rear axle rating

Agreed with heavy axles to pull massive loads. But, a good idea is to make sure it's more than just the suspension and diffs and axles. Single frames are good for up to 105k. But they'll bend and warp with loads higher than that. It's weight and torque that does it.

 

With Meritor (rockwell) rear axles the Model designation is fairly self explanatory.. for example RT40-145 is;

R= rear
T= Tandem
40= 40,000lbs Static weight Limit
145= 145,000lbs Combination weight Limit

 

Some wear the inside front drives. Axle flex hmm?

 

That's what they say. Inside edge of drive tires wear, just like a lose wheel bearing. It actually the axle flexing if truck has the thin or lightweight axle housing. 9mm is the thin axle housing

 

So as you can see, a lot of people put more than 34k on their axles. Here in FL, 44k is legal, other states have 36k, and we aren’t even talking about permitted loads. Those that haul containers typically have a blanket permit to allow up to 100k on 5 axles. There’s far more trucking operations than just interstate 53’ van. Once you get into permitted oversize loads, you can be close to 50k on a tandem. Every state has different limits though.

 

My steers were rated for 13,700 lbs. And up here in the great white north, you can put 17,000 kgs on the drives and the bogies if you're only a tandem. That's 37,400 for those lucky enough to still have imperial measurements. I don't think in metric myself. And if you have a tridem, you can take the bogies up to 23,500 kgs, a whopping 51,700 lbs.That would take you to the max for a tridem at 102,400 lbs total gvw.

Now try that on 2 lane goat trails in the land of mountains, BC.

 

I don't know much about highway spec stuff but I do know all my relatives logging trucks (7 and 8 axles) just ran single frames. They were 3/8" thick and were something like 11-3/4" tall. With all that crap they spray on the roads out here I'd stay away from a double frame if at all possible. When I bought my 1980 project truck it had an insert where the suspension bolted on. So much rust jacking that it took me 2 days of sledgehammer, prybar, torch and grinder to get them out lol.

 

Get a gallon or two of Rust Mort, a good wire cup wheel for your grinder. Take the rust off, doesn't have to be done to bare metal. Wash then let dry. Then use a brush and paint 2 or 3 coats of the Rust Mort on (let it dry between coats). Then use your favorite rattle can gloss black paint. The rust gets eaten and neutralized, so rot stops. The paint seals it.

For a couple of hundred bucks you get a frame looking almost like it was sand blasted. Good for diff casings too.

For evil environments and conditions, it'll last a year. For highway trucks it'll last 2 to 3 years.

And once it's done the first time, you can spot repair when needed.

But if you're truly lazy, the Rust Mort turns the rust matte black anyways.