Nearly finished tack welding my McSorley 7+4 chassis which I had intended fitting with a DeDion rear to Rorty’s design.
Having a small re-think and before finalising the rear end am considering whether I should go with the Rorty IRS instead but looks like it could be
somewhat more expensive, especially since I was made redundant and no longer have easy access to a fabrication shop.
What’s the general feeling? Is the IRS much more expensive to build and is it worth it for normal fast road work with perhaps a very occasional
track day?
I dont know much about DeDion but i can see how irs can be expensive, especially if your donor has it.
IF i made a car i would go dedion but i have a Indy for know with irs
Jacko
I'm building the IRS.
Not only the driving benefits but IRS is easier to make adjustable.
Grtz
de dion always gets my vote and always has done
sorry I'm still learning, I know what IRS is, but does a de dion go with a live axel?
Sorry for ignorance!
Sorry for newbe question but DeDion has the solid rear axel and IRS is independant rear suspension? just checking, it can seem like you all speak another language at times.
If you look in jroberts photo archives there is a dedion axel
jroberts sell the kits,
and its a very good quality kit also !
put one on mine at the start of the year,
no probs yet !
even my welding has held together
paul
My IRS cost a few pounds to make, its 1" tube chassis tube, 6 rose joints and 8 bushes.
The uprights are chopped 1/4" flat bent and welded to shape with the wheel bearing carrier let in and welded.
Dedion needs 8 bushes and 2 rose joints, 2" steel and fabrication of the bearing carriers so the difference is only 4 rose joints @ £4 each
although the 2" tube for a dedion will cost the extra.
So no real cost difference at all if you do it yourself.
Regards Mark
Rescued attachment NSR_suspension22Jan2005.JPG
As a mechanically challenged person, I would have gone de dion if it was an option for my frame, but I went MX5 IRS. Can't figure it out yet, so I don't know what to think. I know IRS is more adjustable, but that's just more to go wrong as far as I'm concerned. I want the car for Sunday drives and a bit of gymkhana/autocross so performance won't matter to me.
A well designed IRS can work very well, but if you are building one from scratch with little experience it's probably easier to create a poor
handling IRS system than it is to create a reasonable De-dion system.
Also if you already have a chassis designed for a live axle, the de-dion will require very little modification (primarily diff mounting brackets and
possibly strengthening of the chassis around the diff mounts). An IRS will pretty much require the back end to be cut off and rebuilt.
I came to the conclusion that De-dion is the best option for track use, and IRS for road... but both are very good if set up correctly.
As to ease of manufacture and cost I don't know!
Cheers
Dan
Hi why would the dedion be best for track use when the live axle can be used and installed so much lighter.
Yes assuming you can get an axle.
cheers matt
quote:
Originally posted by procomp
Hi why would the dedion be best for track use when the live axle can be used and installed so much lighter.
Yes assuming you can get an axle
cheers matt
) 
Hi yep if using the english axle NOT the atlas. The unsprung weight is no problem just requires dampers with the right valving to do it.
Adjusting the toe and camber on an axle is no problem. all our kits come with this done as std.
As to overall weight most setups using a sierra diff will be 25-35 kg heavier than a english axle setup.
Also back to the original question. the axles cost about £75 but installing the setup means verry little extra cost. So is also the easiest and
cheapest option. Untill you decide to go for a full disc and Lsd setup then it can get a bit more expencive but still cheaper than a IRS setup.
cheers matt
Hi Matt, didn't consider live axle, but this should compare o.k to the de-deion and is a lot simpler (but as pointed out unsprung weight needs to
be considered). But it's also not perfect, but then none of them are!
But for occasional track use, but mostly road use I would choose IRS, as you get a better ride, and use the sierra running gear... But it's down
to the individual preference!
Dan
quote:
Originally posted by MikeRJ
A well designed IRS can work very well, but if you are building one from scratch with little experience it's probably easier to create a poor handling IRS system than it is to create a reasonable De-dion system.
Also if you already have a chassis designed for a live axle, the de-dion will require very little modification (primarily diff mounting brackets and possibly strengthening of the chassis around the diff mounts). An IRS will pretty much require the back end to be cut off and rebuilt.