The question of rear axles comes up often on this forum. Perhaps we should do a little tech article about 9" rear axles with 4 1/2" bolt patterns. I've saved some of the info from this forum, so I can start it with what I already have. I also have a 9" axle ready for conversion for my '54 so I can try it out as the article is written.

Maybe the article can be created as a thread on this forum, and then moved to the tech article page when it's ready.

 

Paul...
here's some good info to start with



john


9" Rear Axle Information

Axle Widths:
„h 65-66 Mustang 57.25 inches
„h 67-70 Mustang 59.25 inches
„h 71-73 Mustang 61.25 inches
„h 77-81 Versailles 58.50 inches
„h 67-73 Mustang, Torino, Ranchero, Fairlane 9" 59.25 inches to 61.25 inches
„h 57-59 Ranchero and station wagon rears, 57.25 inches
„h 66-77 Bronco 9", 58 inches
„h 77-81 Granada/Versailles, 58 inches
„h 67-71 Comet, Cougar, Mustang, Fairlane, 59.25 inches
„h 71-73 Mustang, 61.25 inches
„h 64 Falcon 58 inches
„h 67 Cougar 60 inches
„h 67 Fairlane 63.50 inches (coil springs)
„h 72 Ford Van 3/4 ton 68 inches
„h 73-86 65.25 inches
„h 57-59 Ranchero and station wagon 57.25 iches (narrowest 9" housing)
„h 66-77 Bronco 58 inches but has 5-on-5 1/2 inch diameter bolt circle
„h 67-73 Torinos, Rancheros, Fairlanes 59.25 inches or 61.25 inches
„h 67-71 Comets, Cougars, Fairlanes 59.25 inches

Where To Find:
„h 67-73 medium and big block Mustangs and Cougars
„h 66-71 Fairlanes, Torinos, Montegos, Comets, and other Ford intermediates with big blocks
„h 57-59 V8 Fords and Mercurys
„h 77-81 Lincoln Versailles & Trucks

Type Of 9" Housings:
„h 67-73 Mustang/Cougar - light duty, thinnest housing material, small axle bearings, 28 and 31 splines
„h 57-68 passenger car and 1/2 ton truck - medium duty, stronger than Mustang type, 28 and 31 splines
„h Ranchero/Torino - heavy duty thick wall housing, 3.25 inch diameter axle tubes with flat tops
„h 69-77 Galaxies (coils), Lincolns (coils), and late pickups (leaf)- 3.25 inch diameter all the way to the backing plate, coil housings have upper control arm mount

How To Recognize 9" Housing Centers:
„h 57 - no dimples, flat center band up the center of the rear cover, bottom drain plug
„h 58-59 - two dimples on back of housing, flat center band, some had drain holes
„h 60-67 - two dimples, flat center band, oil level hole in back cover
„h 63-77 Lincoln, LTD, Thunderbirds had 9.375 inch centers, housings were cut away at the gasket surface for ring gear clearance, one curved rib at the front top portion of differential, strong but no gears

Types of 9" Axles:
„h 28 spline axles cannot be shortened and resplined (they're tapered)
„h 72 and earlier 31 spline axles have the ability to be shortened
„h 73 and later 9" (cars) have a 5-on-5 bolt circle and the axles cannot be shortened
„h 67-73 Mustang axles identified by wheel flange:
„h oval hole - 28 splines
„h two large holes and counter sunk center - 31 splines

More Facts:
„h 5 on 5 lug pattern is a truck pattern
„h A 9" complete rear axle is approximately 35 pounds heavier than an 8.8 rear axle with approximately the same components.
„h It is common to find a 9" in a old Falcon or Comet that has had a HIPO SMALL block with 31 splines and a locker.
„h If the case has two verticle RIBS ,from top to middle of case it is a good IRON type IF in the very center of this case there is the letter "N" than this is a NODULAR CASE (GREAT) this is the strongest factory case made BY FORD!!!
„h The ranger truck works good with a 9" from a 64 to 71 Falcon, Comet, some 65 to 69 Mustangs or 64 to 67 Ranchero V8 cars.

