8.8 REAR VS 9"

[brianj5600]

My calculations put an Explorer cut on one side at 57.25". That should work great in a 65. I would not be suprised if you could do it for $500 or less. Disc brakes, posi, 31spl axles, 3.73 or 4.11 gears what is not to like? I have less than that in my 95GT 8.8 swap including a new driveshaft. I may look into an Explorer to allow off the shelf 15" wheels to fit my 67. You would have to do some serious shopping to get those things in a 9" for that price.

 

[brianproctorla]

Ratio 411 Raises a good point.
I have a 67 ford 8". I should be able to find a cheap nine inch center housing and pumpkin donor and weld it in. I have the axles already.

Can someone explain the 8.8 pinion offset?

I came across a Lincoln Versailles 8.8 disc rear (not 9"). If this was the same dimension as the Lincoln Versailles 9 inch (which should fit), would the pinion offset cause a problem?

I'm not sure if I would go with the Versailles rear anyway. I've heard mixed reviews on the availability of parts.

I had planned on going with a rear 10 x 2.5 rear drum that I pulled of an 86 Lincoln Town car. This was a cheap solution considering I had pretty much blown my budget on the front disks, roller perches, quick steer kit, bumpsteer kit, etc.

 

[D.Hearne]

The Explorer/Mountaineer/Ranger 8.8 has the pinion offset 4" to the right, hence the reasoning in shortening only one side (make the long side shorter, this used to be done with the 68-74 Econoline 9" rear too) The Mustang 8.8 pinion is centered. The Versailles rear parts are neither expensive nor hard to find. Just a trip to the local parts house. The Lincoln 8.8 rear has nothing in common with the Versailles rear. It's a 4 link airbag suspension deal.

 

[D.Hearne]

Everybody talks about "C" clip eliminators as the panecea for what ails a rear end. The key is getting the right thickness of "C" clip and properly maintaining your differential. Most people don't realize there are different thicknesses, and end up with lateral axle play. Which causes heat and wear problems.
,

There's another reason for eliminating the C clips and axles. This is also to rid it of the inferior bearing/race and replace it with a stronger bearing and harder, thicker race. Just me, but I don't like the fact that with C clip axles, the inside race for the bearing IS the axle. Once the bearings wear thru the hardened part(which is only a few thousandths thick) of the 8.8 axle, it's just a short time till the whole thing fails. So it's not just a matter of eliminating the clip retention.

 

[stangman67]

I too just finished an 8.8 install. 86 rear into a 67. I rebuilt the traclok, put in 4.10s, moser 28 spline axles, rear girdle, and c-clips. The rears were virtually the exact same width (67 8"). All said and done I have about $750-$800 and quite some labor, but that is free to me in my spare time. I am glad i did it, and I have no worries about it.

 

[ratio411]

The Fox version is lighter by quite a bit.
The Explorer and Ranger are heavier due to the larger and longer tubes. And the Explorer brake swap is heavy due to the P-brake setup.

This comes up so much...
I could care less what it came out of, the comparison was of 3 rears of proper length to fit a 67. So the tubes were same-same.
The 8.8" was 15# heavier than the 9", which was 15# heavier than the 8".

You'll have to do a search to find the threads... The info came from good links and in one thread a member here even weighed his rears to check and came up with same or similar results.

Folks say the 8.8" is lighter all the time that folks think it's true.

After being here for 5 or 6 years and seeing it all the time,

 

[ratio411]

...the Explorer brake swap is heavy due to the P-brake setup.

I didn't even notice this comment, I was so worked up about the weight misinformation...

Drum brakes, 10" drums= 22#
Drum brakes, 11" drums= 26#
Exploder rear discs, 11.25 rotors= 25#

For what you get with the Exploder rear discs, I don't see 25# as a handicap here!


Edit:
Forgot to post the real heavyweights!

Versillies 10.5" rear discs= 30#

Now that is heavy...

 

[mikethebike]

9" is the way to go. But, the correct width is the fun part. Didn't 9" housings from late 1950's fords fit?

