9" rear ends?
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9" rear ends?
A couple weekends ago I managed to blow apart the diff housing in my 78 F100 2WD. I pulled it apart and found a 28 spline diff housing and axles, non track lock. Now it has been a lot of years since I last worked with these rear ends and have forgotten most of the details. Now I'm counting on you guys to fill in the blanks for me. I found a guy with another 9" from a Crown Victoria police car which includes the housing, drums and all with 31 splines. Do you suppose the axle shafts are the same length and that it would have the track lock diff housing? It also has a 3.50:1 gear ratio, but I have a bran spanking new 3.89:1 ratio ring and pinion I was going to put in my truck before the spider blew. Will they fit the 31 spline diff housing? I'm going to be calling the guy back today to ask what year Crown Vic the axle come from. Assuming that will matter. I'm assuming that this will all work, but I want to know for sure before I spend the dough. It would be nice to upgrade my rear to the beefier 31 spline.
Thanks for any info,
Bill
Thanks for any info,
Bill
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Joined: Nov 2007
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From: Montgomery, IL
Hmmm, what year CV are you looking at? The newer ones have 8.8 rears I believe. You would have to go back several years to find a 9 inch in a CV.
What were you doing when the rear blew? Were you off-roading and abusing the truck or were you cruising down the highway? The reason I ask is that a 9 inch is pretty strong and can take abuse, even the 28 spline. A 31 spline is better but again, how are you using your truck?
Does this 'new' rear come with the axle shafts? I can't tell from your question. There are different length axle shafts and different center section offsets for various vehicles, You will have to measure everything.
The easiest thing to do is find an axle out of a truck at the junkyard.
What were you doing when the rear blew? Were you off-roading and abusing the truck or were you cruising down the highway? The reason I ask is that a 9 inch is pretty strong and can take abuse, even the 28 spline. A 31 spline is better but again, how are you using your truck?
Does this 'new' rear come with the axle shafts? I can't tell from your question. There are different length axle shafts and different center section offsets for various vehicles, You will have to measure everything.
The easiest thing to do is find an axle out of a truck at the junkyard.
Hotshot
Joined: Feb 2004
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From: The Shenandoah Valley
You aren't going to find a Crown Vic with a 9" rear axle that came that way, police car or otherwise.
Most police cars did NOT have a locker or posi, etc.
Here is a good page on 9" rears:
Kevinstang's Ford Nine Inch Differential Page +
Most police cars did NOT have a locker or posi, etc.
Here is a good page on 9" rears:
Kevinstang's Ford Nine Inch Differential Page +
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Hmmm, what year CV are you looking at? The newer ones have 8.8 rears I believe. You would have to go back several years to find a 9 inch in a CV.
What were you doing when the rear blew? Were you off-roading and abusing the truck or were you cruising down the highway? The reason I ask is that a 9 inch is pretty strong and can take abuse, even the 28 spline. A 31 spline is better but again, how are you using your truck?
Does this 'new' rear come with the axle shafts? I can't tell from your question. There are different length axle shafts and different center section offsets for various vehicles, You will have to measure everything.
The easiest thing to do is find an axle out of a truck at the junkyard.
What were you doing when the rear blew? Were you off-roading and abusing the truck or were you cruising down the highway? The reason I ask is that a 9 inch is pretty strong and can take abuse, even the 28 spline. A 31 spline is better but again, how are you using your truck?
Does this 'new' rear come with the axle shafts? I can't tell from your question. There are different length axle shafts and different center section offsets for various vehicles, You will have to measure everything.
The easiest thing to do is find an axle out of a truck at the junkyard.
No the truck hasn't been abused or anything drastic. At least not anything out of the ordinary in the past 7 or so years I've had it. I did put in a 351W with MEFI and an E4OD a few years back. But I would think even the 28 spline could handle that. It has also been being used to haul a small excavator and a lot of scrap to the junkyard this spring. It has been loaded down pretty good, but still hasn't been squatting from the load and the trailer. It hasn't been any more than a few tons at a time. I also have to remember that the truck is 33 years old too.
I do remember all that stuff from many years ago from when I had a bearing seize up in my 66 ranchero and lost a wheel while going down the highway. That's when I learned about all the difference between one rear and the other. But I couldn't remember all the details. for sure. Now days I can't remember if I'm thinking about the 8", 8.8" or the 9". I was thinking there was the 8" or the 9" that look similar. But now I keep seeing 8.8". And now I don't know anything for sure anymore.
More Turbo
Joined: Apr 2004
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From: nortonville illinois
ALL 79+ crown vics had 7.5 or 8.8's in them. plus if you tried them youd find they were a 4 link houseing not a leaf sprung like the truck, ford fullsize cars quit running leaves in 65 if i recall.
to find a 28 spline axle look in lincolns, ltds, t birds, and cougars up till 79.
to find a 28 spline axle look in lincolns, ltds, t birds, and cougars up till 79.
Super Moderator
Joined: Apr 2004
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Forget the car axles. Millions served in trucks. Watch for PM.
8 inchers, think small cars like Mustang, Comet, Falcon, Maverick, Grandad.
9's, big cars, F & E 100/150s up to '86.
Both are drop out carriers.
8.8s are integral carriers and you will want to steer clear--not going to be an easy swap in for you.
You want a 31 spline 9er from a truck. 28s do break, 9s do break, so go with the stronger unit.
8 inchers, think small cars like Mustang, Comet, Falcon, Maverick, Grandad.
9's, big cars, F & E 100/150s up to '86.
Both are drop out carriers.
8.8s are integral carriers and you will want to steer clear--not going to be an easy swap in for you.
You want a 31 spline 9er from a truck. 28s do break, 9s do break, so go with the stronger unit.
More Turbo
Joined: Apr 2004
Posts: 673
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From: nortonville illinois
if im not mistaken the 28s in the f100s were an offset houseing where the 31 splines were not. and some lincolns had a 31 spline in them ( if im not mistaken they were were in 9 3/8s houseings)
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Thanks for all the input thus far guys, this is the memory boost I was needing, and the kind of info I was looking for. I knew this was the right place to go.
I have a loaded diff housing I found on ebay that should be here early this week.
But I will also be looking to track down 31 spline shafts and diff for an upgrade later down the road as well as a drum to disc upgrade as well. Not many of those big old cars with the discs on them left around the yard in my area anymore, so I'm sure I'll have to go through Summit or the like. What are the good kits? What kits should I stay clear of?
Thanks,
Bill
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Got my diff case delivered yesterday and got it cleaned up and ready to go. Now does anybody have the torque specs and such for the 9" 28 spline so I can put the new ring and pinion in? Or know where to find them? Otherwise I may just have to go out and buy a manual. That is if one is easily available around town.
Also, what does the tool look like for tightening the "adjusting nuts"?
Bill
Never mind, I found the torque specs in "Ford 9 Inch Rebuild/Gear Setup" after searching for a bit more. I didn't see them the first time I skimmed through it. But I still can't find anything on how tight the "adjusting nuts" should be.
Also, what does the tool look like for tightening the "adjusting nuts"?
Bill
Never mind, I found the torque specs in "Ford 9 Inch Rebuild/Gear Setup" after searching for a bit more. I didn't see them the first time I skimmed through it. But I still can't find anything on how tight the "adjusting nuts" should be.
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