 

I'm going to cut-and-paste some stuff I have saved on my email account. I apologize to the original authors for not giving proper attribution.

if you use the 57-72 F100 rearend, it is almost a
bolt-in. I just found out that if you use the driver's
side axle, backing plate, and drum from a 72-79
Torino, Ranchero,LTD II,or 77-79 T-bird or Cougar,
they will swap into the truck housing. That will give
you the car (4 1/2") bolt pattern

A 9" from a 57-72 F100 will bolt in (to a 53-56 F100). In fact,
if you have the
correct long yoke, the driveshaft will fit too. The axle housings
are bigger so the u-bolts and mounting plate will have to
account for that.

 

Hey Paul... I like the idea. I need more to do than clean my shop while I'm waiting on my front springs. Thanks for noticing a few threads back.
Let me wonder aloud about how '57-72 F-100 rearends with springs might work under a '54? How much adapting would it take to incorporate springs and all? Worth it? My spring supplier in PA doesn't do rear springs for my truck... so I'm seeking options that don't make a pair of rear springs cost me $400. Best. Himmelberg

 

The thread where I researched all the 4.5" axle lengths and other info to put into a truck 9" for Joe should still be in the archives.
If anyone has a particular question ask away, I have a Hollanders collection as well as a complete application tag decode for all 8 and 9" centers.

And dont knock the 8.8, they are quite rugged for a modest amount of torque.
BTW, a cheap and "secret" 8.8 source is rwd Volvos from roughly 77-96. Most ratios are in the 3.5 to 4.1 range, lockers and rear discs are fairly common. Early patterns are metric, after 87 they are Ford SAE. Widths vary a bit depending on brakes but most Ive used ( not in trucks tho) are about 54" between axle tube ends. Easy to remove the coil spring perches and add leafs. Fit is perfect under Model A and 30-50's Ford cars. Many retain the very rugged and visually appealing trailing arms.

 

Here's the thread Carl mentions.

https://www.ford-trucks.com/forums/s...threadid=53668

Also agree with carl on the 8.8. They'll take a good beating just like a 9 inch.

Peter,

I don't know what the spring hangers look like on a 57-72. You would have to use them if the springs are wider on the later model. (And I suspect they are) Biggest problem with this solution is you are going to have 30 year old springs when you're done.

 

Paul,

FYI -

I submitted a short tech article last Nov. (with an update approx. Feb.) on 9 inch rear ends and lowering alternatives specifically for the 53-56 F100s. I beleive it has some useful info in it (or I wouldn't have written it) but it was never intended to be the difinitive guide to 9"s....

I can send you what I submitted, so that you can use it as a guide to ensure your's is more thorough or takes a different approach to the subject.

Without any intent to p*ss off our host - here we are in June and it (my tech article) still isn't posted yet, so you may want to post it directly in this forum rather than submit it as a tech article.

Maybe Kenny could "sticky" it to keep it at the top of our forum....just a thought.....

If you want my pending tech article, send me yourhome email address to the_fergusons @ sympatico.ca

Regards,

 

'fenders, I can only pull up the last page of that thread, must be having a brain fart.

 

Carl

My bad, try this one.
https://www.ford-trucks.com/forums/s...Axle+%2BDebate

 

I cut and pasted the article that Carl searched for here:

From Joe (Blue Oval Rage)

After a satisfying evening in the shop, I finally have some preliminary results to share. For anyone who may have missed this in the previous two threads, it had been mentioned that the '77-'79 T-bird, Cougar, LTD II, Ranchero, and '73-up Torinos all had the same 9" rearend and the books showed that the left side axle happened to be nearly the exact same length as both axles in the '57-'72 F-100 9" that most of us seek out to bolt in to our earlier '48-56's. The debate was to whether or not the T-bird style axle would drop in to the truck housing to give us a 4 1/2" lug pattern to match all the popular Chrysler, MII, and LTD front IFS swaps for our trucks without getting our old axles redrilled or the use of dangerous adapters. Dad's '77 Cougar rolled (barely) into the shop tonight for a desperately needed tune-up and I "borrowed" the left axle out of it to find out once and for all if this will work. Here is what I found out:

