account for the angles of the links?!? Your kinematics will fall apart and the thing will probably get stuck at 10% throttle on the final lap! Better start over :P
Engineering blasphemy, right?

Early in my career, someone smarter than me told me that simulations give you about 80% of the answer in the first 20% of effort you put in. The remaining 20% of the answer requires 80% of the effort. In this case, I think the 80% answer works OK!
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  #232  
Old 07-09-2015, 08:35 AM
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Progress on getting the fuel system functional:

First was getting the fuel filter attached to the car. This is a Peterson 600 series with a ball valve shutoff built in. IMO, Peterson makes some of the nicest parts available. The bracket is 1/2" x 0.058" wall tube, with the saddle made out of a piece of 2" x 0.049" header tubing. The filter is just under 2" OD, but after splitting and welding on the saddle tube, the filter fits right in.



The plan is to add an extended knob to the shutoff lever that will poke through the body panel so it can be accessed from outside the car in case of emergency.

I'm a big fan of the band clamps like I'm using here. They're not horribly expensive from McMaster-Carr, and are way better than hose clamps.

The other thing I finished up was the line connecting the fuel filter to the pump. I used 304 stainless hard line for this because it takes up less room in the car and can be bent on a tighter radius than -12 hose. This took some careful measuring to lay out. There are four bends in a ~30" long piece of tube, but I got it right the first time!



I really need to get a decent laptop and Bend Tech. That would have saved about an hour of layout work.

Another view:



I need to add an Adel clamp in the middle of the section going toward the front of the car, mostly for peace of mind. This is really rigid as it sits now.

This was my first time bending stainless with my large bender, and I noticed that annealed 304 doesn't spring back anywhere as much as either 4130 or DOM tube. I'm sure the "annealed" part is the reason why. This is 3/4" x 0.065" wall.

I did the flaring with an Imperial tool I picked up off Ebay a while back. Their Rol-Air stuff is really nice, and it seems like the big tools (mine does 3/4" to 1-1/4") go pretty cheap relative to what they cost for a new one. The tube nuts and sleeves are from Fragola. One added benefit to doing hard line is the parts and materials are a lot cheaper than AN hose and fittings...after you make the investment in bending and flaring tools.

Now to get fuel to the engine, and back to the tank...

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  #233  
Old 07-09-2015, 12:27 PM
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Looks great as usual.

I love the solid rivets in the throttle linkage. I need to look into getting some and figuring out how to install them, heh.

Also, the bending and flaring is so good. I checked ebay and found what I think is the exact flare tool you are using for $200. Very tempting. I have a large Imperial kit, that does 37, 45 and swedging but I think it only goes up to 1/2".

Dan
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  #234  
Old 07-09-2015, 02:29 PM
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Quote:
Originally Posted by juicedz4 View Post
Looks great as usual.

I love the solid rivets in the throttle linkage. I need to look into getting some and figuring out how to install them, heh.

Also, the bending and flaring is so good. I checked ebay and found what I think is the exact flare tool you are using for $200. Very tempting. I have a large Imperial kit, that does 37, 45 and swedging but I think it only goes up to 1/2".

Dan
Thanks!

You have to watch out for the solid rivets...they're addicting! I've gotten to the point that I only use a pop rivet if really, really necessary. Installation is pretty simple, just takes a bit of practice to get onto holding the gun and bucking bar so they come out square and you don't put little smileys in the surrounding metal.

Ebay is a good source for rivet tooling. I buy my rivets from Aircraft Spruce. Good news is they're cheaper than buying pop rivets. The next thing I want to pick up is a squeezer, which looks to be the hot setup when you're doing small parts that require three hands to do with a gun.

I saw an article in Rodder's Journal about an old Bonneville car that had war surplus Dzus fasteners on it, built before pop rivets became commonly available. The springs were solid riveted to the plates...so guess what I do now. Yeah, it's a sickness...

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  #235  
Old 07-09-2015, 02:50 PM
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Quote:
Originally Posted by Graham08 View Post
Thanks!

You have to watch out for the solid rivets...they're addicting! I've gotten to the point that I only use a pop rivet if really, really necessary. Installation is pretty simple, just takes a bit of practice to get onto holding the gun and bucking bar so they come out square and you don't put little smileys in the surrounding metal.

Ebay is a good source for rivet tooling. I buy my rivets from Aircraft Spruce. Good news is they're cheaper than buying pop rivets. The next thing I want to pick up is a squeezer, which looks to be the hot setup when you're doing small parts that require three hands to do with a gun.

I saw an article in Rodder's Journal about an old Bonneville car that had war surplus Dzus fasteners on it, built before pop rivets became commonly available. The springs were solid riveted to the plates...so guess what I do now. Yeah, it's a sickness...

Haha, I was thinking the same thing. They just look so good, how could you NOT put them everywhere.

Dan
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  #236  
Old 07-13-2015, 09:28 AM
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Some progress on the fuel system plumbing this weekend. Not as much as I had hoped, but there was a fair amount of head scratching on a few things...

