I want to change the differential in my 92 rs. I don't know what gears I have but it is non posi. I am upgrading the engine to a 454 so I want a posi strong rear end. I want to know if I could swap for a 86z28 posi. Don't know what size gears either. Could someone please help me.

 

Neither the 28 spline axle you have now, nor the 26-spline '86 axle, is going to hold a 454/T56 combo, even if you baby it. The cheapest route is a salvage yard, drum-brake Ford 9" axle, with the Currie bracket for the turque arm, and carefully grind the control arm brackets off a stock axle, like what you were hoping to use. If you do this, find a 9" that's 61.75" across without the drums, if you like the wheels you have, or 64.75" if you like the '94-'02 wheels. 9" axles from trucks and vans tend to have 31-spline exles, while 9" axles from station wagons tend to have 28-spline axles. But if you find a 62" housing from a car, leave those axles there because the longer truck axles can be shortened and resplined. If you get 31 spline axles, be sure to use a matching differential, preferably a Traction-Lok, which were more common in 4x4 trucks.

 

Here's a FAQ on the 10-bolt that you may find thought provoking:

https://www.thirdgen.org/forums/tran...-10-bolts.html

JamesC

 

This is where it gets ugly. What is the difference in the spline? Where is the 61.75 differencial most commonly found in cars. Is there a serial number to identify the 9" by. I know the questions may sound really stupid but I'm all on my own except for the help you guys are giving me. Thanks

 

More splines equals more strength. As for what Ford might have a 9" axle between 61.5" and 62", I have no clue of my own, and no clue where to research it besides taking a tape measure to your local salvage yards.

 

So I would have to keep my stock torke ark?

 

not at all, you could get a tubular chrome-moly torque arm from BMR or Spohn or whoever. But you should stick with a torque-arm-design rear suspension. Currie's bracket makes it cheap and easy while still gaining the strength of the 9". After you get the control arm brackets off your stock axle, then position them on the 9" and weld. just don't do it in such a way as to warp it with too much heat. If the 9" you choose uses larger-dia tubes than your stock axle, then you'll just remove the appropriate metal from the brackets before positioning and welding.

 

Is there a video of the swap anywhere in the Internet. I have been looking at other threads that talk about beefing up a 10 bolt, but like you said it won't hold much. Are the sway bars and all the other bars fit the same.

 

What is the difference between the Dana 60 and the 9" ford. Which is stronger.

 

How can I tell what spline the axle is.

 

In stock form the Dana 60 is stronger. The 9 inch needs some after market parts to make it strong. The Dana is a rear load and the 9 inch is a front load. There are more parts in a 9 inch and it cost more to build one. The Dana could be had with 35 spline axles from the factoy. The largest 9 inch factory axles were 31 spline.

 

Is there a way to identify the Dana 60 and what car or truck did it normally come on.

 

The Dana 60 was used in Mopar muscle cars with hemi or 440 engines with 4 speed transmissions. The car version is very rare. They were also used in many 3/4 ton trucks with full floating axles. These housings can be used, but the housing ends must be cut off and car ends welded on. After market axles will also be needed. The Ford and Dodge trucks used the 60 more than the GM trucks. GM started using their own 10.5 14 bolt rear end somewhere in the '70s. The 60 has 10 bolts in the cover and has the number 60 cast into one of the gussets in the center of the housing.

 

The truck Dana 60 isn't an option mostly because of the torque arm issue, but it also uses much larger and excessively heavy axle tubes compared to the Strange S60 that's been redesigned to be a direct bolt-in to our cars. But it's $2500. The 9" is not difficult to play with, the Currie bracket is the only aftermarket part you need.

 

If the car is going to be a weekend driver not a 550+ hp motor do I really need to change the 10 bolt I have right now. What is the biggest spline # I can use in my 10 bolt.

 

28 spline axles are the largest available for the 7.5 10 bolt. If it's just a street car with street tires and you don't allow it to wheel hop then the 10 bolt should be all right.

 

The 7.625" ring gear is important, since it's what fails first with stock 28-spline axles. Forget the '86 axle, because the 26 spline axles will fail before the ring gear.

 

So the first upgrade should be the ring gear to a 7.625.

 

Do I need any special tools to do the posi swap. Thanks for all the help to everyone.

 

'84 was the last year for the 7.5" ring gears, all '85-up third gens that used this axle had a 7.625" ring gear. Once GM did that, then the 7.5" ring gears stopped breaking, and the 26-spline axles started breaking. So around 1990, GM went to 28 spline axles, and that ended the broken axles, but once again the ring gear was the weak link, and there's no room to go any bigger than 7.625" without an all-new casting. All they could do from there was use better metal for the gears.

 

As far as what gear I could use, for a street car would a 3.73 be good or would a higher or lower be best. Whick of highers or lower Gear are good for short range run or cruising and smashing every once in a while? Sorry for the starter questions but I really don't know much, at least I want to learn for my next project. Thanks

 

I know money can be tight, believe me, I know but seriously, there is no way a 10 bolt is going to hold a 454, period. I'm launching my 10bolt on slicks with my 305 auto and am surprised it hasn't grenaded yet. Now you're looking at a rear end swap and unless you really really know what you're doing, you would be better off buying an after market (strange, moser etc) 12bolt, Dana60 or Ford 9". I know they're expensive but if you're going to go to the headache and expense of putting in a 454 anyway, you might as well do it right and you won't have any trouble down the road.

Dan

 

https://www.thirdgen.org/forums/tran...-fan-10-a.html
Maybe you should be reading this thread. The Moser 12 bolt starts at $2200 with an Eaton Posi. Is it worth it? Look at the picture and see what you think.

 

I'll do That as soon as tax time comes around. Thanks to all for your help I really appreciate all help.

 

choosing a gear ratio depends on what cam and heads your engine has, but while a 3.73:1 gear is popular for small V8s, it's usually way too much gear for a stock, mid '70s - mid '90s, truck 454. Think more like 3.23:1 if that's what you have.

 

What do they include.

 

Are you asking about the Moser 12 bolt? It comes with a new housing that is made to fit the torque arm, Eaton Posi, gears of your choice, 30 spline c clip axles, axle studs, Timken bearings, chrome cover and 1310 yoke. It is all assembled except for the axles, which you will have to put in after the brakes are installed. Your '92 brakes might fit if you have 4 bolts in the backing plates. There are several optional upgrades for these rear ends.

 

Who is selling them? I have been looking and the cheapest I've found is a strange 12 bolt complete for 1927+ shipping and is not a posi is a spool.

 

I sent you an email with some more information.

 

So the size of the differential I have right now is 61.75 in lenght.

 

Strange is way better than Moser, because the Strange 12-bolt is 33 spline, and Strange does offer a posi for a few dollars more than the spool.

 

Moser also has 33 spline axles. It's a $65 upgrade.

 

this is what my differential looks like. ( crap)

IMG_0175.JPG