Bolt In Roll Cage

[BBS-LM]

So I went to look at a track car today and noticed that it had a bolt in roll cage which was bolted straight through the car chassis floor, is that a default way to install one of these.

I always thought where you fix the roll cage to the car chassis there would be welded fixing points to the chassis, and then the cage would be bolted to that?

Edited by BBS-LM on Saturday 22 April 15:28

[E-bmw]

I think maybe you might need to look closer as your first thoughts are correct.

I fitted one to a previous TD car many years ago & I had to weld in proper mounts for the cage to bolt to.

Either that or it is a "show cage" that they are calling a bolt in cage.

[BBS-LM]

Here is a photo of the front fixing of the roll cage, there is no welded in fixing bracket for the cage to attach to, someone has just drilled 4 holes into the car chassis and then a metal plate underneath the chassis, which then just bolts them all together, which I thought looked suspect to say the least?

[BBS-LM]

And this is how I thought it should be done with welded in support fixing in the chassis for the roll cage to fix to?

[E-bmw]

BBS-LM said:

And this is how I thought it should be done with welded in support fixing in the chassis for the roll cage to fix to?

Which is basically exactly how I did mine.

Heavy wall section "box" welded into the corner of the footwell & drilled feet on the ends of the tubes.

[E-bmw]

It doesn't look ideal but having said that.

1. To remove it & weld in some additional bracing isn't the biggest home diy job if you have a welder.

2. It will still be more rigid than the majority of TD cars that have no cage at all.

[Xcore]

Proper way is with boxes, but I’m sure the risk of caving the roof in and punching the foot through the floor is a lot lower on a track day.

[LastPoster]

It’s not about one way being wrong and the other right

Older cages typically mounted directly to the floor pan with plates above and below the floor to spread the load and also to ensure a flatter mounting point in the days when production tolerances were less tight

Boxes are a newer concept and a half way house from a fully welded cage

More expensive cages tend to have brackets or boxes, cheaper not. You pays yer money and takes yer choice

[QBee]

Cages for racing in FIA regulated events have to be welded in.
Cages for track days don't.

[smokey mow]

QBee said:

Cages for racing in FIA regulated events have to be welded in.
Cages for track days don't.

Judging by the opening post I wouldn’t expect BBS-LM to be using the car for any FIA events any time soon. Maybe club level motorsport under MSUK regulations where bolted in cages are perfectly acceptable providing they are either of a homologated design (check for the homologation sticker on the cage) or alternatively of a design that complies with the tube diameters and fixing details in the MSUK yearbook (see below).

MSUK Yearbook said:

1.3.2. Mounting of ROPS to the Bodyshell. Minimum mountings are:
1 for each leg of the main or lateral rollbar. 1 for each leg of the front rollbar.
1 for each backstay (see 1.3.3).
Each leg of a main, lateral or front rollbar must be attached, via a mounting foot, by at least three bolts, minimum M8 ISO grade 8.8 and utilising a steel reinforcement plate of a material of at least the same thickness as the wall of the tube to which it is being welded (minimum 3mm) and of at least 120cm2 area which is welded to the bodyshell (see drawings K13 to K18). The mounting foot or leg may alternatively be welded directly to the bodyshell/reinforcement plate in accordance with drawing K13.

[BBS-LM]

The car was raced in the SW MOTORSPORTS CLUBSPORT TROPHY but I'm not to sure if there where any wielding point for the cage, it just drilled though the floor and then a fixing plate attached underneath the chassis, but I guess It cannot be that bad as it would never have got past Scrutineering?

smokey mow said:

QBee said:

Cages for racing in FIA regulated events have to be welded in.
Cages for track days don't.

Judging by the opening post I wouldn’t expect BBS-LM to be using the car for any FIA events any time soon. Maybe club level motorsport under MSUK regulations where bolted in cages are perfectly acceptable providing they are either of a homologated design (check for the homologation sticker on the cage) or alternatively of a design that complies with the tube diameters and fixing details in the MSUK yearbook (see below).

MSUK Yearbook said:

1.3.2. Mounting of ROPS to the Bodyshell. Minimum mountings are:
1 for each leg of the main or lateral rollbar. 1 for each leg of the front rollbar.
1 for each backstay (see 1.3.3).
Each leg of a main, lateral or front rollbar must be attached, via a mounting foot, by at least three bolts, minimum M8 ISO grade 8.8 and utilising a steel reinforcement plate of a material of at least the same thickness as the wall of the tube to which it is being welded (minimum 3mm) and of at least 120cm2 area which is welded to the bodyshell (see drawings K13 to K18). The mounting foot or leg may alternatively be welded directly to the bodyshell/reinforcement plate in accordance with drawing K13.

[braddo]

BBS-LM said:

The car was raced in the SW MOTORSPORTS CLUBSPORT TROPHY but I'm not to sure if there where any wielding point for the cage, it just drilled though the floor and then a fixing plate attached underneath the chassis, but I guess It cannot be that bad as it would never have got past Scrutineering?

In other words, the top right image in the pic?