How can you tell the differance in 9 bolt and 10 bolt and which is stronger?

 

A 9 bolt has 9 bolts on the diff cover and a 10 bolt has 10 bolts.

9 bolt is stronger.

 

A 10 bolt will also have little "horns" at the bottom of the housing. One on each side.


Cheers!!

 

Parts are also more rare for a 9 bolt, hence why some people "upgrade" their 9 bolt to a 10bolt, because they just can't get the parts to rebuild their 9 bolt.

 

Well that is the most obvious part. There is also a rubber plug on the diff cover plate for filling it with oil the 10 bolt doesn't have. Pretty easy to spot that.

As far as "upgrading" to a 10 bolt you're right. The parts are hard to find for 9 bolts and usually, well... always more expensive. Even little things like seals are a bit higher. There are new parts like ring gears and posi's from Austrailia and there's even a cap girdle now.

Now I'm not going to get into the "which one is better" debate but the 9 bolt is beefy for a little 7.75" ring gear. (oxymoron?) I really was impressed by the construction when I tore mine down. If I had to start from scratch I'd probably opt for the 10 bolt just because of the part selection/availability issue. So for the same $$ you can build a rear that probably just a strong if not stronger by going 10 bolt.

 

The 9 bolt also uses a 4 pinion carrier for more strength. The axles bolt in like a 9" instead of being held in with c-clips.

9 bolts are only moderately stronger but as mentioned above, parts are hard or impossible to find. You'll have a hard time finding a listing just for gears. They were only available in third gens from 87-89 so there's not a big selection of parts for them. They're used a lot in Australia in Holdens but importing parts gets very expensive.

Now if you're able to find one of the rare, over the counter, Dana 44 diffs for a third gen, that's a good strong diff with lots of parts available for it. Trouble is, if you do manage to find one for sale, it'll cost almost as much as buying a new bolt in Ford 9".

 

Are you sure 9 bolts were only available from 87-89? Reason I am asking is because I have a 1990 with a 9 bolt.

 

They were actually in Firebirds from 85 to 89, and in Camaros from 87 to 89.A very very very few 90s from the earliest production run got leftovers from 89. But in general, 89 was the last year, except for those "stragglers". And of course, anybody can put any rear into any car, so unless you bought it brand-new, you have no way of knowign that it came in the car, as opposed to merely being in it right now.

 

Thanks for the info, it was probably made in 89. My 1990 mustang was the same, it was considered a 25th anniversary car because it was made in 89. Or at least that is what I was told and it had the 25th badge.

 

Thanks for all the help guys. Building a road racer so there should not be a lot of shock from dumping clucth at a high RPM, but was reading threads and noticed that the 9 bolt was a little stonger. I suppose I will just build 10 bolt and use c clip eliminators. Have you heard of axles in 10 bolt maybe being on the fragile side? I can buy new axles but if I don't have to that would be great.

 

Have you checked 9bolt.com at all?

 

no I just plan on using what I have. The cost for parts and how difficult they are to locate I wiil just buy good parts for what I have. Thanks

 

Another tip for ya. If you want an excellent type of posi to use in a 10 bolt set up for road racing, go with the Zexel-Torsen type posi that came stock in the 98-02 10 bolts. The only catch to using one of them is that you'll need 28 spline axles, which came in 90 and newer 10 bolts. So if you start with a 90-92, 10 bolt axle, you'll already have the correct spline count. If you use an 89 or older 10 bolt, you'll have to buy some 28 spline axles. The older ones are 26 spline. Do a search here on the boards using "torsen", and check it out.

 

Thanks just trying get as strong as I can with out breaking the bank