Re: 1951 CD - 9" drum brakes "grabbing"


Jim Liberty
 

I always turn the drums, and have the (Always) new linings radiused to the drums. That way you get full contact as soon as you stop the first time. You can do this yourself, but it's much better to have a brake shop do it.   ......Jim.

On Sat, Jul 3, 2021 at 2:37 PM Bob H. <bob@...> wrote:
I didn't do either of those things. I just replaced the cylinders, bled the lines, adjusted, reassembled.

After taking both sides back apart, I noticed that the linings on both sides were a little tacky to the touch. Maybe contamination from brake fluid? I got a little more aggressive with 220 sandpaper and removed the tacky surface from all four linings. Then, I went back through the adjustment procedure and took my time. The brakes are much improved! I suspect all of the lines need bleeding, which I'll do tonight, but the "grabbiness" is gone. I think you were right on the money about brake fluid in the linings. I'll plan to pick up a set at Wauseon but it stops well enough to get from the trailer to its spot!

Jim, thank you very much for your time today. It was most appreciated.

-Bob 

On Sat, Jul 3, 2021, 5:10 PM Jim Liberty <jimliberty356@...> wrote:
What you have done is right. A slight drag is OK too. Did you turn the drums, and have the shoes matched.   .....Jim.

On Sat, Jul 3, 2021 at 12:29 PM Bob H. <bob@...> wrote:
I think so but would welcome a second opinion. The linings are installed with the longer lining toward the front of the car. I have the passenger side apart again now so I've attached some photos. I also took photos of the lining surfaces in case it's obvious that they're contaminated. 

As for adjustment, I adjusted the top (eccentric pin) first by turning until the drum dragged and then backing off until the dragging stopped (which didn't take much). Then I did the same with the bottom (anchor points). I didn't use feeler gauges; maybe I need to? I have standard feeler gauges like for a valve adjustment but I'm not sure those are right for a curved brake drum surface? 

Thanks!

On Sat, Jul 3, 2021, 3:17 PM Jim Liberty <jimliberty356@...> wrote:
Are you sure the shoes are installed correctly? Sounds like you did the rest correctly. Is it possible the new cylinders are leaking again. It does happen even with new parts.   ...... Jim.

On Sat, Jul 3, 2021 at 12:08 PM Bob H. <bob@...> wrote:
I don't have much experience with drum brakes but the linings didn't look wet or discolored to me. Would it be obvious if they were damaged from fluid? I did very lightly clean them up with some medium sandpaper before reassembly just to remove any extra dust.

Thanks a lot for your help!

Bob

On Sat, Jul 3, 2021, 2:51 PM Jim Liberty <jimliberty356@...> wrote:
Did you check the linings for brake fluid. The leak may have contaminated them.    ......Jim.

On Sat, Jul 3, 2021 at 11:33 AM Bob H. <bob@...> wrote:

Hi all,

After sitting for a couple of years, I'm working on getting Dad's '51 wagon back on the road (and to Wauseon next week!).

Both of the front wheel cylinders were leaking and one was seized. So, I replaced them both and bled the system. Once done, I (think I) followed the service manual brake adjustment steps and took it down the road. It's immediately obvious that the car is pulling badly to the right and it takes very little pedal travel in order to engage a LOT of stopping power.

My son and I put it back up on jack stands and observe the following. While I'm spinning a front wheel forward, he very slowly/lightly applies brake pressure. Just a second or two after I start to feel the linings contact the drum, the wheel STOPS. I mean, it stops like it hit something. The front passenger side is worse than the front driver's side but both exhibit this behavior. When I spin either front wheel backwards, they slow and stop smoothly as they should. The rears, which I didn't touch, slow and stop smoothly as they should in both directions. My son noted that it took more pedal travel to engage the rears, but of course I don't know when the last time the rears were adjusted (and I'm not inclined to touch them at this point!).

I'm going to try adjusting the fronts again but is there a particular mistake during adjustment or procedure that can cause this? I suspect that maybe contact with the drum is causing one of the linings to "shift" in such a way that it is suddenly pushed against the drum with great force.

Thanks! I'm looking forward to my second real Crosley meet!

-Bob Hodgeman

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