Hello,

I've managed to secure something of a bargain on Ebay

eBay - The UK's Online Marketplace

It's an entire RX8 back end complete with LSD for only £51

However I need a way of building a back end to either accommodate the entire RX8 cradle or do I fabricate a framework, brackets etc and transplant all the components. If anyone could give me any pointers before I break out the saw it would be much appreciated.

Thanks

GM

[Edited on 9/12/11 by Gear Monkey]

I would discard the carrier and make a set of bones up, lightness is key.

If you have a look at pictures of the rear of the frames you will see plenty of examples, you could also carefully measure the pickup points and transfer across.

As an RX8 revs very high what diff ratio is that?

Looks ideal BTW, and a bargin

[Edited on 9/12/11 by mark chandler]

as before make wishbones and carriers

Basically, as Mark and Austin Man say. You don't need the carrier, trailing arms etc. Make your own wishbones to suit a) your inner chassis mountings and outer hub carriers both of which you'll need to design and brackets on the chassis to carry the diff, adapting as necessary to allow provision for 1) handbrake, 2) brakes and spring/shocks.

You may be able to utilize the top "wishbone" that mazda made. Can't see what's at the bottom, but if it's another bone, you may just need to transfer the carrier pivot points onto your chassis - making chassis the appropriate width (and all the aggro that will entail - such as one-off bodywork)

Cheers

ATB

Simon

[Edited on 10/12/11 by Simon]

What a shame you can't just bolt that lot straight onto a modified chassis, couple up the prop and brakes and Bobs your uncle. Apart from the weight is the design so poor that it would be useless?

You can probably utilise the bones, the shocks and springs and carrier all go back on ebay

This is all designed to support a car of twice the weight.

If you have a look in speedyxjs's archive he did the same thing with a Jag rear end.

Regards Mark

Here are some pics of the chassis and RX8 back end. The chassis is based on the 2nd edition or Ron Champions book and was started back in 2005 and only just res-erected. Despite living in a ultra dry barn this past 6 years it's gone a little rusty but it's very light surface rust which will easily vanish with it's pre powder coat shot blast.




As the Ron Champion chassis is 4" narrower the more modern Haynes roadster the rear wheels are going to stick out quite a bit.




The RX8 back end weighs around 80kg (170lbs) so I'll take everyone's advice and ditch the cradle




Fancy and incredibly light carbon fiber prop is far too long....Such a shame




The discs are huge so I'll need wheels from an RX8 to cover them. This pic shows the upper links which I'll look to restore and retain.




The bottom links I'll also keep once cleaned and painted. Anyone think I'll need or would benefit from the anti roll bar?




Some mods I'm making to increase overall stiffness. I've got quite a few ideas which I believe will make the chassis unique and super stiff.

I think it's a great project, but honestly, why not consider selling the diff/cradle for £150 which will get you a sierra LSD disc braked rear axle which would be far easier.

Otherwise you're into a world of complications, plus you'll need either hub adapters or different wheels front and rear (different stud arrangement).

I'm hoping (maybe someone can help me here) that MX5 front uprights are the same stud pattern as the RX8 and if so I'll get myself some fat RX alloys.

Regarding the complications, which I'm no doubt going to be up against, I love an engineering challenge and I'm keen to create something totally unique.

GM

Yes -

http://forum.miata.net/vb/showthread.php?t=205820

Ratio looks interesting 4.444 or 4.777 ...very high ratio....

quote:

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Originally posted by stevebubs
Ratio looks interesting 4.444 or 4.777 ...very high ratio....

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I had exactly the same, I got the complete rear end from a lsd 200sx, then looked at how much wider it was than the chassis and how much weight there was in the cradle.....in the end I decided to sell the chassis (although haven't got round to shifting it yet) and starting something new....

Not sure if it will be the same for you, but the offset of the diff and the total dimensions meant it would be utter ball ache to modify the champion chassis to fit - would also have left me a small driver seat width (which would have proved a logistical problem given the size of my ar$e)

Good luck!