The Stovebolt Site Forums The Shop Area Engine Shop 10 bolt, 12 bolt, 14 bolt, whaaa???

Five bolt, six bolt, eight bolt, ten bolt, twelve bolt, fourteen bolt, not being an insider, I sure do get mixed up then you guy throw around these cryptic descriptions. The nephew is a four-wheeler and he’s always talkin’ the talk also, so to be polite I just pretend I know what he means. Now of course, if your talking about five bolt, six bolt it’s obvous that you mean lug bolts/nuts that’s pretty straight forward so lets skip that! But when you jump to the center section that’s where it gets foggy to me. When you say it’s a ten bolt, twelve bolt, fourteen bolt rear end, do you mean ten bolts in the cover or ten bolts in the pumpkin itself??
I think that there are people that are swapping these terms about as they see fit also. So what’s the official industry wide assignment for the location of those BOLTS???
Denny Graham
Sandwich, IL

Usually it means the number of bolts holding the ring gear onto the differential case in GM products, the more bolts the larger the ring gear diameter & strength should go alone w/that. Ring gear diameter is usually used to ID for parts actually. And yes, I hear alla time "that's a 10-bolt cause theres 10 bolts on the cover" when its actually a Dana rearend. Brian

What's the deal Denny, you want to upgrade your old bolt? If so I have a couple of 10 bolts I could turn loose.

whats the difference between a 8.2 10 bolt 8.5 or 8.875 etc etc how do i know what i got??
i think mine is an ex camaro 10 bolt axle with a 3.23 gear but i have no idea about 8.5 8.2 etc

10, 12 and 14 bolt refers to rear ends.
the 8.x is the ring gear diameter size.
5, 6, 8 lugs refer to rim/ wheel holes.

http://www.drivetrain.com/GMtrkratio_posidata.html
http://www.wilcap.com/diff.html
http://www.mag-hytec.com/differential%20covers.htm
http://www.nastyz28.com/decode.html

hope this helps

Just to make sure its clear, the relationship between the number of bolts holding the cover on, and number of bolts holding the ring gear on, is commonly used on Salisbury type GM rears.

I give up! Now we got 10 bolts in the cover and 10 bolts in the pumpkin and 10 bolts in the ring gear. I guess I should have heeded the old adage, “if it don’t stink, don’t stir it!”
We started out with two interpretations and now we’re up to three.
Funny, every time I go to the sites that specialize in rear ends, they always show the rear covers when they identify a rear end. After spending a few days looking over Drivetrain’s site a few weeks ago I thought I had it figured out, but a few of the recent threads on rear ends made me wonder.
Drivetrain says; “The following figure presents differential cover/cover gasket shapes. Counting cover bolts and cover shapes is a common method to determine which ring gear diameter differential you have in your rear wheel drive vehicles.”
So when I hear 10 bolt, 12 bolt etc. , I‘m gonna assume the person generating the question or reply knows what he is talking about and that they are looking at the cover and counting bolts!
Denny Graham
Sandwich, IL

Either you're trying to be funny or you need to spend some more time learning the lingo LOL!

In your thread starting question you refer to the center section. The center section and pumpkin are the same thing. That piece has a number of common names but differential is probably the best.

The strength of a differential is relative to the diameter of the ring gear and commonly given in inches, as in the 9 inch Ford or 8.25 GM. Another way to classify strength (and ring gear diameter) is the number of bolts required to hold the ring gear and in Salisbury GM differentials they are are grouped into strength class by the number of those bolts. 10 bolt, 12 bolt and 14 bolt are the sizes you most often see. Generally on those rears the number of ring gear bolts and cover bolts are the same.

While the number of cover bolts may help identify other rears, far as I know its only on the GM Salisbury rears that there is a direct relationship between the count of cover bolts and ring gear bolts.

Have I made it better or worse?

Call Summit Racing at 800-230-3030 and request a free catalog. There is a wealth of information in the ring & pinion section, including the bolt pattern for the covers on GM and other makes.

I have noticed that these terms are thrown around quite a bit in the magazines. The one that I see turning up the most is the "nine inch Ford" or in short form "the nine inch". I think in Hot Rodder's heaven, there are only nine inch Ford rearends allowed!

Most folks that "throw the terms around" honestly dont' know and are afraid to ask!!! Denny, you probably did the Stovebolt world a favor by asking...at least for some!!

Robin58...That's a perty good link. Helped clear it up for me. Looks like another website to go in my "truck" folder.

Thanks,
~Ron

Thanks Fred and Munk, you get the point. Seems like every one has their own inturpritation of how to apply the terms. Like a few have chimed in with here, if you state the bolt pattern, and the ring gear size then we have a pretty good Idea of what your talking about.
Can't speek for the rest of ya, but I'm about 10 bolted out on this subject!!!
Denny G.