AE86 IRS Conversions

[PRIMRK]

I've been looking at the prices and crunching the numbers on this one and the option between installing a g series diff or an IRS setup from a dollar point of view is comparable (the IRS is cheeper but not by much).

Now as the car I'm building will be an all round grip/drift/drag car as I want to get the use out of it the rear end has stumped me for choice.

Now IRS will camber on squat this is bad for drift/drag but can be somewhat counteracted by dialing in some positive camber to make it as close to zero as possible while on the juice. IRS also offers much less unsprung weight and the options of diffs/LSDs is nice and wide. And if I use the S13 rear setup with R33 diff and hubs I'll have a strong diff internal drum hand brake and 2 pot rears where as the g series is tough but the brake options are lacking somewhat.

At the moment I'm torn between the 2 and am slightly leaning to the IRS from an S13 using R33 diff and hubs as it can be tuned to be used for each different event to a point, I also know that there will be somewhat of disadvantage in some events depending on the set up I choose. The thing that may tip me at the end is that the IRS looks better when slammed.

Well let me know what you think and back it up with some sort of reason so I can start some sort of pro and con list.

Cheers

[Skylar]

What do you mean IRS "looks better" slammed? geometry or stance/fitment?

[PRIMRK]

Stance really, negative camber on the rears.

[johl]

what will the car be used for? live axel will be fine for 99.9% of anything a normal driver can do to a car. unless your doing a build like magicman and will be competing with it then i say go for it.

for me it is too much of a hassle for what you get in the end. i see what your saying about all the adjustability, cheap lsd, brake upgrades but it will cost more to do. the amount of time and stress involved in measuring and building the irs into the car, is way more than just dropping in an f series, throwing some r32 discs and calipers on it and driving the next day.

my 2c, but if your just doing it because you can, then why not

[slydar]

i'd suggest you stick with the live axle.

1 question i'd start with is do you have much experience with that level of fabrication? irs conversion i mean. youre talking rotiserie etc with the irs. compare that to just swapping some mounts on a diff. its 1 days work v's possibly months..

a well exceuted live axle conversion would be a lot better than the.. "average" IRS conversion. converting your live axle set up to equal 4 link will also makes big gains and its pretty easy.

there is no real shortage of G series lsds. theyre a little more expenive/harder to buy 2nd hand but you only have to buy it once.

ive spoken to 1 or 2 guys that race IP. and in their oppinion, they didnt notice the differece converting to a heavier rear axle handling/lap time wise.

G series also has the advantage of readily available ratios for 3.7 to over 5.XX.

[hachi_dk]

have you thought about a live axle set up with bent axles for rear negative camber?

[PRIMRK]

Well the cost of fabrication to get it done right has been factored in to it, ill just generally brake down the costs quickly...
For G series
Diff $700
LSD $900
Diff Mounts $400-600
Brake mounts (using R33 callipers and disks) $400-600
Total $2600 ish

S13 Rear cradle (all adjustable) with R33 diff inc. LSD and struts and tower mounts $550 (Friend smashed their S13, so chop chop and away we go)
R33 hub assembly + cables $400
Fabrication $1000-1200
Total $2000 ish

The other good thing about the IRS rear end is that it has an mechanical internal drum hand brake so I wont have to use the twin calliper hydro handbrake set-up that will cost a bit more on top (looking at another $400 for a handbrake unit)

[johl]

can you do it or do you know someone that can do this type of work accurately?

[PRIMRK]

Oh and no i personally haven't got that level of fab skill but i do have a rotisserie so i can stitch weld the car later on and will be getting my local fab guys to do the work (they are currently putting an S15 rear end into an old fiat abarth) that way i know its done right, plus they are quick, looking less than a week turn around.

I do want to compete with the car at some point down the track (though i dunno what class a 4.3lt V8 AE86 with this level of moded suspension will fit into) and don't mind forking the money out early and doing it right the first time. Ill prob do time attacks or something...its a case that i want it to be able to be used any weekend no matter what event is on so i get the most out of the car.

[PRIMRK]

I looked at this sort of set up (at least one that I believe your getting at here) and the cost was above and beyond any other options i had looked at (looking $8k for it done right)