New Cast Iron Drums Problems

TinCup

TinCup

Well-known member
I have been helping install new cast iron drums from Snyders. This work is being done on an absolutely fabulous 1931 Slant Window Sedan. We are having issues with the front drums.

First thing I did was to back the brakes off completely and disconnect the front brake rods. Now when I install the drum and tighten the nut the wheel locks up as if the brakes are too tight. I first thought that the drum was going to far up the spindle and was rubbing against the backing plate but there is plenty of clearance. I completely removed the shoes and the hub spins perfectly on the spindle. Put the shoes back on and it locks up.

Where the shoes ride in the drum could it not be deep enough? Or could if be that the shoes which were arced to the old steel drums too tight?

Toss this dog a bone if you have an idea!
 
I would mark the brake shoes with a dye or something that would transpose where they are rubbing.
Chances are the drum isn't machined deep enough on the inner edge and the outer portion edge of brake shoe is rubbing on the inner corner of the drum.
Since you said that you tighten it up and the wheel stops.
 
Both sides are doing the same thing. One of our local club members has a 20 ton press and does all the hubs for us. Our plan for tomorrow is to coat the shoes with chalk and see where they are contacting the drum.
 
You did not say if the drums were cut on a brake lathe. This should have been done after the install to the hubs. Some of these drums come smaller on the inside than what they are suppose to be. They should be mic'ed for size. If they were turned on the lathe, were they cut deep enough on the inside, next to the studs?
 
No they were not. Another club member has cast drums and he is going to measure his from the outside edge in to give us a comparison.

fordfixer said:
You did not say if the drums were cut on a brake lathe. This should have been done after the install to the hubs. Some of these drums come smaller on the inside than what they are suppose to be. They should be mic'ed for size. If they were turned on the lathe, were they cut deep enough on the inside, next to the studs?
Click to expand...
 
How does the drum fit over the shoes ?? In other words, does the drum slide over and turn easily until you snug the spindle nut ?? If so, then J &M is on the right track.. If the drum is hard to slide over the shoes then tightening the nut could be aggravating that problem and the shoes are not retracting as they should or they could be just too 'fat' for the drum diameter.. Did you put sand paper inside the drum and sand the shoes to fit and then adjusted to center them ??
 
Aah, I was typing during the other posts.. I tend to believe that drums should be cut and trued-up[ which I kinda assumed you did] which adds a little to the drum diameter which could certainly help with your problem..
 
The drum slides easily over the shoes and does snug up until I tighten the spindle nut.

Patrick L. said:
How does the drum fit over the shoes ?? In other words, does the drum slide over and turn easily until you snug the spindle nut ?? If so, then J &M is on the right track.. If the drum is hard to slide over the shoes then tightening the nut could be aggravating that problem and the shoes are not retracting as they should or they could be just too 'fat' for the drum diameter.. Did you put sand paper inside the drum and sand the shoes to fit and then adjusted to center them ??
Click to expand...
 
A black sharpie pen marked on the drum can be used to show the contact marks also. Was that hub the same hub off that spindle? Could there be a difference in the bearing race or its set point to cause the drum to install further. If the drum diameter checks out, I would look at that next.
 
Bet the drums are too small. They are made a little small because they NEED to be cut true after install. Cut them to 11" and they will work. Also, if you didn't true up the hubs, that might have an effect on the drum fit.
 
My plan is to install some brake shoes without linings that I have. I will also measure them and see what I get. Thanks for the reply.

James Rogers said:
Bet the drums are too small. They are made a little small because they NEED to be cut true after install. Cut them to 11" and they will work. Also, if you didn't true up the hubs, that might have an effect on the drum fit.
Click to expand...
 
When we pulled the old hubs and drums we used a paint stick to mark each hub.
ctlikon0712 said:
A black sharpie pen marked on the drum can be used to show the contact marks also. Was that hub the same hub off that spindle? Could there be a difference in the bearing race or its set point to cause the drum to install further. If the drum diameter checks out, I would look at that next.
Click to expand...
 
