I could be wrong but ....

[TalonMotorFabrication]

If the drop off in sales are any thing to go by I'd say there seem to be a definite slowing of new Sierra based cars being built. I know that Sierra donors are few and far between on ebay, gumtree and even in the scrap yards so are people that are just starting to build 'book' cars by buying their running gear from just parts? Has the Sierra Roadster had it's day and now moved on to using the MX5,
I think it may be time to publish the drawings for the extra tubes,mounting lugs and diff nose mount needed to fit the MX5 diff in to the 'book' rear suspension cage.

[TheArf]

you could well be right Phil, Sierrea's are becoming as rare as rocking horse sh1t and hens' teeth

[CJ27]

The mx5 based build just makes sense to me, as you say Phil sierras are thin on the ground now days, you can pick up a mx5 for £350 for an mot failure if you look in the right places, a lot more parts available and sacks of tuning potential.

[jason 82]

I sent the request to Ash for him to put one set of approved plans in the sticky section a few months ago. He must be a bit busy.

[jason 82]

It would be really handy to clarify the mx5 build for newbies. My car is being built using 3 sets of plans ! Haynes plans, gillham & ssc. Shock legnths are a grey area, not to mention spring rates ! if we don't take steps now to allow for mazda & bmw donors, by using 1 standard set of plans for a specific donor, the haynes Roadster will start to fizzle out. Maybe it's time to form an owners club now, group buys et , where we pay £40 a year or whatever, & start having club stands at shows & just celebrate the mark. We work 3 times harder than any other kit car builders, why are we not shouting about our achievements ? Over the years on here, there have been roadsters produced of a much higher quality than a factory kit ! Locost ? No chance ! Just sweat & graft. oh, and shed loads of ear ache !

[TalonMotorFabrication]

Here I have to be careful as some one once said to me 'beware of advice given by some one trying to sell you some thing' so with that in mind I'm trying to be objective about what comes next...

I think you would struggle to get people to agree about one set of 'approved' plans as these have mainly been produced by companies/suppliers and not Haynes themselves. While AshG and Twinturbo can turn posts in to stickies on here about versions of how to use the MX5 diff and rear uprights at the end of the day they are forum moderators and is it really for them to decide which design should be used in favour of another?

As you say there are various plans/designs of how to use the MX5 diff and rear uprights one I had a 75/25% hand in designing/reworking which was never completely finished due to Vodou disappearing and another that I came up with using the book cage as a starting point. AndyH at Saturn published his version using the complete MX5 diff but he too only gave every body 3/4 of a design which lead to people learning the hard way about the effects of torque acting through diffs.

From my own point of view looking at it as a customer/builder I can see where both Vodou and Saturn where coming from in publishing their designs, how ever it should only have been done if it was complete and had been tested to the point that it could not be broken under 'normal' use.
In my observations as some one who has fabricated other peoples designs seen the faults in them and built rough terrain race cars neither Vodou or Saturn had enough engineering/structural understanding of the forces involved and the possible failure points in their designs.
The Saturn wishbones where too compromised with the short top wishbone and damper mounting point and the lowers with those adjusters just does not sit right to my mind, as for the Vodou wishbones they left no clue as to where the coilovers should go at all which made them useless to every body.
Neither design was completely finished, road tested or IVA'ed before publishing them which to my mind is not how it should be done,people have said 'it's only a guide' this is true but that guide has cost a few people hard earned money and time spent in the garage.

Suspension settings and spring rates is a grey area simply because no body has done the research or put the money into it because every body has closed shop before doing it. To get the correct spring and damper rates you need a car to be complete, with a full tank of fuel and the driver sat in the seat for it to be corner weighted and the maths to be done to work out spring poundage. There is also the small matter of how you want the car to react to what will you be using the car for, B road blasting on a sunday, trackdays only, full race set up? A set up for one of them will not will suit all of them a car set up for track days will most likely jar your back and knock your teeth out on a bumpy B road at 50-60mph.

Warning some one giving advice while trying to sell you some thing

My approach to the design was 'how do I make that fit in there?' as in the MX5 fabricated cover fitting the book suspension cage rather than what do I make to fit around it. Looking at the 'book' rear end/suspension cage it's a pretty simple thing to make and it's all ready part of the book which cuts down on additional required info/drawings.
The fabricated cover does away with the Mazda built in failure points and replaces it with four solid mounting points or some thing that can be welded to at home. The wishbones fit the brackets same as the drawings in the book and the top wishbones use double adjusters for camber but are not stressed the same as the fabricated uprights in the book.

When I have tested this design by trying to break it repeatedly and only when this has been done I will publish the designs for the diff nose bracket plus SB4 mounting plate and the upper/lower tubes and mounting lugs for the fabricated diff cover.
I have learnt from others that it is better to make sure it works first before unleashing it only for it to turn and bite you in the arse.


As for a club... we have one already, you are part of it, your using it now and it's free!

If you have sat and read this load of ramblings from this idiot...thank you.

[baz-r]

my 10p on the subject is that the value put on remaining sierra cars and parts are increasing that combined with most of the kit industry already using sierra bits has started to exhaust supplies.
that said there are still quiet a few bits and cars still kicking about and meny of us still have sierra bits needed squrilled away (i have all of the main parts to build another car) where as mx5's are still in plentyfull supply at the moment but for how long?

the std design only really needs a few sierra parts and im sure some of thease could be easily switched for a diffrent part of the same style.

the problem is if you use a diffrent donor car you realy need to take into account things like the change of ackerman angle. i take it this is why the the orignal kept the sierras wheelbase and track.

with so meny cars now fwd the sylva riot way of doing it seems a more logical route