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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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  #361  
Old 07-08-2016, 10:10 AM
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Graham08 Graham08 is offline
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Join Date: May 2006
Location: Denver, NC
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Some more progress toward front axles...

Left side axle brackets. I opted to make these out of 1" x 2" x 0.120" tubing this time around to save time and some weight. I still have to put the notch in them to sit on the axle tube and add bushings in the holes for the radius rods to center the rod ends and bring them down to the correct diameter.



The bottom bracket is long because it also supports the Panhard rod bracket. I'm making a minor revision to the geometry to use four radius rods on the front axle. Previously I had been opposed to running this setup because it will bind if you're not careful setting the car up. It's a geometric special case that allows good articulation in roll if the rods are parallel and equal length. The positive side of this is it keeps the axle from winding up in braking, which should help stability because the axle wind up introduces caster split. According to my rough calculations, it would be approximately one degree at max braking, which is a noticeable amount of split.

Set up to weld a new left side onto the axle that was damaged in the crash. It's sleeved in the center. It took some careful setup to get the kingpin bosses clocked correctly relative to each other.



Welded up! There are a total of four plug welds on either side of the joint (at 90 degrees to each other, spread about 2" apart). I did the main weld in two passes to get good penetration into the reinforcing sleeve and fill the bevel completely.



My setup for notching the ends of a new tube. I tacked a short piece of channel onto the tube to have a secure point to use to ensure everything is clocked correctly. I'm using a short magnetic level from Stabila to level it. I ran across the level in my local hardware store and it followed me home...it's a handy little guy for tight spaces.



Boss welded into the new axle tube, ready for some torch work to finish forming the end of the tube around the boss.



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  #362  
Old 07-15-2016, 11:11 AM
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Graham08 Graham08 is offline
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Continuing to plug away...

Got the radius rod brackets welded on both axles. The upper one on the left side is tacked until I can mock up the suspension and make sure nothing binds. I know it should work, but won't believe it until I can do it for myself...



I did some folded gussets in my little press brake to reinforce the right side brackets due to the angle of the radius rods. I'm not 100% sure this is required because the long axis of the tube is aligned with the rods, but it doesn't hurt.



Right side brackets from the outside...



Adjustable Panhard rod brackets for two axles. Still doing Dykem and scriber layouts while I dream of a CNC plasma table. Material is 12 gauge HRPO mild steel.



First one welded up. The notch is to access the nut for the LF lower radius rod.



After fitting and welding to the axle...



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  #363  
Old 07-15-2016, 12:11 PM
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entropy entropy is offline
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Quote:
Originally Posted by Graham08 View Post

Simply BA work as always.
__________________
When did empirical knowledge get replaced by a theoretical education?

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  #364  
Old 08-02-2016, 08:47 AM
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Graham08 Graham08 is offline
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I'm starting to feel as though I've turned a corner on this one...I have the axles completed and I'm working toward getting the rest of the damaged pieces repaired or replaced.

Panhard rod brackets on both axles. Naturally, the second one came out nicer than the first!



A couple of Vise Grips to fixture the rack mounting plate. I did this one slightly differently than the original axle, with the main difference being that I'm using socket head screws that are counterbored into the mounting bungs so the bolts are shorter and lighter. I'm planning on using Nylon locking screws to keep them from vibrating loose.



This is also a better piece than the original...the original one required a 0.003" shim under one of the mounting points on the rack to keep it free when torqued down...this one doesn't.

Next up was to make the clevises to replace one of the radius rod mounts on the chassis and for the drop link points on the axle. These start on the lathe to bore a 3/4" hole down the center and turn a radius on the end.



Next, it's off to the milling machine and the Super Spacer to do some milling:



Almost there! I don't have a pic of the last operation, which is to notch the back side with a hole saw so they sit on tubing. I have a small fixture that I use in the vise to secure them squarely for that operation.



New LF lower radius rod mount. The last step was to tack a couple of 1/8" thick spacers in it to center the rod end.



Drop link point on the axle:



Got the new shock bracket welded on the chassis:



New front axle mocked up. At this point, I also replaced the left rack monoball to repair crash damage. That part is almost a fuse in the design to keep further damage from occurring to the rack.



It was also at this point that I had mocked things up to check travel with four radius rods...which didn't work! It was bound up tight sitting still. I'm pretty sure the reason for this is the difference in the top view angle of the radius rods left to right, which causes some caster change in roll. If they were symmetric about the centerline of the car, I think it would have worked, but in this scenario they don't. I would have to either move the right side inward on the axle (no room for that, plus it's not as stiff or strong), or build an outrigger on the right side of the frame. I think the other builders that run four rods get away with it because the right side has to be set inward on the axle to clear the steering arm used with a conventional steering gear, so everything winds up pretty symmetric.

I cut the upper mount off the axle (I had just tacked it for testing), as well as removed the upper clevis from the frame (much more work). Removing the clevis from the frame saves a few ounces and it simplifies making the body panel in that area.

I had picked up some decent used spindles to save a couple pounds. These are partially aluminum vs. the steel ones I had on the car. Here I'm heating one on a hot plate to make replacing the kingpin bushings easier. Being used, they had some wear and were a little looser than I would like on the kingpin.



Pressing new ones back in.



Repairing the steering shaft support that was damaged in the crash. The tabs are 3/16" thick and were both folded over (in opposite directions). This time, I added gussets to the sides to hopefully prevent that from happening again. This contributed to the air box and the upper U-joints and shafts getting damaged in the crash.



New steering shafts. I was able to salvage the lower telescoping section, though I did have to replace the inner splined portion.



I'm in the process of modifying front bumpers to work with the redesigned front crossmember, as well as redoing the radiator mounting.

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  #365  
Old 08-13-2017, 11:37 AM
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Graham08 Graham08 is offline
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Well crap. Looks like I'm a casualty of Photobucket's cash grab.

At some point I'll find another way to host the photos and fix the links. Damn!
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