Just checked the search tool about how to setup my new de-dion back end, ooo-er! I'm a bit concerned about it:
- I know te camber is spot on as we made the axle off a jig,
but if I rotate the axle forwards or backwards the toe in and out adjusts. So if I make the top trailing arm shorter than the bottom I get toe in, and vice versa. Anyone got any easy solutions on how to set it up properly for the road? Cheers. Oli.

i thought if you made the top & bottom arms a different length then they would start the bind as the axle went over bumps. this would wear out your bushes over time.

i thought that to do what you want you need to have made (welded) this into the axle.

with most thing i say, there is a fair chance i'm wrong - but i'd be interested to hear why i'm wrong.

I think (not done it myself yet mind) that the idea is to set the axle up with eaual length links (as Mike says anything else will cause it to bind) and use shims on the bearing carriers (where they mount to the DeDion) to adjust for toe in/out and camber.
Camber I suppose will be a matter for testing on road/track but about 1/2 deg of toe in seems top be regarded as advantageous to handling.

Does that help any?

Cheers

Alex

[Edited on 28/4/07 by ecosse]

Would equal lengths but offset mounting points on the chassis help at all.

(Random thinking out of the box here, too hot / tired to work it out myself)

Sorry to sound a muppet but why would it cause the axle to bind? Surely it would only cause it to rotate when compressing or extending which in turn would induce toe in/out.
We welded it to a jig made from the Sierra back end so worst case scenario I'll shut up make them equal lengths and see what happens......Cheers anyhow. Oli.

My trailing arms are all the same lenght on my de-dion. as was said use shims to do the fine adjustments

As the DeDion is a bent tube rather than the straight tube you get with a conventional axle changing the trailing arm length "rolls" the axle which will change the toe. Shortening one of the links will cause the adeadion to roll as the axle raises and lowers so the toe will change as will the position of the axle. I think there is a method of using this to make the rear axle "steer" as the roll increases, this will give under-steer when the bottom link is shorter and overseer if the top link is shorter providing you get sufficient movement in the axle. IIRC!

Oli glad you have got rid of the scrap you were dragging around! did you do the engine swop as well?

caber

Still got the boat anchor in the front but the zetec is painted and on the engine stand awaiting some bits (gaskets mostly) to put it back together.
Have decided to get on with the axle this year since Mark was around to guide me and put the engine in next year as it should be a relatively simple job. Learnt a heap doing the conversion including how to use my TIG welder properly (well sort of). Can't wait to get it all back together and taxed! I thought thats what the toe in/out would do from looking at it but wanted to check. Also there should be no binding as my trailing arms are all fully rose jointed so no issues with bushes and can easily adjust the lengths etc. Gonna have a bash at it tomorow hopefully (and put the brakes back on etc....) Cheers. Oli.

What happens if you go over a single wheel bump?

As i think about it,

That wheel moves up and due to the trailing arms moves forwards.

This then will cause the axle to move around a pivot point (i'm not 100% sure where but i'd say the other side of the axles trailing arms.) This will then cause the car to steer.

It will also invoke a twisting action in the de-dion beam - i'd hope not a huge amount but i've no idea how much or what stresses that will invoke on all the other components.

(i'm determined to write it will also change the angle between the diff and the prop as thats forced to turn with the axle, but this is complete rubbish as i keep forgetting the diff is bolted to the chassis.)