Mx5 Rocketeer V6 Conversion Project

[Richyvrlimited]

Is there a thick plate under your shiny bit of metal? If not there needs to be or the roll bar is pointless. As strong as you think that shelf is, in a roll over the bolts will just be ripped through.

[Lewis's Friend]

Richyvrlimited said:

Is there a thick plate under your shiny bit of metal? If not there needs to be or the roll bar is pointless. As strong as you think that shelf is, in a roll over the bolts will just be ripped through.

I hadn’t realised the necessity. I may have a word the manufacturer, but I would have assumed that a decent sized plate was only required on the interior side, as in the event of a roll all the force would be acting from the top of the car?

[remould]

The issue is no car just lands upside down,they normally roll or hit something on the way to being upside down so you can get all different forces acting on the bolts.

[Boobonman]

I fitted a very similar bar to my mx5 recently, can confirm supplied spreader plates go underneath the car

[Lewis's Friend]

Cheers for the info chaps. I’ll have a word with the manufacturer in the new year. Possibly the plates just got missed from the order.

[AceOfHearts]

Just checked in on this Jon, looking good, you are cracking on!

[227bhp]

Richyvrlimited said:

Is there a thick plate under your shiny bit of metal? If not there needs to be or the roll bar is pointless. As strong as you think that shelf is, in a roll over the bolts will just be ripped through.

I can't think how there would be any actual pulling forces on a roll over bar? It'll get pushed downwards and sideways.

[Super Slo Mo]

227bhp said:

Richyvrlimited said:

Is there a thick plate under your shiny bit of metal? If not there needs to be or the roll bar is pointless. As strong as you think that shelf is, in a roll over the bolts will just be ripped through.

I can't think how there would be any actual pulling forces on a roll over bar? It'll get pushed downwards and sideways.

I can, if the car goes over while still travelling forwards there’ll be a lot of force applied at the top of the cage trying to push it towards the back of the car. This will have the effect of trying to lift it off the mounts, and in this case will probably tear it straight off.
I’d make up a big right angle plate and weld it to the piece of body frame that’s adjacent to the spreader the op made.

[227bhp]

Super Slo Mo said:

227bhp said:

Richyvrlimited said:

Is there a thick plate under your shiny bit of metal? If not there needs to be or the roll bar is pointless. As strong as you think that shelf is, in a roll over the bolts will just be ripped through.

I can't think how there would be any actual pulling forces on a roll over bar? It'll get pushed downwards and sideways.

I can, if the car goes over while still travelling forwards there’ll be a lot of force applied at the top of the cage trying to push it towards the back of the car. This will have the effect of trying to lift it off the mounts, and in this case will probably tear it straight off.
I’d make up a big right angle plate and weld it to the piece of body frame that’s adjacent to the spreader the op made.

That would be a pretty weird accident whereby the car flipped forwards on its nose and performed a perfect 180. If it did it would want to pull on the front fixings and push down on the rears and likely snap the bar off at the welded point where it meets the base plate, but yes fair enough, to be as safe as possible we have to allow for every situation. Like you say some triangulation could be put in, maybe in the form of some tubes at say 45' on topside going forwards and/or backwards.

[Super Slo Mo]

227bhp said:

That would be a pretty weird accident whereby the car flipped forwards on its nose and performed a perfect 180. If it did it would want to pull on the front fixings and push down on the rears and likely snap the bar off at the welded point where it meets the base plate, but yes fair enough, to be as safe as possible we have to allow for every situation. Like you say some triangulation could be put in, maybe in the form of some tubes at say 45' on topside going forwards and/or backwards.

That wasn’t what I meant, perhaps I didn’t explain it very well. I meant the car had flipped while going forwards, and was still going forwards but now skidding on it’s roof.
I think that’s not an uncommon accident, and is something you see quite a bit on track day or racing footage.
The triangulation ought to provide some support but there’s be a large force still trying to rip the roll bar backwards off the Car, which would try and lift the front posts upwards (rotating backwards around the triangulation bases if that makes sense).
This is where the bracing is needed under the front posts.

[Lewis's Friend]

AceOfHearts said:

Just checked in on this Jon, looking good, you are cracking on!

Cheers dude - getting there slowly...!

[Lewis's Friend]

I just spoke to TR Lane, who very generously answered the phone on boxing day to some random nutter...

There is a spreader plate (of appropriate thickness) with the kit, which I managed to lose in the packaging. Located now, and loosely installed until I can get a second pair of hands to help me get the bolts to a suitable torque.

So cheers for the wise words from observers - very useful.

[LewG]

From what I remember the torque figure is around 5 ugga duggas

[Lewis's Friend]

LewG said:

From what I remember the torque figure is around 5 ugga duggas

I think you've been working on British armour for too long....!

[SonicShadow]

LewG said:

From what I remember the torque figure is around 5 ugga duggas

No no no, this kind of thing requires a delicate approach with hand tools. Fetch the big ratchet and tighten til she loosens!

[LewG]

You're forgetting the extra six feet of scaffold tube

[PhillipM]

Tighten until stripped, then back of a quarter turn.

[TekoTime]

[ATM]

Mike335i said:

Brilliant, looking forward to seeing how this pans out. I have seen a Rover V8 powered MX5 that must be fun, but a lightweight V6 seems right for the car.

I bumped into a lad with a lexus v8 powered mx5 while I was waiting to get my car aligned in Dudley. I may even have the pics if I dig a bit. It seemed to fit quite well. I've always liked the mx5 but never been brave enough to buy one myself because I believe they are light but not very strong. I was told the sides bend in easily so if involved in some form of side impact then you're not well protected. The roll bar makes a lot of sense. Now that I've seen it I cant understand why they don't all have them.

[ATM]