Half rollbar / frame rail bracing - weight vs. handling?

[vrsmxtb]

I have done almost everything planned to my MX5 over the last 4 years - nice wheels, coilovers, exhaust etc but still find the little bit of scuttle shake annoying. The next potential step is to go down the extra bracing route, however is the gain in weight by fitting something like a TR Lane roll bar and a frame rail brace kit worth compromising for a bit of extra rigidity? Anyone know how much weight would be added with the two fitted?

Also how much extra stiffness can I expect from both frame rails alone and rails plus rollbar. Would it be similar to an MX5 with a hardtop with the latter? I had a hardtop fitted when I first bought the car, and it was noticeably tighter and less scuttle shake with it attached.

[snotrag]

Definitely worth it. I have TR lane with harness bar and full diagonals, car feels good. Admittedly I have stitch welded the door shuts and windscreen frame, but I think the half cage is still worth it.

Frame rails are supposed to make a good difference too.

[Gilhooligan]

I have a Carbing half cage which bolts to the floor etc. So it's bigger than the TR Lane roll bars but still doesn't weigh that much. I doubt you'd be able to notice the extra weight at all. What you can notice though, is the increased rigidity in the chassis. Defintely worth going for the extra bracing.

[GravelBen]

I put bolt-in 4 point half cages in both of my Mk1s and you could definitely feel the improvement. Didn't have frame rails, but underbody braces between the lower suspension mounts were worthwhile too.

[vrsmxtb]

GravelBen said:

I put bolt-in 4 point half cages in both of my Mk1s and you could definitely feel the improvement. Didn't have frame rails, but underbody braces between the lower suspension mounts were worthwhile too.

Mine's a 1994 1.8 so has the standard extra bracing. Weirdly, somebody had removed the seatbelt tower brace so I replaced that with one from a breakers, although noticed very little difference to be honest.

Assuming it passes the MOT with no major issues, I think perhaps a 4 point bar and frame rail may be the upgrades for this year!

[JamesHayward]

I've got a six point Cusco cage with door bars in mine and it makes a huge difference. It has added 20kg but I've lost that by replacing the standard seats with buckets anyway. The only thing to bear in mind is that if you are a taller driver (5ft 10+) you might struggle with restricted seat movement if you have a 'down to the floor' type roll bar.

[Actus Reus]

vrsmxtb said:

Mine's a 1994 1.8 so has the standard extra bracing. Weirdly, somebody had removed the seatbelt tower brace so I replaced that with one from a breakers, although noticed very little difference to be honest.

Assuming it passes the MOT with no major issues, I think perhaps a 4 point bar and frame rail may be the upgrades for this year!

Probably had a style bar at some point - I can't have a style bar and a brace (using the style bar I bought with the car).

I may also fit some sort of roll-over protection as I want to track the car - I just wonder if it's worth it for the odd track day? Ask me that, I suppose, when I'm in the middle of flipping the car... I'm a bit of a novice basically and not sure how seriously I should be taking this.

[Sad Weevil]

Frame rails make a big difference, well worth the small extra weight, combined with a proper roll bar. The standard extra bracing on later cars was added for better side impact protection, designed to deform and absorb energy, not to stiffen the car. The 'brace' behind the seats is just a thin piece of flat bar clad in plastic.

[MX-5 Lazza]

It was mostly added for side impact protection reasons but it did help to stiffen up the chassis a fair bit too. Well worth having at least the braces from the later cars.