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Agreed, I spent many years testing "twist beam" axles V beam is stressed torsionally, any lightening holes, slots will create a stress raisers and possibly induce fatigue failures, would advise to look elsewhere, away from the V beam;) .Quote:
Originally Posted by Stuart
Use to work for a company that made axles for Ford Fiesta, Escort, more recently Current Honda Civic;)
A few extracts from the MSA's 'Hillclimb and Sprint' regulations, which I need to comply with;Quote:
Originally Posted by mowgli
12.4.1 The chassis or unitary construction must remain to the manufacturer's original specification in construction and material withon the wheel hub centres. Re-positioning of suspension pick-up points and engine mountings are permitted.
12.8.2 The original type of suspension must be maintained (e.g. twin wishbone set-up cannot replace a single wishbone suspension; a sliding pillar cannot be replaced by a MacPherson strut; a trailing link cannot be replaced by wishbones or coaxial springing).
12.8.3 A live rear axle may not be replaced by an independent system or De Dion.
12.8.5 Suspension pick-up point positions may be altered, providing the suspension system is maintained as being the original type.
i'm not sure how much weight could be saved & still keep some sort of strength in it, but if you are up against minis , i'd put money on the fact that their rear subframe has been replaced by some amazingly flimsy beam axle.
i reckon you could make something out of round tube, but i'm really not sure how you'd keep the rear camber fixed.
what does a standard beam weigh??
Yes, the quick Minis all use a beam axle, some of them are using titanium;Quote:
Originally Posted by mowgli
http://www.force-racing.co.uk/rear-suspension/
If I remember rightly the Nova rear beam, once stripped of anti-roll bar and stub axles, weighs about 13kg, so there probably isn't a lot of scope for dramatic lightening.
In view of what people have said about the twisting forces, I'm inclined to go with my original plan and just take off the excess brackets and non-structural metal to be on the safe side.
Much as I would like to fabricate a BTCC-style multi-adjustable set-up, it might be a cost too far!
is the actual rear suspension setup working to your liking? cos it might be a case of working with what you've got, as the mini rear beams are probably 2 grand all in, and thats a lot of money for maybe 5-8kg gains.
with the amount of stuff you've got i would say experiment. having the proper anti roll bar screams out to me you should try "weakening/lightening" one alot just to see what its like
i've rebuilt bike calipers before, had a gsxr with 6 pots on, the calipers split in halp with only o-rings to seal them where the flid passes from side to side. could you not get a spacer made to go in the centre of the caliper in that gap to widen them up to fit car discs? cant see why this wouldnt work. mine had standard tociko 6 pots on but i've seen a few track bikes with pretech calipers fitted, these thinks are fookin awesome on bikes and lighter than stock.Quote:
Originally Posted by novarally
http://cgi.ebay.co.uk/Honda-CBR-900-...item3a5f8843a9
Thanks Alan, that's very useful information. I haven't heard of Pretech before, but I shall do some investigation.Quote:
Originally Posted by AlanH
Rather than spacing the caliper to fit a car disc, the plan is to machine a steel disc to suit the caliper. The disc can be replaced frequently if that proves necessary.
Alternatively I need to look into whether there's a way of mounting a suitable sized motorcycle disc onto a bell to suit a car hub......
colin. you could go the other way, and actually cut material from the pad & leave the disc intact... for the miles you do in a season, i think they'd last quite well
Fair point, thanks.Quote:
Originally Posted by mowgli
I'm still tempted to get a thin disc machined though, just to save the weight.