i thought i'd better start a new thread for this question, as it's got nothing to do with my gas mileage post.

i was looking at ordering a pinion and ring gear installation kit for my 9 inch rear, but just my luck, there's several models of it.

apparently from one manufacturer you've got kits for 27 splines and 31 splines. another manufacturer sells kits for a smaller and a bigger diameter pinion bearing. this leads me to assume that the splines mentioned are the splines of the pinion shaft, NOT the splines of the axleshafts into the spool.

i just wanted to know if i can find this out without taking the entire carrier off, counting, and then putting it back together, order, and do the same stuff all over again....

gracias guys

 

The spline count has to do with the number of splines on the axle shaft.

 

The number of splines refers to the axles. Nine inch rears came in 28 and 31 spline versions. The ring and pinion gears are the same for either one. There is a standard and large pinion bearing. The large is sometimes called the "Daytona" version which has a much larger diameter than the standard version and its pretty rare. IIRC, only the Boss cars used them. That's why you are being told there are a couple of different installation kits. The Daytona pinion has larger seals. This site has a wealth of information about nines: http://www.kevinstang.com/Ninecase.htm

 

you see, that's why it's always better to quickly throw a post on the forum and find out whether or not your right or wrong. usually, i'm wrong....

thx guys.

 

right, another question then: i read the site of kevinstang that you referred to, and indeed it gives a lot of info, among other things about splines and such. so i went to summit's site, and they literally say PINION spline count in their wearch engine under ford 9's....

not that i question you guys authority over mine in these matters, but you must admit that it is a bit confusing now...

third opinion anyone? or anyone that has actually ordered these kits and came up right (or wrong?).

hope to figure this out.

 

http://www.maliburacing.com/ford_9_i..._nine_inch.htm

 

You are supposed to be able to remove the rear drum and depending on whether the inside ring is oval or circular to tell whether you have 28 or 31.

 

If it's an oval hole, it is a 28" and if there are two large holes and counter sunk, then it is a 31. Here is a pic of a 31 spline axle.