Just to clear things up a bit, this is all theoretical from my end as I don't have a chassis built as yet, just an MX5 front end (to look at wistfully ;) )

I'm assuming from Andy's pics etc the MX5 rear end seems to be used un-narrowed and thus the rear and front track will be as per MX5.

So I'm then guessing the new front wishbones are longer than stock MX5, (ie the pivots
are closer together than the rusty bits in my garage) so making original rack
inappropriate?

I thought that maybe the reason for using the Escort rack came from the Haynes being an adaptation from the original Locost and its just sorta 'stuck'

What ball joints are you using Andy?

Sorry for so many questions; I'm just trying to understand the geometry changes and rationale behind using certain parts is all.

Cheers

Hi TQ,

I think as everyone realises suspension geometry is a bit of a minefield luckily , coincidence or not, the Mx5 geometry is very similar to the roadster the main work was to adapt wishbones to work with the mx5 uprights and the Haynes chassis keeping the wishbone brackets in the same place and the haynes chassis as close as possible to the original and adapt the wishbones to give the correct geometry. The safest option for me was to use the tried and tested geometry of the roadster as is. Rear geometry is quite straight forward and uses mx5 track width with adjustable lower wishbones to alter camber and toe in of rear wheels. The front was setup using the software below:

http://www.flickr.com/photos/saturns...7625932340212/

giving a SAL figure of 1134mm giving the following ride:

Hints: From the Competition Car Suspension book.

Short SAL (500 – 1000mm) gives very good roll centre location, keeps the outer wheel vertical in corners, but going badly to positive camber in droop and negative in bump (accelaration squat and braking).

Long SAL (1800 – 4500mm) provides lower roll centres but less control over their sideways movement, minimal scrub (track variation), poor outer wheel control going into positive camber, but only small camber change in bump/droop.

Medium SAL (1000 – 1800mm) is the transition area between long and short with, as you might expect, a bit of this and a bit of that.

Ultra-long SAL (near parallel) provides excellent vertical control of very low roll centres but possible enormous sideways movement, wheel angles virtually unaltered in bump/droop but very poor control of wheels in roll, with near equivalency to body roll angle.

Also the front can be fully adjusted with twin adjusters on lower wishbones for camber, castor, track width.

Ball joint are standard Mx5 lower joints and transit drag links for top with upright reamed out slightly. With Sierra drag link ends. Escort rack used mainly to retain the Haynes chassis design as much as poss plus escorts racks are readily available new in different ratios.

I suppose the proof will be in the pudding, shouldn't be too long before we can give it a try it - cant wait......:D

Also starting to mold up a grp rear diffuser for the car this week, which will fit the standard Haynes to. Should be good.

Andrew

Cheers for that - reading back through my posts I think I could probably have asked things a bit clearer :o

Makes much more sense now though :)

Thanks TQ,

Helps get it all clear in my head to, there's a lot to think about.....:o

Just wait for the single seater next..........:o :o

Andrew

Race car needs one !!!!!:p

Is it the single seater book about to land on the shelves then?:)

Do you know something we dont ........:confused:

No I tried emailing Mr G but email came back to me, bloody sure I never wrote it on a boomerang but sometimes I don't know what day it is let alone what I have been doing....:D

I'm getting no response from MrG either Mark.

I am talking of the project to come after the Mx-5 donor roadster - if my head doesn't explode first.....:cool:

Got some updated pics of the Roadster / Ginetta race car progress, thanks mainly to Paul, Flyerncle. It's certainly getting there now......:D

http://www.flickr.com/photos/saturns...7625812138411/

Happy Reading.....Andrew

Well if the single seater book bombs.. then you have done enough work to go indy on it and seek different publication.

TT

Wiring harness/injection system is in, fuel pipes fitted,roll cage is being made by AAS and after initial trials and testing a new exhaust will be fitted.

Front and rear suspension is also fitted but needs setup.

You've had a hell of a week so far, give yourself a large pat on the back Paul. Brake bias bar and adjuster will be arriving tomorrow so i'll set that all up in the pedal box. Only thing is its my birthday on Saturnday and Anja has put her foot down and has got the kids round on the afternoon and wants me back so if okay i will come up Friday afternoon with bits and get the fuel tank. Spend the afternoon up at Teamtrain.

Cant wait to get setting up the suspension, i'll bring up my inclinometer and it can be setup initially. Did Jim order the temp probe for the tyres?

Thank You....Andrew

This might be a stupid question but are you going to keep the PPF frame or does the roadster chassis act as an effective PPF (Power Plant Frame)? Oh and does the propshaft need to be shortened? Is there mx5 based build FAQ anywhere?

Hi CT,

The PPF would be nice to use but will not fit in the roadster without the tranny tunnel being widened a fair amount and losing valuable width from the cockpit. The lightness of the roadster should put less torque on the diff during acceleration and therefore less of a need for the PPF, the PPF is mainly to stop the diff from twisting during acceleration so the chasis is perfectly adequate without it.

Yes the prop will need shortening but there are plenty of good prop firms that can do this.

Regards....Andrew

Thanks Andrew, and the polo mk2 rad is good for the mx5 donor car too. So many questions...sorry!

