street driven 5's and rollbars

by **vrmmmpshhh** » Wed Apr 04, 2012 4:54 pm

hey guys.. looking into getting a rollbar but the aim of the car is for the street with maybe 1-2 track days a year (im close to mallalla) if i get the time. For street driven cars, is the extra 10-15kg additional weight noticeable or does the extra chassis rigidity make up for it?

does anyone know what the rollbars weight? i just measured a 1.5m 3mm walled 2inch tube and it was already 3.5kgs

by **PaulF** » Wed Apr 04, 2012 5:11 pm

I don't think you'll realistically notice the weight on the street.

Site-specific Google search gave me these results.

Brown Davis weight thread

MX-5 Plus wrote:Weights are as follows:

Single Hoop TB Roll Bar - 21.0 kg

Twin Hoop TB Roll Bar - 19.1 kg

Single Hoop TB Roll Bar (Single Diagonal) - 21.5 kg

NB: this includes all the mounting plates and fasteners, not just the bar on its own.

Regards,
Danny
MX-5 Plus

(Sourced from http://www.mx5cartalk.com/forum/viewtop ... 44&t=35960)

by **hks_kansei** » Wed Apr 04, 2012 5:16 pm

First up, for things related to Rollbars and road usage, see here:
viewtopic.php?f=28&t=45995&hilit=rollbar+road

A Brown Davis rollbar is roughly 20kg (And I'm fairly sure the MX5 Plus is similar)

When I put the Brown Davis in my car I didn't notice the extra weight, and I didn't notice any extra rigidity except for exiting an angled driveway.

Granted, I also felt no difference with a strut brace, none with the rollbar, none with wider and heavier wheels.
The only mods I've felt any difference on are the LSD, and lowered springs.

So maybe I'm not the best one to answer

by **Lokiel** » Wed Apr 04, 2012 5:55 pm

You won't notice the weight difference on or off the track.

I have an SE/MSM which has the best factory chassis stiffening of all NBs and I noticed "The Stiffening" immediately just turning out of the MX5 Plus parking lot onto the road at a very slow speed.

It's one of the best modz you can do for your car; rollover protection is a secondary function as far as I'm concerned - I haven't needed/used that yet.

by **NitroDann** » Wed Apr 04, 2012 6:00 pm

20+ kilos of steel bolted to major structural parts on opposite sides of the cabin would want to stiffen it a little.

Dann

by **lee** » Wed Apr 04, 2012 6:07 pm

The weight gain is less than the weight difference between a full and an empty tank. If you're not terribly concerned about shedding kilos, a roll bar will be an insignificant hinderance. For what its worth, I noticed my car stiffened up dramatically with the BD bar installed (stock shocks & springs, whiteline sways, no other chassis stiffening).

by **vrmmmpshhh** » Wed Apr 04, 2012 6:09 pm

20+ kgs

by **NitroDann** » Wed Apr 04, 2012 6:12 pm

People also notice that the hardtop stiffens the car up, except mazda engineers found no change whatsoever under actual torsional testing.

Lots is in peoples heads.

Dann

by **hks_kansei** » Wed Apr 04, 2012 6:18 pm

NitroDann wrote:People also notice that the hardtop stiffens the car up, except mazda engineers found no change whatsoever under actual torsional testing.

Are you suggesting those 4 tiny latches, the 2 nylon bushes at the rear, and a big sheet of plastic and fibreglass aren't capable of withstanding chassis twisting forces :shock:

(note: Sarcasm in this post, writing it down since it often gets lost in text)

by **deviant** » Wed Apr 04, 2012 6:19 pm

1 - 2 trackdays a year? Not worth having one unless you want the roll over protection for the street to.

by **hks_kansei** » Wed Apr 04, 2012 6:21 pm

deviant wrote:1 - 2 trackdays a year? Not worth having one unless you want the roll over protection for the street too.

Or if the track requires it.

I know Winton require a rollbar if a convertible is to run with the top off.
Since I can't fit under the soft or hardtop with my helmet on, I would have to go topless.

If the track doesn't require it, or you're short, then no problem.

by **NitroDann** » Wed Apr 04, 2012 6:29 pm

Surely its cheaper to get new seat/ seat mounts than a roll bar, which forces you to run with the roof off and ruin your aero completely.

Dann

by **hks_kansei** » Wed Apr 04, 2012 6:36 pm

Depends on a person's build, and their state's legal requirements.

I've got a bucket as well, the onyl way for me to get lower is to go without rails, or remove the mounting humps.
Both of which are illegal in Vic (the bucket technically is too)

Rollbar however, is legal.

Aero isn't an issue with me, and presumably most people at trackdays.
I've not had much track experience, the disadvantage to laptimes I would get from the bad aero is far outweighed by the disadvantage of my sh*t driving.

Horses for courses, if it's racing and you're looking for outright laptimes, you're 100% correct.
If it's just a trackday for fun you're only against yourself, so outright speed isn't the main concern, it's improving your driving.

by **NitroDann** » Wed Apr 04, 2012 6:39 pm

Id bet money the rollbar isnt legal in 99% of aussies cars.

Dann

by **sailaholic** » Wed Apr 04, 2012 7:37 pm

You bet wrong than dann. Richard from mx5 plus is an ex transport engineer and say on the committee for the new code of practise. Plus rollbars are 100% legal in qld alone.

Can't comment on a brown Davis Bar.

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