Swapping a 300ZX I.R.S. into a '66 Mustang

[Guest Anonymous]

Hi, I ran this about six months ago, thought I'd try it again. Anybody have any experience swapping this IRS sub-frame into any other cars?

 

Thanks, Kinky6 8)

[Guest Aaron]

I doubt anyone here has any experience with that. You might want to search the web. There is a company that makes IRS kits fot he first gen Stangs that are based on original factory plans, and are bolt in. They are expensive though. I personally think that the best/cheapest route for a mustang would be to adapt the IRS from a 89-96 Thunderbird/Cougar or newer Mustang Cobra.

 

You might also want to consider a Vette or Jaguar rear. There are lots of places that are familiar with swaping those rears into all kinds of cars.

[BRAD D]

http://www.turbobuicks.com/members/scottiegnz/vette-irs-swap.htm

[Trevor]

Here is an IRS from a Toyota Supra:

http://www.spkorb.org/suprang3.html

Transplanted into an early Mustang.

[Guest Anonymous]

Thanks for the replys so far. The link to Coleman racing in the 'Vette IRS article was perfect for the front end/Monte Carlo brace set-up that I want to make.

 

The early six cylinder Mustangs came with four lug wheels and drum brakes, and I want to change over to disc brakes and to be able to run some vintage five spoke mags. For the most part, I want to keep the car as stock-looking as possible, from the inside and out. I do have to replace my rusted rear frame rails with replacement stampings, so we'll be doing a lot of welding back there as it is.

 

The '93 300ZX IRS, with its subframe type design, has some advantages for my situation: good ratio for a T5 trans, my planned 175-200hp certainly won't stress it, it has the 5x4.5"(114mm) bolt pattern that I want, and it looks like it will only require six mounting points; four for the subframe, and two for the struts. Plus, I got the whole assembly for $300.00, including the rear floor pan to use for a mounting template.

 

The worst problem that I can see at this point is having to narrow it from 62" hub-to-hub, down to 57". Since this IRS uses fairly short upper and lower A arms, it looks feasible to remove 2.5" per side from the subframe. This will allow the pivot points to remain in the same relative positions, except moving inboard some, and the steel subframe can be welded back with appropriate reenforcement (boxing, fishplates). Shortening the steel drive axles by 2.5' each would be standard stuff for a good driveline shop.

 

A Volvo 760/960 IRS would be very similar to the 300ZX in terms of mounting position, w/ the same five lug pattern and a 3.73:1 ratio, but its about the same width, and the one I have is still in my Volvo.

 

The 'Vette is even wider, looks like a lot of engineering, is pricey, and has the wrong bolt pattern. I suppose I could get it redrilled. I've looked at the Jag unit, also. They're great for street rods, but it doesn't look like it would lend itself to the unit-body Mustang without a lot of work.

 

I've read the article on the Supra IRS into the '65 Mustang a few times. This was a car that was gutted for racing; and required a bunch of fabrication to meld the Supra floorpan into the back of the Mustang. I don't think you could ever get a stock looking interior back in there. Plus, its a 4 lug bolt pattern.

 

The Ford products aren't much help, either. The T-bird IRS is also a four-lug. A professional shop in Denver has come up with a kit for mounting the late-model Mustang 8.8 IRS into Mustangs as old as '67. The '67-'68's used a wider axle than the early ponies, and the shop indicated that they had no way to narrow this unit to fit the '65-'66's.

 

I suppose I could just bolt a V8 Maverick 8" rear onto the stock leaf springs, buts whats the fun in that?

 

Later, Kinky6 8)

[cobraz240z]

if your going to put a irs use the thunderbird irs i have a 1993 ford thunderbird Super Coupe 5 speed and it has about 350 horse power and 400 torque and the rear end handles it fine its a 8.8 and it is posi traction it will be better for you

[Guest Anonymous]

Cobra,

 

Is your T-bird rear 4 or 5 lugs? Do you have any idea of what the hub-to-hub measurement is? Is it designed in a subframe like the 300ZX or the Volvo, or does it need attachment points more similar to the 'Vette or Jag unit? Oddly enough, the U.S. made Volvo IRS units have the 8.8 center section, as well.

 

Since I haven't started modifying this car yet, I'm not married to any one idea yet; I'm just looking for the most feasible option. I do like the idea of a rigid subframe that bolts to the car, as the mounting looks easier to fabricate.

 

Kinky6.