It works fine with a 170hp 2.0l zetec so at the moment i can only say yes, there are different variations, thicknesses, available for the different clio engines. I will get a part number for the rad that has the greater thickness.

Andrew

That's right, and the point behind the PPF is to make the car feel more responsive under acceleration.
Because the diff is solidly mounted to the engine via the PPF torque is transferred directly to it, rather than through the engine mounts -> then through the chassis -> then through the diff mounts.
The Haynes can make do without the PPF as it's going to be pretty blooming responsive anyway weighing half what the MX5 does!

Plus not using it means less weight, and more bits to sell on ebay :)

Yes I can see the logic, great thread this really useful. Thanks for getting me part numbers Andrew. :)

Just been reading a book about the mx5's development never knew they but so much effort into these cars, really quite impressed! Should be fantastic in the roadster chassis. Has anyone completed an mx5 roadster?

Ron Champion licensed the Locost to Champion Motors in the USA. They then developed a Locost chassis for a MX5 donor, sold a bunch of chassis. The Build a Cheap Sportscar book was about assembling one. Tanner spent most of the book complaining about it not being perfect.
http://www.amazon.com/Build-Cheap-Sp...1590284&sr=8-1

Westfield are making a model for the MX5 now. Flying Miata in the USA have a build diary about putting one together.
http://www.flyinmiata.com/westfield/Torgan/index.php

MX5 based cars are a better choice for the USA because we never had many Cortinas here, and very few Sierras (Merkur XR4ti). Unfortunately there are no prebuilt chassis or chassis plans available for us at this time.

Thanks minicountryman great info and thanks for the links I think they got the pricing wrong though!!:D

OMG, it has gone out of print! I hadn't noticed. It ain't worth that much, it doesn't even include chassis drawings. It is a book about building a kit with a chassis from a company that is out of business!

The Gibb's book is actually useful.

This WayBackMachine link may work to the Old Champion Motors site

http://web.archive.org/web/200503230...motorcars.com/

Anybody got any tips for Google Sketchup, apart from pay hundreds for a proper 3D cad package......:(

All is ready with the chassis and components just spent the last few nights trying to cad it all up and although i used to be a dab hand with basic cad and sketchup i just cant get it done (i will though). I know Chris used sketchup for all the schematics and diagrams in the book so just want to keep it as similar as possible for other builders.

Few more sleepless nights and it will be done........Andrew

Can't wait, visited a local steel fabricators we do some work for this morning, he was very helpful and is letting me use some of the fabrication equipment for bending and cutting, and will be supplying the steel for my build.

Hi All,

Hope you all enjoyed the fantastic weekend weather, had a great blast out yesterday, 150 mile in glorious sunshine and some great roads. Really makes you remember what its all about......:)

Got the Mx-5 chassis all rolling now with engine and gearbox all in to. Will be making a big effort to get it all cadded up this week with the build guide put together.

Latest Pics below:

http://www.flickr.com/photos/saturns...th/5442665532/

Regards.....Andrew

My build table is ready and waiting!:D Perfect Timing I'd say.

egarly awated after this morning :)

Afternoon All,

Just to let people know, there have been some pretty major developments recently with the conversion of the roadster to Mx-5 as donor. This will benefit the Haynes Roadster community massively but will take a little time to come to fruition. As a result of this the build guide for the Mx-5 conversion will be delayed a bit, but shouldn't take too long.

Exciting Times.........Andrew :)

I can't stop looking through these images....

You'll go blind if you're not careful

Exciting aren't they!
I have mixed feelings about the MX-5 build though. Problem is, I had planned on using my tuned 2ltr Ecotec out of my Vectra (once the IVA is out of the way obviously) but now I'm 99.9% sure I want to go the MX-5 route which means I'll have a spare engine knocking about that has less potential and will be less reliable than the Jap lump.

:cool:


How are you getting on with yours?

They are very good engines, I went out for a spin in my donor when suddenly we coasted to a stop with steam from the bonnet and no ignition.....:(

Turns out the auxillary belt had gone AWOL! I think I smelt it shredding and the battery negative terminal had come loose! New belt fitted and the engine was fine, non the worse for it's abuse!

My friend works for a mazda dealer as a mechanic and he said to me when I asked if he could get me a belt "Stop trying to break the unbreakable car!" :D

I so need an unbreakable car!! :D
From the (very) limited amount of research I have done on the Mazda lump, I believe you can just bolt on a turbo, or supercharger with very little other work being needed.
Obviously a remap or standalone ECU would benefit that situation massively, but when you consider other engines need the compression lowering and uprated internals, etc, to accomplish the same thing, the little Mazda lump starts to look very appealing.

Well exactly! Apparently the standard internals can deal with 250bhp and the gearbox can cope with that too. Although the open/viscous diff may not. Being a uk build too with the steering clutch and brake hydraulics on the right you have a big empty space on the exhaust side of the engine! Intercooler might be a bit more of a challenge though!:rolleyes:

You could probably get away without one if you don't go daft on the boost, however I wouldn't like to try it. :)

Very slowly. Starting to feel like the whole world is conspiring against my build at the moment!

Good things come to those who wait! :D

And even better things for those with extreme patience and attention to detail:)