I am not all that in the know of rear-ends and would like to know more. I just have a few quetions....

-What are the various types? I have heard about 10 bolt, 9 bolt, etc. What's the difference? which will fit in our cars? which one has better performance, etc.

-I am guessing that the fatter the rear-end, the more it holds. What are sum of the sizes and how do they compare?

This is mostly for reference for our beloved 3rd gens but is also for general reference. Any extra tidbits you can add would be nice, and links to some good articles or anything similar would be GREAT!. Sorry for such a newb post, just trying to learn.

 

The difference bwtween 9-bolts and 10-bolts is .... {drum roll please} the number of bolts {cymbal crash}

OK now that we've gotten past that, it's the number of bolts that hold the cover on, so it's something you can instantly see and use as identification.

These cars have a suspension system whereby the rear end MUST BE equipped with a bracket, for mounting the torque arm; no other kind of car has it. So no other car's rear will swap into one of these. The only way around it is to install a completely different design of rear suspension, as is often done in race cars.

There's only one kind of 9-bolt. It's relatively uncommon. These are the only cars it has ever come in, in the US.

There are several models of 10-bolt. The ones in these cars have a ring gear with 7½" or 7-5/8" diameter. That number is how the various models are identified. Alot of other vehicles use the same model of rear, but with different exteranl features cast into the housing and different length axles; S trucks, A & G body cars, some B body cars, etc. etc. have this rear. Many internal parts interchange but the rear as a whole will not.

The 9-bolt is a stronger piece, but parts selection is slim, and they're much more expensive to maintain or modify than 10-bolts.

Now my fingers are tired.

 

Thanks .

What are some of the more popular choices for our cars? I am guess a 4th gen rear would be one of the more wanted ones but what aftermarket options do we have?

How much horse/torque does the 4th gen rears hold? Talking all stock....

Thanks again guys.

 

The 4th gen rears are exactly the same as the 3rd gen rears, except they are wider, requiring you to run 4th gen offset wheels, or have the tires stick out past the wheelwells (illegal in most states, and tacky everywhere).

Bolt in 12-bolt and 9" rears are by far the most popular. 8.8 Ford rears are gaining popularity as a swap, but there is no bolt in package available for this rear at this time.

If there is one weak link in the 3rd gen F-car it is the rear. If serious power is your goal the stock rear needs to go in the dumpster.

 

Wait, to my knowledge the 4th gen rears hold a lot more horse/torque. How much can they hold stock?

Are the 4th gen rears the same on ALL of the years/models? If not, does anyone have any info on what models/years got the best rear?

I believe some of the 4th gens came w/ posi rear ends correct? Anyone know which yrs/models came w/ em?

Hope you guys can help me out w/ my questions, thanks.

 

Whoever told you that the 4th gen rears can handle more power than the 3rd gen ones was blowing smoke up your @$$, or trying to sell you a 4th gen rear!

There is no difference between a 4th gen rear and a 90 and up rear with 28 spline axels. A 4th gen rear is about 10-15% stronger than an early modle 26-spline 3rd gen rear, but as long as both rears have 28 spline axels they are of equal strength. The 4th gens may also have a stronger posi, but that doesn't really contribute to a stronger rear end, just a stronger posi unit. 4th gens are just like 3rd gens. Some had posis, some didin't. There isn't necessarlity and reasoning behind it.

Axel strength comes from ring gear diameter (the bigger the better), gear design (pinion head mass & ring gear thickness), axel spline count (the more the better), bearing size (again, bigger is better), and housing rigidity. The 7.625" ring gear in the 10-bolt found in 3rd gens is a weak design from the get go, and it can't be substantially improved, at least not enough to warrant the expense. The ring gear size is carved in stone and can't be changed. 28 spline axels are the limit for axel size and spline count. The bearing size is fixed too, though they are adequatley sized for even a modified rear. The housing rididity can be improved by using studs in the caps, and a TA girdle, but the weak link is always going to be the puny ring gear, or the axelshafts.

By comparison a stock 9" could be had with 33 spline axels, and all 12-bolts had 30 spline shafts. THe 9" uses a, suprise, suprise, 9" ring gear. The 12-bolt uses a 8.875" ring gear. Both rears use substantially bigger bearings than the 10-bolt. The housing rigidity of both pieces is way better too.

If serious power is your goal, and you don't like the smell of gear oil, I would highly recommend considering a swap to a stronger assembly, instead of trying to get the strongest 10-bolt. As I said before the expense just doesn't justify it.

 

So basically I need to get a completely different suspension AND a different rear end if I am going for any serious power because all the rear-ends made for our cars are pretty weak?

 

no you can get a 9 bolt, if you're really lucky a dana44, several people make 12 bolts and 9" that'll all bolt in with no other changes.

 

Does the Moser 12 bolt go right in without any modifications? I have been lookin around and they seem to be a rather popular choice. They cost $$ but seem well worth it fro mwhat I hear.

 

moser, strange, currie makes 9" or 12 bolts that are a direct bolt in

 

Sweet, thanks for all the info guys. I think the moser 12-bolt is the one I am going to end up getting. Looks the best from what i've seen and from what people have been tellibg me. later.