Hello everybody

[beardydave]

Hi, my names Dave. I've been reading the forums for a couple of days looking for more "inspiration" regarding the use of an MX-5 donor.

I'm currently in the planning stages of a roadster build using a real mixture of donor bits. The original plan was to modify for a BMW diff and gearbox as I already have those (abandonned due to size, weight and the lack of a cheap limited slip option), which then changed to sticking as close to the Sierra plans as possible, and after reading all the info and seeing the Vodou VR5 chassis has changed to using an MX-5 base for reasons of availability of MX-5s and simpler build.

In fact, the only thing that's remained constant throughout the planning has been to use a Saab B234 turbo engine as the powerplant, coupled to a SaaBMW gearbox (a bmw box that's been modified with a Saab/GM bellhousing - very popular in Scandanavia for the big power RWD conversions and far stronger than the GM R28 box from an Omega).

All my planning is being done in 3D on Solidworks to try to minimise swearing time during the build, and so that I can get most of the custom parts laser cut for me as my sheet-metal skills aren't the best. I may or may not do the welding depending on how brave i'm feeling and how much a bought-in chassis and suspension set will cost.

The plan afterwards is to make as many of my 3D models available for general use as possible for others to plan their builds with. Estimated completion time is about 2 years at the moment.

Always open to comments or querys, as soon as i've got something physical to actually show i'll be starting a build thread too.

[vmax1974]

Welcome to the forum dave

For the mx5 donor you really have 2 chassis options talon for the voodo chassis and the saturn book amendments search google for saturn sports cars or if you get stuck I can email you a copy. if your looking to go prefab then that limits your options to just talon but if you want a flat pack kit to weld yourself you can use either handyandy or talon but best to contact both to work out how you want to proceed and who with maybe have a road trip to meet the guys and maybe they will let you lose in there roadster

[robo]

Welcome southerner our numbers down here are on the up:) :) There`s a roadster being built near you in rowlands castle and I am in guildford.

bob

[will_08]

Welcome Dave :)

[K4KEV]

Hi there Dave....it looks like your mind set is in the right mode good luck with the build.

[beardydave]

I've got the Saturn instructions, but looking at the screenshots of the Vodou chassis on another topic that one looks like a better arrangement for mounting the diff, especially with the re-designed rear end i'm contemplating to house a longer range fuel tank and the battery - space is going to be at a premium in my engine bay with the extra pipework for the turbo and chargecooler, and the dry sump i'm going to have to fabricate.

I'd like to experiment with 3D models for both though before making a descision.

The only problem i've found with the Vodou kit is that I can't get the instructions as the website is down. Anybody have a copy of them that they can email me?

Also, does anybody know how much torque an MX-5 diff can take? The Saab engine packs quite a punch (300ft/lbs on a mild tune!)

[chrisponter]

I've got the plans saved if you want to pm me your email address.

I'm building a vodou chassis aswell, mainly because I just wanted to be different. A word of warning on the suspension, its quite hard to work out from the drawings, especially the front wishbone brackets which appear to hang almost in middair on my chassis. I think I'm going to have to widen the front track to make it fit properly. Plus there are a few little niggles which I'm still not sure on. The website seems to come and go.

[alga]

Hi and welcome! You have, of course, found fabrun's and mopple's Solidworks models of the roadster? Might save you some effort. If not, the links are in the FAQ, link in my sig.

[beardydave]

Hi and welcome! You have, of course, found fabrun's and mopple's Solidworks models of the roadster? Might save you some effort. If not, the links are in the FAQ, link in my sig.

Yeah, I did get fabrun's model, but it's of limited use to me as it was made on an educational version of solidworks (in french too!), and my full version can't edit any of the parts. Gave me some usefull ideas on modelling the nose cone though which was a part I was having trouble with.

Spent the last few days researching Mazda diffs, and i've gone back to the original idea of using the BMW diff, although I will be keeping the mazda suspension. The reasoning behind this is that the mazda diff will only reallistically have a design torque of a couple of lb/ft of torque to give a safty factor on the engine torque, and the Saab engine i'm using can pack out 400lb/ft on only a mild tune, and my aim is to one day rival the Veyron on power to weight ratio... No-ones ever broken a BMW diff to my knowledge.

The other reason is that the mazda diff will only ever be open, viscous or torque sensing. I don't think that i'll ever have the loading to get the temperature up on a visous diff, and i don't like the idea of the sudden leap in torque transmission if it do, and a torque sensing diff is useless if you have one wheel only spinning. The BMW lsd is a true, clutched lsd, with variable locking if you know how to fiddle with them.

[robo]

I think by the time your done you will end up like me without a donor. I have gone bmw diff and they come with the same 108mm six bolt flange as the cossie drive shaft so then you end up with the cossie rear hubs+shafts with the vented disc. Then you move to the front and realise after a read up the hubs are none to clever so I ended up with fd rx7 hubs which fit a treat and give you 300mm vented discs and a huge ali 4pot caliper. Then you look at your engine which aint a lightweight and wonder how your gonna steer the thing with a quick rack so you end up with a corsa leccy steering colomn. And it goes on and on. The single donor is great as an integrated package and works well if thats what you want, but thats not everyone:eek:

Bob

I am keeping the chassis book spec but 2mm box and all the suspension/ shock mounts as per book. Then if all my mods are a cockup I can back track. It will only be wishbones that are altered.