Brake chamber lifespan?

My 98 KW were all original when I bought it

 

I am not sure there is any definitive answer. Operational environments play such a large role.
I have seen cans rust out in less than 3 years(cheap replacement parts likely) Trailers used in city P & D have their brakes applied, both service and anchor a lot more than line haul. Loading factors, heavier loads, more stress on the components.

But, being the conscientious operator you are, you are looking for a preventive maintenance angle, which is commendable.
Brake chambers are cheap to replace in your driveway as opposed to on the road.
The problem is the replacement market is rife with poor quality stuff, even with a brand name. (China)
The OEM probably did their best to avoid that, but I could see you replacing a perfectly serviceable OEM chamber with a lesser quality replacement and have more, not less failures.

As my old boss used to say.
If it ain't broke, don't fix it.
Carry a spare and a way to block off the offending chamber until you can get it replaced.

 

That was a lot easier when all you had to carry was a cage bolt and a biscuit!

 

If you run in the winter on salty roads they rust out. But I don't have an idea for how many years. Check metal for bubble rust and hit with hammer. So you can change at your convenience. Carry a spare? I know people that do.

 

One of biggest causes of can failure is the spring breaks and ruptures the bag .. many drivers make the same mistake without realizing it . They set the brakes before truck comes to a complete stop which is hard on the spring .

 

I run Colorado in the winter. I had to replace all of my cans when my trailer (that I purchased brand new) was only 5 years old. Not because of the diaphragms, they held air just fine, but because the springs became weak/broke and I had only one wheel that would stay locked when trailer was disconnected. It would actually pass an inspection but the springs wouldn’t hold.

 

One of the best things you can do for brake chamber lifespan, is to make sure the plug in the cage bolt hole is fully seated.

 

I put 4 MGMs on my Truck at least 8+ yrs ago. Been planning on replacing all of them again. Did Trailer last summer. They’re cheap enough. Sucks to have one go bad in winter especially. The cheapies will come loose where the rod is attached to the disc. Rod makes a hole in center of the pancake. I carry an extra pancake. Only changed one once. Rather change the whole thing, spring brakes seem to fail just as often as the pancakes. Had 3 bad springs on my Trailer. 1 was obvious, it was loose. Others seemed good, but were broke. I hear it depends on where or how the spring breaks. They can be broke and still have tension. Safely disabling an old 30 30 requires cutting the spring in 2 places. They can be dangerous if disposed of improperly. Never know who may get injured down the line. That’s why I no longer carry an extra under the bunk.

 

There is one more advantage to replacing the cans routinely.

Inspectors LOVE to see new brake parts. The glint of the new shiny surface may put them in a trance, and they just go back to their vehicle and in a fog give you a completely clean inspection, and a coupon for a coffee at McDonalds