I was understanding after drums are installed to hubs they were to be turned true and to 11" if that was not done you are creating yourself problems.
 
Hi,

Humble opinion:

1. First, every time new cast iron drums are installed on used, 80 year old hubs, (which may have been beat up & re-drummed several times), to avoid being installed & pressed in slightly off center, the inside diameters of the new cast iron drums have to be trued up & cut to insure that they are concentric, i.e., centered with the tapered holes inside the used hubs. Sometimes the meeting faces of the used hubs have to be trued.

2. Second, because your shoes are centered on the axles, & because the shoes more or less fit inside the new cast iron drums prior to tightening the hub on the axle, it appears that the outside diameters of the shoes can be adjusted to fit within the new drums.


3. Third, when the used hubs are tightened on the axles, the centers of the used hubs are now "forced" to coincide with the center of the axles, i.e., axles & hubs are now concentric; however, the problem appears to be that centers of the used hubs are not the centers of the new drums.

4. Fourth, this brings one back to the requirements in paragraph 1, above.

5. Fifth, even after the drums are trued & cut, & the brake bands are mounted on the brake shoes & shoes are ground down to fit the inside diameters of the new drums, a bit of final fitting may still be necessary for an almost perfect fit. Quite a few articles on forums on how to accomplish same with vendors tools, or marking with chalk, etc. Usually both ends of shoes require a little sanding.

Hope this helps.
 
The hubs are only 5 years old but your logic is sound.

QUOTE=H. L. Chauvin;404905]Hi,

Humble opinion:

1. First, every time new cast iron drums are installed on used, 80 year old hubs, (which may have been beat up & re-drummed several times), to avoid being installed & pressed in slightly off center, the inside diameters of the new cast iron drums have to be trued up & cut to insure that they are concentric, i.e., centered with the tapered holes inside the used hubs. Sometimes the meeting faces of the used hubs have to be trued.

2. Second, because your shoes are centered on the axles, & because the shoes more or less fit inside the new cast iron drums prior to tightening the hub on the axle, it appears that the outside diameters of the shoes can be adjusted to fit within the new drums.


3. Third, when the used hubs are tightened on the axles, the centers of the used hubs are now "forced" to coincide with the center of the axles, i.e., axles & hubs are now concentric; however, the problem appears to be that centers of the used hubs are not the centers of the new drums.

4. Fourth, this brings one back to the requirements in paragraph 1, above.

5. Fifth, even after the drums are trued & cut, & the brake bands are mounted on the brake shoes & shoes are ground down to fit the inside diameters of the new drums, a bit of final fitting may still be necessary for an almost perfect fit. Quite a few articles on forums on how to accomplish same with vendors tools, or marking with chalk, etc. Usually both ends of shoes require a little sanding.

Hope this helps.[/QUOTE]
 
Tincup , Did you center the brake shoes by replacing or building up the roller track ? Another thing I have noticed is the holes for the roller pins in the shoes are sometimes wallered out oversize and if the shaft on the roller pins is undersize ( some are) it makes it harder to get shoes centered. Bubby Sharp in KY
 
TinCup said:
The hubs are only 5 years old but your logic is sound.
Click to expand...

Hmmm, ...care to elaborate on this?


The one thing that I guess I am confused is I thought the interference area was not on the machined portion of the drum where the shoes expand to, but the inner wall of the drum. Did I misunderstand??

Also, trueing up the hubs can have just as much of a negative impact too. The more of the mating surface that is faced off of the hub allows for the drum to ride closer to the brake housing (backing) plate. This affects the centerline of the shoes on where they contact the machines surface of the drum.
 
Wrapped up the rear wheels today. Only had to sand the leading edges of the shoes to get the new cast drums to fit. I had the owner take the front drums and make sure they were trued up. I believe the outside of the drum was fine but as the drum is tightened up is when it binds. We will get them back from the machine shop and we will know more. Thanks for all the great input.
 
You must log in or register to reply here.
Back
Top