1. I am pleased to announce that the Cougar axle is almost a dead ringer for the truck axle with the obvious exception of the flange diameter and lug pattern. They are both 28 spline axles and they both have the exact same wheel bearing. The length difference is negligible. At worst, the Cougar axle would have to be ground just a hair on the splined end to eliminate interference with the spider shaft in the differential, but I'm not certain. It may even be a tad shorter. I will be taking better measurements in the next couple of days and I will post more specifics then. The axle diameter was checked with calipers at the bearing end and they are identical meaning that the original seals in the truck housing will work.

Noted difference: The pressed-on bearing retainer ring on the Cougar axle is thicker than the truck retainer. I honestly can't see where this would make any difference as even the thick retainer would not intrude into the seal area.

2. The truck axle retainer plate uses larger bolts (7/16" I think) to secure it through the backing plate to the axle housing. The Cougar uses smaller 5/16" bolts. (I think - note to self: Pay more attention to bolt sizes.) The bolt pattern is also different. The simple solution here would be to use the truck retainer on the Cougar axle. The bearing and bearing retainer ring must be removed to do this, but after 25 years, new wheel bearings ain't a bad thing anyway.

3. The use of the car's backing plates and brake drums to maintain proper brake offset and parts compatibility was also debated. As mentioned above, the car's axle retainers and backing plates are drilled for smaller bolts and in a slightly tighter bolt pattern. This precludes the use of the car's backing plates on the truck housing without major rework. Since the whole point of this exercise is to find an option for those of us who are too lazy to have our axles redrilled and would rather put something together with standard parts, major rework isn't likely to happen. The truck backing plates will have to be retained.

4. As for the brake assemblies, they are the same diameter on both vehicles, so this shouldn't be a problem. The wild card here is the brake drum. I had initially thought that the simple solution would be to just redrill the truck drums in between the original larger 5 1/2" pattern to 4 1/2" and be done with it since we have to keep the truck's backing plates anyway. That would maintain all the proper offsets and compatibility. On closer examination, I noticed that since the axle flange is a smaller diameter on the car axle, the original 5 1/2" bolt circle on the drum would come close to falling around the edge of the axle flange once the drum was installed over the studs. This looks too much like a weak link in the drum to attempt it in my opinion. As if that wasn't enough, the big center alignment "dowel" on the axle flange is roughly 1/2 inch larger in diameter on the truck axle than the car's. That would force the wheel studs to bear the responsibility of keeping the drum centered over the brake assembly. Not good.

So where I am at so far is that assuming we re-use the truck backing plates and axle retainer plates, the Cougar style axle will work if we can identify a brake drum with the correct dowel diameter, lug pattern, and offset. The Cougar drum may work, but I have not gotten far enough to find out for sure yet. If it does not, I guess we are back to scrouging for a suitable drum. I will keep you posted on the rest of my findings. The Cougar is ailing of a sick carburetor and serious ignition woes, so I will have the axle at my disposal for a few days should someone want a specific measurement.

Special thanks to Carl for pouring over the Hollander books for me!!!! We might need help again on the drum before this is over.

After yet another successful evening playing in the gear lube (two good nights in a row - this is scaring me), I have the rest of the story.

