1 ... 14 15 16 17 18 ... 41
pres589 (djronnebaum)
pres589 (djronnebaum) PowerDork
12/10/20 12:24 p.m.

52" x 70" black & white vinyl sorta-plaid table cloth for $4.59

Probably enough material in three of those to cover the car.  Add a couple cans of spray adhesive and boom, vinyl wrap!

Rattmandu New Reader
12/10/20 2:03 p.m.

If you did louvers instead of rear windows you could get the race car look and still see the engine at some angles. 

12/10/20 2:43 p.m.

This finish comes out of a spray bomb



Bit further back

nocones GRM+ Memberand UltraDork
12/10/20 2:46 p.m.

That is spraying over one of those foam shelf liner things isn't it..


I'm not sure if I will have a window behind the driver or a solid bulkhead.  I do like the idea of louvers.  Provided there is not an Aero reason to avoid them.    I like the idea of a patterned/paisley convertible top over the driver.  You guys are the best at ideas!

12/10/20 3:15 p.m.

In reply to nocones :

Get this man a cupie doll for guessing on the first try! My friend petey makes it look easy.

gumby (Forum Supporter)
gumby (Forum Supporter) GRM+ Memberand Dork
12/10/20 4:41 p.m.

Crap, I think I am coming in a bit late with an NHRA rule gut check....

It appears you may be running afoul of the minimum frame member requirement to which a roll cage member is attached at the lower point of your rear cage stays. I am going to blame my E36 M3ty week for not noticing earlier.


I was hoping to see some sort of plaid or houndstooth fabric for the top, but paisley works too!

nocones GRM+ Memberand UltraDork
12/10/20 6:32 p.m.
gumby (Forum Supporter) said:

Crap, I think I am coming in a bit late with an NHRA rule gut check....

It appears you may be running afoul of the minimum frame member requirement to which a roll cage member is attached at the lower point of your rear cage stays. I am going to blame my E36 M3ty week for not noticing earlier.


UGH..  I figured something like this would happen at some point.. 

So Options to fix (None of which are great because they all end up costing ~$ and weight and require me to cut apart my tire rack that used the remaining 2x2 tube I had leftover)

1.  Replace Red Tube with 2x2 x .083 MS or with 1-5/8 Roll bar tube tied into the rear down tube (Black line)  would probably do 2x2 and have it angle to accommodate the rollbar rearstay)

2. Replace Yellow tube with 1-5/8 roll bar tube. (Seems least likely to be per rules)

3. Replace Green Tubes with 2x2 x .083 MS (Seems like best option to put 2x2 all the way up to the roll bar, looks most like the "2x2 frame" ties to the roll bar frame.  Only adds about $6, adds about 7lbs)

I can also explore options to lower the node some if that would help.  Bummer that I have to redo it all though..  OH well like I said this was bound to happen.


gumby (Forum Supporter)
gumby (Forum Supporter) GRM+ Memberand Dork
12/10/20 7:04 p.m.

I would consider running a continuous 1.625" tube up the red path, over the drivetrain in place of your 1x1 crossbar, and back down the other side. Tie into the base of the main hoop vs. the square tubes. Rear stays go directly on the new rear hoop, and then you land the green and yellow 1x1's in a node there.

The rear subframe junction can go on the green tube directly below the new node and will not look out of place as it will be roughly in line with the rear stays.

I know this requires getting the bender back out, and bending on multiple planes again, but at least you wouldn't hafta give up the new tire rack. frown

nocones GRM+ Memberand UltraDork
12/10/20 7:11 p.m.

In reply to gumby (Forum Supporter) :

Do you think that would be more legal then the option to do the red like with 2x2? 

Reason, 2×2 is $1.67/ft, need 6'.  1-5/8 I'm at $6.50/ft and what you described is almost 9'.   That's a big $$ hit.  If it's the only way it's the only way.  But I would prefer to avoid it.  The rules don't seem to require any cross bar at the back unless I am miss reading them.  (Which I'm apparently prone to do frown)

gumby (Forum Supporter)
gumby (Forum Supporter) GRM+ Memberand Dork
12/10/20 7:43 p.m.

