So, today, I bought a 9" rear end with an open 3:50 gearset. I though about using it in my '66 Mustang. But I'm trying to find out what it was originally in. It is right at 57.5 inches from brake drum mounting flange to flange. The leaf centers are around 43", maybe plus a bit. The tubes are tapered on the ends but not as small as an early Mustang housing. Could this be an early Bronco housing?
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Newbie here with a parts question. Diff.
- Thread starter rose62
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Hey rose62, welcome to classicbroncos!
Never bothered to memorize the axle dimensions on these things for some reason. Always relied on the others to do it! Plenty of members have that info off the top of their heads though, so you should get an actual answer at some point.
In the meantime, just bumping this back to the top.
Does it happen to still have the data tag under one of the bolts on the center section? Someone might be able to decode the numbers from that to get an exact model and year possibly.
Also, if it still has axle shafts then the Bronco and F100/150 bolt pattern is 5 on 5.5 vs the much smaller Mustang bolt pattern. Isn't the Mustang in '66 a 4-bolt pattern anyway?
Good luck.
Paul
Never bothered to memorize the axle dimensions on these things for some reason. Always relied on the others to do it! Plenty of members have that info off the top of their heads though, so you should get an actual answer at some point.
In the meantime, just bumping this back to the top.
Does it happen to still have the data tag under one of the bolts on the center section? Someone might be able to decode the numbers from that to get an exact model and year possibly.
Also, if it still has axle shafts then the Bronco and F100/150 bolt pattern is 5 on 5.5 vs the much smaller Mustang bolt pattern. Isn't the Mustang in '66 a 4-bolt pattern anyway?
Good luck.
Paul
Thanks for the reply DD. Yeah I'm really confused about this rear. It measures like an early Mustang (the V8 cars are 5-lug and 4.5" bolt centers) except that the tubes are larger. It has the hump on the housing and no fill plug. Early Mustang 9" units were smooth on the back with a fill plug. The guy said that it had been in an early Comet but the back of the housing would indicate that it was originally installed in a later model. I am going to remove the axles and brake backing plates and get some accurate measurments. On this page, https://maliburacing.com/ford-nine-inch-g-body/, about halfway down the page, in the section about housing i.d., there's a photo with the caption, "note hump in the middle," that looks like the housing that I have. It is said to be from a Bronco. On an early Bronco, what is the overall housing length and the distance between centers of the leaf springs? Thanks for any help. Oh, no data tag. But as I may have mentioned, it's a 3:50 ratio, open diff.
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Sounds like a Bronco then. The larger tubes (3.25" diameter by any chance?) are the "truck" size, where the cars were 3.0" diameter.
Only the '66 Broncos still had the fill plug in the housing and no fill in the chunk/3rd member. After that there were no truck housings that had any opening in the housing other than the vent on top.
A 3.50 was probably not that common on passenger cars, but it was the base gearing for all the 4-wheel drive trucks. If it's a stock bronco still, it's got 28-spline axle shafts and we can compare measurements on the chart we have for axle lengths of the various years.
Another thing with the truck housings is the big-bearing and small-bearing ends. With yours sounding like a small-bearing (better for a car anyway I would think).
Here are some bolt patterns for the housing ends/backing plates for the Broncos: https://www.wildhorses4x4.com/category/bronco_rear_axle down near the bottom right of the page you can see the diagram in the section for the retainer plates.
There were very slightly different length axles (based on brake offset) for the different Bronco models too.
I'll go measure my spring perch width if nobody comes up with an answer. I've seen it here hundreds of times, but as said I never remember them!
I could be wrong, but I thought all 9" rears had the hump in the back after a certain year. The smooth back was a throwback to the old 8" housing probably, but I've never researched it. It was probably a necessity for the trucks with their often lower gear ratios.
You can still buy the smooth centers (or at least you could a few years ago) from places like Currie Ent. for doing religious restoration, or if you just like the smooth look as many hot-rodders do.
Personally I like the hump because that's what I'm used to, and I believe it adds some structural rigidity to the housing overall. Not necessarily a deal-breaker for a lighter car, but for a race car or heavier truck, the added strength would be a good thing.
Paul
Only the '66 Broncos still had the fill plug in the housing and no fill in the chunk/3rd member. After that there were no truck housings that had any opening in the housing other than the vent on top.
A 3.50 was probably not that common on passenger cars, but it was the base gearing for all the 4-wheel drive trucks. If it's a stock bronco still, it's got 28-spline axle shafts and we can compare measurements on the chart we have for axle lengths of the various years.
Another thing with the truck housings is the big-bearing and small-bearing ends. With yours sounding like a small-bearing (better for a car anyway I would think).
Here are some bolt patterns for the housing ends/backing plates for the Broncos: https://www.wildhorses4x4.com/category/bronco_rear_axle down near the bottom right of the page you can see the diagram in the section for the retainer plates.
There were very slightly different length axles (based on brake offset) for the different Bronco models too.
I'll go measure my spring perch width if nobody comes up with an answer. I've seen it here hundreds of times, but as said I never remember them!
I could be wrong, but I thought all 9" rears had the hump in the back after a certain year. The smooth back was a throwback to the old 8" housing probably, but I've never researched it. It was probably a necessity for the trucks with their often lower gear ratios.
You can still buy the smooth centers (or at least you could a few years ago) from places like Currie Ent. for doing religious restoration, or if you just like the smooth look as many hot-rodders do.
Personally I like the hump because that's what I'm used to, and I believe it adds some structural rigidity to the housing overall. Not necessarily a deal-breaker for a lighter car, but for a race car or heavier truck, the added strength would be a good thing.
Paul
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Doing a quick eyeball with a floppy tape measure, I get approx. 35.5" between locating holes in the spring perches, and approx. 53" wide inside the brake backing plates, flange-to-flange.
With an added four inches, yours could be out of a big passenger car or even a full-size pickup truck.
The wheel bolt pattern would indicate a truck or not, as those are the only ones with the 5 on 5.5 bolt pattern.
On a side note the smooth housing you reference for the older cars is nicknamed the "Banjo" style, which has basically morphed over to the later housing with the bump-out on the back. Because the overall profile is the same, nobody seems to have worried overmuch about the naming.
The '77 Broncos, and the later seventies full-size trucks had the "Heavy Duty" housing where the center section of the housing tapered down more gradually, leaving a wider center housing for more strength. Looks like this in the center: https://www.wildhorses4x4.com/category/Bronco_Rear_Housing
The line illustration above shows the early Banjo style, where the #8689 housing uses the HD center. Then there are the fully fabricated housings such as the #8657.
Again, all truck housings used the 3.25" diameter tubes originally. Nobody reproduces the truck centers now, so all modern built housings are the 3" diameter version.
Fabricated housings usually use 3.5" diameter tubing for the most strength.
Paul
With an added four inches, yours could be out of a big passenger car or even a full-size pickup truck.
The wheel bolt pattern would indicate a truck or not, as those are the only ones with the 5 on 5.5 bolt pattern.
On a side note the smooth housing you reference for the older cars is nicknamed the "Banjo" style, which has basically morphed over to the later housing with the bump-out on the back. Because the overall profile is the same, nobody seems to have worried overmuch about the naming.
The '77 Broncos, and the later seventies full-size trucks had the "Heavy Duty" housing where the center section of the housing tapered down more gradually, leaving a wider center housing for more strength. Looks like this in the center: https://www.wildhorses4x4.com/category/Bronco_Rear_Housing
The line illustration above shows the early Banjo style, where the #8689 housing uses the HD center. Then there are the fully fabricated housings such as the #8657.
Again, all truck housings used the 3.25" diameter tubes originally. Nobody reproduces the truck centers now, so all modern built housings are the 3" diameter version.
Fabricated housings usually use 3.5" diameter tubing for the most strength.
Paul
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Oh, and the leaf centers of yours, at 43" or so, are again consistent with a full-size truck that has a 37.5" wide frame to the outside. Add the size of the spring hangers to that, and 43 inches is a pretty close match.
I guess the bad news is that it's probably too wide for a Mustang if used as-is, but the good news is that a full-size truck differential could be 31-spline already, and you can pretty much build one up from scratch to match.
New housing ends welded on to shortened tubes, reinforcements and skid plates if it's going into a race vehicle, 31 and even 35 spline axle shafts, and whatever gear ratio you want.
A 3.50 would be quite an uptick in acceleration over a 3.0 or 3.2 series gear setup.
Unless you want the old Drag-Pack options like 4.11's or something low like that!
Paul
I guess the bad news is that it's probably too wide for a Mustang if used as-is, but the good news is that a full-size truck differential could be 31-spline already, and you can pretty much build one up from scratch to match.
New housing ends welded on to shortened tubes, reinforcements and skid plates if it's going into a race vehicle, 31 and even 35 spline axle shafts, and whatever gear ratio you want.
A 3.50 would be quite an uptick in acceleration over a 3.0 or 3.2 series gear setup.
Unless you want the old Drag-Pack options like 4.11's or something low like that!
Paul
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Ok, so a wider reference point. I couldn't do that since wheels and tires were in the way. But you could get a housing end to housing end measurement and compare.
Generally speaking, although the differential spline counts are the same, the axles are NOT interchangeable between most vehicles because of their overall length AND their brake offset.
Even among Early Broncos you can't change axles from one model to the other because the brake drums will not fit properly on the backing plate. Even the housing flange bolt patterns were different between the different setups. Big brakes, small brakes, big bearing, small bearing, "medium bearing" (big bearing, small brakes) are different so you can't always just bolt on a big brake setup on a small bearing setup. And vice versa.
I have a set of cut down and re-splined full-size 31-spline axles that I fitted into my '71 and then realized that the drums did not fully encompass the brake shoes because the Bronco had the narrower shoes and the pickup had the wider shoes.
So long way of saying, some will swap, but most will not.
Paul
Generally speaking, although the differential spline counts are the same, the axles are NOT interchangeable between most vehicles because of their overall length AND their brake offset.
Even among Early Broncos you can't change axles from one model to the other because the brake drums will not fit properly on the backing plate. Even the housing flange bolt patterns were different between the different setups. Big brakes, small brakes, big bearing, small bearing, "medium bearing" (big bearing, small brakes) are different so you can't always just bolt on a big brake setup on a small bearing setup. And vice versa.
I have a set of cut down and re-splined full-size 31-spline axles that I fitted into my '71 and then realized that the drums did not fully encompass the brake shoes because the Bronco had the narrower shoes and the pickup had the wider shoes.
So long way of saying, some will swap, but most will not.
Paul
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- 49,228
The older Ford Rangers were that wheel bolt pattern, and might even have been close to this in width, but they did not have 9" rear ends that I'm aware of. Only the 7.5 and 8.8's I'm pretty sure.
So still seems like a big T-bird or station wagon maybe.
What about a pinion snubber? Does the pinion yoke have a big flat plate almost covering the top of it? Looks almost like a protective plate, but it's a bump-stop landing.
Paul
So still seems like a big T-bird or station wagon maybe.
What about a pinion snubber? Does the pinion yoke have a big flat plate almost covering the top of it? Looks almost like a protective plate, but it's a bump-stop landing.
Paul
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Welcome aboard Rose.. You got the right old timer dude w/the knowledge to keep ya moving..
Get out to your bronco events near you and put faces to the names..
Removed an axle today. 53" overall length. 43" leaf centers. 28 spline axles. And the end boss doesn't match any illustration that I've found on line.
https://www.facebook.com/photo.php?fbid=3810630258964066&set=a.132567040103758&type=3&theater
and this. https://www.vintage-mustang.com/cdn...stang.com/attachments/ford-9-inch-jpg.763528/
Photo on my facebook account.
https://www.facebook.com/photo.php?fbid=3810630258964066&set=a.132567040103758&type=3&theater
and this. https://www.vintage-mustang.com/cdn...stang.com/attachments/ford-9-inch-jpg.763528/
Photo on my facebook account.
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Looks like an older end to me. Don't see many of them around anymore, and maybe that's another point in favor of it being a passenger car or 2-wheel drive truck.
Passenger car likely did not have leaf springs, but perhaps some still did back then?
From these diagrams it kind of looks similar to the old big bearing setup, but not exactly like yours. But maybe you can see something in these images:
At least you can compare dimensions, if not the precise shape of the housing end.
Paul
Passenger car likely did not have leaf springs, but perhaps some still did back then?
From these diagrams it kind of looks similar to the old big bearing setup, but not exactly like yours. But maybe you can see something in these images:
At least you can compare dimensions, if not the precise shape of the housing end.
Paul
