The DUNGBTL Build

[DUNGBTL]

Thank you!
Truth be told…although I’ve resto-modded many cars in the past as a hobby, this is probably the pinnacle of my bodywork. I was nervous about doing this in the beginning. In the end I told myself it was only a $100 part, removable from the car, so just go for it! Just took my time…having some OCD probably helped w/the outcome…

J.

[Kafer_Mike]

[vamram]

[DUNGBTL]

Thanks!

Intuitively you might think it may help. However, I know the vw engineers did a lot of testing on the cooling intakes and exits. And even when increasing emissions requirements created hotter running engines in the 70’s, they did not put vents in the lower valence. Instead they opted for more vents in the deck lid…even one under the license plate!

My opinion is that because of the low pressure area behind the bumper, the hot exhaust and engine air may just get sucked back in the eng bay via the deck lid intake venting. I wouldn’t recommend this for an air cooled car.

J.

However…Porsche engineers thought it was a good idea for the Carrera 2! So go figure!

[DUNGBTL]

1302R Bonnet Handle

MORE DRILLIUM!

Been working under the rear of the DUNGBTL on some suspension stuff lately (to be revealed later) so I needed a break from under the car. A ‘standing’ project…making the bonnet handle sexy again!

It appears original to the car, complete with the single repaint overspray.

Used the round tube center marking trick to find center of handle. Slid sharpie along one side, flipped and did other side. The center is btwn the two lines…

Measured, marked, piloted, drilled and chamfered. I used hole sizes ~1/2 the width of the handle….

Sexier handle…

Back to working under the car…

J.

[H2OSB]

Those look awesome!
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(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants.

[agramer1966]

Niiiiiice 👍
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1966 VW1300
1973 VW1302
1974 VW Trike
1984 924
Bunch of old Jap motorbikes
Instagram & YT: #agrameroldoctane

[DUNGBTL]

Roll and Kafer Bar

For better handling and power transfer I wanted to make the pan/body stiffer. To that end I installed a 6-pt roll ‘cage’ and a so-called Kafer-bar. I wanted the roll cage and Kafer bar to be bolt-in. In case I ever wanted to separate the body from the pan, I didn’t want to have to cut bars out.

I also wanted better egress than the typical SCCA style 6-pt cage, so the door bars are a compromise towards getting in and out of the car…actually, my wife, having experienced my other modded cars insisted on it. I’m running DOT legal 3-pt seat belts, so no harness bar. Also, no SCCA required diagonal bar for better seat room and access to rear (for the dog!). But otherwise, tube size and angles and landing pads are per SCCA specs.

I started w/locating where the main hoop (1 5/8”, .120 wall DOM) feet (or ‘crush boxes) would go. I looked at other vintage beetle cages and settled for this locn…

I then made a template of the crush box and fabricated it out of 1/8” plate.

After tacking in place and checking fitment, I welded in the captured nuts for the inbd two 3/8” bolts…the outbd two bolts go thru the floor and bolt to 1/8” doublers. I welded the boxes up and coated the pan area and inside of boxes w/weld thru zinc primer. Then welded to the floor.

I made the plates for the main hoop ends that bolt on to the boxes and the floor doublers and check for fitment….

Rhodes Race Cars made the main hoop as I do not have access to a proper tubing bender. The main hoop is a great fit, tight with ~3/8-1/2” clearance to the roof, however, I had to peen clearance in the roof sills to facilitate installation. I bought the DOM tubes for all the other bars.

The rear diagonals I landed on the package tray specifically because I wanted to tie the Kafer-bar (truss) to the roll cage diagonals (more on this later). I stiffened the package tray by welding a 1/8” plate to the base and welding a doubler underneath including a 3/16” threaded nut plate for a top-sided blind bolt install.

I used stepped tube connectors for tube removal for rear access…

For the door bars, I originally wanted to land the fwd end on the ‘A’ pillar/rocker intersection, however, the wife informed me that she wanted to be able to get in and out easier than she had experienced in my many other “performance cars”. So a compromise was reached. I landed the bars ~6” short of that structural intersection to allow for a clearer foot sweep in and out. To create a load path to the ‘A’-pillar, I boxed in the rocker section with 1/8” plate. I boxed in the bar end landing area after plating over the heater vent. All box sections are 1/8” thick. Again, I used stepped tube connectors for bar removal.