Not so much "more legal," but more that I prefer round tube, and I have a tendency to overbuild in place of doing engineer math.... 

nocones said:

Noting the significant budget hit and looking at your node before plates were added, I would replace the yellow tube with 1.625" round tube. Leave it a bit longer than the current 1x1(like ¼" to gain a bit of space for easily welding other tubes), if that won't foul the subframe plans, and cap the end. Add the subframe mount as you had shown previously without the additional gusset plate. Land the rear stay directly on the new horizontal tube, then tie the crossbar, green 1x1, and the red diagonal into the new node. Or, in more or less your words, option #2 yes

nocones GRM+ Memberand UltraDork
12/10/20 9:08 p.m.

Ok so I read the rules like 3 times and then stood by the car for a bit trying to be 1 with the grinder.  

After looking at the angles in person this is what I am thinking of doing.    I believe that it clearly meets the rules.  The roll bar will terminate at a 2×2 tube that will run as a "continuous" connector between the bottoms of the roll bar similar to the pictures.  The rear stay will be at the correct angle.  I will still use a 4130 plate just like all the others but it will be pretty flat.  I will move the chassis bolt bung to the end of the 2*2 tube that will be horizontal.  I am planning to align the inside of the 2x2 to where the 1x1 was so I will just reuse the cross bar.  

Red=2x2, Yellow=1×1, Blue=1.625, Green rear subframe

I may still decide to replace the 1x with 1-5/8 tube.. or use some of this random 32 MM 4130 stuff I have.  If I did that tube as roll bar it would take 4' (Increase of $24).  This design is about $4 more then how it was.   I know it's not what you suggested but I think it still meets the rules and makes sense for the actual dimensions of the chassis..  

gumby (Forum Supporter)
gumby (Forum Supporter) GRM+ Memberand Dork
12/10/20 9:32 p.m.

That should satisfy the rule. I was struggling to see your vision for reworking the node with 2x2 running into it at such an angle, but the kink at the top fixes the issues I was battling.

Are you planning a lateral connector for the lower corners of yellow 1x1, under the drivetrain? The new proposed yellow diagonal seems superfluous; especially so if you tie the lower corners to each other.

nocones GRM+ Memberand UltraDork
12/10/20 9:39 p.m.

The lower corner will be tied together through the green removable part.  There will also be triangulated to the middle of the chassis at the cross car lateral (where they will pick up the engine cradle part of the subframe). I will post some pictures that will make it make sense soon.

Your probably right about not needing the triangulation there.  It's entirely possible I will skip it.  

I will move forth with the recovery efforts.

nocones GRM+ Memberand UltraDork
12/11/20 12:21 a.m.

Ok that was a big night.  Thanks to Gumby for pointing out my issue with the NHRA regs before it became late enough that I had a crisis.  This way it was just a mild annoyance.

So I cut out the original stuff but cut the crossbeam and the upper 1x1 tube to the correct angles to re-use.  I then mittered some 2x2 and this is the result:


So for accounting:

+2.5 Hrs, +5.38' of 2x2 ($8.98) -10.25' of 1x1 (-$7.45) -0.44sq-ft 4130 plate (-$4.84).


That brings us to the 100 hr update:

101.5 Hours

$1033.54 spent (GC8, WRX uprights, Radiator, Rod Ends, Metal used to date)

$347.29 Recouped (Subaru Shell, Transmission)

$686.25 Total 

Tube / Metal used is now

4130 - 585.75"@ 6.50/ft = $317.28

2x2 - 331-7/8" @ 1.67/ft = $46.19

1x1 tube - 363-1/2" @ $0.67/ft  = $20.60

4130 Plate - 1.43 sq-ft @ $11.00/sq-ft = 15.72

3/4 x 3/4 tube - 41-1/2" @ $0.69/ft = $2.39

3/4" x .25 Wall 4130 Tube - 29.6" @ $0.50/ft - 1.23

1" x .125 Wall DOM Tube - 27.2" @ $1.35/ft - $3.06

Total = $406.46

maschinenbau (I live here)
maschinenbau (I live here) GRM+ Memberand SuperDork
12/11/20 8:10 a.m.

I like this solution a lot. Looks very "frame rail", like one continuous well-thought-out chassis. I am following along very closely for my future Lotus build, so thank you for figuring all this out for me laugh

nocones GRM+ Memberand UltraDork
12/11/20 1:44 p.m.

In reply to maschinenbau (I live here) :

Thanks.  I actually agree.  After seeing how it looked in steel it really made sense. 

