Fox T-Bird/Cougar Forums

Ok guys.  Been reading all I can find on this.  I swapped the Fox mustang 8.8 into my Bird last weekend.  Now I can swap over the axles, backing plates and brakes for a stock width wheel track right?

If disc brakes then yes. Drums no. The axle tubes on the drum brake rear are longer.

I had to buy an 88 XR7 8.8 to keep the 10" drums and have the correct track width. Also, as a FYI, if you want stronger axles buy aftermarket axles for a 93 Mustang Cobra. They are the same length as the Thunderbird/Cougar axles. I've got 31 spline Moser axles for a 1993 Cobra and a 31 spline Traction-Lok and they fit like factory in the 88 XR7 housing.

Ya I was meaning drums.  Guess I will deal with spacers or new rims with a different back spacing.  At least until an SN95 diff comes up for sale.  Cougar and TBird parts are rare around here.

They are rare here too. With the newest ones now 30 years old I have a hard time finding parts, especially since most rusted away 10 years ago. I ended up getting the 88 XR7 rear from a forum member in Iowa about 5 years ago. It was a process to get it even though it was only a state away...

Ron, is there any V8 '94-'98 Stangs being parted in your area? That would have everything you'd need, pretty much....

'99 stuff would work, but the rear housing is wider yet than a Fox CatBird so you'd be going the other way with that setup, but an option if need be, worst case.

Edit; if you wanted disc brakes...drums, no idea. I converted my TC rear to drums a few years ago, wasn't hard, Ranger axles, '88 Crown Vic drums (10 inchers), and then I used the stock Sport backing plates and brake shoes. Worked great. Had to put 5 flat washers over the studs on one side before the drum went on, else the drum sed the backing plate and screeched.

I sold that rear to a guy here, was a bit of a job getting the rear into the trunk of my Lexus. Ughh

Should have asked but are you going 5 lug?

What year car are you working on?  On my 84, I swapped the 7.5 for an 8.8 from a 88 mustang lx. The axels, drums and backing plates bolted right back on like the 7.5.

On the older (pre '85) you can, but I think he's got an '87 or '88, so that's not an option.

Mines an 84.  I wasn't planning to go 5 lug right now.  But down the road at some point.  If I swapped a rear in with disc brakes I wouldn't be taking a step backwards and bolting drums on it. That doesn't make sense to me. 

I guess since I want to change the fluid in the diff anyways I will rear it all apart and see if they will interchange and give me the width back I want.  If not, I'm not too concerned really.    SN95  GT's  are hard to find up here too and every idiot that is parting one thinks they are on a gold mine.

With an 84 the rear is the same width as the Mustang. Just swap your brake parts over to an 86-93 Mustang 8.8 and you should be good.

That may be true of American Birds, but not true of the Canadian versions.  The wheels definitely set in further.

Interesting..

Got a pic of how it sits?

Mine is Canadian. The only way the wheels will sit further in is if you use the Mustang axles and drums. They are 3/4 " shorter per side.

It's a complete mustang differential so....  Ya it has the mustang axles and drums.  But that is what the question was.  I can swap the 7.5 axles and brakes onto it and get my width back right?

Where abouts in Ontario are you quickshift?  I work in Hamilton and live in Cayuga

The HOUSING on your 84 is the same width as the Mustang 8.8. The axles are longer on the TBirds/Cougars. Pull the axles and brakes from your 84 Tbird and swap the whole thing over to the 8.8.

It's possible that you can just use the axles and drums from your TBird. It's been a LOOOONG time since I messed with this swap and I don't recall if the backing plates are the same between the two, or not. The extra 3/4" is made up in the backing plates or the drums.

Thanks Chuck. That's going to be tonight's project.

yes.

If the brakes are the finned, 9 inch version, yes, direct swap.

It's when you do the ten inch swap like I did that things get really wonky...

So I guess it's a good thing I was finally doing this swap anyways as the 7.5 was definitely showing signs it was ready to die and I'm sure the punishment the 6.0L was going to give it would have finished it off




The pin is actually stuck there.  I had to take a hammer and punch and pound it that far to get the axles in

I shattered the pinion bearing on the 7.5 in my car when I launched it (with the same engine/trans combo it currently has). Pinion was slapping into the carrier housing making a nasty racket. https://www.youtube.com/watch?v=4xzkctodX0E

Hence why I finally built and installed that 8.8....

Ya I have broke 4 of those 7.5s behind my stock 302 in that blue cougar I had years ago. Lol. And same thing.  Carrier caps fragmented

For anyone curious on the difference between the mustang and the TBird here is a pic of the only difference.  TBird is on the right

 

Yeah, we have the lengths of those axles listed in a stickied post here.

I *think* that 3/4" difference in length is made up in the drum height. You might post up a comparo of the drums, if you get around to it.

Yup. Difference is made up in the drums.  Changed the backing plates even though they are the same.  Gave me a chance to clean them and paint them.



Stick out from fender comparison.
Tbird axle :


Mustang axle: