90's tbird 8.8

[snowb07]

I can get a 90's tbird IRS for cheap and I am wondering if anyone has any information on them. Would I be able to use this rearend in my 68 fastback. would it be to wide or narrow. Any more information would be helpful

 

[96 DOHC Cobra]

Too wide, and wrong bolt circle pattern.

 

[Rusty67]

The Tbirds had IRS... ever ? Also, I thought the 5 lug Tbirds had the same bolt patern as the Mustang ?

What year car did this come out of and with what engine ?

 

[Hack]

Too wide, and wrong bolt circle pattern.

Yes, but not so wide that you couldn't fix that problem with a non-stock wheel backspacing.

If it has the early 4 lug pattern, that's more of a problem. With a 8.8 solid rear you can swap in Ranger axles, but for this unit that's not an option. I'm sure you can overcome it, but I don't know how or what the cost would be. I wouldn't encourage anyone to run rear 4 lugs and front 5 lugs.

 

[88gt]

The IRS 'birds had a 5 on 4 1/4" b.c. IIRC..

Jim

 

[D.Hearne]

Wasn't that IRS the same setup used on the later IRS Stangs? If so, it's nearly a bolt in deal. Seen one done in a magazine and all they had to do was mount two angle brackets and bolt it in.

 

[runawayabc123]

I have a 91' Thunderbird. While it is a 7.5 over a 8.8, it is still a 5 lug and I couldn't imagine where you would start to put that in the 65 mustang I got. You would need a ton of new mounting points and other custom parts.

The gear housing actually bolts the the frame of the car in the middle, where the gas tank would be on a mustang (the thunderbird tank is under the rear passenger seat).

Like mentioned above, it can be done, but at what cost?

 

[96 DOHC Cobra]

All 89-97 T-Birds and Cougars as well as 93-98 Lincoln MK VIIIs had IRS. Swapping one into an early Stang would require a ot of welding and some huge fender flares. It's about 5-6 inches wider than a 68 Mustang rear.

 

[D.Hearne]

The Mustang I saw done was the IRS from a late Stang and the whole thing was mounted under the late Stangs in a cradle, 4 bolts, remove the driveshaft and brake lines and roll it out from under the car. It was retrofitted to a 67 Stang fastback along with a DOHC 4.6. The front two mounting points aligned with two holes in the 67's frame and the rear just needed two angle brackets to bolt onto the rear mount points. (or it was vice-versa, it's been about 3-4 years since I saw the article)

 

[Helmantel]

The bolt circle issue is easily solved by using some Cobra IRS hubs. That's what T-bird guys do when upgrading their brakes, wheels etc.

Here are a bunch of pics:

http://www.mn12performance.com/mn12how-to/irs/irs.html

On another site, I found that the width (hub-hub) is 63.25" for a Lincoln IRS, T Bird is probably the same. That's 4" wider than a 68 rearend. A lot of BS would be needed, but beware that although late model Mustang wheels have 1.5-2" more BS than, say, most vintage 15x7 wheels, they're also an inch wider, so the front of the rim moves only 0.5-1" more inwards.

 

[96 DOHC Cobra]

I still say it's too much work. The Cobra hubs will work on it, but then you also need Cobra rotors and custom brackets for mounting the calipers. As for the front, everyone that I've seen using the late model wheels with big backspacing has had to use 1 1/4" spacers in order to clear the upper control arm.

 

[Rusty67]

For SN95 wheels you only need a 1" spacer to clear the front control arm. The 2005 and newer rims take a 1.5" spacer.

 

[bnickel]

the t-bird IRS is totally different from the mustang unit. completely different cradle system, different weaker axles, the bolt pattern difference already mentioned and the shock/spring mounting points are different too. it could be done and made to work but it's not very practical at all and it's still too wide for a 65-66 car.