But, on the 8.8 you can put on rear discs.....

Not sure about the late 50's fitting but the 57 Ford station wagon was the most narrow rear you could get and we would buy those for drag cars because you only had to shorten one end (the 3rd member was offset for some reason I never cared to look-up).

 

[ratio411]

Not sure about the late 50's fitting but the 57 Ford station wagon was the most narrow rear you could get and we would buy those for drag cars because you only had to shorten one end (the 3rd member was offset for some reason I never cared to look-up).

57-59 Ford passenger car rears are a direct bolt in.

This is from Ultrastang... (Steve Ainsworth)
One of the best 9" directorys on the net.

1957-1959 FORD BIG-CAR 9-INCH REAR END WIDTHS & PHYSICAL DESCRIPTIONS:
The housing widths are determined by measuring from the inside of one housing end flange, to the inside of the opposite housing end flange. (this would be the flanges at the extreme ends, where the brake drum backing plates attach to the housing).

The 1957-1959 full-sized Ford passenger car 9-inch rear ends had a housing width of 52 ¼" across, flange-to-flange (same as 1965-1966 Mustang 8-inch rear end). These rear ends also share the same leaf-spring perch locations as the 1965-1978 Mustangs with a 43-inch distance center-to-center. (direct swap for '65-'70 Mustang [will give '67-'70 Mustangs slightly more wheel well clearance]. These "narrow" 52 ¼ housings will also fit the '71-'73 Mustangs but wider wheels & tires will be mandatory unless spacers are used with the stock wheels to space them back out.

The '57-'59 Ford big-car rear ends came in two housing configuration styles: (1) Large axle bearing housing. (2) Medium axle bearing housing (same bearing size as early Mustang 8-inch rear end).

(1) The Large bearing housings can only be found in the '57-'59 Ford station wagons and in the '57-'59 Ford Rancheros and also in the *1960 model T-Birds.

(2) The Medium axle bearing housing will be found in all the other '57-'59 Ford passenger cars.

I know many guys running these, no mods needed... Unless you consider brake upgrades. The old drums are big, heavy, and harder to find parts for. No self adjusters either.

 

[dennis112]

57-59 Ford passenger car rears are a direct bolt in.

This is from Ultrastang... (Steve Ainsworth)
One of the best 9" directorys on the net.


I know many guys running these, no mods needed... Unless you consider brake upgrades. The old drums are big, heavy, and harder to find parts for. No self adjusters either.

This is the route I took originally with my 65'. It is a bolt-in and I pulled it out of the car for $150. It originally had 3:50 gears, although 3:10s are more common. Very easy swap

Since I pulled it out of a common 59' passenger car I was able to use the stock 8" Mustang axles, backing plates, and brakes which are 28 spline, like 57-59's. Only things to note about the swap are that the axle tubes have a larger diameter (3") on the 57-59 rear so you will need to use the larger U-bolts and under spring perch, which also can come from the donor car.

 

[brianproctorla]

Wrong...
The 8.8" is actually heavier than a 9"
8.8" disc brakes will bolt to either small or Torino bearing 9" housings.
You just have to get Vic discs for small, or Exploder discs for Torino.

Do you have an 8" now? (5 lug)
They are the same axles as a 28 spline 9"...
Do what Ford (and Shelby) did in 65-66:
Cut the axle tubes off your 8" housing center, then weld a 9" housing center in it's place.
Now you have a small bearing, 28 spline 9" in the correct length and pinion angle to bolt right back into your car.
This method is much cheaper than narrowing any rear and cutting the axles.
Just make sure you use a common 9" housing for the center donor...
There are 2 teirs of 9" housing values:
Expensive and dirt cheap.
Any narrow car housing is expensive.
The rest are abundant and cheap (even free).

After doing this mod, throw a set of Crown Vic 8.8" discs.
Use a 28 spline chunk.
Easy-cheezy.

In order to perform this swap, I have to get a 28 spline center, right?

