what ford 8.8 to narrow for healey 100-6

[maxwedge5281]

i am contemplating changing the rear axle in my 1959 100-6 with sbc zz4 motor and 200 R4 aod transmission. i would like to have posi-traction?? and a low 3.?? ratio with axles for a 5 on 5 inch bolt pattern and disc brakes. what model or make would be best to look for a donor to shorten to fit the healey rear? thanks in advance for any advice or suggestions.

[Moderator]

FWIW, I think using any 8.8 is a mistake. Way too heavy... and certainly way heavier duty than you need in lightweight sportscar on relatively narrow tires. I've had a narrrowed 8.8 (from a '92 Mustang, 3.27:1, TractionLok, drum brakes) under my MGB since ~1994... and I dislike it, because all that unsprung weight compromised my ride quality. An 8" would be a much better choice... (Have a look at the axle under <a href="http://www.britishv8.org/MG/SteveEngelman.htm">this car</a>.) There are some very attractive Japanese options too, although with fewer gear ratio options.

[maxwedge5281]

can you elaborate on a choice of 8 inch rears or the possible japanese that might work!

[Moderator]

I thought by now someone would jump in and defend the 8.8. Please! Someone! Which 8.8 is better than the rest?

---

Of import options, I'm most familiar and enthusiastic about Mazda GSL-SE axles.

In my opinion, they are to axle swaps what the BOPR is to engine swaps!  

Click <a href="http://www.311s.org/phpBB3/viewtopic.php?t=9547">here</a> for good photos and a description of how to narrow them.

However, I think the link fails to show or adequately describe some of the advantages of the GSL-SE axle.

Firstly: Torsen limited slip differentials from Miata are interchangeable with the GSL-SE's clutch type LSD. There's nothing "wrong" with the GSL-SE clutch type unit. It's easily/cheaply rebuildable and tunable... but IMHO a Torsen is a huge upgrade for most applications. You can choose either a Type 1 or Type 2 Torsen because Miata came with one and then the other in the mid 1990s. See Carroll Smith's book "Drive to Win" for a good description of the differences. (While you're at it, you'll may also like the Miata's larger driveshaft flange.)

Secondly: very nice OEM disc brakes. They feature a cable operated parking brake integrated into the caliper and also vented rotors.

Thirdly: Mazda elegantly packaged a lightweight and narrow anti-roll bar to the axle. And when you install it on your car, you can unbolt and reinstall it so it's arms point rearward to facilitate easy adjustment.

Notably: Mazda mounted a Watts link mechanism on these axles! They did so in an odd way, with the pivot point relatively high and off centerline and with peculiar links... but I think it's very cool that they came with a Watt's link even if everyone who ever raced a first gen RX7 replaced their factory-installed Watts link with a Panhard rod.

Downside? Just one: limited gear ratio options. (Though 3.63:1 gears are available brand new from Mazda, they're not inexpensive. You might find one in salvage yard... but they're getting very scarce.)

[BlownMGB-V8]

Dana 44? 10 bolt Chevy?

[tr8todd]

I'll defend the 8.8.  Its a great rear end.  They come in 3 basic varieties.  Independent, 28 spline car based units and 31 spline truck based units. I'm guessing you want to go with the solid axle.  That leaves the 28 spline car based and the heavier beefier 31 splined.  If you are set on 5X5 the you will need custom axles.  Ford used 4X4.5 and 5X4.5 for wheel bolt patterns.  Some F150s might have a 6 bolt pattern as well.  No matter which axle you find, you are going to have to narrow it and order custom axles.  The narrowest ones you will find will be early Fox Body Mustang GTs from the mid 80s.  Every itineration of Mustang after that got wider.  The addition of disc brakes and antilock sensors and reluctor rings added to the width of the rear end housings as well.  Finding a limited slip unit, with disc brakes, and in the ratio you want will be the holy grail.  Mustangs, Rangers, Lincolns, Mercury all used the 8.8 in some configuration or another.  There is a website called ranger station that has a comprehensive list of axle sizes, and wheel bolt patterns.  They also list axle door sticker codes so you don't have to go and crawl under every Ford in the junkyard.  I have a 31 spline unit from an Explorer under my TR8, but there is also 500 hp of LS3 engine in front of it.  Stick with the 28 spline units found in cars and in some of the Ford Rangers.  They are lighter because the axle tubes are smaller, and the shafts are slightly thinner.  Don't rule out a 7.5" if you can find one.  Plenty strong enough for a LBC, but they are harder to find and parts are more expensive.  The 7.5 and the 28 spline 8.8 use the same axles.  The 7.5 carrier and gears are just smaller.  Cute little buggers.  I have a nice 7.5 limited slip carrier with 3.08 gears I'd like to use some day.  Just need to find a decent housing to put it in.  The one it came out of was rotted beyond belief, but the carrier, clutches, and gears are mint.

[mgb260]

Also a fan of the 7.5 Ford and 7.65 S10 rear. Both stronger than you would think. Did you know they are both same splines and axle bearings? Also,Toyota 4x4 8" FourRunner rears have decent ratios available. Here is a guy that narrows the 86-95 rear using Dutchman resplined axles. The 7.5 Toyota in 2WD pickups are already 5X4.5 (Ford) pattern.

http://community.ratsun.net/topic/42550-narrowed-toyota-8-inch-axle-for-521/

[mgb260]

Picture of Chris Gill's 7.5 axle for his MGB:

http://forum.britishv8.org/read.php?6,55614,55638

[ex-tyke]

FWIW, I think using any 8.8 is a mistake. Way too heavy...

 I won't defend using my 8.8 ('96 Mustang) or say that it's the best in the application - but it's a fine robust axle that has some benefits of good availability in the wreckers, several ratio choices, and availability of Tru-trac. and disc brakes .
 (and, according to Jim Blackwood,) has an additional operating efficiency over the old 8" based on the pinion design/location.
 Was there any comparative axle weight chart ever published?

[roverman]

Since we are mentioning LBC's and handling, in the same sentence....  Why not a nice, relatively-light, IRS modular diff and suspension package ?  I refer to Mazda RX 7 of late eighties/ early nineties. Not sure of low 3's in the gearing though.  art.

[BlownMGB-V8]

The Jag IRS under the MG-Roadmaster has done quite well to date. We had some early issues caused by settling of the mount cushions but once those were sorted out it has been a fine unit. The ride is smooth, suspension is compliant, handling is right there. It adds a bit of unsprung weight to the rear of the car, just the thing to offset a heavier engine, and with light weight wheels and tires and the brakes inboard, unsprung weight is really low. It isn't cheap or simple, but it does fit without removing the battery boxes. Dana 44 differential.

Jim

[maxwedge5281]

thanks for all the suggestions and experiences. i still think that i am leaning toward an 8.8 unit with positraction and disc brakes and axles for a 5 on 5 bolt pattern. i am using widen healey steel wheels on the car....7 inches which is really not so wide. i would think that aftermarket calipers and rotors would help the overall weight of the rear. so my next question is....who in the southeast might be able to build such a unit to bolt into the healey?

[HealeyRick]

Larry,

You might look into the Explorer rear axle as mentioned here:  http://forum.britishv8.org/read.php?3,23840  I would think some of the stock car shops near you could handle the work.  If not, you could always custom order something from Strange, Currie or Moser.

Rick