View Full Version : Brakes: Yeeow, What caused this? Photos

07-17-2012, 09:51 AM
I have a 1957 Silver Hawk. Was originally a six cylinder, now has a 289 in it. I completely rebuilt the brakes. I replaced everything except the hubs and backing plates. That was about eighteen months ago. I have driven it about 2,000 miles. Everything works perfect no problems. I had between 5 and 6 inches of brake pedal.

The car always stopped fine. Sometimes I would even stop a lot faster than necessary just to see how the brakes were working. However, I never locked the wheels up. The other day I decided to see if I could lock the wheels in the event of an emergency.

This is what happened. I was moving about ten MPH in my long driveway. I hit the pedal hard. There was a loud CLANG from the front left wheel, the brake pedal went to within an inch of the floor and there was a grinding noise. It took the car about ten feet to stop.

I removed the front brake drum and lo and behold, I saw that the drum had split into two parts. In a way I was relieved because, not being a mechanic, I assumed it was something I had done wrong when I rebuilt the brakes.

What I hate the most is I paid a machine shop $70 to turn that drum and replace the stripped left hand bolts with new right hand bolts. I am not sure what to do now. If I buy another old brake drum, will this happen again? Will this happen to the right side next time? I don't know.

As you can see from the photos, it also ruined the brake shoes. Has anyone else had this happen?

I have read about Turner brakes. First, i am not sure if I have the expertise to install them and second, will they fit what was a 6 cylinder car?

Any input will be appreciated.

07-17-2012, 09:59 AM
If you have the drums truned when you did the brake job. They may have gotten the drums to thin.

07-17-2012, 10:18 AM
I have good drums, 10" right? PM me if interested or call me at 510-266-2522

07-17-2012, 10:18 AM
Chances are excellent the drum was turned too far.

Did you supply the shop with Studebaker specifications for maximum drum diameter? If they didn't have specs from you, they may not have had books old enough to look it up, and simply turned the drum until it looked good.

I say this because of the number of threads showing on your adjuster screw. Those were new shoes/linings; if it took that much star wheel adjustment to bring new shoes out far enough to get a good pedal, at least that drum had probably been turned too far. If you stay with drum brakes, be sure to have the other three drums checked for maximum diameter as well.

Turner Brake disc conversion will fit your car. It makes no difference if it is/was a V8 or Six originally. If you accomplished all that brake work yourself, you probably have the expertise, or could learn enough OTJ, to install the Turner Kit. BP

07-17-2012, 10:28 AM
The federal government has a standard for the maximum amount you can 'turn' (machine) the brake surface on a drum.
That is usually .060" more than the 'new' surface. (say 10" diameter new, the 10.060" max diameter)
If your drums have worn, due to normal surface wear, to (or past) the .060" max allowed, and the tech machined it more than that, then the drum gets so thin it could fracture.
Most shops measure first and give the customer a 'go-no go' as far as cutting the drum and staying within legal specs.
Problem is, if that were to happen and you were in a serious accident, the crash investigators will measure and then backtrack to see who did the work.
You could be exposing yourself to litigation by going past the legal amount allowed by law.

63 R2 Hawk
07-17-2012, 10:32 AM
The drum looks very thin in the photo, I would agree with others that they were turned too far. Most drums have the max diameter cast into them somewhere on the front outside edge of the drum, my 11" Hawk drums have it cast into them. I wouldn't have any qualms about getting another GOOD set of drums and replacing the ones you have. You would probably have to replace the shoes also, to match the radii of the newer drums.

07-17-2012, 10:48 AM
One additional point I would like to add to the comments of others. In your initial post, you said this...

"What I hate the most is I paid a machine shop $70 to turn that drum and replace the stripped left hand bolts with new right hand bolts."

In addition to turning the drum beyond its safe limit, no telling what stresses were applied to that drum and hub when removing and replacing the studs. Cast iron is rather brittle and I have cracked and broken my share of it.

The only other time I saw this was on a used jeep CJ5 I bought years ago. Someone had used it "four-wheeling" in a creek bed and it picked up an obviously hard pebble that cut the flat drum part free from the flange as if it had been done in a lathe.

You are extremely lucky to have discovered this problem in your driveway and not in a life endangering emergency situation!

07-17-2012, 10:59 AM
Step one: check all the other drums for cracks, and to see if they are cut oversize. This is a safety matter.

Step two: I don't know your relationship with the shop, but if that drum was cut way beyond its safe limit, I'd say you are in lawsuit territory. A prudent machinist would not cut over .060" unless he had a spec allowing it.

If the drum was bad enough to need to turned way beyond limits to clean it up, the shop should have refused to take your money.

Dick Steinkamp
07-17-2012, 03:10 PM
I had between 5 and 6 inches of brake pedal.

Not to your question, but if you had 5-6" of brake pedal TRAVEL, that is 4-5" too much. Something wrong there.

07-19-2012, 12:19 PM
Bob Palma - Good observation on the length of the adjuster screw. I noticed as I adjusted it from the backside through the little slot, that it took a lot of turns but I never looked inside at it. That should have warned me something was wrong.

Gordr- The machine shop that did the work is suppose to be a good one. I only took the drum in to have a Right hand bolt that someone had stuck in and tack welded it in place, removed and replaced with a new Left hand bolt swaged in place. He pointed out that a couple of other bolts had the threads buggered up pretty bad. He did not have a left hand bolt and suggested replacing all of them with Right hand thread bolts and I agreed to do so. When I picked it up, he said "Oh, by the way, I turned the drum for you. It is getting pretty thin but it will be OK." I had not asked him to turn it. I did not keep the receipt and it has been too long to bitch about it.

I went out and did a little measuring with a ruler. The drum is 10 3/16. Measuring the thickness of the material it is 1/8. My measurements may not be exact but I am sure they are close. As I said earlier, I am not a mechanic but I should have caught this. I guess I thought the machinist knew what was OK. Looking at it now, it was obviously unfit to use.

Dick Steinkamp- I only had about two or three inches of travel. I had five or six inches of firm brake pedal.

Thanks for all of the input. I now need to decide rather to spend $150 or so to buy used drums and have them shipped and buy new shoes or spring for the big bucks and get Turner disk brakes. A tough decision for me.

07-19-2012, 01:26 PM
3/16" is 180+ thousandths, so close to double the maximum allowable oversize. No wonder it failed.

07-19-2012, 05:53 PM
The 1956 shop manual says drums may be cut to max of 10.100 Also mention the use of shims if drums cut over .020