jon200
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| posted on 11/10/11 at 06:21 PM |
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how to change English to a DiDion axle
is there a guide anywhere on here to tell me what's needed? I think I will need to do this if I buy the Locost I'm looking at and changing
the engine. Its for strength rather than handling.
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snapper
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| posted on 11/10/11 at 06:31 PM |
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You need a DeDion tube made up with the double trailing links bracket to suit your chassis.
The Sierra drive shafts are longer than the English axle.
You will need a modified rear chassis to take the diff and will need a mount for the panard link.
The English axle is ok, the benefits of DeDion a little hard to quantify.
[Edited on 11/10/11 by snapper]
I eat to survive
I drink to forget
I breath to pi55 my ex wife off (and now my ex partner)
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Sam_68
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| posted on 11/10/11 at 06:44 PM |
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Is it for a 'book' Locost?
Have you got the 'Rorty' de Dion plans (contact me U2U with your e-mail address if not and I'll send them to you). They're not
the most elegant bit of design in the world, but they're a good starting point.
Otherwise, the main thing you will need to figure out (apart from fabrication of the de Dion tube, of course,) is how to mount the diff to the chassis
(with sufficient localised stiffening).
You're literally just over the hill from me if you live at Dursley, by the way. 
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MikeR
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| posted on 11/10/11 at 07:14 PM |
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i.ve 95% done mine. Did it escort width which in hind sight was a mistake as i need custom drive shafts - easier if you don't have to bother as
i can do welding and can't make drive shafts.
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MikeR
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| posted on 11/10/11 at 07:14 PM |
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i.ve 95% done mine. Did it escort width which in hind sight was a mistake as i need custom drive shafts - easier if you don't have to bother as
i can do welding and can't make drive shafts.
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jon200
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| posted on 11/10/11 at 07:27 PM |
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quote:
Originally posted by Sam_68
Is it for a 'book' Locost?
Have you got the 'Rorty' de Dion plans (contact me U2U with your e-mail address if not and I'll send them to you). They're not
the most elegant bit of design in the world, but they're a good starting point.
Otherwise, the main thing you will need to figure out (apart from fabrication of the de Dion tube, of course,) is how to mount the diff to the chassis
(with sufficient localised stiffening).
You're literally just over the hill from me if you live at Dursley, by the way.
well I have not bought it yet so I don't know if its a book one. Its running a mk2 escort rear setup. I will u2u you anyway if you don't
mind. Where are you?
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Sam_68
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| posted on 11/10/11 at 07:33 PM |
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OK, no problem... I guess the Rorty design will probably be a valid starting point whatever the origin of the car. Drop me your e-mail address and
I'll fire it over to you.
I'm sort of between Stinchcombe and North Nibley.
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owelly
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| posted on 11/10/11 at 07:48 PM |
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I'm hoping to get cracking with my de-dion conversion. I'm hoping to make a subframe that picks up on the original trailing arm chassis
mounts and the top coilover mounts. Some piccies here...
http://m56.photobucket.com/albums/moshty/LSRalfa/de-dion
http://www.ppcmag.co.uk
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Thinking about it
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| posted on 11/10/11 at 08:34 PM |
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I have an Escort width De Dion going spare. U2U me if you are interested. I travel regular past your way.
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jon200
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| posted on 11/10/11 at 09:18 PM |
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quote:
Originally posted by Thinking about it
I have an Escort width De Dion going spare. U2U me if you are interested. I travel regular past your way.
When i get the car i will look you up and see if you still have it. I think i'm going to take the plunge and get the one i have looked at. I
just keep finding other things that need to be bought too. Like Doors and windows for the house!
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Thinking about it
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| posted on 11/10/11 at 09:24 PM |
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The house will always need work, plenty chances to do work on the house.
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MikeRJ
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| posted on 11/10/11 at 09:55 PM |
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quote:
Originally posted by snapper
The English axle is ok, the benefits of DeDion a little hard to quantify.
The English axle is great for smaller engines. It's much easier to justify the De-dion as an upgrade if you have an English axle fitted and
want something that will take 300bhp reliably.
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owelly
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| posted on 11/10/11 at 10:08 PM |
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I popped two English axles so fitted an Atlas. Now I need an LSD so got one from a Sierra 4x4. That's the only reason I'm changing to
De-dion!
http://www.ppcmag.co.uk
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jon200
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| posted on 11/10/11 at 11:05 PM |
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quote:
Originally posted by MikeRJ
quote:
Originally posted by snapper
The English axle is ok, the benefits of DeDion a little hard to quantify.
The English axle is great for smaller engines. It's much easier to justify the De-dion as an upgrade if you have an English axle fitted and
want something that will take 300bhp reliably.
This is what i am hoping for really so it would make sense to go for it. Does it take much calculation for the geometry of it all?