First of all, I lied in the preliminary post. Tonight, I actually installed the Cougar axle in my truck housing. As I had mentioned, the bearing retainer plates are drilled on a different bolt pattern, but I found that if I rotated the plate a bit, I could get two small bolts through diagonally and get the thing fastened together well enough to see how it all fits. I immediately noticed some interference when I tried to turn the axle. I initially thought that it was the end of the axle binding on the spider shaft in the differential, but realized when I pulled it out that it was the bearing retainer collar rubbing against the wheel seal in the housing. I pulled the seal out and put the axle back in and everything was just hunky dory. Remember when I said that I didn't think that the thicker retainer collar would make a difference? Well, it does. The seal in the truck housing sits outboard about 1/2" more than it does in the Cougar housing. That issue is solved easily enough, though. The collar will have to be split and destroyed to remove the bearing and bearing retainer plate. When reassembling with the truck retainer plate and a new bearing, just use a new smaller collar designed for the truck axle. The axle shaft diameter and bearing part number is the same, so it will be a simple replacement swap. I will get pics off both axles and the dimensions of the collars posted tomorrow evening.

Next, the drum. With the axle installed in the housing, the first logical thing to try was putting the Cougar's drum on. This is too easy, guys. It absolutely fits like it was built that way. The offset spacing and clearance to the truck's backing plate is perfect. I even measured to make sure that the shoes would contact the drum in the correct place. The shoes center in the drum exactly.

So, in conclusion, here are the final results. The left side only axleshaft and either side brake drum out of a '73-up Torino or '77-'79 T-Bird, Cougar, LTD II, or Ranchero will install easily in a '72 Ford F-100 9" axle housing on either side assuming that you use the truck housing's brake backing plates and brake assemblies, axle retainer plates, and bearing retainer collars. This swap nets the common 4 1/2" on 5 lug pattern with the truck housing.

I should also mention that all the above mentioned cars have 11" x 2 1/4" brake shoes as did my '72 F-100 axle. As, Dewayne mentioned above, some of the trucks had narrower brake shoes, so your mileage may vary on parts fitment on other '57-'72 housings. I can only vouch for my particular housing. A quick glance in an interchange manual should confirm whether or not your rearend has the same backing plates, bearings, and housing as mine. If you are palnning this swap and have not yet acquired the truck housing yet, I would strongly recommend getting a housing with 2 1/4" brakes and as close to the '72 model year as possible. It looks like this may be the 9" rearend for the vintage effie's that Henry built and never knew it.

_________________
If WalMart is dropping prices every day, why isn't anything free yet?!?

All of the above was from Joe.

 

Paul,

Well you never asked for it so maybe you didn't want it, but since you're trying to gather all this info into a single thread - here's my pending "tech article" referred to above (very brief but hopefully of some value) -

"53-56 F100 Rear End Selection and Rear Suspension Lowering

The purpose of this article is to simply provide all the info I’ve gathered on the subject in one, easy to print document and share it with others with a common interest. The information was compiled from numerous sources including the FTE forums and;

- John’s F-Fun Hundred 2002 catalog
- RB’s Obsolete 2002 catalog
- Various websites with Ford rear end info
- WWW.F100Connection.Com website
- discussions in the FTE forums

None of it is original information. It was all gathered from the various sources listed above. While believed accurate, I make no promises it is. (I have tried to avoid the conflicting measurements offered in several different charts found on the web.)



Part 1 : Rear ends that “will” fit in 53-56 F100s ;

My 54 F100 measures 55” wide between the two narrowest points on the backing plates. The flange to flange measurement (drum face to drum face) is 61 ¼”. Based upon my “research”, these rear ends will work;

1. 1957 –1972 F100 9” heavy duty - 5 on 5 ½” bolt pattern
Bolts right in without moving spring pads.
Measures 61 ¼” flange to flange
To switch to the 5 on 4 ½” car bolt pattern - Use two driver’s side axles, both side backing plates and drums from 72-79 Torino, Ranchero, LTD II or 77-79 T-bird or Cougar on/in the truck axle housing. See more detailed discussion on this in the 48-60 Ford truck forum on FTE.

Above is the number 1 choice for ease of installation , price and availability.
It doesn’t get any easier than this.

2. 1971 – 73 Mustang & Cougar. 9” , but lightest duty of the 9” family.
Have the 5 on 4 ½” pattern
Measures 60” flange to flange
Measures 54 – 55” backing plate to backing plate.

