Brakes: GT front brake drum rubbing on backing plate

[subforry]

Hi,

I had replaced the left front brake drum as all was fine except for pulling to left. I was working on the brake adjustment to correct the pulling. But I also decided I should have gotten a pair of drums. So I ordered and installed a new drum on the right. It sounds like the wheel is going to fall off. I adjusted the bearings , not much change, inspected the drum and found the upper lip of backing plate is hitting the groove in the drum. Looking for a quick fix, I hit the backing plate with a hammer, seems to have made it worse. I plan to do a proper inspection with paint or chalk to see where the contact is. I wanted ask if anyone else has had this problem? Maybe the drum was not machined properly.

Thank.

[JoeHall]

Whatever you do do NOT hit the backing plate anymore, lest you screw up shoe alignment, then you might as well toss it. As for the drum, is it a repro? If so, that's your problem. No matter, if you can determine where it's rubbing, you can grind away that area of the backing plate. Alternately, you can take the drum to a machinist to remove metal from the area that's rubbing, but grinding the backing is easier, cheaper, and will solve the problem just as well. Did I mention not to hammer the backing plate again???

[JoeHall]

No need to remove the backing plate to grind it, just a careful, steady hand with a hand held grinder.

[fh4ever]

I had the same issue on a replacement drum for a Ford. I had to remove 1/8" from the edge of the drum. I guess since the drum is not made anymore, the supplier finds a later drum which is close enough in dimensions and sells it without ever checking the fit.

[Jeffry Cassel]

As above, but also consider bearings; are they correct? If the backing plate is bent at all, you will probably need to replace it. Is drum deformed? I would avoid hammers and grinders--find out why!

[JoeHall]

Re-reading the OP closely, you ordered a "new drum" for the right side, to match the new drum on the left side. So I am guessing both are now new repros? If it was not scraping before, but is now, that points to the new drum. As plentiful as good, used front drums are still, and for cheap, I'd never buy a repro. But to deal with what you now have, if it is scraping where you say it is, you can grind the backing plate as I said, but you still may have problems with the drum casting, or being off center, or positioned too deep. and there's several possible reasons. The simplest, easiest fix is what I suggested. Also, there's no mod to the new drum involved, so you may be able to return it if something else weird shows up, i.e. in handling or braking. Btw, I hope you also replaced both sides' rubber brake hoses, since they swell internally over the years, which causes fluid flow problems, which can cause pulling to one side, delayed braking, harder pedal etc..

Another potential problem is with the spindle; the outer bearing race surface, on the bottom, around 4 to 8 o'clock may be excessively worn. You can easily check that visually and by feel, and confirm with dial calipers, measuring at 6 & 12, and 3 & 9 o'clock. But again, if the problem only began when you installed the new drum, that pointe to the drum.

[subforry]

Yes, repro drums. It seems this has happened to others before. I though it might be the new bearings, but swapping back to the old ones didn't fix it.

Thanks for the tip on the spindle, I will check that. Most likely I will grind the backing plate (after some more investigation).

BTW, I would take a big hammer to do much to the backing plate. I think my small hammer just dinged up the surface.

Thanks all. I will report back once I have time to look into it more.

[Jeffry Cassel]

When is the last time you were happy with a repro part? They are expensive, they don't fit, and they either don't work well or don't work at all. I'd send 'em back and try to find used ones from a junk yard. Gotta still be a couple out there. My 58 packard pulled to the right; nearly drove me nuts. Finally replaced the drum and backing plate on the left (it would not stay adjusted. Problem fixed. I do not know why. (All the internals replaced twice before I did this) ???? A little warpage in either one is a bad thing and I would never bet on a repro drum being true.

[subforry]

The first one is fine, second one not good. I would hope more that 50% are good.

[Studebluecar]

Newbie question: How can I recognize an original from a repro drum. I've only ever seen the ones that I pulled off my 62 GT that I'm servicing now.
Thanks.

[Jeffry Cassel]

It looks like the repros are different than originals. Would a repro have "China" stamped on it somewhere? I've only ever replaced drums that have been turned beyond their limits or have been run for miles and miles with shoes worn down to the rivets. Don't think I've just worn out a brake drum.

[yeroldad]

DO NOT GRIND ON THE BACKING PLATE!! They are thin enough without grinding! If you already did grind on the backing plate, get another backing plate. If you are gonna grind, grind the drum! Personally, I would return the drum, or just throw it away. If it's crappy enough to scrape the backing plate, what else is wrong with it? Then when you grind on the drum, it's gonna be out of balance, if it was ever balanced to begin with. Get one that fits right and works right. This ain't rocket science!

[willys54]

Had the same problem.........Put both new drums on a brake lathe and removed .030 off the inner flange to provide proper clearance between drum & backing plate. Easy fix.

[swvalcon]

To bad your so far a way I have a complete set up off a 62 GT Hawk I don't think I will use. Why not just pull the whole brake setup off and go Turner disc brake set up.

[StudeRich]

Are those of you with expensive purchase suggestions or scrapping a New drum for Cole, forgetting that he has $500.00 Plus invested in this "repair" so far ?

I find it hard to not believe that this Drum is seriously out of round, if it hits in one place, unless the backing plate is bent.