The rear end of my Magenta LSR is crap. It's currently running a standard Capri Atlas on trailing arms with a Panhard rod.

I've bought a Sierra LSD and cobbled together a De-dion. I've just spotted Rortys design and mine doesn't look too wrong but what do you folks think??




And the reason for using the Diahatsu calipers......


To fit inside a 13" wheel.


I havn't welded the trailing arm brackets on yet as I intend using the brackets on the forward (car body) end to fix the subframe to hang the diff off as there is no steel work rear of them!! I'll then move the trailing arms out a bit.

i voted to fit urs!

but wouldnt it be better to just use one piece of bar with a bend in it rather than 3 welded together?

The only thin walled tube I had was 3" and I couldn't bend it!

couldn you get a local engineering firm to bend it for you i cant see it costing much?

Costing much?? Have you seen the car?? A fiver would be more than it's worth!!
Did I mention I'm a tight arsed Yorkshireman?!

lol so am i but if u went on a weekend to an engeering company when gaffers arnt in im sure a lad would do it you 4 £5 or £10 max

i have just finished mine and it looks remarkably simar to yours.
I also have it in 3 sections. Almost looks like a copy.

should be strong enough.

I have used a small shim on one side to align it just right.

i thought the aim was to save unsprung weight ?

could have cut a 340 one up, there about a fiver from the scrappys .

That looks fine, I'd just go with it although I'd be tempted to grind down the joints between the centre of the axle tube and the two angled pieces and weld over the existing joint with some 3mm plate to act as load spreaders. Just takes a bit of the reliance away from the single welded joints.

The only other thing you might have difficulty with is fitting a panhard rod because of the angle it would have to run at longitudinally to get around the longitudinal depth of your axle. Easy solution would be to build a watts linkage instead which is technically better than a panhard rod anyway. If you do decide to use a panhard rod then remember it needs to be as long as possible and should be parallel to the ground at ride height.

Watts linkage in Wikipedia:
http://en.wikipedia.org/wiki/Watt's_linkage

Good luck!
Craig.

[Edited on 23/7/2009 by craig1410]

Cheers folks. I'll go with the majority and fit the thing I've made!

I was intending to fit a Watts linkage and I've already welded a plate to the back of the tube to fit it. The welds that are on there are far stronger than the rest of the car so I'm happy that they'll outlast the car!!

The set-up is light enough to lift with one hand and that's including the brakes and discs. The diff will add more weight but I'm sure the whole lot will weigh less than the Volvo axle. If I'd had a Volvo axle in my shed, I would have fitted that as I'm prone to use whatever I have close to hand!!

Cheers folks!

Just a quick update as I've had a few minutes here and there...
De-dion and subframe made to locate on existing trailing arm mounts, fitted with diff, shafts, brakes etc, and the coilovers balanced on top to get an idea of the weight...


It comes in at 105kg. I can lose a bit more weight by making a lighter Watts pivot and using thinner walled tube for the subframe, but I used whatever I had kicking about the garage.

The Atlas I took out weighs 80kg, including drums, coilovers, backplates, etc. So a 25kg increase in weight, but a lot less unsprung weight, disc brakes and an LSD.

And yes, it has only taken me three years to get around to finishing this.....

that looks quite neat

That's about what I reckon mine will end up weighing, although mine is a narrowed Caterham version, so has a straight tube. The only difference is that mine is in a Sprite will extend the tunnel to mount the diff.

Rather than using a panhard rod, would it be any better to use the trailing arms angled outwards to provide lateral location? It would mean making new ones though, and I'm not 100% sure if you'd have space at the outer edges of the tube to mount them.

The problem with triangulating the set-up using the trailing arms is that the beam becomes over-located. When cornering, the axle would be in a twisting force. It wouldn't be a problem if there was a sliding joint in the de-dion.....

quote:

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Originally posted by owelly
The problem with triangulating the set-up using the trailing arms is that the beam becomes over-located. When cornering, the axle would be in a twisting force. It wouldn't be a problem if there was a sliding joint in the de-dion.....

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I did think of making a single centre mounted A-frame type thing to mount of the subframe to the de-dion but that may be for a future developement...

That's exactly how mine works, being a Caterham set up. In my case, the lower A arm is parallel at what should be ride height, so despite sticking down a fair bit, it's still level with the sills.

How heavy is your main tube? I can pick mine up with just my little finger, but I've obviously got all the diff, shafts and hubs to add as yet and they're most of the weight.

My plain tube with flanges and brackets, but no hubs, brakes, arms etc weighs about 6kg. Its very light!

I preferred it going up the 1/4 in a clown car stylee myself

It's strange you should say that Froggy, I dissapponted a few folks by not taking the Tupperware Turd to Santa Pod yesterday. They all wanted to see my crap car jumping up the strip....

What you really need is a clown wig and red nose for Mallory park next month .

quote:

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Originally posted by froggy
What you really need is a clown wig and red nose for Mallory park next month .

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Maybe this isn't the right place to ask but what actually is the advantage of a De Dion axle over full Sierra IRS? To me, it looks like it adds weight unnecessarily or is it just an easier way of going from a rigid axle without fitting wishbones?

Thanks.

Discussed here: http://www.locostbuilders.co.uk/viewthread.php?tid=14769

I was on my way to buy steel to convert my car to IRS when I found an old steel lamp post at the side of the road, so I used it to make the De-dion tube. That is why I chose De-dion......

I presume the de-dion relies on the diff been located solidly to stop any sideways movement? And the rear of the diff is held in place by the box section running rearward from the cross pieces at the front? What about adding 2 triangular cross braces from the box sections near the rear of the diff out towards where the trailing arms mount? Might add some strength for that high G cornering

quote:

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Originally posted by Nickp
I presume the de-dion relies on the diff been located solidly to stop any sideways movement?

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Mike, Nick was referring specifically to my set-up.
Nick, feck-off.........

quote:

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Originally posted by owelly
Mike, Nick was referring specifically to my set-up.
Nick, feck-off.........

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In fact, can't your mate Rob do it for you if you can't manage?

From this piccy, you'll see the diagonal bits bracing the diff to the front of the frame which has lower brackets that bolt to the chassis.

The diff housing holds the rearward tubes rigid enough to hold the Watts link solid. Or put another way; there are plenty more things to break before the axle gets loose.
I've got Super Rob on the books as a consultant. The Magenta he had, had a supercharged V16 Mirrlees engine in it and he made the rear axle out of pubes.

[Edited on 3/4/12 by owelly]

As long as you're sure it's strong enough mate, I'd hate to say I told you so.

Btw- did Robs Magenta 'crab' down the road?

It didn't suffer from crabs, but handled like a bag of watch springs..

Nothing wrong with my mate,get it on!

Rich

I was thinking something like this-



There'll be a lot of sideways force at the rear of the diff / carrier when cornering and it's got to help IMHO. I know you'd probably have to nick some more red-lead but I'm sure you can manage that mate

I had thought of a few extra bits of triangulation but I'm pretty sure the frame will be strong enough. If there's any signs of bending, I can soon flop out the MIG.