Getting weight over the front for grip?

[DORIGTT]

Hey FJ,

Do you have any additional photos of your 6 point bar that you've got in your Ghia? I'd love a roll cage, but as this car will be street driven and I don't want to get a closed head injury when I get into a minor 'bump'. I'm looking for ideas for a bar that offers some side impact protections.

[Ol'fogasaurus]

Your question got me interested as I am in the process of figuring out my cage design so just for the heck of it I did s search and found this: https://www.jegs.com/i/Rhodes-Race-Cars ... 4/10002/-1 The search I did was for a Ghia and this was part of the answer I got.

https://vwparts.aircooled.net/RLR-Weld- ... 60-900.htm this is a "you weld it kit"

While it won't work in my case some of the ideas here are interesting. Also note that a lot of cage designs are referred to by the sellers as "show cages" which tells me that they are not up to real use standards. The Samba had some discussions on this (I don't normally go there but the search posted the post and they were not really of much help).

Lee

[FJCamper]

Light, strong, six-point. The two most forward supports are just behind where your feet rest. This type of bar is legal in Historic Sportscar Racing because it is period correct to bolt-in bars from the very early 1970's and approved by SCCA.

[Ol'fogasaurus]

Interesting FJ! Gives me some ideas.

It is similar to the one I posted but for another vehicle. Just got back in from looking at what I need based on the one I posted previously and now yours.

Its low side bar is something I need (along with the body lift) because I still have the front pan's head support which, (I am pretty sure is going to be a necessity) is another part of my design problem. My blue buggy has different mounting methods that are not available in my black buggy. My beam loading is going to be a lot different than yours and in several ways.

Hmmmm!

Lee

[Ian Godfrey]

new cage.jpg

here are a couple of pics of my cage. My car is still street registered so no bar over the front.
there are side intrusion bars low down that can be taken out, you can just see it between the seat and the door of the first photo. in the second you can see the main hoop mounted to the edge beside the 'rear seat', below that is a post down to the floor and heater tube. You can also see the small bar that connect to the rear torsion housing through factory bolt holes. It really stiffens up the car and should save my head in an accident.
if you want a better photo of the side bar i can take one for you

roll cage mount.jpg

[DORIGTT]

What is under the mount that bolts to the side panel Ian?

[Ol'fogasaurus]

roll cage mount copy.jpg

Not use to seeing cap screws for this situation but they should be OK and... there can be advantages to using them. But a couple of things I think I see bother me:

The connection to the hoop using what looks like a single corner gusset (we had a discussion on this a couple of years ago and I was proven wrong with the single center mount gusset. The way shown here was the way I was taught years ago [as far as I know we didn't allow gusseting this where I worked]) and especially not with a load attached directly to the gusset. There also was the gusset that is attached to one side of the tube which I had seen fail and the load transfer can be not as great as the center gusset has the potential of transferring. The proper way was to use a three sided join structure like a rectangular tube with the bottom short side removed so it attached to both sides of the tube and across both tubes.

Another thing is the fastener is in shear so the bolt should not be fully threaded (without knowing about the bolt itself).

The other thing is shouldn't there be a plate on the floor with a doubler underneath. This is because you are attaching to fairly thin materials (the unibody materials). Any potential of shear loading might be able to do damage to the thin floor material.

Anyway, my opinion for what it is worth.

Lee

[Ian Godfrey]

Dorigtt and Lee, a few more details....
There is a doubler welded to the shelf for the main hoop, then there is a post underneath the shelf with a plate on the floor.
Then there is a doubler under the floor for every mounting plate. The bolts are all metric 12.9 and part thread for strength.
Lee, I agree the small diagonal bar is a bit marginal but it is not a structural safety component of the cage, but I had it added to provide another connection between the torsion tube and the car. As you would know there is a lot of load on the small casting that joins the torsion tube to the pan near the spring plate. I've often seen these broken. I'm also tempted to add a connection between the top of the rear shock mounts and the plate under the cage in the parcel area.

[Ian Godfrey]

Here is some better shots of the removable door bar.

[Ol'fogasaurus]

door bar side view copy.jpg

Thanks for the additional pictures Ian as they show a lot of the design here. I am designing a cage for my buggy you have given me a lot of design information that I think I can use in my cage but what is bothering me is this area:

roll cage mount copy (2).jpg

This is what I am concerned about as there is a structural piece of tube attaching to the corner/join brace which is not usually done (I worked with higher normal and emergency loads so I still think in the directions I had to follow). The fastener looks like it is more load bearing (shear load) and is just not clamping or... is what I am seeing more like a connection as you would find in the tie-rods. Concern: still, is the corner brace thick enough to handle all the different potential loads. The designer is putting a lot of "potential" load into this corner brace.

What is there is probably OK but, since I was not an engineer but a draftsman/Tech Designer plus I also checked other's drawings as well as drawing up plans for their presentation mostly (crossing the T's and dotting the I's and staying within the federal, international and military presentation rules) but if I had a question/concern, I could freely talk to the engineer about it. I would question this for sure.

Lee