1973 VW Super-Beetle(1303) Hill-Climb Build

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Super1303
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Re: My 1974 1303 I bought for a dollar

Post by Super1303 »

[quote="walterclark"]Post some pics focusing on the cage. Its difficult to tell much except that it has something in there and it looks like it is an old design.

How close to this does it look?

Pretty close. I can't seem to find much info on installing a roll cage in a Super Beetle so I've been doing image searches of Kafer Cup Beetles for comparisons.
The Tubing is 1-5/8X.120 DOM, Bought from ( http://autoweldchassis.com/ ) as a 10 point kit for a Beetle. The main hoop is one piece, not sectioned as well as the roof bar. I've added bars and tied it to the body to stiffen up the chassis and will add gussets similar to the diagram you have sent. The Tubes terminate at the floor on 6x6 plates to new floor pans of a heavy duty design.

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The seat mount is another concern. It's tied to the frame(inside) and I'm planning on adding a second door bar. I'd like to tie the seat mount to this tube(outside) and also weld in an anchor for the harness.
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This is one thing I worried about as being not passing tech. I put the flanges in to aide in removing the body off the frame for future mods.
The rear bars have one horizontal brace(at the bottom) and one diagonal(from inside of upper, rh flange too inside lower, lh flange), at this time, thinking of go with the X.
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What do you think, I'm trying to finish up the cage to move on to paint but will wait for feed back. Thanks.
Last edited by Super1303 on Mon Feb 19, 2018 8:29 pm, edited 2 times in total.
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1973 Super Beetle, #666
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walterclark
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Re: My 1974 1303 I bought for a dollar

Post by walterclark »

The cage tubing size and material looks OK. I assume it is mild carbon steel and not a high nickle/chrome tube.

Since the main hoop lacks a full diagonal, V or X, you will need a V or X in the backstay. Speaking of backstays...we dont encourage bolt-in bits but (following the FIA Article 253 - http://www.fia.com/sites/default/files/ ... 9.2013.pdf) some elements may be made removable and backstays are included in that "may be" by the FIA. In your case I think sleeved butt joints is the best among the choices the FIA offers. These are to be made by using a coupling with a sleeve tube over the tube joint which is then held with 2 bolts. See fig 253-41 and 253-42 in the referenced FIA article. In fact the closer you follow this article with everything the better off you will be. Note: Removable elements are not permitted for Mt Washington (it has its own rules - I am writing from the perspective of NEHA).

In the roof you have what looks to be half of a V. This is unsupported on the main hoop and an impact on the passenger side A-pillar would end up bending the main hoop as a result. To correct this I would add a second bar to make it a V in the roof with the junction at the main hoop as in fig 253-14, then go with an inverted V in the backstay so everything is supported and triangulated.

The mounting feet look OK.

You should gusset the junctions of the roof level bars.

You should (and if the car doesnt have substantial factory side bars in the doors - you must) add a second door bar. I recommend running one horizontally and as near the floor as possible between the main hoop and the foot of the drivers A-pillar bar.

It looks like your harness bar is at a good height based on the seat openings - hopefully the bar and openings are about on level or only slightly down from where harness shoulder belts pass over your shoulders while wearing a head and neck restraint.
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Re: My 1974 1303 I bought for a dollar

Post by Super1303 »

Thanks for the response, very helpful.
To complete the V in the roof would put a bar over my head. Am I allowed to bend this bar up to get the clearance not to bounce my helmet off it.
The other bar is straight and I'm glad I put in the center now just in case.
I think I will redo the backstay to a fixed set-up. Good thing I'm not planning on putting anything back there.
Just so I understand, your saying to put the V in the roof and a V in the backstay to make essentially an X bent at the intersection? Is this correct?
Also is it a good idea to tie the seat mount frame to the cage, horizontal bar that you spoke of, because it's tied to cars frame?
And yes the harness bar sets the shoulder belts at level.
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walterclark
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Re: My 1974 1303 I bought for a dollar

Post by walterclark »

