Just to show that my Spit6 project isn't dead...

"BiTurbo228 - Dr Frankenstein of Spitfires" (biturbo228) 07/10/2017 at 07:36 • Filed to: spit6

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Inbetween fixing up the bike (whenever i’ve run out of money for the next step) I’ve been chipping away at this. It’s a mock rear spring so i can weld the suspension mounts to the chassis in the right position. Lots of fiddly measurements here but it seems pretty true to me :)

BvdV - The Dutch Engineer > BiTurbo228 - Dr Frankenstein of Spitfires 07/10/2017 at 07:47

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Didn’t know the spit has a transverse leaf rear suspension, so it is basically a Corvette! ;)

Good job though, you’re getting ever closer to mounting the rear suspension!

BiTurbo228 - Dr Frankenstein of Spitfires > BvdV - The Dutch Engineer 07/10/2017 at 08:38

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It is! Except I think the Corvette has the leaf mounted on the underside as the lower wishbone and uses the halfshaft as the upper link (like the Jaguar IRS). At least the older ones do.

I actually really rather like suspension designs that do clever stuff with dual-use components. The Corvette’s a great example of that. Other cool ones are the Lotus Europa which uses the halfshaft as a suspension link and the TR7 which uses the ARB as the front link of the lower wishbone on the front suspension :)

BvdV - The Dutch Engineer > BiTurbo228 - Dr Frankenstein of Spitfires 07/10/2017 at 09:01

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Well, almost the same then..

Yeah, those suspension designs are neat, making the suspension more complicated, but at the same time less complicated.

someassemblyrequired > BiTurbo228 - Dr Frankenstein of Spitfires 07/10/2017 at 09:28

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Wow, I thought the 6 swap was pretty much a bolt in affair with some front suspension tweaks to accommodate the extra weight. Didn’t realize it was so involved.

Trevor Slattery, ACTOR > someassemblyrequired 07/10/2017 at 09:31

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It is. My man here is taking things to another level.

You can just swap in the Triumph 6, but hangs WAY out over the front axle. Kills the handling.

The rear suspension is a known weak spot in these cars, hence the work he is doing. Again, dude is going way over the top on this one.

BiTurbo228 - Dr Frankenstein of Spitfires > BvdV - The Dutch Engineer 07/10/2017 at 10:20

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Yeah they are neat :) little engineering easter eggs that while they might not necessarily make things better beyond cost savings are still neat little bits of engineering imagination :)

BiTurbo228 - Dr Frankenstein of Spitfires > Trevor Slattery, ACTOR 07/10/2017 at 10:21

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Haha thanks man ;) ‘way over the top’ is probably accurate seeing as it started as a rolling resto 5 years ago and still isn’t done!

Trevor Slattery, ACTOR > BiTurbo228 - Dr Frankenstein of Spitfires 07/10/2017 at 10:27

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I got mad respect for your vision bro.

BvdV - The Dutch Engineer > BiTurbo228 - Dr Frankenstein of Spitfires 07/10/2017 at 10:28

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I’m all for engineering imagination, and seeing your work, I’m sure you are too

BiTurbo228 - Dr Frankenstein of Spitfires > someassemblyrequired 07/10/2017 at 10:32

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Yeah it is basically. As a bare minimum you need to swap over the suspension turrets, radiator, engine, gearbox, propshaft, bonnet, and probably front springs from a GT6 and you’re away.

That’s fine for a cruiser, but once you start pushing it the deficiencies start to show. Just the above will get you ~57% front and swing axle rear suspension. TBH you could swap to a rotoflex rear, fit a fibreglass hardtop and stick the battery in the boot and get to 80% of what I’m doing. That’d get you ~54% front and what amounts to a double wishbone at the back).

It’s that last 20% that takes all the work! Yes you’re at 54% front, but you’re also at nearly 800kg. Also, that rotoflex rear end is ok but has some slightly iffy bump-steer characteristics (not nearly as much as an E30 though I might add!). Plus, it’s a lot of unsprung mass and the chassis’ still a bit floppy.

So, body’s been welded to the chassis to make it essentially a monocoque (no-one’s been able to come up with an adequate reason why it’s not!), with a welded on hardtop and a roll hoop for stiffness. What you see above is the last few stages in my custom lower wishbones which should sort bump steer, provide a better camber curve (by dint of being longer and at a less steeply raked angle than the rotoflex), be adjustable for camber and toe, and be lighter to boot! Add to that some pretty thorough lightweighting (as in I’ve run out of ideas of stuff I can remove/affordably change to alloy or fibreglass/cut holes in) and I should be at about 750kg and 54% front despite all of the metal I’ve added in with the roof, roll hoop and plating in the chassis :)

So yeah, making it far more involved than it actually needs to be!

BiTurbo228 - Dr Frankenstein of Spitfires > Trevor Slattery, ACTOR 07/10/2017 at 10:47

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Thanks man :) comments like yours definitely help the enthusiasm for getting it done! Need to get this motorbike sorted ASAP then I can crack on with it :)