I also tied the ‘B’-pillar to the main hoop via the seat belt captured nut. I designed the brackets to work in conjunction with the seat belt hanger and they do not interfere with any of the belt function.

So, that’s the 6-point. I still have to remove and finish weld the door bar connectors to the main hoop and ‘B’-pillar clips to main hoop.

This post is getting way too long! I’ll cover the Kafer-bar, or truss, in next post. It started out as an off the shelf aftermarket kit and ended up full custom! Go figure There’s a lot to cover there!

Cheers,
J.

[DUNGBTL]

Kafer-bar (truss)

Let me start off by saying that with the body on the pan, this is probably the hardest install/mod I’ve done to date on the DUNGBTL! Access is tough with the body on the pan and 2’ off the ground!

I thought about designing and fabricating my own Kafer truss. But again, making measurements and mock-ups would be tough w/body on. So after considering that and adding up the cost of all the hardware, tubes, plates, etc, for a few dollars more I bought a 6-pt one from a popular manufacturer of bling-bling VW hardware.

The design is not optimal, imo, due to truss member’s load being reacted mainly in bolt bending at the shock towers (due to bar geometry). But the bar connecting plates, at 1/4” and ‘C’-like cross section, is robust and offers plenty of room for other ‘attachments’. Likewise, the truss bars are reportedly chromoly steel with nice clevis attachments. To the manufacturers credit, all the hardware and construction is robust and top notch. And the bars (tubes) come nicely powder coated.

I had a plan to engineer out the bolt bending issue by attaching the truss plate to the roll cage’s rear diagonals. However, I couldn’t even begin to attach the truss plate to the damper because the plate’s threaded tube interfered w/the cutout in wheel well! I had to extensively open up the cutout to allow the tube to clear with an 1/8” of clearance…both R & L sides!

Strike one!

Then I discovered that there was no way to attach the trans mount clevis eyes. I’m using an OE mount, yet I could not fit them to my rear trans mount in the manner the manufacturer prescribed. So, I re-engineered the clevis attach tabs to be welded directly to the OEM mount. STRIKE TWO!

I then spent lots of time under the car designing and fabricating a set of bolt on brackets which would provide a stiffer load path for reacting the truss loads. Much stiffer than the pin-in-socket (bolt) connection the original design uses at the shock towers.

The welded on doubler for the roll cage diagonals is threaded (3/8” thick nut plates) and using extra long 3/8” bolts allows for bolting up the brackets.

In the end, the purchased 6-pt Kafer truss provided an excellent starting point, some re-engineering was required. The brackets bolt up nicely after the Kafer bars are adjusted and locked down. I’m please on how it turned out and believe it should be quite solid.

Oh, one last note…I also purchased a longer damper bolt which threads a good 1/2-5/8” further into the truss plate.

The stock bolt does not thread in far enough imo. I think a longer engaging bolt should have been provided in the kit to begin with. As the design relies on this ‘pin in socket’ as the only thing reacting the truss loads into the towers, a longer bolt would be better.

Cheers,
J.

[H2OSB]

Truely amazing work. You design your parts like an engineer or something . CONSTANTLY impressed, my friend. You turned that Mendeola bar from something I wasn't willing to use into a quality, functional structure. Tying to the roll cage completely bypassed the design flaw.

BTW, excellent photo documentation. Really Really makes what you're doing very clear.
H2OSB
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(o\_i_/o) I'm not a vegetarian because I love animals, I'm a vegetarian because I hate plants.

[SnowDaySyncro]

Really excellent work! I'm planning on a kafer bar on my '71 Super and was planning on installing it when the body is off. I didn't realize it passes through any part of the body until I saw that you had to enlarge holes in the wheelwells.

I've been back and forth on the question of a roll bar/cage. Other than the very occasional local autocross, it won't be driven competitively (and probably not competitively in the autocross either, given my previous efforts ) and I like the idea of retaining full use of the rear seat. I am seriously considering a minimally-intrusive stealth idea to stiffen the car up a bit: I have a '71 convertible body shell that will soon be cut up for another project. The heater channel reinforcements are in good condition (unlike many other areas of the body) so I'm very tempted to graft those and the cross-body bracing at the leading edge of the rear seat into my sedan when I replace the heater channels. The bottom 8-9 inches or so of the body would essentially be convertible-spec.

