The answer is maybe....you have to pay attention to the spline count on the axles. There are 32 spline and 28 spline axles. The 32 spline units are generally tougher.

What are you using for power in your truck? That 8.8 is a pretty tough rear end and the price is right if you already have it.

Dan

 

351w, alum heads, comp cam, bored and honed. That's all I know. It came from PO rebuilt by machine shop. I have the paperwork. Don't know what size cam though. Gonna buy custom axles from moser. Can I run a 31 spline 3rd member with 28 spline axles? Sorry more dumb questions...

 

your spline count has to match (for pretty obvious reasons when you think about what turns what inside there) - 28 spline is super common in the years we have as donor options. 31 spline is super rare for donor but super popular for aftermarket parts, welcome to the delima many of us are in. If you have M$ XL take a look at the spreadsheet I put together:

http://www.brainsbivouac.com/cars/19...20Database.xls

 

No....the receptacle that the axle slides in to is unique to the axle...I mis stated the spline count...you're correct the spline count is either 28 or 31. Both are tough, but the 31 spline units are tougher and are usually used for trucks and high performance cars. To answer your question, no...they are not interchangeable. The 31 spline axles also tend to have bigger bearings, so that could hinder your ability to use any third member with any housing.

I used a stock 9" from a 65 F100 with 28 splines. I also have a 351w, but it is basically stock. So far it is working well. By the way, I went for driveability, so I kept the stock open differential....so it's a 1 wheel drive truck.

 

The spider gears would need to be the same number of splines for the axles to interchange.

 

... and they need to have the same kind of bearings. Some have parallel rollers, some have Timken-style tapered, plus there are different diameters.

 

Ross, Which bearings are you referring to that would make a difference in swapping out an entire pumpkin or carrier from one axle housing to another?
I meant the number of splines in the spider gears in the new carrier must match the spline count of the axles (typically 28 or 31) in the housing for the axles to go back into the spider gears. As long as you are using the same axles and axle bearings that were originally in the housing, the type or size of the axle bearings doesn't matter. You do not need to swap axles to swap pumpkins unless the spline count doesn't match. You are correct that if you switch axles, you need to match axle bearings to the housing.

 

Not a factor for the center section, but if you were switching axles out. I think he wants to do that to get the bolt circle he wants?

 

I think it is about time someone added this link:
Kevinstang's Ford Nine Inch Differential Page + (oh wait it's already been linked above

lots of "early research" questions here - basics about 9" like what differences are, what swaps, etc - time to point the PO to the basics....

and I'm sure what Ross was referring to was not carrier swap, but axle swap (1st and 17th post the PO suggests swapping axles [on that kevin page about half way down he clearly shows the different axle bearings side by side - right above the taper picture]).


[edit] typing at the same time, Ross beat me to it

 

If he is going to get Moser custom axles he can get them with any bolt pattern, but he will need to know how many spline spiders are in his centersection (you can put 28 or 31 spline spiders in any 9" pumpkin, but it will require dissassembling the centersection to change them. He will also need to know the axle length(s) (some 9" housings are asymmetrical, and use two different length axles) and the axle bearing type and diameter. If he gets custom axles with a non standard bolt pattern he will also need to get brake drums that work with the backing plates and are drilled to the same pattern. Currie offers drums that are undrilled and will drill them to any pattern. Note that there are 3 different brake shoe widths that came on 9" housings. When ever you start making modifications, the other needed changes keep snowballing. Ain't this hobby fun!?!?

Jrock, I suggest you back up and first figure out exactly what you have now, and then decide if you really need to change it.
1. do you have an 8", an 8.8" or a 9", and what year? Look at the reference articles and pictures as well as wheel mounting surface to wheel mounting surface widths to figure this out.
2. Does the current axle have drum or disk brakes?
3. What is the current bolt pattern? (easy way to determine bolt pattern: measure from the far outside edge of one stud to the center of the next stud. That measurement = the bolt circle.)
4. Jack up one rear wheel with the other on the ground and the truck in neutral. Can you turn the raised wheel in either direction? If you cannot turn the wheel, you probably have a locked or spooled differential (a spool replaces the spider gears with a solid piece that constantly drives both wheels). A rear axle is sometimes locked by welding the spiders to the carrier (sometimes called a backyard or goobered spool). You do NOT want to drive a locked rear axle on the street! If the axle is not locked, jack up the rear axle so both wheels are off the ground, and again try turning one wheel. The other wheel should turn in the opposite direction if you have an open differential (OK for street driving, most cars and trucks have an open differential) If both wheels turn in the same direction you probably have a limited slip differential (desirable but not necessary unless you are going racing, off roading or plan on driving in mud or ice/snow)
5. If the axle is an open or limited slip differential, drop one wheel back touching the ground, and put a chaulk or tape mark on the tire sidewall and one on the pinion U joint or driveshaft. Turn the wheel exactly 10 revolutions while counting exactly how many revolutions the pinion or driveshaft turns. If it turns 37 times, you have a 3.7:1 rear axle ratio, if it turns 41 and a little more you have a 4.11:1 ratio, if it turns 32 times you have a 3.2:1 ratio, etc. Make a note of the ratio.
6. Measure the front axle bolt pattern. If the front and rear pattern are different decide which you prefer. Note, if you use the narrower 8.8 out of an explorer, you will likely want the use wheel spacers to move the wheels outwards. If so, you can get the spacers with 2 different bolt patterns to adapt the axle to use whatever wheel bolt pattern you'd like, killing two birds with one stone! Another advantage of using the 8.8 axle!
When you get all the above answers come back and post the results here for more help.

 

indeed, hence I spent the time looking up specs and figured out the long list of donors (shoebox broncos, torinos, cougar, mustang, van, etc etc) - take a whole stock axle and swap it keep the same pattern etc, save a TON of money on snowball.

 

I have an 8.8 from a lincoln mark vii or viii(can't remember), the gears are 3.25 or close,(3 and 1/4 turns), bolt pattern 5x4.5 all four wheels, disc brakes all the way around, prob limited slip diff(haven't checked it), Garbz is donating a 9" housing(early 70's ford truck)and disc brake calipers, I have to find a 3rd member. Looking for 3.50 with track loc limited slip. Called Arizona differentials and they can set me up for $650 for a 9" 3rd member. Cleaned and inspected with correct gears and limited slip. Then we can order correct moser axles (depending on 28 or 31spline 3rd member). Down the road eventually, wanna go bigger and badder motor. Can't thank u guys enough for the knowledge and information

 

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This was the question guys, nothing about axles. Granted it may have been the next question but it was not the one he asked. So, to answer the question YES. You can put any year 9" third member in any year 9" housing. Axles are a different issue that so many have already touched on.

 

Hey Jrock,
Sounds like you have a plan. Just for information purposes - we are running a 351W with an Edelbrock top end kit - 400hp. We are using an 8.8 axle out of a 2001 Explorer with limited slip & 3.73 gears - I haven't noticed any problem with this set up. We cruise for the most part so we aren't running it hard - though my son is (21) so I'm not going to take an bets.

Good luck over there.

Ben in Austin
1950 F1