Rat Rodding a Subaru IRS

[1951sms]

  I've got a 1984 GL 4WD Station Wagon. Thinking about using the IRS in a 1929 Ford Hot Rod with a V8 with 300 HP. How long do you think it would last?

[987687]

You want to use the r160 and subaru rear axles with 300hp? hahaha It'll last until the first time you hit the skinny pedal. There are other higher hp cars with IRS I'd go after.

[suprjohn]

You might make it around the block. 

 

If it were me, I'd look for a '90's t-bird rear end, or the rear end out of a vette, or an'80's jaguar, or any number of others. 

 

Just my opinion, your actual mileage may vary. 

 

John

[1951sms]

You might make it around the block. 

 

If it were me, I'd look for a '90's t-bird rear end, or the rear end out of a vette, or an'80's jaguar, or any number of others. 

 

Just my opinion, your actual mileage may vary. 

 

John

[1951sms]

      Ok, Ok that's all the tongue lasing I need!No, I started working as a Subaru tech in 1978 and continued till 1990. We've been using a couple of the early low-high range 4wd on our hunting camp for years. The Fuel tanks went out just after the rear brakes, lol. we've replaced doors exhaust ( so as not to start fires) they both are a lot of fun.Just didn't know bout' the gears and really wanted more than ever just to get the little boogers attention!                               How much do FF1 and 360 Manuals go for?           

Edited March 18, 2014 by 1951sms

[TallonX]

Cheaply... Find yourself a MK2 Supra, if I remember right the rear is rated for up to 800 hp

[Numbchux]

I disagree with these guys, I think an EA81 rear end would be excellent for a Rat Rod. The suspension geometry is all self contained, so you don't have to worry about fabbing several different mounting points in exactly the same dimensions as they came on the donor car (strut towers and trailing arm brackets on most modified Macpherson rear suspension on modern cars). Torsion bar adjustability, just need to make shock mounts.....easy peasy.

 

 

The r160 rear diff might not last, but that depends on the use. Rat Rods don't typically have big racing slicks, so the tires would *probably* spin before the diff blew up. And if the car gets used for cruising more, with more gentle use of the loud pedal, it might hold up just fine.

 

Keep in mind, the r160 is the same diff used in all subarus (except the STi and BRZ) up to and including the current model year (and will probably be used for some time to come). Now, none of those are quite putting out 300hp (230ish in the WRX, and 260ish in the new 3.6 H6), and they have the front diff to help take some of the strain, but it's not exactly made of paper mache.

 

If it does blow.....r160s are cheap and plentiful in a myriad of gear ratios.....or, it's not terribly difficult to put an r180 in there. I know there are a few WRXs with LSx engines....I wonder if any of them are running the stock rear end. A friend of mine is putting an LS in his '98 Legacy, and intends to use r160s until he runs out (I think he's got 3 or 4....).

 

 

The other issue, is wheel bolt pattern. 4x140 isn't ideal....converting to 5x100 is possible, but requires increasingly rare 4WD XT6 rear hubs. Converting to 6 x 5.5 is easy, but primarily just leaves truck wheels. Or....bolt-on adapters......blech

[Adam N.D.J.]

The diff is not really the problem with them, it is the axles, the cups shatter once you start getting higher in the horsepower. After I put the ER27 in my Brat and switched to rear wheel drive I could not keep a set of axles in it for very long.  Anything over half throttle and it would just shatter one of the cups.  I used the same differential that came in Brat with no problems. Perhaps if you used the Gen 2 rear suspension components with the Datsun u-joint axles you would have a reasonable set up.  I have seen some of those early Z cars with some pretty high horsepower.