Topic: Roll Cage Down Bars and Seat Back Brace

My team and myself have not built a roll cage in 10 years, so bear with me a bit. We're planning out a cage for this car and some questions came up that I don't think the manual can answer for us easily.

In placing our down bars, SHOULD the down bars be going as far forward in the cabin as possible? Is there a reason they cannot be, say, on the outside of the dash support you can see in the picture? What angle in regards to the floor SHOULD these be at?

https://i.imgur.com/tqtRL5o.jpg

As well, the Lemons store sells an adjustable seat back brace, but according to the how not to fail tech manual, it states that you require a fixed back brace. Can anyone clarify that the adjustable back brace is acceptable? This will have an effect on the position of our main hoop.

Thanks for any help.

Re: Roll Cage Down Bars and Seat Back Brace

On the seatback brace - the one they sell in the store is adjustable but locks into place, making it fixed.  It's for seats with sliders. 

I've always placed my down bars vertically as far forward, as far outboard, and as close to the A-pillar as possible and never had a problem.  I don't know what you mean by outside of the dash support so I can't help you.  An email to John Pagel would be in order.

--Rob Leone Schumacher Taxi Service
We won the IOE at Southern Discomfort.
We got screwed at The Real Hoopties of New Jersey  and we took cars down with us.
We got the curse at Capitol Offense but they wouldn't let us destroy the car.

Re: Roll Cage Down Bars and Seat Back Brace

[tldr] I'm looking at designing a cage as well, BUT: I'm not a tech inspector for Lemons; this is just my thought process:

I read the manual as describing - at least for the main hoop - [and I presume the front hoop as well] that the vertical member(s) should be just about that - vertical.

P.12 describes "backstays" as required to be "right around 45° off _horizontal_". The diagram indicates an angle between the backstay and the main hoop as also 45°. Since that closes a triangle, that means the vertical member of the main hoop must be "right around perpendicular to the floor".

In each diagram, the front vertical member appears parallel to the rear vertical member; I presume that's deliberate.

///

I did not find the section in the manual requiring a "fixed back brace".

I did find the diagrams suggest the "retaining bar/harness bar" (welded to the cage) OR "fixed seat back brace".

I do see the rules strongly recommend a "permanently attached seat back brace", but I don't read that as requiring it to be "fixed". I read that as "a brace permanently attached to the seat back", perhaps with a support bar which can be pinned in several places, which would then allow movable seats [yay!]

The rules indicate:

3.F.1.c Seats Without Seatback Braces. If a seatback brace is not used, a strong, seat-width element such as a shoulder-harness bar must be located within six inches of the seatback to prevent the seat from failing rearward.
3.F.1.d Solid Mounting. All seats, including seats on adjustable tracks, must show minimal looseness and no back-and-forth freeplay.

My conclusion was that we have six inches of adjustment for a seat on tracks with _just_ the welded harness bar; OR, more, but: must have a seatback brace permanently attached to the seatback (but it could be fabricated to be adjustable in tandem with the seat), OR, a fixed seat position.

Re: Roll Cage Down Bars and Seat Back Brace

Yes you are correct. once the seat goes more than 6 inches forward of the cage bar, you need to have an adjustable back brace mounted to it and employed.

As for the front, take the dash support out, put the cage in as far forward as possible, then re-install the dash support over the cage. You want the cage foot perpendicular to the floor.

Or remove the dash support and replace it with a cage dash bar and reattach the brackets for the steering and such to that.

Mistake By The Lake Racing (MBTL)
88 Thunderbird "THUNDERBIRDS ARE GO!", Ex Astris, Rubigo / Semper Fracti
A&D: 2014 Sebrings at Sebring (NSF), 2014 NJMP2 Jurassic Park (SpeedyCop), 2012 Summit Point J30 (PiNuts)
2018 Route Sucky-Suck Rally Miata, 2019 World Tour Of Texas 64 Newport

Re: Roll Cage Down Bars and Seat Back Brace

We have a DIY version of this: http://store.24hoursoflemons.com/produc … -brace.htm

Instead of a pin, ours has split sleeves that are tightened on each bar with T-shaped handles that provides the clamping force on the bars. Super quick and easy to adjust by hand with no tools required. Our seat can slide linearly and it can also tilt/rotate forward/aft so ours is more of a gimbal setup. Never been questioned in tech (been doing Lemons since 2013).

We Audi Be Faster
'85 Audi Coupe G(in &) T(onic)

Re: Roll Cage Down Bars and Seat Back Brace

Thanks for the replies, gents!