Super1303 wrote:Thanks for the response, very helpful.
To complete the V in the roof would put a bar over my head. Am I allowed to bend this bar up to get the clearance not to bounce my helmet off it.
Yes, it can be "bowed" up for clearance.
Super1303 wrote:Just so I understand, your saying to put the V in the roof and a V in the backstay to make essentially an X bent at the intersection? Is this correct?
Exactly. This way the rear directed loads from the A-pillars and windshield are transferred to the chassis thru the backstays and not absorbed by the main hoop (i.e. bent). Think in terms of multiple impacts. We want to keep the structure around you as much in place as possible for more than just one impact, which is very possible in the event the car goes rolling down an embankment. Dont want the main hoop bent back in the middle just before the car lands hard on the center of the roof...
Super1303 wrote:Also is it a good idea to tie the seat mount frame to the cage, horizontal bar that you spoke of, because it's tied to cars frame?
That is fine. You can also stitch the lower bar to the door sill. In fact you can stitch or gusset any of the cage bits to the car including A-pillar to front bars, B-pillar to main hoop, halo (top side and windshield bar) to the door frame and windshield support) front cross brace to the firewall, etc.
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Re: My 1974 1303 I bought for a dollar

Post by sdwarf36 »

I suppose it all comes down to personal preferance, but isn't that seat mounted kinda high?
Translating road racing to hillclimbing:
Proper tire selection== nothing hooks up on moss or wet leaves.
Staying on the racing line==anything paved is considered good.
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Re: My 1974 1303 I bought for a dollar

Post by Super1303 »

sdwarf36 wrote:I suppose it all comes down to personal preferance, but isn't that seat mounted kinda high?
Yea, I suppose but it's where I was most comfortable. Before making the mount I tried all different positions and found this one to be the best option or best compromise to all the controls.
Believe me my friend was getting sick of me moving the seat around for two weeks. But as you know the cage layout, kind of, follows the seat position so I wanted to be content.
I like the feel of the wheel no elbows to the chest cross-up the shifter is right there the peddles, welllll, legs are bit tight but the best it will get and I like my line of sight in this position feels right to me. Plus I've messing around with these cars for so long this is where I'm at, you know? The seat is where it's always been with every thing else in it's place. Anyway it's only metal if I get to not liking it I'll cut it out an redo it over the winter. ;)
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Re: My 1974 1303 I bought for a dollar

Post by Super1303 »

A couple of pictures of my tubing notcher. I find it works pretty good.

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Last edited by Super1303 on Mon Feb 19, 2018 8:36 pm, edited 2 times in total.
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Re: My 1974 1303 I bought for a dollar

Post by Mopar 151w2 »

If you keep using your holesaw in a keyless chuck, you will eventually shatter the guts of the chuck. Been there, done that..... A Hougen "Rotabroach" cutter, held in an R-8 collet, does a much nicer job without all of the nastiness associated with holesaws. Making a rigid mandrel to hold the holesaw (no pilot drill needed in a mill), and holding it in an R-8, helps quite a lot.
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Re: My 1974 1303 I bought for a dollar

Post by Super1303 »

Mopar 151w2 wrote:If you keep using your holesaw in a keyless chuck, you will eventually shatter the guts of the chuck. Been there, done that..... A Hougen "Rotabroach" cutter, held in an R-8 collet, does a much nicer job without all of the nastiness associated with holesaws. Making a rigid mandrel to hold the holesaw (no pilot drill needed in a mill), and holding it in an R-8, helps quite a lot.
Totally agree that the Rotabroach is the way to go, man those are real nice.
Problem for me is that I'm running a M-head mill, can't fit anything larger than a 1/2" shank. Uses those old MT-7 collets.
All I could find was 3/4" shanks for a 1-5/8" hole.
Is the shank solid, like, no hole in the center on that size cutter? Could buy the size I need and have it ground down....
Oh, wait your saying to make a ridged mandrel for the hole saw? That would be a step up, would keep the tooling closer to the spindle too.
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Re: My 1974 1303 I bought for a dollar

Post by Mopar 151w2 »

A setscrew style end mill holder would hold a rotabroach . IIRC, a 1/2-13 bolt (head cut off)and nut make the cheezy holesaw mandrel.

Bonus trick - if you gotta holesaw thick material (thicker than the holesaw tooth depth). drill a chip ejection hole or 2 to the inside of the holesaw's path.
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