If you need/want any details for ideas I can take more pictures.  I've thought often about building a regular Locost and have done some CAD modeling a bit different frame then is typical but then I always manage to draw it up as a Bugatti Type 57 Atlantic instead.   It's wierd how that happens.

nocones GRM+ Memberand UltraDork
12/13/20 9:59 a.m.

After another 2 hrs we are almost back to where we were.  Welded in all the new tubes, and installed the new base plates.

I'm satisfied with the fit of everything.  Next step will be the actual rear tubes.  After those the roll cage is "Done" except for finish welding. 

preach Reader
12/13/20 10:09 a.m.

Get some! I love this thread.

nocones GRM+ Memberand UltraDork
12/14/20 12:09 a.m.

Rear downtubes are done.  Which means the Cage is Done*.  

*Still needs finish welded, and I need to decide how many if any gussets I'm adding before the challenge.  

Next step is finish the 6 rear subframe bungs.  I am happy with how this turned out despite needing to cut out some tube and re-do it.  Thanks for pointing out the Issue Gumby.


+1.5 hrs, +52" 1.625 4130 Tube @ 6.50/ft = $28.71

Total for the NASA/SCCA Legal 1.625 x .095 wall 4130 for the cage is 53.23' @ $6.50/ft = $345.99, 82.6 lbs Est.

Had I used just NHRA legal 1.625 x .083 wall 4130 it would of been 53.23' @ $4.55/ft = $242.20, 72.76 lbs Est.

This would have been a savings of $103.79 & 9.84 lbs.


Dusterbd13-michael (Forum Supporter)
Dusterbd13-michael (Forum Supporter) MegaDork
12/14/20 5:32 a.m.

Oh man. Thats AWESOME. 

gumby (Forum Supporter)
gumby (Forum Supporter) GRM+ Memberand Dork
12/14/20 6:20 a.m.
nocones said:

I am happy with how this turned out 

As you should be. Looks great! 

sleepyhead the buffalo
sleepyhead the buffalo Mod Squad
12/15/20 10:38 a.m.

Looks like you've got lots of great room for diffuse activity.  Maybe more height than you can take advantage of.


nocones GRM+ Memberand UberDork
12/16/20 8:37 a.m.

In reply to sleepyhead the buffalo :

There has to be suspension and stuff back there, but I do believe there will be plenty of room for activities!


Only had 1 hr last night so I got all the parts ready for the remaining chassis bungs.  The tube is a dumpster sourced part.  The metal is some .125 thick plate that was an offcut from a project and I need to figure up the value but it's 1sq-in each.

bentwrench SuperDork
12/16/20 12:01 p.m.

I'll just leave this here for inspiration.



nocones GRM+ Memberand UberDork
12/17/20 9:51 a.m.

I welded up the subframe bungs (Used the rest of my Argon again), and installed the upper chassis side mounts.  I decided to notch the tube slightly just to add a bit of stiffness to the plate.  

I also trimmed the removed lower tubes to fit the new 2" diagonals. 

It was at this point that I realized I have made an error.  In my haste to rebuild the chassis..  I built the rear structure off-center..  it's about 1" shifted left.  I based the location off of the body.  Apparently the body has shifted slightly as it's been removed/reinstalled and had all semblance of structure removed.    Thankful there is enough clearance to the structure I built that the body can be recentered without modifying the frame.  Ultimately it won't matter as the engine/drivetrain will mount to a subframe so the only impact is that the supports for the subframe will not be identical side to side.  It's a stupid mistake but it happens.  

Here you can clearly see the offset?  Ironically it looks like the right side is low compared to the left.  They are equal..  I think.  But again ultimately it doesn't matter as long as the suspension mounts in the front and the rear suspension mounts on the subframe are in the right spot.  The subframe to chassis interaction doesn't have to be perfect.  Remember chassis is big bracket, locates the suspension geometry, transfers load, and allows for clearance to the engine and protects the meatbag.

Body on its obvious by the location of the bungs in the taillights.

I also figured out the layout for the middle and front bungs.  A tube will be ran diagonally to the main crosstube. A bung will be added at that intersection.  I will add a diagonals in the plane of the roll bar down to the 2" tube to tie it to the harness bar node.  

+1.75 Hrs, +2×6" 4130 plate ($0.92), +58" 1x1 ($3.29)

1 ... 14 15 16 17 18 ... 41
Our Preferred Partners