Just to exhaust all possibilities, is it possible to put a 8.8 center into an 8" rear?

 

[ratio411]

In order to perform this swap, I have to get a 28 spline center, right?

The differential unit itself must be 28 spline...
Or if you intend to get a 'chunck' already built, you must make sure the diff in that chunk is 28 spline.

 

[D.Hearne]

Just to exhaust all possibilities, is it possible to put a 8.8 center into an 8" rear?

If the axle tubes are the correct diameter, yes.

 

[Hack]

The Fox version is lighter by quite a bit.
The Explorer and Ranger are heavier due to the larger and longer tubes. And the Explorer brake swap is heavy due to the P-brake setup.

I happen to have a Fox 8.8 from an '85 and a 9 inch small bearing rear from a 67 Mustang. The 9 inch small bearing rear was lighter. I posted the exact numbers on here a couple years ago. IIRC it wasn't a lot, maybe 10-20 pounds difference.

I believe that a large bearing 9 inch would be heavier than the 8.8. I had a rear diff from a '79 pickup which was WAY heavier, but it was also significantly longer as well.

As far as the length of the Fox 8.8s, they are slightly longer than the '67 Mustang rear diffs. I have a diagram that says 58.36" tread width. If you use Fox backspacing (I think it's 5.72") on the wheels, you get your tires in very nearly the exact same spot as the 4.5" backspace wheels on the early Mustangs. At one time I was considering using the Fox 8.8 in my '70 with Mark VII flip discs and Fox wheels. The only problem is making the parking brakes work.

 

[brianproctorla]

If the axle tubes are the correct diameter, yes.

Do all 8.8's have the same diameter tube? Would this eliminate C-clips?

 

[mikethebike]

I happen to have a Fox 8.8 from an '85 and a 9 inch small bearing rear from a 67 Mustang. The 9 inch small bearing rear was lighter. I posted the exact numbers on here a couple years ago. IIRC it wasn't a lot, maybe 10-20 pounds difference.

I believe that a large bearing 9 inch would be heavier than the 8.8. I had a rear diff from a '79 pickup which was WAY heavier, but it was also significantly longer as well.

As far as the length of the Fox 8.8s, they are slightly longer than the '67 Mustang rear diffs. I have a diagram that says 58.36" tread width. If you use Fox backspacing (I think it's 5.72") on the wheels, you get your tires in very nearly the exact same spot as the 4.5" backspace wheels on the early Mustangs. At one time I was considering using the Fox 8.8 in my '70 with Mark VII flip discs and Fox wheels. The only problem is making the parking brakes work.

But that is 10-20 lb. of UNSPRUNG weight. Take that, add the difference in the weight of fiberglass leafs and stel multis and you could drop your rear axle weight by something like 50-60 lbs.!!!
I gotta call Flex-A-Form.

 

[D.Hearne]

Do all 8.8's have the same diameter tube? Would this eliminate C-clips?

I don't know the dimensions of the 8.8 center castings, so I can't answer that. If 8 or 9" tubes will fit, yea that would be a way to get rid of the C clips and bearings riding on the axles themselves. As for whether the 8 or 9" stock axles will then fit, that I can't say either, as pertains to length, not diameter. Diameter is the same in same splined axles for all. A 31 splined 8.8 axle will slide right into a 31 splined 9" differential, ditto for 28's.

 

[brianj5600]

Don't get too exited about the weight savings, 9" rearends come with a HP penalty. Don't be suprised if the car slows down at the strip if you go. My nephews car slowed down about 1/10 of a second. There was a company making center chunks that use 12 bolt ring and pinions that address the low pinion, but I can't remember who it was.

 

[ultrastang]

There is only a 2-3% effencientcy advantage in an 8.8" vs. 9-inch, in favor of the 8.8". --not a huge difference.

 

[D.Hearne]

A tenth of a second? That's something that definately won't register on the seat of the pants meter. And to most, hardly something you'd notice given all the other variables involved in getting down the strip.