FIA / Replacement Roll Bars

18 posts / 0 new
Last post
Richard_W
Richard_W's picture
Offline
Last seen: 1 hour 32 min ago
Joined: 13/09/2019
FIA / Replacement Roll Bars

Hi All,

I am sure this has been done to death, but I haven't quite got the info I am looking for from doing archive searches.

I am doing some update to my car and as ever things mushroom... Having decided to fit new adjustable dampers and springs all round I decided that with the rear dampers out I may as well change the standard bar currently fitted to one that allows me to run in club track days etc. I have also pulled the rear arches but that is another mushroom effect...

I am in the process of thinking about ordering a new bar and am deciding between a single diagonal and a double diagonal. What are the pro's and con's of each? I never use the hood, I've taken the frame etc out of the car, so hood clearance and bar height doesn't bother me; so which is best to go for? I am angling towards a double diagonal at the moment.

The car is an imperial, De-dion S3 on the off-chance that anyone has a spare bar kicking around!!

Thanks!

Geoff Brown
Geoff Brown's picture
Offline
Last seen: 3 hours 51 min ago
Joined: 17/04/2014

Double diagonal obviously due to its structural integrity.

sforshaw
sforshaw's picture
Offline
Last seen: 50 min 26 sec ago
Joined: 17/04/2014

"obviously" ???

It's rarely quite so simple ... unless you have access to test results! Both bars are FIA approved (with their relevant forward (Petty) struts fitted and are different in more ways than just an added diagonal - shape, dimensions, tube diameter etc. You'll not go wrong fitting either.

Stu.

Lotus Seven Club AR Working Group

The register for all numbered limited-edition Caterhams ....... www.thecaterhamregister.net ...... www.instagram.com/thecaterhamregister

Mcalvert
Mcalvert's picture
Offline
Last seen: 20 min 5 sec ago
Joined: 17/04/2014

Hi Richard - there have been some good articles in Lowflying on the subject that you might want to read.  I'd point you to the following:

http://lowflying.lotus7.club/2016/2016_03_05_Rollbars.pdf

http://lowflying.lotus7.club/2018/2018_01_03_ROPS.pdf

http://lowflying.lotus7.club/2016/2016_04_09_Rollbars.pdf

However, I'm not sure that any of these address the actual question you're asking about the single vs double diagonal (sorry!).  My belief (but may be wrong) was that the single diagonal was the design for the imperial chassis, but that when they came out with the metric chassis, they took the opportunity to resesign the rollover bar to the twin diagonals (which has the advantage of being universal for LHD and RHD cars.)

However, I may be talking out of my posterior so do please check Byebye .

Michael Calvert

Lowflying Editor ([email protected])

James B
James B's picture
Offline
Last seen: 5 hours 34 min ago
Joined: 17/04/2014

Michael is right.  Rollover bars for imperial cars were made by Arch and have a single brace; bars for metric cars have been produced by Caged and have the double brace. 

Both types are recognised, as appropriate, for use on Club trackdays.

James

Edited to say: this isn't exactly true as both single (Arch) and double (Caged) braced bars were available for fitment to imperial chassis cars.  See #9 for a less hasty, less lazy and more accurate summary!

 

Richard_W
Richard_W's picture
Offline
Last seen: 1 hour 32 min ago
Joined: 13/09/2019

Thanks all, those articles are useful.

I guess my question was whether one was inherently better than the other, my initial thinking being that more triangulation seemed like a good thing.

The conclusion seems to be that both are better than what I have and it comes down to what fits best!

By the time I've finished I'll have replaced significantly more of the car than I expected! Good job I've been working at home for three months and not gone anywhere... The fuel savings have updated the car!

 

Nick Chan
Nick Chan's picture
Offline
Last seen: 3 hours 21 min ago
Joined: 17/04/2014

I suppose from an aesthetics (sp?) point of view, the Caged double diagonal is a more modern look.  Arch have produced a double diagonal but I think they were special request whereas Caged would be off the shelf

7 wonders of th...
Online
Last seen: 4 sec ago
Joined: 17/04/2014

Had 2 Imperial cars both with double diagonal bars, both made by Caged, the first was supplier by CC in a new kit.

there are a lot of Imperial cars with that set up.

 

James B
James B's picture
Offline
Last seen: 5 hours 34 min ago
Joined: 17/04/2014

Well, just goes to show what I know!

Maybe I was relying too much on memory.  In fact, that is definitely the case.  So in an attempt to salvage some credibiliy in this area here's what I believe to be a more accurate summary of trackday (sometimes called 'FIA') rollover bars.

  • Until 2003, all trackday bars were supplied by Arch, with the main hoop manufactured from 1.5" CDS tubing in 12g.  These bars are characterised by a single diagonal.  There was a tall bar option available.  All cars were imperial chassis at this time.
     
  • From 2003, Caged became the main supplier of trackday rollover bars.  The spec remained broadly the same apart from the double diagonal bracing.  All cars were still imperial chassis at this time.
     
  • In 2007, Caterham Cars introduced the metric chassis with trackday rollover bars continuing to be supplied by Caged.

I think it's therefore accurate to say that imperial cars could have been fitted with either Arch or Caged supplier bars, depending on the purchase/supply date of the bar, and that all metric cars will have been equipped only with Caged, double-diagonal types.

James

TomB
Offline
Last seen: 25 min 15 sec ago
Joined: 17/04/2014

 Is it possible to fit the FIA cross bar with Tillet seats? 

bluenose
Online
Last seen: 1 min 35 sec ago
Joined: 17/04/2014

Is it possible to fit the FIA cross bar with Tillet seats?  Yes