can this be done? Like havinging the 2 bars on each side, or does it have to be A-arms? does the motion of the axles need to be able to swing in an arc? if anyone can direct me to some info on seting up IRS it would be much appreciated. How much does the chassis rear end get changed around to support the IRS?

I started planning on using a solid rear axle and came across an IRS. SO, I am using a Mercury Merkur IRS rear end which I believe is similar to the British Escort. I am using upper and lower A-arms with a coil over. I will look for a photo and post it.

Not the Escort, but the Sierra.

each rear hub/upright would ideally have 3 attachment points. Less than 3 and the rear wheel would be free to steer itself, and with 4 it would be harder to connect it all (if anything was distorted etc) and you would have no adjustment.

As a minimum i would want to be able to adjust rear camber and toe. To this end i would rose joint it. It allows you to be more fliexible when assembling it all. If you only used bushes you would have to calculate the precise length for every component, and any errors would not be correctable.

I guess most people have two joints to the bottom of the rear upright to keep weight low. The one at the top just controls camber then.

[Edited on 19/11/06 by JoelP]

D'you want to do IRS with a fixed diff and open driveshafts or adapt an existing 'live' (solid) axle?
If your intended route is the latter you'll need five links, two each side (typically trailing arms) to allow the axle to move up and down and either a Panhard rod, fixed to the body one side and the axle the other, or a Watts linkage/woblink to control sideways movement.
If your looking at double wishbone/A arm IRS you might be re-inventing the wheel if you don't refer to one of the many tomes already in print with details of how to build such a system.
More information as to intentions required pliz!

i've asked almost the same q a while a go.

I am making the lower wishbone like the tiger avon.
The upright like rorty
Only difference is that my upright will have two brackets at the top.

One for the rosejoint 16 mm and one for the coil-over.

So i can adjust toe, camber.

I''ve made the bracket 50 mm and the bushes 32 mm. This gives me some adjustment for wheelbase.

At the front also this gives the possiblity to give more or less camber.

look in photo-archive -> running-gear

[Edited on 19/11/06 by t.j.]

Sorry about that, the Sierra. I have heim joints connecting the lower a-arms. I don't know if this is right but that's what I did.
I have an old timer that I have been bouncing my ideas off of. He owns an alignment shop and also builds circle track cars. I have to trust someone so if he agrees with my idea, then I build it. It took me four times building front A arms before he was satisfied. All this did was frustrate me but hopefully it will all work out.

Only thing against it is that you are building squares, a thin diagonal would rectify this.

ok i was looking at it all, i am thinking i wanna do IRS cuz its easier for me to source parts. I just dont wanna mess up the design and have a crap setup. I want it to be adjustable for camber and maybe toe. I am pretty much getting my parts from a MkIII supra. I wanted IRS also to make the tranny tunnel where the drive shaft is to take less room.

For full location Each wheel needs 5 locating links --- a wishbone (aka A arm) counts as 2 converging links.