IRS Knuckles, diff w/ LSD?

What is the defacto, cheap junkyard knuckle and aluminum cased LSD for people making their own IRS?

I am looking for strong, light parts that are cheap and plentiful in junkyards. Good choices in available gearing would be swell in a diff too. I am thinking that the diff and knuckles from a C4 vette would be strong and available as well as the 944/911 knuckles, etc... maybe even the front knuckles from an Evo/Subie/Audi but I am in uncharted territory as far as my own experience goes. I'd hate to design around a $10 knuckle to find the axle spline requires a $500 axle... that I then have to narrow.

Power levels are under 350hp, 350ft/lbs. Car will be 2000lbs.

Ford MN12 Rear 7.5" or 8.8" IRS 8.8" also found in the late model Explorer in IRS fashion. LSD are available from a multitude of vehicles.

T-birds will be the cheapest. I've seen DDs as cheap as $500-$700, so I'd imagine the whole rear subframe should be pretty cheap at the junkyard.

RossD wrote: Ford MN12 Rear 7.5" or 8.8" IRS 8.8" also found in the late model Explorer in IRS fashion. LSD are available from a multitude of vehicles. T-birds will be the cheapest. I've seen DDs as cheap as $500-$700, so I'd imagine the whole rear subframe should be pretty cheap at the junkyard.

Is the 7.5 or 8.8 an aluminum case? Do they have the same gearset selections at similar prices to the 9" stuff?

I don't have much exp. with Fords at all but - the junkyards are brimming with Explorers, I should be able to snag the whole setup from a pick -n- pull pretty cheaply.

What's the diff Subaru/Datsun/Nissan uses? The R180?

8.8 in the Cobra is Al, and the late model Exploders is Al. I've narrowed it down to either a Ford 7.5 or an E30 rear to get a short pinion, and in the range of ratios with some form of LSD I'm looking for, and a challenge friendly price. I thought one might be able to find surplus Hummer diffs like you can with the wheels/tires/lights and what have you, but that doesn't seem to be the case.

Copy and pasted from my "Delusional GRM 201X Drivetrain" notes:
- Ford 7.5" 2.73:1 3.08:1 (Track Lock LSD avalible)
- BMW E30 325e/es 2.79:1 2.93:1 (LSD option on e, LSD on es)
- Hummer H1 2.56:1 2.73:1 3.08:1 (Torsen LSD or Locker)

Those aren't the only ratios available, just ones I'm interested in.

I remember comparing the 7.5 to the 8.8, and both to the Al 8.8. The 7.5 wins on price, and the Al 8.8 doesn't save enough weight to justify the price premium in my book.

• Lee

T-birds are the cheapest, but are iron case diffs, Lee listed the aluminum ones. I would use the T-bird diff, the weight isn't that much different and at least it is on the right end of the car, help balance out front end weight. Plus the iron diff case is stronger, not that it would matter in a 2000 lb car. Heck the 7.5 could handle that reasonably well, unless you are going to really abuse it.

Ford Performance parts has the hubs that attach to the t-birds spindles so you can run standard mustang bolt pattern wheels.

http://www.fordracingparts.com/parts/part_details.asp?PartKeyField=8397

I'm not sure about the swapability of the 'sploder spindles/hubs and t-bird axles or even if you'd want to use the spleder's spindles, but at least it has the normal 5x4.5 pattern hub.

Here's a great site for finding stuff out about axles. Sometimes geared* towards trucks but works just as well for cars: http://www.ringpinion.com/PartsList.aspx?SearchMode=Diff&TypeID=4&DiffID=165&Diff=Ford+8.8%22+IRS+Passenger+Car+28+Spline&CatID=35&Category=Ring+%26+Pinion+Sets

*pun intended!

http://cgi.ebay.com/ebaymotors/Ultimate-BMW-E30-Street-Machine-Turbo-S52-Tubbed-Corvette-Rear-Runs-10s-/250895928836?pt=US_Cars_Trucks&hash=item3a6a900e04

Look at his build threads, C4 I believe.

Mark 8s have the same rear suspension setup as the MN12 T-Bird and Cougar, but use an aluminum 8.8 housing, and aluminum lower control arms as well. Even if you don't want to use the control arms, you can sell them to a T-Bird/Cougar owner to recoup some of the cost.

Mark 8s all had 3.08 open diffs, but any gear and diff combo you can think of is available and will fit. I have a Mark 8 case w/Truetrac diff and 3.27s in my Supercoupe.

there are almost as many gear ratios available for a Ford 8.8 as there are for a Ford 9".. and i think there are quite a lot of different ratios and diffs out there for the little 7.5, as well.

Don't know the ratios, or if there's a LSD for them, but I've seen the underside of a lot of Muranos and Rouges since I started writing service for a Nissan dealer. Both the AWD Murano and Rouge have a compact Aluminum rear end, and it's got a trailing arm/A-arm hybrid-ish rear suspension, the upper arms are Aluminum too.

Random, I know, but I saw another one today and instantly thought of this thread.

• Lee