looking for Advice and Ideas
 

Hi everyone.

I'm looking at building a roadster powered by a hayabusa, either turbo or supercharged. Before i go out and buy a donor, i'm wondering what would be ideal for my kind of build. Would the running gear from a sierra or mx-5 donor be sufficient to handle the power from the hayabusa? would i need to get bigger brakes? would i need to add strengthening to the chassis?

Advice on these points is greatly appreciated and if there are other things that i need to look at then i would love to know... thanks in advance

Martin

Personally the things I would be looking at would be the diff ratios you can get and how you'll do the reverse gear.

Plus, as you're doing a mixed engine/drivetrain car, I wouldn't worry about getting a specific donor; you'll struggle to find that many Sierras and the MX5 parts market is so flooded with cheap parts that you'll find it difficult to get any sort of decent money for unwanted parts.

Just to give some idea of MX5 parts cost at the moment...

a good condition 5 speed gearbox I recently saw had an asking price of £15. One of the MX5 breakers was asking £25 for their boxes. An open diff can be had for £25-50, brakes (especially early 1600) are dirt cheap, there's no call for the uprights apart from kit cars, driveshafts are £10-15 each...

i didn't realise mx-5 parts had dropped in price. there's a company in Bradford called moss. they apparently sell parts for the mx-5 now so ill order a catalogue. what about the brakes, wouldn't they need upgrading or anything?

standard cars are much heavier than the roadster so i would think the standard brakes would be ok

Moss have done MX-5 parts for quite some time, but it's mostly aftermarket bits.

A lot of people with turbo MX-5s (200-250bhp) seem to run 1800 sized brakes with uprated pads, which was what I was going to run until I changed my mind. I'm running early 1600s with uprated pads. It's good enough for the MX-5 racers, so it'll be good enough for my car :)

One other question - do you really need a turbo'd Busa? If you've little/no experience of these cars, then the 500-700bhp/tonne figure you'll get is not for the novice or faint of heart...

It might be worth considering a BMW or Freelander diff if you have a BEC and getting custom driveshafts to suit, the longest standard MX-5 diff you can get is 3.6:1.

The callipers are the same for 1600 and 1800 models. All you need to change is the mounting bracket and the disks. You also need to use 15" wheels. Quite an easy and cheap upgrade for anyone running 1600 brakes

David

The rears are, the fronts are not. The 1600 front calipers will fit the 1800 brackets, but you have to swap the caliper sides. Not something I would do personally.

And the 1800 brakes will fit under 14s. With the exception of the RS-Ltd (15" BBS), all mark 1 MX-5s (and Eunos) were fitted with 14" wheels.

thanks guys really appreciate it. is there anything else i should look into?