I was reading the installation instructions for the Boss Frog roll bar (here), and read:
Is this true? I’m fitting springs this weekend, do I need to buy 3 more jacks and lift each corner little by little until I can 4 axle stands underneath? Seems a little unlikely.
Having read those instructions, I can see why they suggest jacking all 4 points - you need to get under with a drill.
Could be a pain - made easier on a lift (i.e. exhaust centre), or a pit.
Good luck!
In extreme circumstances I’d say yes there is a posibility the body could twist slightly when jacked (although MX-5’s are pretty stiff). The Boss Frog instructions state that the chassis twisting could be an isue when fitting their bar so I suspect it’s just a bit of covering their own arse! It’s perfectly acceptable to jack one corner only when changing a wheel! If I were you, I’d jack on the diff & front cross member then axle stand each end with a pair of stands one end at a time. You may have to raise one side a little with the scissor jack to enable you get a trolly jack under & then remove it after lowering. I think jacking points are stated in the owners manual.
Hmm. Haven’t got a trolley jack, but I can lay my hands on another scissor type jack to avoid lifting one corner by itself. The stands I have are quite high, so it has to lift a fair amount to get a stand under. I’ve got to get some spring compressors, maybe I’ll invest in a trolley jack if one catches my eye.
Cheers for the replies 
I don’t like the idea of lifting to the height require for axle stands using the standard scissor jack. It’s only designed to get the car high enough to change a wheel/tyre. I have always found that the easiest way is to run the car part way onto a set of ramps, then lift the car with a trolley jack to the height needed for the axle stands. You can buy a decent jack from halfords for under £25 and a set of ramps for about £30 they will last a lifetime and pay for themselves over and over again
Yeah, I use those metal ramps and it feels much safer underneath than when using axle stands - worth the money just for peace of mind.
That said, I replaced the front dampers just by jacking one corner at a time with the normal scissor jack with no problems at all - can’t see why the car would twist - if it was that weak then how could it survive hitting a pothold or a kerb etc…?
I think the avoiding twist might be due to fixing cage - best if car is level & square rather than on a twist whilst fitting the cage…???
Go and buy a trolley jack, Aldi and Lidles do perfectly good ones for £10-20.
You are correct 
Well I bought a trolley jack, has made it much easier so far.
I might have to abort the spring fitting until I’ve bought more bits though. Must remember to read the task description in the manual before placing on stands and removing all the wheels. Saves standing in front of a wheel-less car scratching one’s head wondering how to get to an auto-factors
done that so many times!!! made my car totally undrivable and then realised haven’t got half the bits i need…