Minicooper
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| posted on 3/4/05 at 05:31 PM |
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De Dion
Hello All,
What are the pro and cons of a de dion setup as opposed to the wishone IRS setup also what do you do for camber or toe in adjustment.
does the GTS De Dion come with any camber, toe in built in
Cheers
David
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craig1410
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| posted on 3/4/05 at 08:32 PM |
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Hi,
This has been covered in great detail many times on this forum. I've certainly taken part in a few debates so try searching for posts in the
last 18 months by me using keyword de-dion.
You can effect camber and toe adjustments using shims between the axle and hub carrier. You don't need much of a shim to give the desired
effect. However, bear in mind that one of the key benefits of de-dion is very good camber control where the wheels remain perpendicular to the road
regardless of suspension squat or body roll. You therefore don't need so much static camber than you might require with IRS for example.
Toe-in is, in my opinion, worthwhile having to some degree to stabilise the back end when powering out of corners. The weight transfer to the outside
wheel will cause it to "steer" the back end in a bit which counteracts any tendency towards power oversteer. Of course you don't
want to completely eliminate power oversteer... 
Quick summary of benefits of de-dion: Good camber control, low unsprung weight, simple, easy to adapt book Locost to de-dion, easier to set up than
IRS.
Hope this helps,
Craig.
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ChrisGamlin
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| posted on 4/4/05 at 09:38 AM |
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Out of interest, does anyone have some real world costs of how much it would be to convert a live axle book chassis to de-dion, including buying the
de-dion axle and diff, modding driveshafts, hubs, brakes etc?
cheers
Chris
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craig1410
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| posted on 4/4/05 at 11:58 AM |
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Chris,
This depends very much on whether you are talking about buying brand new bits (diff etc.) or getting them off an old Sierra as per Locost
tradition.
I got my Diff (non-LSD), brakes, shafts, hubs and hub carriers for free when I got my de-dion axle kit from a fellow Locost'er. I think it cost
me something like £80 for the lot.
Also, depending on your setup, you may be able to use the existing trailing arms and panhard rod but it depends in the lengths being compatible of
course.
Changes to the chassis are minimal and GTS Tuning supply a PDF document detailing the required changes for their axle. I'm using an old MK
Engineering designed de-dion axle and I have not had to make any changes to my chassis beyond moving my trailing arms inboard 2" each side due
to the fact the de-dion axle I bought was designed for a book Locost and mine is a McSorley 7+4" wider chassis.
I would point out that you may have trouble using a "book" petrol tank with a de-dion axle (not sure about the GTS setup) to clear the
panhard rod which on my car is a bit farther back than on a book locost. This is not a big deal and just needs a slightly different shape of tank. The
other thing to consider is that the Sierra rear disc brakes will not fit inside 13" wheels. You will either need to get the running gear from a
drum braked sierra or use 14" or 15" wheels.
In summary, I would say that going the de-dion route right from the start of your build is probably no more expensive than live axle and you should
find it easier to find second hand sierra bits than escort bits nowadays. However, to convert a working live-axle car over to de-dion is less
compelling in my view unless you have a specific reason.
[Should have said, the driveshafts don't always need to be modded because my kit uses full length shafts as does the GTS de-dion kit as far as I
am aware]
Hope this helps,
Craig.
[Edited on 4/4/2005 by craig1410]
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ned
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| posted on 4/4/05 at 12:30 PM |
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the dedion axle is around £150, then as said anything from £25 (what i paid for my disc braked open dif sierra rear end a couple of years back) to
about £150 for a 4x4 lsd based disc brake back end from an expensive scrappy.
problems i expect you would face would be finding a suitable dif ratio (sierra diesels are getting expensive on ebay!) and the weight which i expect
would be greater than your current live axle. unsprung would of course be lower, but overall i think it would be a heavier setup.
A book fuel tank does not fit darren's conversion as I bought one from it but had to return it as it fowled the panhard rod. I had one made to
my own dimensions which makes quite a small capacity tank (read: should have made it a bit taller) i can let you know the size i used if you like.
Only other consideration, I'm not sure if the sierra dif flange will be the same as your current prop uses, so expect to have to have the end of
your prop changed (you've probably only just had this done for the r1?)
I'm in guildford, and the car should be back from the powder coaters i a couple of weeks, so you can come and see how i've done mine if
you'd like...
Ned.
beware, I've got yellow skin
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ChrisGamlin
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| posted on 4/4/05 at 12:32 PM |
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Thanks for that. I would imagine that for a book width Locost you'd need modded driveshafts the same as Westfield need for the IRS setup,
otherwise they would be too wide? Interesting what you say about the rear calipers - again isnt that what Westfield use on theirs? 13" fit fine
over those.
The tank isnt an issue as Im thinking about putting the tank inside the rollhoop stays above the diff anyway, to give it more protection in the event
of a rear end crash (if Darren gets back to me with measurements of his plastic tanks.........).
The only compelling reason I may have is that the English diff isnt as strong as the Sierra one, and once I convert to the R1 if I have too many diff
problems I might consider the change. It would have to be vital though as Ive currently got a Quaife ATB for my live setup, so would would cost more
to replicate that setup (although I could go for a normal Sierra LSD)
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ned
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| posted on 4/4/05 at 12:51 PM |
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i'm sure you remember that jasper ran with massive (2" each side or something) spacers on the back of his car to fill the wide wings he
had, so I'm sceptical that the track difference would cause much problem (maybe a good excuse for a wide track conversion aswell?!). stuart
taylor or luego can probably supply cut down/sleeved sierra shafts (don't know price), or NS Dev's contact GB engineering can make custom
shafts for £70 a side i believe.
re: the rear calipers I have 'heard' 13" rims don't fit as standard, but i've also 'heard' that if you
modify/bend the handbrake cable return spring or something that they can be made to fit...
Ned.
beware, I've got yellow skin
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craig1410
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| posted on 4/4/05 at 10:12 PM |
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Re driveshafts, I understand that the GTS Tuning car uses full length driveshafts on a book width chassis by running wider arches.
As for 13" wheels, I can personally confirm that the sierra discs and calipers will not fit inside 13" Capri Laser four spoke alloys
because I flogged mine after they wouldn't fit. To be honest the disc itself would barely fit, never mind the caliper!
I currently have 14" Sierra steel wheels on the car for moving it around and looking through the spokes there is not much room and I don't
think that "every" 14" alloy wheel would fit. I think they would have to be quite a neat and tidy (and usually more expensive) type of
alloy or split rims to give enough clearance for the calipers. I'm going for 15" wheels just to be sure.
On my fuel tank (designed in fact by one of the guys on the forum here and made by another) it has a slightly different cross section to accommodate
the panhard rod without losing too much capacity. I'll post a pic in a minute if I can find one. My tank will be about 8 gallons which should be
fine.
Cheers,
Craig.
 
Fuel Tank Profile
[Edited on 4/4/2005 by craig1410]
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ned
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| posted on 4/4/05 at 11:14 PM |
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hope you don't mind me saying craig, but that looks like its gonna be a bit top heavy, hope you've got good straps!
Ned.
beware, I've got yellow skin
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