Jon_Valjean

Ok, so the factory Mazda diff, even in LSD form is relatively weak. Sure, it's good if you don't thrash it, but where's the fun in that? Plus, this car ('81 GS) will be running over 450Hp when I'm done, and there's no way the factory diff will cope with that easily.

I managed to source the rear end of a 1990 EA Ford Falcon for free. This is a car only really seen in Australia and New Zealand, so I've attached a picture for our foreign cousins:



What a piece of ****. Anyway, here's the diff after it's been narrowed and had all the brackets welded back on. It's now 100mm narrower than factory, and exactly the same width as the original RX7 diff.



Time to attack it with primer!! 2 coats, followed by 4 coats of gloss black, then 2 coats of clears.



Mmmm.. glossy... note new Nolathane bushes for the lower trailing arms. The top bushes were not replaced, as it's always good to have more play in the upper arms on a Watts linkage setup to reduce the chances of snap oversteer when cornering.



Here's something you don't see every day... an old RX7 with 10.5" rear disk rotors and five stud wheel pattern. The disks will be replaced next paycheck with DBA slotted examples. I'll be running semi-metallic Bendix pads, and the calipers will be painted with high-temp matt black paint.



Total cost, including fabrication, paint and transport - around USD$750.00.

If anyone wants to do this and needs advice, feel free to PM me

Jon.

GavinJuice

That car just looks and probably is a european taurus, ish. What the hell is nolathane, and what's it's advantages to stock or a poly combination?

Pele

iTrader: (28)

They don't make the Taurus in RWD over here.

Was thinking the T-Bird uses the same 3.8L V6 as the Taurus, but the T-Bird is IRS...

**** it. Just gotta gut a Mustang. They have 8.8" rear, right?

Jon_Valjean

Nolathane is an Australian brand of eurethane bushes. It's technically the same stuff you use to glue your windscreen in with. It's quite a bit firmer than factory rubber-based bushes, and quite cheap

Brianhsval

I thought mustangs were a 9". WTF get it anyways that is my next project also.

FB II

so how do you make the rear end more "narrow"??? i need to do this mod as soon as possible.

Jon_Valjean

The mustang (from what I know) is an 8.8" unit. We don't see too many mustangs over here so I'm not 100% on that. I think directfreak bought a 8.8" unit out of a mustang so you might be best to ask him.

The diff tubes are narrowed on a lathe, and the axles are cut then resplined. The whole unit needs to be balanced and the brackets rewelded to the housing. It's not something you can do in your back yard, it needs to be done by professionals.

FB II

shiiiiiiiiiit i wonder what shop could tackle a project like that? there aren't any machine shops around here ahhhhhh!

680RWHP12A

my mustang rear end isn't narrowed and works fine!!! i saved alot of $$$ not having to pay x-tra for custom length axles, or having my rear end housing shortened!! more cheese for me!!!!!!!!!!

FB II

ahhhhhh!!!! ROBERT what offset rims do you use in the rear then? i dont wanna fork with all this narrowing mess. i just wanna be able to launch the **** outta my car!

djmtsu

iTrader: (3)

Actually the T-Bird has the same solid axle as any other RWD Ford car, no IRS unless you have a Cobra.

The following Ford vehicles use the 8.8 rear end:

Ford Mustang (4 or 8 cyl)
Ford Thunderbird
Ford Aerostar (yes a minivan, basically a T-bird chassis, also a lot cheaper to scrounge cause its......a......minivan)
Ford Crown Victoria
Mercury Grand Marquis
Mercury Cougar (old school RWD models, all pre '96)

So they basically they are all the same except certain ones get disc brakes, look for XR7 Cougars, Eddie Bauer Aerostars, SVO (good luck) Mustangs, Turbo Coupe (good luck) Thunderbirds, and SC Thunderbirds. Also Crown Victoria Police Interceptors get discs out back.

Working at an auto parts store gives you all kinds of worthless info.

Wankelguy

Some of the Ford 8.8 rearends were 4-lug, weren't they?

setzep

What is the width of a 8.8" 80's mustang 4 bolt rear and what is the width of a FB rear?

Pele

iTrader: (28)

Why is is that I can buy CV boots for an 87+ T-bird/Cougar? They are IRS...

eViLjAy

Hell almost anything ford has an 8.8!! look under the *** of almost any mid 70's (eww, i know!) luxo barge. These can usualy be had for under $200 for the whole car and ya can scrap the rest of it or sell it

Excellent work by the way!!!!!!!

Eville140

Most car 8.8" housing are the same, but axles and brake setups can change the width a few inches. A 8.8" from a 87-93 mustang fits pretty darn good without narrowing. You just need to use front drive offset rims.
All total I probably have $100 in my swap not incuding the $50 for the driveshaft.
Here are a few pictures
http://www.eville140.com/rearend.html

Later
Randy

FB II

fork yes. thanks so much for those pics! do you by chance still have your measurments for how far in and where the brackets must be welded? hahahah, i know that's a long shot. anywho, that looks so good in there. I CANT WAIT! WOOOOO!

grantmac

Which ones come with disks and LSD though? And a 5x4.5 bolt pattern?
Grant

CarlRx7

wut size tires can you fit eville140?

Eville140

I am running 205/50-15's on 15*6.5" rims.
My slicks are 24.5*8-14's and they fit no problem also.
The mustang 8.8" makes the rear darn near the same wisth as a gsl-se rear end.

As far as the brakes and lug pattern is concerned. And brake setup that will fit a mustang will work. I started to do 11" rotors and calipers from a linocln mark7 (has to be modded to work with mustang axles, lincoln axles are longer. You just have to move the caliper bracket to the opposite side of the backing plate for it to work. Google will show you how to do it.) But doing this would more than liely require a master cyclinder upgrade since the pistons on ford rear disks are larger than any thing that came on a rx7..even the front disks.

For axles, to get 5 lug axles in mustang lenght you can either rder some from a driveline shop, or pull a couple long axles from a ranger or aerostar van. This is the cheap way and how a lot of musatng get there 5-lug setup.

I just redrilled my 4-lug axles for 4*100mm to use the cheap and easy to find honda rims. On the front I am using lug adapters to change the 4*110 to 4*100. Been running them for close to 3 years now and they are working great.

Later
Randy

Kenku

Here's what I want to know though... what about weight? I'd imagine the 8.8's a bit heavier than the Mazda axle, but how much?

Jon_Valjean

I didn't actually weigh both axles, but I'm fairly sure the Ford setup is between 40 and 50 pounds heavier than the RX example.

Kenku

Hm, damn... back to thinking about the 7.5" or new axles for the Mazda one.

JDuncan

iTrader: (3)

Honestly, if you are running the kind of horsepower that requires this swap, the added weight is gonna help more than hurt...

Kenku

I'm not *really*; mostly I need a way to get 5x4.5" on the rear and I don't really trust adapters. I fail to see how more unsprung weight is *ever* helpful.