Rollers not rolling

pooch

pooch

Well-known member
Moved question from end of another thread on grinding tracks , that got no response as it might be buried ......


In a perfect world, with new shoes, new rollers and new pins, how much clearance should there be between roller and shoe.

I think mine must have some play and rollers maybe jamming on shoe.

I have just rear left backing plate/shoes on and only one inside lower roller turning.

Is the head of the pin supposed to turn as well to roll across track or does it skid?

I see on this left rear, the lower rollers/pin is being pushed clockwise which is correct direction if it all turns together, but......

The upper rollers are being pushed clockwise too, and the pin on track should move anti clockwise if it was to roll on track.


So, should I see the top rollers move clockwise and the pin move anti clockwise, or is this asking too much of the design?
 
Pooch, often times I am finding the holes in the shoes excessively worn where they need to be welded up and redrilled. Could this be the issue with your shoes? <jeesh, no wonder it takes so long to "restore" everything!! :D >

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If the pins rolled, would we all have brake-tracks with a dip worn in the center ?

Not sure whether they were supposed to roll or not, but given the history of worn brake tracks, I would bet they didn't for very long...

I think the diameter of the pin where it contacts the track is too small, and there's too much friction where it goes through the rollers and shoe web to make the pin roll; instead, it just slides back and forth on the track, eventually wearing the dip into the track.

Pooch, I think your theory is correct, given the direction of movement of the various parts, but I think friction prevents the pin from rotating.
 
OK, you are probably correct, the friction in the shoe hole would be greater than the actual pin head on track.

And the top rollers would have friction in there holes too, as the pin , if it were to roll would have to go backwards.

I was thinking about grinding a small roller relief dip in back of shoe, to allow for any small wear.

Does anyone make a modified double ended cam, with a slight less ramp profile . for more purchase on rollers given the same pedal pressure?
 
Pooch, the pins should be snug in the brake shoe hole, but they need to turn, otherwise you will get flat spots on your rollers. The pins should have a square shoulder to go on the track. (not the rounded ones that some venders sell, or they will try to slip off the track) The rollers need to be snug on the pins, but they need to turn as well. Sometimes when the roller is right up against the head of the pin they lock up. (The rollers are not chamfered properly or the plating on them is junk) Check to make sure that the rivets in the brake shoe holding on the lining is not binding on the roller. I usually glue the ends of the lining and then countersink the rivets flush. There is a special lubricant you can get for brake parts like rollers.

Everything should roll and turn, sorry, your clockwise and anti-clockwise stuff is hurting my head.
 
Jim Parker Toronto said:
Pooch, the pins should be snug in the brake shoe hole, but they need to turn, otherwise you will get flat spots on your rollers. The pins should have a square shoulder to go on the track. (not the rounded ones that some venders sell, or they will try to slip off the track) The rollers need to be snug on the pins, but they need to turn as well. Sometimes when the roller is right up against the head of the pin they lock up. (The rollers are not chamfered properly or the plating on them is junk) Check to make sure that the rivets in the brake shoe holding on the lining is not binding on the roller. I usually glue the ends of the lining and then countersink the rivets flush. There is a special lubricant you can get for brake parts like rollers.

Everything should roll and turn, sorry, your clockwise and anti-clockwise stuff is hurting my head.
Click to expand...


LOL.gif
 
Jim, I am new to model A/s and this is my first foray into the brake workings.

But I see (on the rear left), both rollers, are pushed clockwise.

The pins must go in opposite directions to roll.

Sorry about your head.
 
Pooch, welcome to the frustrating world of mechanical brakes! It sounds to me that one of your pins or rollers is too tight and preventing it from operating properly. I know you don't want to do this but, take it apart again and make sure all the parts, rollers, pins and shoes, turn without too much resistance. Check the roller when it is tight up against the pin. The cheaper ones will lock up. Are you using new springs or old ones? Some of the new ones have too much tension and don't operate properly.The long spring will overpower the two smaller ones.... Are you using all new parts, or did you manage to save some of the good original ones?
 
All original parts still.

The speedo says 30 K miles.

With the mechanical condition of everything, I am thinking this is all it has done.

Except for the brake drums being so thin.

I saw today, that they are not worn down, they have been machined , or else there would be a huge step where the linings run, but it is the same diameter right to inside flange.

Just thinking out loud, what if I was to make an INTERNAL band of 1/8th steel and make it a perfect press fit and fully MiG weld in to outer and inner?

It would have better heat transfer than an outside press on only band, and I could turn it to factory tolerance for new woven linings.

I will have to see my brake machinist and make sure he can turn steel .

(I am presuming the original AR drums ARE steel?)
 
Pooch, very creative thinking, but...... The original ID is 11.000" +/-.005". I thought someone on the other post said he had some and you could have them if you came and got them? Is it too far? Don't forget, if you are using AR drums, you must use AR wheels. You cannot mix them!
 
Yep, a member from NZ is looking for me, but has only found 2 used ones .

He is across the pond from me, and shipping may be prohibitive.

I am touring USA in feb/march. and might have a prepaid airfare that is now not going, so will have an extra 23KG baggage allowance to return.

Guess what will go on that weight?

Model A parts of course.
 
Jim Parker Toronto said:
Check to make sure that the rivets in the brake shoe holding on the lining is not binding on the roller. I usually glue the ends of the lining and then countersink the rivets flush. There is a special lubricant you can get for brake parts like rollers.

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Click to expand...

Jim, yeh I do think the last set of rivets interferes with roller.

I mashed the last 2 down a lot more and now roller is clearing and turning.

Pin still isn't, but I doubt it ever will.

When I fit new linings, I will countersink shoe on the last 2 rivet holes, so they mash in level with shoe.
 
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