Rear axel question

[Joeturtle]

I just traded my 1989 c2500 for a 1989 c3500 dually. I want to do a full frame off restoration. I do know it’s a 454 (block), automatic transmission with 14 blot rear end full floating /4.10 gears.
How do I know which transmission size and rear end ( name)I have so I can buy the right replacement parts? Is it a Dana? Also Has anyone converted from drum to disk brakes?

 

[RanchWelder]

Here, read this like 10 times...
http://www.billavista.com/Tech/Articles/14-Bolt_Bible/index.html

Unless you have a degree in fluid dynamics, adjusting the brake proportioning valve, depending on what transmission, tire size, engine HP and GVW; "stock brake drums are really cheap to keep". They wok well, save you hundreds in modification costs and the stock brake lines fit and work well, for your dual-ee.

Resist the urge to mod because the heard tells you to. Unless you buy a new Strange Rear Axle with all the boxes checked so a professional re builder sizes, welds and designs your brake conversion, things can get a bit squirmy.

Technically, it is not legal to run an adjustable brake proportioning valve on the Gubermint's roads. It's cool on the track and for rock climbing, but if you ever get into an accident and the cops find one in your car, your insurance carrier will leave you out to dry. They can and will call the accident "operator error" for failing to know Federal Brake Mod regulations and restrictions.

Finding the exact OEM unit is very difficult, because they made so many and very little documentation is available to us truck enthusiasts, regarding flow rates and which discs work on what trucks. There are guys who spent thousands of dollars trying to swap them out because they had junk yard parts access and the time to try. Getting proportioning wrong, has killed people at the track.

Call Strange or another reputable rear axle machine shop, and get it done right, or consider it not worth the effort, as a home enthusiast builder.

I'm swapping a 10.5" full floater into my Blazer. The stock GM Drum brakes are going with the axle.

Your project is very cool. You know that rig has hauled engines and dragged some wrecks, in it's day.
Good Luck!

 

[Erik the Awful]

In 1989 GM transitioned from the Dana 70 to the 14-bolt. If your diff looks like the picture below, you have a Dana 70.

You must be registered for see images attach

The only good reason to switch from drum to disc brakes is ease of maintenance. Drums will stop you just as fast as discs, unless they're out of adjustment. If you're going to be doing any serious towing with this truck, and since you're moving from a C2500 to a C3500 it sounds like you are, you really don't want to mess around with the brakes. There are liability issues there.

Technically, it is not legal to run an adjustable brake proportioning valve on the Gubermint's roads. It's cool on the track and for rock climbing, but if you ever get into an accident and the cops find one in your car, your insurance carrier will leave you out to dry. They can and will call the accident "operator error" for failing to know Federal Brake Mod regulations and restrictions.

I haven't ever heard this before. Got a reference so we can study up?