Half-cage that doesn't require drilling into body?

[bigjae46]

Tc Design who's done a billion competition grade spec e36/ e30/e46 etc, boxes the feet by joining them to structural points and then welds accordingly. This is definitely not punching through like your drill into sheet metal setup on the floor pan that doesn't have a proper foundation support.






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I can agree that would be stronger.

Sheet metal flexing is a measure of stiffness which doesn’t equate to strength. Carbon fiber is much stiffer than sheet metal but isn’t necessarily stronger or tougher. Sheet metal can better resist elongation without failing. Carbon will quickly fail.

Either way, a bolt in roll bar is a harness bar. I don’t think it serves any real benefit.

If the purpose is rollover protection then you should absolutely have window nets and a containment seat based on crash data.

Go to 5:30 in this video…

https://youtu.be/5hbYwHUOipg

Basically he’s saying most injuries are caused by parts of the body making contact with something out of the car, not from a roof caving in.

In a BMW, a roll bar is mostly pointless but not sure it’s realistic to think the mounting plates will readily punch through the floor. As with anything aftermarket or custom fabbed except for the Schroth quick fits…it’s an educated estimate.

I was instructing in a stock F80 M3 that struck the wall at 79mph at COTA. We were ok but the driver’s head was
stuck between the curtain airbag and door jam. If the drivers side hit the wall or ground if we were rolling over he certainly would have suffered a head injury.

[Gt4]

You can make a box style for a roll bar without drilling the floor pan and using the 2 holes of the seatbelt bar. Wouldn’t be as good as a full weld kit but better than a plate directly bolt on floor like Kirk, Autopower, …

[Albino09]

But aren’t you bolting to the same spots? I believe the Kirk bar has a backup plate.

genius46M posted the photo where you can clearly see that boxed feet =/= bolted backing plate.

[thegenius46m]

Tc Design who's done a billion competition grade spec e36/ e30/e46 etc, boxes the feet by joining them to structural points and then welds accordingly. This is definitely not punching through like your drill into sheet metal setup on the floor pan that doesn't have a proper foundation support.






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[t44tq]

Is Autopower bad? I haven't really done the research, but that appears to be pre-built, so easy install, relatively speaking.

[Ianb]

Shibui - who are the UK manufacturers of cages that don't require drilling?

[bigjae46]

Boxed and welded-in feet spread the load, and typically would be welded to high-strength sections of the floor pan such as the sill extrusions.

But aren’t you bolting to the same spots? I believe the Kirk bar has a backup plate.

[Albino09]

aren’t you welding to the same flimsy sheet metal?

Boxed and welded-in feet spread the load, and typically would be welded to high-strength sections of the floor pan such as the sill extrusions.

[bigjae46]

Don't forget how strong the SHEAT METAL is on these cars. Laughable. I can flex it with my 140lb body. To think that will save you in an accident is comical. There's a reason no proper cage is bolted to weak sheat metal.

If you want this done right OP, you need proper boxed in and welded in feet and then you can bolt the bar into extensions if you want a removable setup. At least that will be structurally safe.

aren’t you welding to the same flimsy sheet metal?

[thegenius46m]

I don't think they care about securing the half-cage. Its about looks/hard parking. They seem to explain it away by believing that bolting up to fixtures like seat belt bolts will bear the weight of the car.

Don't forget how strong the SHEAT METAL is on these cars. Laughable. I can flex it with my 140lb body. To think that will save you in an accident is comical. There's a reason no proper cage is bolted to weak sheat metal.

If you want this done right OP, you need proper boxed in and welded in feet and then you can bolt the bar into extensions if you want a removable setup. At least that will be structurally safe.

[bigjae46]

I'd bolt in a half cage. If you decide to remove it...its welded in. If you want to go with a full cage then it will be difficult to get a 360 weld on the forward bars. You'll have to remove the roof or cut holes in it or have the bar start really low which then makes it more likely for your head to hit the forward bar and much harder to get it and out of the car. Among other issues.

I too am interested in a 100 percent bolt in half cage. Not wanting to drill into floor boards on my example either. The cage is for aesthetics for me not functionality.

Anyone have input on a cage that fits this bill?

Just get some cardboard tubes and duct tape. Or make one from CF and glue it to the floor...do you know how many guys that would attract?

[Nate047]

I do remember this being a popular option back in the day, but yeah I haven't had any luck with getting them to respond either. Might just go with a Kirk Bar or Studio RSR bar if I can't find anything good.

If you're in Japan I would just find a local cage builder and get one made. Any of the NA or European options are going to cost you more than it's worth, especially when you have a plethora of excellent fabricators at your doorstep.

[Gt4]

Looks really good! Do you still make the U-weld one?

https://nam3forum.com/forums/forum/main-forum/e46-2001-2006/211483-testing-water-e46-m3-custom-roll-bar-gts-style-you-weld-kit

[shibui]

I can make you one if you wish. Would be pretty similar to the U-weld kit I was making but without the rear subframe tie-in.

Looks really good! Do you still make the U-weld one?

[shibui]

https://ravenperformance.ca/products/rollbars.php

this company is canada based and used to be a popular choice because it was full bolt on.
it's important to acknowledge that functionally most would consider this an overbuilt harness bar and not an actual "half cage"

I do remember this being a popular option back in the day, but yeah I haven't had any luck with getting them to respond either. Might just go with a Kirk Bar or Studio RSR bar if I can't find anything good.