59 Belair diff upgrade advice.

[Simon]

G'day All,
Wishing to upgrade the stock diff on the 59 Belair once I put in a stroked 348 W and 700R. Looking at approx. 450HP/Tq.
Info I have picked up so far is to weld an additional rear control arm to the L/H side of the chassis/diff. As the 59 does not come with the cross member I will have to manufacture and weld a bracket (mirror image of R/H side) to the chassis. What photos I have seen it looks like the additional bracket on the diff attaches partially over the diff rear housing. Any advice or pitfalls here?
In regards to the diff centre I'm leaning towards a Eaton Posi. I believe I have to cut out a web in the centre housing to accommodate the Posi.
Since the 59 axles are 17 spline do I upgrade and to what (ie 30 spline)?
Obviously the Posi will have to match.
As I am interested in fitting Willwood rear disc's do I need to change the axle offset?
Last of all since I live in Australia I have limited options but there are a handful of wreakers over here. Unfortunately not to many V8 option where offered over here around that time.
Any advise or options would be awesome.
Simon.

 

[61BUBBLE348]

Simon,
It might be just as easy to put a 9" in the 59.

There are a lot of threads regarding rear end upgrades for the 59-64 chassis, spend some time trawling through old threads, some of these threads are priceless.

cheers
PS I sold a 59 Bel Air 4 door sedan to a guy in Perth 30 years ago for $2400.00

 

[models916]

Stock pumpkin will accept the posi with a little grinding on the gusset by the pinion. Eaton has carbon fiber clutches and chrome moly spiders. Sold in various kit forms like ring and pinion and install kit included.

http://www.ebay.com/itm/19686-010-E...ash=item54438afd8f:g:yLYAAOSw4CFYrJUT&vxp=mtr

 

[Simon]

Thanks guys. How will the 17 spline axles hold up?

 

[Don Jacks]

Hi Simon,on street tires,not much of a problem,on slicks,and with a good working suspension set up so that the car "hooks up",with the torque and power that your engine will make,they'll likely fail.If you can find an early posi unit,there is a kit that allows you to change the internal gears to use a 30 spline axel.This kit,along with the straps for the caps that hold the carrier bearings and 30 spline axels will hold up to 500 rwp .

 

[models916]

Better than stock.

http://www.show-cars.com/cgi-bin/commerce.cgi?preadd=action&key=6540

 

[Simon]

Thanks for your advise guys. There is sooo much info on the web to troll through but so far I have gathered this - correct me if you could please!
The 59-64 posi's are all interchangeable running 17 splined axles. As I am looking at keeping mine 3 series I am not worried about the spacer. To fit the posi into my non-posi diff I have to grind away the gusset. For the posi to handle a little bit of abuse it is recommended to convert posi centre and axles to 30 spline and stronger caps. I'm guessing with a good quality ring/pinon gear and bolts the 8.2 10 bolt (along with the fore mentioned modifications) should handle up to 500HP/Tq.
I'm not interested in getting a secondhand posi and rebuilding.
Is there a 1 stop shop in the States that could provide all of the above - leaning towards a Eaton Posi?

 

[Don Jacks]

With an Eaton posi[17 spline],Good axels,the cap straps and quality parts,you'll have more than all the strength you'll need with an automatc trans.,and even drag radials.I'd only be concerened about the 30 spline stuff if you were running a stick transmission,slicks,or an automatic with a fairly loose convertor and a trans.brake.

 

[Simon]

Thanks Don. That has saved me a couple $. I can by what i need straight of the shelf so that easy.
Cheers all for your input.

 

[DonSSDD]

Simon, there are posts as stickies on ChevyTalk by Tom Parsons, he posts as DZAUTO on installing Eaton posi's in a non posi carrier. He has some very detailed pics which you may find helpful. I think he also recommends a Nitro or the Eaton.

 

[Simon]

Thanks DonSSDD.