This would add some weight, of course, but not a lot and not as much as a roll cage. I haven't really seen examples of anyone doing this to a sedan, but I don't see any glaring downside to this idea, especially since I already have the metal. I also strongly prefer the factory jack point on convertibles, which adds to the appeal for me.

[DUNGBTL]

H2OSB Thank you! I really appreciate the feed back.

Synchro Thanks!
I don’t believe all Kafer bars require enlarging the damper bolt hole in the body. However, I’ve talked to other people who have use the same kit as mine and they too had to enlarge the holes.

I think for local AX a roll cage is definitely not required.

I’m into to this kind of pseudo race car stuff and I’m doing my build as if I’m going to run the car at open track events and AX’s. I’m more interested in increasing chassis stiffness for handling performance. Any safety gains are a benefit too.

Yes the 6pt does add weight, however the chassis stiffness gained will pay dividends in power transfer and handling…and, again, I like doing these kind of mods!

I think incorporating the ‘vert stiffening members in your coupe is an excellent idea. If you do, please document it…I know of at least one other Samba member (H2OSB) that will be very interested!

J.

[DUNGBTL]

Bonnet Release Relocation

Relocated the bonnet latch release from the glove box to a ‘secret’ (shhhhh…don’t tell) location.

First off I installed rivnuts to replace the OEM rivets on the latch. Guess they didn’t have rivnuts in 1972…

Made a spacer block and loaded it w/four more rivnuts. Used the original wire tube and wire. Cleaned wire tube w/acetone and used a heat gun to recurve. Used a key ring I had lying around…RESULT!

Cheers!
J.

[SnowDaySyncro]

What are the rivnuts along the bottom of the apron for? Air dam? Radiator ducting?
That remote frunk release is great, I may need to copy that for my 1302 trailer build.

[vamram]

Dungbtl, that's a great idea w/the rivnuts on the trunk latch. What size rivnuts did you use? And are you deleting the trunk pull from the glove compartment?
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Eventually, "we are what we pretend to be.’”
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'74 Super 9/16 - present, in refurb process.
'73 Super - 6/18 - Present - Daily Driver!
'75 Super Le Grande...waiting it's turn in line behind '74.
Click to view image
Save the Supers!!

[DUNGBTL]

[Kafer_Mike]

Impressive ingenuity and fabrication. I am really enjoying watching your build progress.
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Kafer_Mike
Build 'em fast...or let 'em sit.

[DUNGBTL]

Hinge Struts

Love the SB…iconic shape, brilliant engineering design, timeless classic for sure.

HATE THE DREADED BONNET SCREECH! Operation hinge spring elimination!

Bought hydraulic struts for the hood:

They required removing the spring strut to hinge rivet (see my previous post somewhere above). I drilled the holes out to 9/64” for a 6M bolt. I chose a bolt with a long enough shank to allow the strut lug to bear out on the shank and not the threads. This was a longer bolt than I needed so I cut 10mm of the threads off.

Hardest part of the install was reinstalling the ‘E’-clips without them popping off and never to be found again! Lost one…I heard it land somewhere in the shop…probably find it in 20 yrs. Fortunately I had spares in-house.

[thought ahead and bought several 5/16” size at ACE]

OBTW, if you’re going to do this mod, I suggest stuffing the A-pillar ‘black-holes’ with a towel to avoid losing hardware to the infinite gravitational forces that exist there.

Anyway…successful install, if only for a temporary mock up for bonnet fitting and mods. Hinges go up and down smoothly without that gawd-awful VW bonnet screech!

Oh, and I discovered my SB came with a rare factory option…Frunk AC outlets!

Cheers,
J.

[bruceo98]

Man you are rolling . Everything looks great and to perfection. Great work . I had to take a break from mine cause of work . Got too busy, but that’s a good thing .
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I may not be the best, but when the top 10 get together, they all talk about me.

[DUNGBTL]

Thanks bruceo98!

I was missing your weekly post…wondered where you went off to!

J.