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Canley swing spring?

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claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
Pretty much what I said, or tried to say John.

The bar in my Spit is better than nothing, but is too low and unbraced both in diagonal, and more importantly, fore and aft.
It is simply the best I could do and still have a street car that can use both a hard and soft top.

It would offer some protection in a rollover, and as I said, better than nothing, however the seatbelt anchorage points are a major improvement on the stock ones.

I have a proper, approved roll bar in the Clubman, but it is only possible because there is no top, just a tonneau.

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tapkaJohnD Avatar
tapkaJohnD John Davies
Lancaster, Lancashire, UK   GBR
Thanks, Marcus, for not being offended by my apparent criticism, which was not my intent.

There is a balance, when the possibility of accidnet is more likely you take more precautions. This is a typical racing Caterham (SEven successor) ROPS!

Jiohn


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clshore Carter Shore
Beverly Hills, Florida, USA   USA
The most common rollover events on street driven cars happen at relatively low speeds.
Kinetic energy increases as the square of velocity.
So a Racecar crash at 100 MPH involves 100 times more energy than a street car crash at 10 MPH,
16 times more energy than a street car crash at 25 MPH,
4 times more energy than a street car crash at 50 MPH.
That is why racecar sanctioning bodies are such fanatics about rollbar standards and safety.



Edited 1 time(s). Last edit at 2017-10-13 06:00 PM by clshore.

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RobTAR Robert I
Seattle, WA, USA   USA
I like to think of the two point "roll bars" as a giant mouse trap. In a rollover they are gonna most likely fold one way or the other, I'd rather run without a bar than one of those. In the Miata world people are very quick to correct you if you call a two point bar a roll bar, to them it is a "style bar" only good for looks and dangerous in a roll.

Back to the original topic, I am surprised no one put forth the Roto flex conversion. It is after all better than both the swing axle and spring and the parts are readily available to do the conversion. Plus if you use CV axles you can reuse the swing axle struts and mounting points.

claytoncnc Avatar
claytoncnc Gold Member Marcus Clayton
Melbourne, Ivanhoe, Australia   AUS
In reply to # 1491788 by RobTAR I like to think of the two point "roll bars" as a giant mouse trap. In a rollover they are gonna most likely fold one way or the other, I'd rather run without a bar than one of those. In the Miata world people are very quick to correct you if you call a two point bar a roll bar, to them it is a "style bar" only good for looks and dangerous in a roll.

Back to the original topic, I am surprised no one put forth the Roto flex conversion. It is after all better than both the swing axle and spring and the parts are readily available to do the conversion. Plus if you use CV axles you can reuse the swing axle struts and mounting points.

Oh well, we must agree to differ, I would much rather have a bar than not.

I have tried (at great expense) the rotoflex and do not recommend it on a road car. In theory it is far better for camber control and geometry, but in practice, the light weight componentry of the swing axle is markedly superior.
The rotoflex uprights and wishbones are very heavy, and in a Spitfire apt to chatter and shudder over high frequency and mid corner bumps, with the wheel leaving the ground quite regularly.
The swing axle (swing spring) will absorb those bumps and give a better ride, the camber change on sensibly sized tyres (I use 185-60 13) is not noticeable to the driver.

The 2 pics show my car under heavy compression braking from about 130 kmhr, and over a mid corner bump at the limit of adhesion at about 90kmhr.
There is plenty of suspension movement for compliance, a reasonable amount of body roll that helps counter camber change, and an ability to traverse less than perfect roads with confidence.
I came 2nd in my U1600 class at this event, behind a Lotus.

On a race car, the deal is to keep as much tread on the ground as possible, and as on a smooth track compliance is not an issue, a swing axle would be at a disadvantage there unless the spring was very stiff, almost rigid in fact.



Edited 2 time(s). Last edit at 2017-10-14 02:04 AM by claytoncnc.


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