brake drum matched to hub??

[scubaasteve]

bought a NOS hub onebay still in cosmoline. is it true that each hub must be machined to match " each brake drum.

that what I was told the other day by vintage power wagon when I ordered an axel seal. can anyone explaine.

[Gordon Maney]

The hub and drum assembly should be kept as a mated set. When you put a different drum on a hub, in this case your new drum, it should be set up PROPERLY on a brake lathe and turned to establish concentricity.

The rarity of these drums makes it very problematic should you take it an establishment where the machine's operator is a bonehead.

You don't machine the hub. Only the drum, as it is mounted on the hub.

[scubaasteve]

got it thanks.

[maineSS]

These drums aren't commonly done anymore, so you need to ask pointed questions concerning operator experience BEFORE allowing work to start.

Most places have no idea how to set them up properly, and will ruin your irreplaceable drum as they try to figure the proceedure out.

Try heavy equipment/truck shops that have been in business at least 40-50 years- they may still have the necessary equipment and operator skills.

[Charles Talbert]

bought a NOS hub onebay still in cosmoline. is it true that each hub must be machined to match " each brake drum.

that what I was told the other day by vintage power wagon when I ordered an axel seal. can anyone explaine.

To be honest, you may be opening up another can of worms by trying to accomplish this. Brand new drums are rather thin, used drums even thinner. Turning a drum is for the most part useless as it will most likely finish up too thin for any significant use. When they reach this point, they will warp very easily from heat generated by just a couple of hard brake applications.

Dealing with a new drum (if they could be bought) would be one thing, however dealing with worn ones, (most likely severely worn) is quite another. I've done many brake system rebuilds on these trucks; in the case of most doing what you have been advised to do can be pretty much considered "beating a dead horse."

[Gordon Maney]

It is hard to know where to separate turning these drums from turning drums in general.

Two issues here. Drum rarity and the goal of doing the best work possible. Best work translating into best brakes and best safety.

Let's for the moment ignore drum rarity. Let's just talk about drum brake service and best practices. Unless you have a low mileage set of shoes that are being replaced because of a lubricant or brake fluid leak, anytime a brake is serviced, after the typical service life, the drums should be turned.

Drums suffer a number of problems that are resolved by turning them on a brake lathe set up and operated by a qualified, skilled operator. Drum surface becomes impregnated with lining material, the drum surface becomes scored, and irregular wear patterns of a number of kinds can emerge. Drums can also get hard spots in the surface that resemble large mosquito bite looking welts.

Can you run an out of round drum, a drum with runout, a drum with scoring or irregular wear? Yes, you can. Regarding drum wear issues like scoring or other irregular profiles, after a time the shoes will wear fit to the drum. The brake is not good at the beginning due to reduced lining contact. Best practices do not include the assumption that such wear fitting is acceptable.

A drum with runout will never be right with respect to braking effect, and will also yield a pedal pulsation. Turning the drum will restore the surfaces, make the drum concentric and eliminate the lining impregnation. Best practices yield the best brake.

As for drum rarity, that is a different issue that motivates at cross purposes. Our goal is the have the best brake possible. The best brake possible will result from best practices. The 1-ton Power Wagon brake [same as M-series and WWII Dodge] is not the best brake in the first place. It needs all the help it can get. Excellent drums, proper adjustment, and proper bleeding.

Drum rarity is further complicated by idiot operators who have no idea how to be machinists, and how to be careful with your drums. Profit motivated trade practices historically had lathe operators making two cuts. A rough cut and a finish cut. The rough cut was enough to take out all the scoring. The finish cut established a surface finish. Hasty pursuit of these methods on the part of uncaring operators will destroy many drums. It is easy to turn the drum too big, at which point you can't use it.

In the past when I have turned these drums I took many, light cuts. Observe what is happening.

Is compromise of safety acceptable? I will never direct anyone to compromise safety. What have I done? I have turned drums and left a couple of yet visible scores. That has been my compromise.

I want to see someone reproduce these drums.

Regarding setup, the drum must be turned on its own, mated hub. Just as they came off your truck. If the operator says he can turn your drums using hubless drum adapters, leave immediately, because he is wrong. Those large races require very large adapters that many shops do not have.

Some of these old drums have so much runout that I have been unwilling to even make a first cut.

In summary; two issues here. Best practices and drum rarity.

Brake service integrity always dictates that drums be turned. Anything other than that is compromise.

What is your life worth, what is your passenger's life worth, and what is the value of that other person you might hit?

[Frank Irons]

It is hard to know where to separate turning these drums from turning drums in general.

Two issues here. Drum rarity and the goal of doing the best work possible. Best work translating into best brakes and best safety.

Let's for the moment ignore drum rarity. Let's just talk about drum brake service and best practices. Unless you have a low mileage set of shoes that are being replaced because of a lubricant or brake fluid leak, anytime a brake is serviced, after the typical service life, the drums should be turned.

Drums suffer a number of problems that are resolved by turning them on a brake lathe set up and operated by a qualified, skilled operator. Drum surface becomes impregnated with lining material, the drum surface becomes scored, and irregular wear patterns of a number of kinds can emerge. Drums can also get hard spots in the surface that resemble large mosquito bite looking welts.

Can you run an out of round drum, a drum with runout, a drum with scoring or irregular wear? Yes, you can. Regarding drum wear issues like scoring or other irregular profiles, after a time the shoes will wear fit to the drum. The brake is not good at the beginning due to reduced lining contact. Best practices do not include the assumption that such wear fitting is acceptable.

A drum with runout will never be right with respect to braking effect, and will also yield a pedal pulsation. Turning the drum will restore the surfaces, make the drum concentric and eliminate the lining impregnation. Best practices yield the best brake.

As for drum rarity, that is a different issue that motivates at cross purposes. Our goal is the have the best brake possible. The best brake possible will result from best practices. The 1-ton Power Wagon brake [same as M-series and WWII Dodge] is not the best brake in the first place. It needs all the help it can get. Excellent drums, proper adjustment, and proper bleeding.

Drum rarity is further complicated by idiot operators who have no idea how to be machinists, and how to be careful with your drums. Profit motivated trade practices historically had lathe operators making two cuts. A rough cut and a finish cut. The rough cut was enough to take out all the scoring. The finish cut established a surface finish. Hasty pursuit of these methods on the part of uncaring operators will destroy many drums. It is easy to turn the drum too big, at which point you can't use it.

In the past when I have turned these drums I took many, light cuts. Observe what is happening.

Is compromise of safety acceptable? I will never direct anyone to compromise safety. What have I done? I have turned drums and left a couple of yet visible scores. That has been my compromise.

I want to see someone reproduce these drums.

Regarding setup, the drum must be turned on its own, mated hub. Just as they came off your truck. If the operator says he can turn your drums using hubless drum adapters, leave immediately, because he is wrong. Those large races require very large adapters that many shops do not have.

Some of these old drums have so much runout that I have been unwilling to even make a first cut.

In summary; two issues here. Best practices and drum rarity.

Brake service integrity always dictates that drums be turned. Anything other than that is compromise.

What is your life worth, what is your passenger's life worth, and what is the value of that other person you might hit?

Amen Gordon! I personally drive these trucks as if they have no brakes. The brakes are adequate for the original purpose of the truck but in today's society they are not up to par. I leave a big margin between the vehicle in front of me in case I have to stop. Actually I worry more about going than stopping!

Frank

PS: I have 8 hubs and drums for sale