Comes with both 28 spline axles (weaker) and 31 spline axles (stronger)
Oval hole in outer end of axle = 28 spline
2 large holes and counter-sunk center = 31 spline

Above is probably number 2 choice for ease of installation and price.



3. 1989 – 2001 - Ford Explorer – 59 ¼ - ½” flange to flange.
All explorer rear ends are the same 5 on 4 ½” bolt pattern.
8.8” rear end - come with 3.25, 3.55, 3.73 and 4.11 gears.
89-94 = drum brakes only.
94-97 = drum or disc. brakes
97-01 = disc. Brakes only
Can use an 8” rim with 3 ½” backspacing and P235/75R-15 tires

Above is probably number 3 choice for ease of installation and price.


4. 1989 Lincoln Mark VII (per F100Connection.com)
(bolt pattern unknown by the author.)
Dimensions unknown by me.


5. 1968 – 1971 Torino/Fairlane/Montego – 9” but medium duty
Measures 56 – 57” backing plate to backing plate


6. 1960-64 Ford Galaxie 9” medium duty
Measures 54” flange to flange ?


7. 1979 Ford F100 is “ a little wide” but apparently is supposed to fit


8. 1970 –79 Ranchero/Torino 9” high performance version
Measures 56” axle tube to axle tube.

Part 2: Methods for lowering ride of 53-56 F100s;

In my particular case (a 1954 F100) the bottom edge of the extreme rear end of the frame is 17” from the ground. The bottom edge of the running board braces are 13-13 ½” off the ground. Additionally, the present distance from the top of the rear end housing to the bottom of the frame directly above the housing 8 ½” with the rubber stop reducing that by 2” to 6 ½” of upward suspension travel (not including crush on the rubber stop). The axle housing is mounted below the springs. 8 leaves with a total thickness of 2 ½” and the spring perch height is aprox. 1 “.


Here are the various avenues for lowering the rear suspension that I am aware of;

1. Remove every second leaf from the rear springs (removing a total of 3 leaves). According to Mid-Fifty, keep #1,3,5,7and the main leaf. In theory this will lower the rear end approx. 0.31 “. In reality it might yield a fraction more as it will soften the suspension. Cost is near zero.

This should not alter the pinion angle. DROP = 0.31 - 0.50 inches

2. Utilize 2” lowering shackles on the rear mounting end of the rear springs. It is recommended that this be combined with moving the front spring shackle up approx. 1 ½” (necessitates drilling new mounting holes in the frame). This latter step will help to avoid altering the pinion angle. The shackles run approx. $90.00 USD a pair circa 2002.

This may result in the upper edge of the rear shackle coming into conflict with the bottom of the bed floor & may impact pinion angle.

DROP = 1 ½ - 2 inches

3. Combine alternatives # 1 & 2 above for approx. 2 to 2.5 “ drop .

4. Utilize mono-leaf rear springs. Available from several sources including John’s F-Fun Hundreds & Vintage Ford . This should yield a drop of 2 – 3”.
These run approx. $350.00 USD a pair circa 2002.

Mono leaf springs are available with regular eyes for 2-3 inches of drop and reversed eyes for an additional 1 & ½ inch or aprox. 3.5 to 5.0 inches total. If using the reversed eye mono-leaves, it is recommended you flip the front shackle mount upside down to avoid the spring binding on the shackle mount.

DROP = 2-3 inches with regular eyes.
DROP = 3.5 to 5.0 inches with reversed eye monos.

All methodologies above keep the axle below the spring assy.


5. Another alternative is to mount the differential housing on top of the rear springs rather than it’s stock location under the springs. Cost is a bit of welding to move the spring perches from the top of the axle housing to the bottom.

DROP = 4 – 4.5 inches

6. Combining #5 above with reversed eye main leaves would provide further drop but now you’re getting into the area of ground scrapping.