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owelly
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| posted on 11/10/11 at 11:19 PM |
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Just copy the original trailing arms onto the de-dion and decide what you want to use to stop the sideways movement. Panhard rod would be the simplest
but I'm aiming at a Watts linkage. Looked at a Mumford link but it made my head hurt. Thats the geometry sorted, you just need to mount the diff
now!
http://www.ppcmag.co.uk
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jon200
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| posted on 12/10/11 at 01:04 AM |
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You make it seem so easy
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MikeRJ
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| posted on 12/10/11 at 07:29 AM |
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It depends on weather you buy the de-dion axle itself or make your own. If you decide to DIY, then obviously it has to be made accurately or you will
end up with the wheels pointing in different directions! Minor adjustments can be made by shimming the bearing carriers, but it needs to be pretty
close to right to start with.
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jon200
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| posted on 13/10/11 at 07:04 PM |
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I guess it will be a case of seeing what's available at the time really. I am a pretty good welder but not coded, would I need someone else to
weld it up?
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Bare
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| posted on 16/10/11 at 04:39 PM |
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Be careful in what you wish for.
An "imperfectly' setup D Dion (most) will add rear wheel steering... when you want it least.
IMO it's either: a live axle OR a Decent IRS.
A Volvo live axle will be surprisingly strong, but heavy, if that helps
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MikeRJ
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| posted on 17/10/11 at 11:01 AM |
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quote:
Originally posted by Bare
Be careful in what you wish for.
An "imperfectly' setup D Dion (most) will add rear wheel steering... when you want it least.
IMO it's either: a live axle OR a Decent IRS.
A Volvo live axle will be surprisingly strong, but heavy, if that helps
Imperfectly configured live axles and some IRS designs can give undesired rear wheel steering...
[Edited on 17/10/11 by MikeRJ]
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owelly
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| posted on 17/10/11 at 11:19 AM |
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As I'm currently making bits for my conversion, I'd like to know how the de-dion can cause this rear wheel steering. The de-dion uses the
same geometry as the live axle.
http://www.ppcmag.co.uk
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Sam_68
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| posted on 17/10/11 at 05:35 PM |
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quote:
Originally posted by owelly
As I'm currently making bits for my conversion, I'd like to know how the de-dion can cause this rear wheel steering. The de-dion uses the
same geometry as the live axle.
I'm assuming that what Bare means is that it's quite possible to fabricate the de Dion tube itself so that it isn't quite
'true' and so gives unequal or unintended toe/camber to the rear wheels. Depending on the design, it's also possible that the
location brackets will be more difficult to accurately line-up on a de Dion (you're potentially welding trailing arm brackets to a
curved/cranked tube, instead of a straight axle, depending on the design), so that you end up with everything being a bit cock-eyed and
skew-whiff.
As MikeRJ and yourself point out, that's a slightly different issue from imperfect geometry to the locating members, which can be equally
problematical for live axles and de Dions.
Yes, de Dions need greater care than a live axle in jigging/fabrication accuracy, but on the other hand they are more adjustable: if you design them
right, it's easy enough to allow adjustment of camber and toe by shims/spacers.
Live axles are seldom perfectly true (and if they are, will be giving you less-than-desirable parallel toe and zero camber). They are a bugger
to adjust for camber and toe... it can be done - by 'heat stretching' the axle tubes with a blowtorch - but only to a limited extent and
it takes some skill and perseverance, so most people don't bother.
...and unsprung weight is a big issue for a car as light as a Seven, so there's good justification for using one on those grounds alone,
particualrly if the engine is so powerful that it demands a 'heavy duty' drivetrain.
Jon200... did you get my e-mail of the Rorty drawings, by the way?
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jon200
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| posted on 17/10/11 at 06:06 PM |
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Sam, yes I did get them, I had a quick look at work but that's as far as it went at the moment. The drawings are really detailed, would be easy
to get all the bits made at work thanks for that.
did you mean the DiDion is better for unsprung weight?
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Sam_68
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| posted on 17/10/11 at 06:25 PM |
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quote:
Originally posted by jon200
did you mean the DiDion is better for unsprung weight?
Yes, absolutely - the weight of the diff and half of the weight of the half-shafts is carried by the sprung mass, so if you design it right a
de Dion has a much more favourable sprung:unsprung weight ratio.
You can also mount the brakes inboard with a de Dion, if you want (though it makes brake cooling a consideration and is a bit more complicated to
arrange), which results both in another big reduction in unsprung weight and means that your axle location doesn't need to deal with braking
torque reactions
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jon200
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| posted on 17/10/11 at 07:26 PM |
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quote:
Originally posted by Sam_68
quote:
Originally posted by jon200
did you mean the DiDion is better for unsprung weight?
Yes, absolutely - the weight of the diff and half of the weight of the half-shafts is carried by the sprung mass, so if you design it right a
de Dion has a much more favourable sprung:unsprung weight ratio.
You can also mount the brakes inboard with a de Dion, if you want (though it makes brake cooling a consideration and is a bit more complicated to
arrange), which results both in another big reduction in unsprung weight and means that your axle location doesn't need to deal with braking
torque reactions
that's a good point about the brakes on the diff, that would save a lot of mass. Will have to have a look into it
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