28 or 31 axle

[ironman]

how can you tell the different i mean what i am counting here trying to figure out. so when i order my moser axles i will know. Any help would be nice dont have an clue when it comes too these axles.:dntknw:

i have the cover off.

[CheapThrillB2]

pull the shaft out of the diff housing and count the splines at the end of it

[kunar]

what vehicle is the axle originally from? to sum it up, explorers and fx4 lvl2 trucks have 31 splines, all others have 28. axle tubes on 31 spline 8.8 are straight, 28 spline axle tubes 'neck down' toward the end. they are larger diameter near the diff.

[ironman]

it is a four lug rear end from an 91 mustang

[Hahnsb2]

it is a four lug rear end from an 91 mustang
Wouldn't that be a 7.5 :icon_confused:

[ironman]

as far as i know its a 8.8 but what do i know tag says s2151 355
2L73 88 9m08
has 355 ford on the gear .

silly ? how you tell the different in the to sizes.

[ironman]

inside cover from bolt hole to bolt hole is amost 9 inches 8.8 is that how you do it.

http://i206.photobucket.com/albums/bb106/jamieandterry/wharehouse023.jpg

http://i206.photobucket.com/albums/bb106/jamieandterry/wharehouse024.jpg

[ironman]

do the two bolts on each side of the diff.{bolt size 18 mm] hold the axles in i not for sure just dont want to mess up any thing want to do all my self so i can say i build this truck and thanks guys for all your help

[JFA_Spyderman]

Yo,
That looks like an 8.8 to me. I always tell by the shape. A 7.5 is round all the way around the pumpkin, an 8.8 is straight flat on the sides.

[Wicked_Sludge]

are you sure the tag didnt say 3L73, not 2L73? the axle probably had 3.73's in it originally....but if the gear says 355 someone must have swapped in a set of 3.55's for some reason

either way its an 8.8.

dont remove those 4 18mm bolts. those hold the carrier in and if you remove that and mix up the shims you'll be in deep doo-doo.

you can determine spline count two ways: the first, like kunar said, is by the axle housing. if it tapers to a smaller diameter just before it meets the brake backing plate, then its a 28 spline. if its straight, you have a 31 spline.

the other (and more definite for those with untrained eyes) way is to pull the axles and count the splines. for this you have to remove the limited slip spring and unbolt the center pin. slide the pin out as far as it goes, push the axles in and pop the clips off. the axles will then slide out.

[Hahnsb2]

I stand corrected, didn't know there 4 lug 8.8s... Pull the axles and count the splines.

[brendank]

are you sure the tag didnt say 3L73, not 2L73? the axle probably had 3.73's in it originally....


If the axle is indeed from a mustang, it's far more likely that it was 2L73. 2.73's and 3.08's were VERY common in fox body mustangs.

I'm quite sure that all fox-body 8.8's are 28 spline.


What kind of rims do you run on this thing?

[rickcdewitt]

looks like an 8.8 but unless its bolted in your truck already i'de toss it and get one that bolts in your truck(from a ranger)

[ironman]

its 28 spline and yes already bolted up in truck had to put new perches on and weld them up to make it work

[ironman]

ok axles off was alot easier than i thought now on this diff. any thing i need to watch out for when takeing it out.buying a set of 5 lug moser axles and a 31 spline diff to go along with it and thinking of getting 390 gears or 410 in instead of the 355 i have wont be driven much on road more track.

[ashleyroachclip]

All Mustang factory 8.8's are 28 spline .
You will never find an 8.8 from the factory , with 3:73 gears .
All fox 8.8's had 28 spline axles .
I own a Mustang , and also spray it , have had the 8.8 w/28 spline axles in for years , and have never had an axle failure .
Did a 5 lug to my Mustang , with 2 left side ranger axles .

[projectnitemare]

The axles aren't the weak point in that set up, it's the carrier. If you are only after 5 lugs and you indeed have a stang rear here is what you do. Go to the junkyard and take 2 left side axle shafts. The 7.5 and the 8.8 use the same shafts. A mustang uses the same shaft on both sides and they happen to be the legnth of the Ranger left side shaft. If you are upgrading everything then right on; you have the right idea.

Matt

[Wicked_Sludge]

You will never find an 8.8 from the factory , with 3:73 gears

sorry, not true. not only do they come that way quite often in f-150's, explorers, and rangers...but ive seen a few (newer) mustangs with them.

ironman, the housings are different between the 31 and 28 spline axles....you cant convert your current axle to 31 spline by just slapping in a carrier and/or axle shafts. your stuck with the 28 unless you go find a complete 31 spline axle.

[ironman]

i lot of great info. putting a new carrier in this week going 31 instead of the 28 i have now just ordered my new axles 31 spline moser axle and cant wait first time ever doing a complete rear swap.also got a trick flow diff. cover and looking for an auburn carrier/locker.downloaded the sheet to see how to install every thing any thing i used watch out for thanks guys.