DROP = aprox. 6 inches

I am led to believe that a minimum of 3” travel is required to provide safe and comfortable handling in everyday driving situations. Any of the above combinations that reduce the suspension travel (distance between bottom of frame above the differential and the highest part of the differential/springs immediately below the frame) to 3” or less should be accompanied with C-sectioning the frame;

The March 2002 issue of StreetRodder has an article involving No-Limits Eng. doing it in one manner. Apparently they also offer a kit. Don’t know the price or whether it bears any resemblance to the manner used in the magazine article. Hopefully not…..requires extensive welding.

RB’s Obsolete Auto also offer a “kit” that can be adapted to the frame with some welding and cutting. Doesn’t say in their catalog, but it looks like it would give back about 1 ½” of travel. Cost is approx. $110.00 USD . RB’s alternative is the more traditional approach and looks good (cosmetically).

Looking at a picture of either alternative will quickly reveal that C sections aren’t rocket science. It wouldn’t be that difficult to make your own. But unless you have easy/free access to steel, it would be hard to beat RB’s price. "

There you go.........

Later,

 

RMF

Please don't let the following comment take anything away from you. The tech article is excellent. I am hitting the print key for sure.

I do disagree however that pulling 3 leaves only drops you .31 inches. I know you said in theory but not even sure why it would in theory. A leaf is far thicker than .10 inches. (Isn't it? Not that I measured one, but .31 just sounds way off). I believe in reality, you definitely get in excess of an inch drop with the three leaf trick.

One other point would be your comment about pinion angle. If you just installed a 9 inch, you probably already altered your pinion angle just a bit. It should always be measured in any case when you start the major mods like this. Not that you advised against verifying. You might just find that moving the rear or front mount will aid you in achieving correct pinion angle.

 

'fenders,

No offense taken - constructive criticism is always apreciated (or at least accepted gracefully)

"I do disagree however that pulling 3 leaves only drops you .31 inches. I know you said in theory but not even sure why it would in theory. A leaf is far thicker than .10 inches. (Isn't it? Not that I measured one, but .31 just sounds way off). I believe in reality, you definitely get in excess of an inch drop with the three leaf trick.
"

You're right. It's been so long since I actually wrote the article, I can't recall how I would have made the error. Perhaps the thickness of one leave was approx. 0.31" and I forgot to multiply by the number of springs being removed. Although 1/3 " seems too thick for a single leaf..maybe not...????????

I know that I said "in theory" because removing leaves should make it sit a little lower than just the thickness of the leaves removed due to the reduced overall resistance to spring sag due to removing said leaves. (Did that make sense or did I just talk in a circle?)

My bad.

I sort of agree with your comment on pinion angle. With the exception of the 57-72 9" which fits without even moving the spring pads(which may or may not give you correct pinion angle), virtually every other 9" would require new spring perches, which means you'd be setting your perches for proper pinion angle before you welded them to the housing anyway.

(Too bad I didn't vet this info against you guys before I submitted the article....oh well....)

With regard to the weather - Ironic isn't it. Most of Jan. and Feb. was minus 20 degrees celcius (approx. 200 below farenheit) - too draned cold to be trying to heat the garage and now we've had plus 34 degrees (approx. 212 degrees farenheit) for the past four days and expected for another 3 days......

 

(approx. 212 degrees farenheit) for the past four days and expected for another 3 days......

RIIIIIIIIIIIIIIIIIIIIIIIIIGHT!!! If you say it was 212F in Canada this week, then it must be so. Far be it from me to argue with somebody who's right there.

How are the pine trees holding up? Gardening must be easy this year. Straight to the table and add a little seasoning of your choice,

'fenders

What are we going to do with these metric boys George?

 

O.K. maybe I got the conversion factor wrong, but at least 160 F.

It's so hot the needles are drying up and dropping off the pine trees. This is bad cause it removes the air cover from the main crop. Makes it easier for the helicopters to see our special herbs.....


Did you know that it's illegeal for the weather man or radio/tv stations to state the weather in both Celcius and Farenheit here in Cda? They can only state it in Celcius. It's to try to force us children of the 60's to embrace the metric system. Yah I'll embrace it. Embrace this!

Gotta go, I hear a helicopter again.