De-Dion rear ends

[Sam_Q]

I have been looking more into the idea of setting up a De-dion rear end in my Sprinter in the distant future.

I was thinking it might be possible to recycle the trailing arms off an irs car and modify them to suit. Posibly even using the solid rear curved axle out of a FWD car to mount the two arms together, might be a stuid idea but yeah..

I want to hear about anything people know about their experiences or what they have heard with a De-dion.

[ian]

hi
the cars that i have seen with that type of suspension have been vintage cars , the de -dion type setup is old tech and very heavy , the modern irs system works very well there are some great books available on suspension setup and tuning
ian

[JustenGT8]

Why? what do you think you'll gain? what are you trying to gain?

[rob]

maybe he just likes to say de-dion

[Sam_Q]

no, its not for any emotial reasons,

I beleive it would be reasonable easy to setup compared to trying to install an irs system under my car and I would be able to have some of the advantages of irs.

The main one not being unsprung weight but instead a reasonable camber & toe setting.

[Mr Revhead]

i would say the difficulcty in installing either would be very similar
and one will be much better than the other

[thechuckster]

I've seen pics of a UK rally car that ran De-dion rear (pics were in Race magazine) - key object appears to be keeping the rear planted on the loose surface to improve grip.

edit: would this suit australian road (or our bumpy race tracks)?



drawings to save re-inventing the wheel:
http://locost7.info/files/suspension...leAssembly.pdf
as opposed to
http://locost7.info/files/suspension...RSAssembly.pdf

[amichie]

De-dion rear has excellent camber control. Same as a live axle but with greatly reduced unsprung mass. Works well on sealed roads and maybe even good for drags since no camber change on squat.

[Sam_Q]

if I was to fit any double wishbone suspension I would need to virtually chop two massive holes through my sub-frame to make it even remotely close to fit, for a strut type I would need to cut and install a complete set of strut towers so out of my reach.

Someone correct me if I am wrong but I dont need to chop any of my body to make a De-Dion setup and I might be able to do it using ghetto irs parts with a beam suporting it. Also a big advantage is I would be able to use a Torsen diff which I would like.

[oldcorollas]

i think it is not such a bad idea...
less critical points to reinforce on the body (or make new mounting points).
good camber control (much more "stiff" than IRS.. ie.. IRS has bushings with small moment arms that can affect angles more)..
less weight than live axle (hollow tube would be better than solid tube... even for same weight, the larger diameter of a thick walled tube will make it stronger in almost all situations)
more freedom for mounting points of springs and shocks...
easily adjustable angles (shim plates etc), that shouldn't go out of alignment.

downsides?
CV's..
arguably not as light as IRS (but IRS tends to have largish castings)
not independent for bump..

which has better or more favourable control of roll centres?

[amichie]

which has better or more favourable control of roll centres?

Roll centres are determined by the locating points of the panhard bar or watts links, whichever you decide to use. So you can set it up however you like.

[Ben Wilson]

I've always like the concept of the de-dion rear end. The only tricky bit I can think of is the diff mounting. IRS diffs are still subject to a fair bit of load and have to be mounted well.

[Sam_Q]

some hollow bars welded directly to the subframe should make short work of that I think, although I should have a better look how they do it factory before I comment.

Another thing I thought of is that the standard pan-hard rod would no longer fit, however it may suit a watts link very well.

Lastly anyone have any sujestions on the size of the bar between the two arms at each end? the largest cro-mo size I can get is 75 x 2.4mm which I assume is not enough

[Duk]

Stick your head under an 'Alfetta' (Alfetta sedan, Alfetta GTV, 90, 75) type Alfa Romeo to see how they did it. You might even be able to use the DeDion axle out of 1 as a starting point. How wide is the arse end track intended to be?

[Duk]

some hollow bars welded directly to the subframe should make short work of that I think, although I should have a better look how they do it factory before I comment.

Another thing I thought of is that the standard pan-hard rod would no longer fit, however it may suit a watts link very well.

Lastly anyone have any sujestions on the size of the bar between the two arms at each end? the largest cro-mo size I can get is 75 x 2.4mm which I assume is not enough

Sorry, just read this.
75 x 2.4mm would be plenty strong enough. The rear end DeDeion tube in an Alfetta chassis would be about that at it's largest diameter.
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