Ok, here goes

I once read that a Ford 9 inch is a tad bit stronger than a 12 bolt and eats a little more than a 12 bolt.

I have a guy calling me out saying I'm full of it. He happens to be a Ford guy too.

I'd like to hear it from the experts.....is a 12 bolt just slightly weaker than a 9 inch? Or ????

Theoretically, the larger the diameter of the ring gear, the stronger it is. A 12 bolt is 8.875"; a Ford 9" is exactly that.
A slight strength advantage to the Ford.
Due to pinion position in relation to the ring gear, a Ford 9" uses slightly more HP to turn.
Slight advantage to the 12 bolt.

But, the 9" pinion gear fits into the back of the case, preventing the pinion from riding up the ring under heavy load, making the gears always mesh correctly and helping to prevent any chipped teeth. (I'm pretty sure, someone correct me if I need it)

Danny

Thanx Bill, yeah this guy is arguing that a Ford 9 inch uses bolted in axles and a Chevy 12 bolt uses c clips.

So I guess what he's trying to say is the Ford 9 inch is much stronger than a 12 bolt.

I can provide a link if you want to read his reponses for yourself. :)

one positively good point to the 9" is that when you want to change gearsets - you only have to pull the center and go lay it on the table

wish they would have done that with the 12 bolt

the older chevy rears were like that - why did they change them?

Thanx Bill, yeah this guy is arguing that a Ford 9 inch uses bolted in axles and a Chevy 12 bolt uses c clips.

An easy fix!
I had my 12 bolt axle tube ends modified with a bearing cup to accept a Ford type axle (Moser)with a pressed on bearing. No C-clips needed. :thumbsup:

the older chevy rears were like that - why did they change them?
The spider gears in those rearends were the weak link...very fragile!

Also is a 12 bolt not good for heavy abuse such as drag racing with slicks? How well do you guys like your 12 bolts?

Drag racers with slicks like the 9 inch because if they break an axle, the axle doesn't exit the housing. It is also easy to swap a gear ratios if you have another third member set up with a different ratio.

And when you make them a full floater (have hubs welded on the axles ends), when changing gears you do not need to remove the tires. The axles can slide out of the center of the hub, and if you have another "chunck" (gearset) around ready, you can change gears in a matter of minutes (15).

And if you break an axle your wheel is still connect too, because the wheel hub would be welded to the axle housing.

A 12 bolt is plenty durable up to a point - probably the same point as a standard CI case 9". When you get into the 9" nodular case things change. Big advantage of the Ford 9" is the rear pinnion support - as long as it is set correctly and not worn. But neither of these compares to the big Dana that came in the Mopars. Take your pick, each has their limits in stock form. The 9" Ford is a little easier overall to Hot Rod - I have ran both.

PS - by the time you are out of the range of breaking a 12 bolt that is assembled correctly with good stock/replacement parts, you are pretty much out of the range of a similiar 9" Ford under the same conditions.

Back when I was much younger and drag racing every week, the best rearend I found for my Camaro was a Dana 60. I was putting out 730HP at the rear wheels and this thing was unbreakable! If you really want strength, I see that Moser or somebody now has bolt in Dana setups for our A bodies.