brake drum 1963

[Sander B.]

i have let my brake drums milled out a while ago

but they have milled the 1 front drum more out then the other front one
i suspect this will give problems and i will end up with a brake difference

any opinions ????

[Stuart F.]

Re: brake drum 1963

I have a 63 as well that had Metallic brakes which I needed to replace. The only material I could find (though I have learned there are others) was Matrix Ceramic. I was advised that my original drums would be scrap due to the metal brakes and over 40k miles. I bought new replacements before hand, but could never get them to work right (they are enough different). So, I had my old ones checked with a mic and learned they would all clean up w/i minimums allowed. I had them cut and they are now of all different sizes. The self adjustment mechanisms seems to take up the slack and, now that the new linings are run in, they work very well; no pulling or anything out of the ordinary for drum brakes. I used all new parts at each wheel, including new adjusting mechanisms.

[Duke W.]

Re: brake drum 1963

It's not clear to me what you are saying, but I expect you have had your drums "turned" to clean up the friction surface. The maximum allowable diameter is 11.090".

If the linings are "arced-in" to match the ID of each drum, a slight difference in drum diameter should have no ill effect.

Duke

[Sander B.]

Re: brake drum 1963

It's not clear to me what you are saying, but I expect you have had your drums "turned" to clean up the friction surface. The maximum allowable diameter is 11.090".

If the linings are "arced-in" to match the ID of each drum, a slight difference in drum diameter should have no ill effect.

Duke

yes Duke thats what ment

i will check them for this max diameter
but if the largest drum is within these specs , should'nt it be better
to get that same diameter for the other one ?

thanks
Sander,

[Duke W.]

Re: brake drum 1963

I don't think 10 or 20 thou is going to make any difference as long as the linings were arced in for each drum.

Post the measurements.

Duke

[Stuart F.]

Re: brake drum 1963

Duke;

I know what you are saying, and I thought too that the linings had to be "fit" to the drums (or as you say "arched"). But the mfg told me NO, they don't need to do that any more with these linings. I don't know if he meant just these linings (matrix ceramic) or the process in general. My drums all cleaned up (turned) between .020" and .032" (11.020" to 11.032") so it's not as if they were that far out. At any rate, they work to or above my expectations. I'm very pleased with them and would recommend them to anyone.

Incidently, the last time I pulled them down for inspection, the linings looked fairly well scuffed in; i.e. no major high spots or low spots. And the drums looked good as well.

Perhaps this Gentleman has a much more extreme case and/or is using standard linings.

Stu

[Duke W.]

Re: brake drum 1963

If all four drums need to be turned, it is best to turn them to the same oversized diameter. Arching in linings generally shortens the break-in period, and most shops do it because the average driver will rarely follow any kind of break-in procedure that is different from their usual driving habits.

If the lining manufacturer says to not arch them in to the finished drum diameter, then I would follow their recommendation, but do my usual break-in.

Whenever I change pads/rotors I always do a fairly easy break-in - early light braking as much as possible for the first 200-300 miles, which is a very different technique than my usual late moderate to heavy braking.

The reason why most shops want to turn drums and rotors with every pad/lining change is that they will break-in almost immediately, but turning rotors/drums removes a lot of useable material that shortens their useable life.

The drums and rotors on my cars are all severely scored with short radial cracks on the rotors due to running them on race tracks, but they are all true. Installing new pads requires a thoughtful break-in to get the new pads/linings to mate with the scored surfaces to achieve maximum brake effectiveness, but as long as I follow my break-in procedure, the friction material seats and has long life.

I rather dislike the way I have to drive to get the new pads/rotors broken in, but it's a cheap price to pay when you never have to replace rotors or drums.

Duke

[Stuart F.]

Re: brake drum 1963

I agree completely with what you say. I would have preferred all my old drums be sized the same too, but I lost control of the project at our local "Just Brakes". As one guy was doing the cutting, another was doing a power bleed for me (when I was still trying to use the new replacement drums). I was having the old drums cut as a back up because the new ones were not working well and I thought it was an "air in the lines" problem. The jerk doing the bleed had a back splash that got some spots on my LF fender and cowl (I know, if you're going to do something right,---). Need less to say, I was not happy and tried to clean it off before it was too late (it was).

I tried to follow the breakin process as well as I could, but when you live in a busy city there is always some jerk that will pull out in front of you and force you to brake harder than you want to. So far I havn't hit anyone, unless you count the deer I got in 1992 (215 lb Buck). I was only going 35 mph and I braked hard so he just sort of rolled over my hood after taking out my LF headlight bucket. Cops had to finish him with a slug, and I feel bad about it to this day - for him and my car.

[Sander B.]

Re: brake drum 1963

I don't think 10 or 20 thou is going to make any difference as long as the linings were arced in for each drum.

Post the measurements.

Duke

Duke just measured the (to much oversized) drums
they screwed them up
1 has the size of 11,220
the other 11,100

i see some vendors sell repro's with the spring groove in them
are they close to the originals ?

thanks Sander

[Duke W.]

Re: brake drum 1963

Yes, those should be replaced. You should also measure the other two. I'm not familiar with the details of OE replacement or "reproduction" drums.

The last drums I bought were J-65 replacements from Chrevrolet in the seventies.

Duke