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Need help with my 9 inch rear end:-\

pnandy

pnandy

Member
Ok so the previous owner knows very little about the 9 inch rear end he put in my mustang so i need help figuring out which rear disc brakes i can put on it. So how do i tell if i had a 28 spline small bearing or 31 spline large bearing 9 inch rear end, if it helps he thinks it came out of a ford bronco? thanks for the help in advance.

-patrick
 
Is there a factory ID tag still attached by one of the differential to housing nuts?

Worst case scenario, pull an axle. You'll get the bearing size and can also count the splines on the axle while it's out.
 
The manufacturer of aftermarket disc brake swap kits should be able to tell you which brake kit/brackets you need based upon the size and spacing of the four bolts that secure the axle on the end of the tube.

You can pull one bolt without disassembling the existing brake system and you should be able to measure the bolt pattern from the backside of the drum brake backing plate.
 
damnit! and i couldn't have found out that i needed to do this last weekend when i replaced the driver side seal becasue the axel was leaking i wish i had a photo graphic memory. meh i guess this will have to wait unless i can pick the rear set up for a deal in which i have a 50/50 chance decent odds i think
 
you dont need to know the spline for a disc brake conversion do you? Just bolt pattern 5x4.5
 
Can't you simply look at the axle end (where the wheel fastens to) and if it has a large oval hole it is 28. If it has 3 dimples with center dimple being llarger than the other two, it is 31?
 
Can't you simply look at the axle end (where the wheel fastens to) and if it has a large oval hole it is 28. If it has 3 dimples with center dimple being llarger than the other two, it is 31?
Click to expand...

Craig, can you expand upon this or clarify a little?

I have 28 spline axles and there are 3 holes on the flange end.... only one of which is large enough to slip the socket through to remove the 4 nuts holding the axle plate onto the housing. Are these the holes/dimples you're referring to?
 
Mr. Campbell Soup,
I meant in the center of the axle flange. The very center of the axle end that you can see without taking off the wheel. For a 31 there are typically 3 holes. Now that I studied more 1 small center hole or dimple and two larger ones.

Go up to Sluggo's link to Kevinstang, scroll down to "axle shaft". It shows a pic of a 31". The 28 normally has that big Oval or retangular shape in the center.

Oops, I just learned something after reading Kevin's paragraph, that some 28's also came with these three dimpled or chamfered holes. So my theory just went down the toilet.
 
after checking out with that site with the mechanic who helped me replace the rear seal on the axel we've determined its a small bearing 9 inch rear end ;D
 
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