Nine inch housings

Ok well i am in the market for a nine inch for my falcon. Obviously any nine inch i get will most likely need to be shortened and as such i was researching a little about this.

Basically what i found is that 31 spline can be shortened but 28 spline either cant if its early or cant at all. Now is this just the axle shafts and not the housing? Can i run 31 spline axles if the housing originally had 28?

I'm asking because finding a housing isn't the hard part, its knowing if i can shorten it. If all i need to do is get new (made to fit) axle shafts thats no big deal to me but what else should i look for in terms of being able to shorten it.

I'm not too worried about whether its an N case or a War case or what not, i don't plan on running much more if more at all then 300RWHP, but i want to build the car at least somewhat right the first time and have piece of mind when i am driving it that i'm not gonna break something.

All 9's can be shortened. The spline count depends on the spool carrier and bearings....someone correct me if im saying this wrong, im no expert. All 9" housings can be shortened and run any spline.

The two types of 9" are small bearing housing and large bearing housings. The large bearing housings require a large bearing brake backing plate, whereas the 9" small bearing housing will utilize 8" brak e backing plates. making the swap easier.

Im building my 9" right now, I found a 69 mustang housing and I relocated the spring perches and put in 31 spline mosiers, with a 31 spine posi carrier. Good to go.

Both the 8 and 9 inch housings can be narrowed , WhaT is ment by not being able to narrow them is the Axels on the early 8 and 9 inch rears can not be re-splined because the axel tapers to small to except the new spline . I have had some axels re-splined and had hardening problems with them , some were to soft some were brittle.

If I was building a light car like a falcon I would go with a 8.8 they can built to handle nearly as much power as a 9" but do not take take as hp to turn. A 8.8 will take 300rwhp with ease. If your set on a 9" any housing can be shortened and you can get custom lenght axles made for around $300.00.

I run stock replacement 31 spline Mustang axles in my 59' 9" rear that originally had 28" spline axles. No problems what-so-ever.

Originally Posted by dennis111

I run stock replacement 31 spline Mustang axles in my 59' 9" rear that originally had 28" spline axles. No problems what-so-ever.

Stock replacements?

1965-66 mustang width housings never came with 31 spline axles. Back before I got smart and ordered some Moser axles, I used a set that were made from stockers. One was cut down and re-splined, and the other had to have the big end changed around somehow. The big end of one of the axles broke off at the starting line, and the entire wheel fell off. Luckily, the car had a spool at the time, so it spun around sideways (running over the photo-cells at the starting line) and didn't land on the tire and ruin the quarter panel.

Ford never made 31 spline axles that length. Exactly what axles are you running, and where did you get them? Are they not made by Moser, Strange, etc?

Thanks

My advice for switching to a 9 is always the same - buy a housing built to your required dimensions. By the time you hunt up one, get it cut, buy ends and have them welded and then locate the spring perches - you'll have nearly the same money in it. And the bought piece will have better tubes and center than anything you'll fish out of the scrap yard. The just buy axles that fit the housing - Moser, MW, Strange all make affordable 28 and 31 spline units that will put up with a lot of abuse. FWIW, the Mustang has about 320 RWHP and I used a housing made by Currie with the small ends on it. The stock brakes bolted right up and I stuck the stock 28 spline axles out of the 8" back in it. they are on their second year of weekly drag racing with no signs of fatigue.

Originally Posted by n2omike

Stock replacements?

1965-66 mustang width housings never came with 31 spline axles. Back before I got smart and ordered some Moser axles, I used a set that were made from stockers. One was cut down and re-splined, and the other had to have the big end changed around somehow. The big end of one of the axles broke off at the starting line, and the entire wheel fell off. Luckily, the car had a spool at the time, so it spun around sideways (running over the photo-cells at the starting line) and didn't land on the tire and ruin the quarter panel.

Ford never made 31 spline axles that length. Exactly what axles are you running, and where did you get them? Are they not made by Moser, Strange, etc?

Thanks

OK, Ford never made a 31 spline axles for early Mustangs. Maybe it was all advertising gibberish or I misunderstood, but Superior listed them as Stock 31 spline replacements on their website. They are thicker than Mustang 28 spline axles and have no taper.

At the time I needed a set of 31 axles ASAP and purchased the Superiors through Summit since they were in stock. Called Summit on Tuesday, Shipped on Wednesday, Received and pressed bearings/wheel studs onto axle and axle into housing on Thursday, Raced on Friday.

I love it when a plan comes together.

Summit lists them as direct replacements:

Superior Axle and Gear PA6070B - Superior Axle and Gear Production Series Axle Shafts - summitracing.com

Superior Axle and Gear PA6070A - Superior Axle and Gear Production Series Axle Shafts - summitracing.com

Cool. Just because they aren't an OEM replacement, doesn't mean they can't be a direct fit!

Those of you looking for a 9" housing should definitely consider going to the aftermarket. Last I checked, they were just a tad over $300. 57-59 Ford housings are awefully weak and are prone to get bent/warped. (been there, done that) Small bearing housings (all 8" and many 28 spline 9") can't use a conventional axle seal with 31 spline axles, so they have to use a bearing with an O-ring around its outside diameter to seal the oil. (it's wise to order extra o-rings) If a conventional seal is desired, a person has to step up to housing ends made for larger bearings... but then different brake backing plates are needed, as the plates for small bearings won't work.

Good Luck!

My 9-inch was out of a 80's vintage Granada and was the correct width. Both the Ford Granada and Lincoln Versailles used a 9-inch rearend.

It did have the tapered axles so when the time came to narrow it I had to buy new axles so I went with Currie myself. They were around $400 for the pair.

I also swapped with big bearing ends at the time and went with their rear disc brake kit.