The biggest thing was getting all the "dots" in place that needed to be connected by plumbing. I'm a big fan of using bulkhead fittings to help route and secure lines to the car, so after some thought, I added tabs in the right places to secure them. After that, getting the shutoff mounted, things were going OK. Then I got to the secondary and high speed bypasses...

In a mechanical injection setup, the fuel pump and nozzles (in the intake manifold) control the gross fuel curve, but the majority of the adjustment comes from how much fuel is bypassed back to the tank. There's a main jet (pretty much always open) and optionally a high speed and a secondary bypass. The high speed takes fuel away at higher RPM (system pressure) to account for volumetric efficiency decreasing with RPM. The secondary limits the amount of fuel going into the engine with the throttle closed to keep it from loading up.

I'm running Kinsler diaphragm type high speeds for both the high speed and secondary. They allow for easier tuning than shimming to preload a spring with the old style high speeds. Unfortunately, they're an awkward shape to mount to anything, and I didn't just want them flopping around on their hoses like a lot of people do. I thought about just hanging them off a bulkhead fitting, but the secondary is an older model that's brass, and I was afraid of the weight eventually fatiguing and breaking a fitting. So, after some head scratching, I came up with this:



This is just a split clamp for the two parts made out of 1/2" x 2" aluminum bar. The added length is to get it bolted to the car, like this:



This also shows the stainless hard lines that tee the high speed and secondary together. Because the two generally aren't open at the same time, Kinsler says it's OK to run a single line back to the tank.

And finally, hard lines back to the rear bulkhead fittings for the main and secondary/HS bypasses. These are in hard line to save some space and simplify the routing a bit.



Short hoses will go from the rear bulkheads to the top of the tank.

More plumbing is in my future...
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  #237  
Old 07-14-2015, 07:42 AM
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Another hard line pic, this time from chassis mounted bulkhead fittings to the barrel valve for the supply to the engine and the secondary bypass:



This is testing my patience, but I'm happy with the results so far. Learning new skills is like a drug...

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  #238  
Old 07-14-2015, 04:21 PM
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I think you need to demonstrate your driving prowess in your Nova before I give you a shot.
OUCH!
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  #239  
Old 07-16-2015, 02:21 PM
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Can you describe your process for laying out and bending that last pair of hardlines? Do you do any mockup beforehand, like a wire mockup for example? How do manage plane of bend for the hand bender? Eyeball?

I ran one of two steel lines for my transmission that needed to route along the frame and it was not the easiest thing to fit up nicely because all the bends were out of plane and something other than 90 degrees. I would have employed Bend Tech for the job but I didn't feel I could accurately measure everything for XYZ locations. Instead I did the part piecewise; I flared the end and made the first couple of bends to jog partial way, fitted it, figured out where the next bend should go, under bent, went back and forth to the bender and on and off the car bending sligthly more until it went where I wanted, then sort of repeated until it was done. The problem is in a lot of cases due to going in and around or under things, I didn't always have the option of leaving a length of tubing sticking out from one end. Plane of bend was also really hard to get right because I could see what I needed while the piece was fitted, but there was not a very good way to make sure I had it right after taking the part off in order to get it into the bender. The end product turned out okay but there's got to be a better way!

Here are some photos of the tube I'm referring to: link1 and link 2 In the second image if you look closely below the front of the upper control arm there is a small correction bend I added after things didn't fit quite right. I'd like to avoid that kind of thing.
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Last edited by TheBandit; 07-16-2015 at 03:15 PM.
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  #240  
Old 07-16-2015, 03:56 PM
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Quote:
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Can you describe your process for laying out and bending that last pair of hardlines?
Sure. The lines in your pictures look really good to me. That's a tough job because you have no datum to work from.

In my case, I was able to use the left frame rail, the motor plate, and the bottom of the valley plate as datum X, Y, and Z. I had all the fittings in place that I was planning to use. I also had a couple pieces of mild steel tube that I had bent with a 90 and a 45 to help visualize what I was trying to do. After carefully measuring everything, I bent up the bottom tube.

It fit OK. One thing I sort of got caught out by was that the barrel valve wasn't exactly parallel to the center of the intake, so my line angled off to the right side of the car. I put a small bend in to correct it, but the real issue came to light when I started laying out the second line...I didn't have enough room vertically to make the two bends at the back.

So, I got to make the bottom line a second time, this time with a 1/2" offset down to give myself enough room to bend a large enough offset to get the last 45 and 90 in place...barely.

I got the last of the fuel system plumbing wrapped up last night with the hard lines from the pump to the shutoff, and then to the bulkhead that goes to the engine.



The line that goes from the pump to the shutoff was a challenge. It's like you describe where you have to do some of the bends, flare, and do some more measuring to finish. Again, I was able to use the frame rail and motor plate for datum surfaces, but there was still some head scratching and sneaking up on it. The last two bends at the pump were interesting, but I got it on the first try. Good thing because this was my last piece of tubing!

I definitely need to get Bend-Tech. It would have saved time and material for this deal, no doubt.

Here's the tank end, with the hoses for the bypasses connected to the top plate:



It never really dawned on me how much easier hoses are than hard lines. I did all six hoses for the fuel system in the time it took to do the last two hard lines.

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