Brakes: Looking for Ideas, adjusters out of range?

[karterfred88]

On my 63 Avanti, I've been trying to adjust the rear brakes with the eccentrics but can't seem to get them tight enough to get the right rear drum adjustment. The eccentric bolts are brand new from SI, linings brand new from another vendor, drums measure okay, new 3/4" correct wheel cylinders, nothing looks worn at the pivots. I can completely turn them without ever tightening them up enough in any position to get the rears to work right. Any tricks I could try? Most likely it's a combination of too thin new lining material and maxed out drum diameter, or is it possible the eccentrics don't have enough offset? I have to pass a braking test here in Delaware to get plates and right now it won't lock up the rears enough to show maximum braking effort on their test bench. the front disks are fine at 100% but the rears are at 50% and 70% meaning they aren't getting enough contact or pressure. The system is split with a 1 1/8" master matching the original design specs from Bendix. Never having been able to drive it till now, due to assorted mechanical issues, I don't have a reference as to how well it should stop. Although I had a 63 GT with disks in 1966 and drove my dad's Avanti back then, that was a long time ago, and of course I've been spoiled by todays brakes for many years. Other than adjusting the hand brake cables to take up some of the room--any ideas. I don't want to buy new drums and another set of linings as I eventually want to convert to rear disks, and I would be wasting $500.00 for a temp fix. Putting on the Turner kit on the rear only and leaving the fronts doesn't seem like a good idea either.

[64V-K7]

You WILL have to remove the drums to figure this one out, so take some pics... I just had a scenario exactly the opposite... too much lining and the wrong shoe core and I couldn't get the drums on at all.. Until...

I figured out the brakes (box) were labeled PAB53, but the steel shoe cores were stamped B173. This made the slot where the E-brake lever fits, too shallow and the shoe assembly couldn't collapse enough to get inside the drums .. but a little voodoo with a grinder and a file was invoked and all is well.The B53 and B173 shoes both fit the rear Disk brake cars, but this subtle difference drove me up a wall.

Can you effectively apply the handbrake on your car?

[karterfred88]

Can you effectively apply the handbrake on your car?

Yes, I can get the parking brake to engage well, that's why I'm thinking the linings or drums. The parking brake has a lot more travel than the wheel cylinders. I didn't check the stamping numbers on the linings, maybe the "ears" that enter the wheel cylinders are too short? Or maybe the slot for the upper link is too deep or the link itself is worn at the base of the slot? Still that wouldn't explain why the eccentric wouldn't push the shoes out far enough to eventually lock up the drum-or at least make it very hard to rotate the drum, only enough now to get a little bit of drag. on one shoe, but not on the other. The backing plate holes seem okay and not overly large, the eccentric fits decently-not too tight or too loose--so it does spin and moves the shoe outward at both--just not far enough to get the needed contact. Do you know what the proper thickness of the lining should be? I don't have a drum micrometer/gage to check actual inside diameter against the max specs. But even if they were .080 over there still should be enough adjustment, looking at the eccentric offset to get decent lining contact. Will pull the drum and check shoe stampings to start.

[gordr]

What about the fixed anchor at the bottom of the backing plate? Is it OK, and are the heels of the shoes that ride there OK? Will the rear brakes grab if you pump the pedal? If it was just a case of undersized shoes, pumping the brakes should make them apply, or, worst-case, pop the pistons out of the rear wheel cylinders, since there are no stops. I wonder if your rear brake lines need bleeding, still. Other than that, it sure sounds like your shoes are assembled on the wrong cores.

[karterfred88]

Well getting ready to "pop" the drums to see what it is I installed. Here's images of what came out 2 years ago. Note-one side was riveted linings one shoe less lining than the other, one side bonded, same length each shoe, both had 2 different shoes- looking at the area going into the wheel cylinder. One side a thin long nose, one a thick nose. The bonded set, on one shoe was the number 48154 on the riveted set one shoe labeled 313548. The bonded linings were much thicker on one shoe than the other and the thickness of both greater than the riveted ones. Any ideas which, if any was the correct shoe-shoes for my Avanti? A picture of a correct pair would help to compare to my installed ones to see what I need to do to fix it right. None of the areas marked in red are the same between the two and not even consistent on each set. The parts book shows different shoes for trailing and leading but no details showing what actual differences were. I suspect the lining coverage on the trailing and leading shoes were different coverage of the steel shoe, but were there other differences in the steel shoes themselves front and rear placement?
Footnote: They were all soaked in brake fluid from blown wheel cylinder, a lot cleaner looking now.

[57pack]

Don't know if this is your issue but, back in the day working on a brand x I found a very worn brake drum on one side with oversized brake shoes on that side.
No adjustment there either untill brake drum was replaced.

[karterfred88]

Don't know if this is your issue but, back in the day working on a brand x I found a very worn brake drum on one side with oversized brake shoes on that side.
No adjustment there either untill brake drum was replaced.

I suspect you may be right. Studying the old brake linings, it looks like there was a concerted effort to get the thickest possible linings (and possibly modifying similar shoes), then hand ground those with course sandpaper in the high spots. I was so concerned with the leaking cylinders and the rusty goo filling the gap between the shoes and the drums, that I cleaned up the drums with brake cleaner, looked good, put everything else in new from Stude vendors and bolted it back together, to attend to the next problem, and on and on. Now that I have come full circle, back to the first problem that kept me from trying to get the car registered, in Delaware, where brake performance is tested, not a visual inspection. I'm guessing the last state inspection from PA. was a visual one and they were fixed just enough to pass and could be driven sparingly that way. It appears that didn't work out so well, by the bent front bumper, bent brake pedal, bent and seized pivot pin in the booster bracket (that kept the master cylinder travel limited). I'm trying to avoid the inevitable purchase of $400.00 worth of drums, which will summarily be discarded with a rear axle swap soon after. Although I once read an older forum post that "there was nothing as expensive to repair than a cheap Avanti", this one was not that cheap, just filled with hidden problems from 50 years of butchery.

[StudeRich]

It IS your Car I understand, but here is a better option for you.
Do not get all wrapped up in the idea that all Cars NEED Rear Disc Brakes!

Absolutely NOT NECESSARY, what I would do is, rebuild the Rear Brakes with New 11 Inch Finned Drums NOW, and install the Turner Front Discs. when you can afford it, your Avanti will stop as fast as you will ever need. Using the stock rear setup does not require an equalizer valve, residual valves or anything to run the Turner Front Discs.

Once the brakes are locked, you are at the mercy of the Tires to stop you, and you can't stop any faster than they allow.

[karterfred88]

It IS your Car I understand, but here is a better option for you.
Do not get all wrapped up in the idea that all Cars NEED Rear Disc Brakes!

Absolutely NOT NECESSARY, what I would do is, rebuild the Rear Brakes with New 11 Inch Finned Drums NOW, and install the Turner Front Discs. when you can afford it, your Avanti will stop as fast as you will ever need. Using the stock rear setup does not require an equalizer valve, residual valves or anything to run the Turner Front Discs.

Once the brakes are locked, you are at the mercy of the Tires to stop you, and you can't stop any faster than they allow.

I know. But, driving this car with a 4.09 rear makes it worthless over 45 MPH. If I add the cost of brake drums, new differential carrier for
3.73 and down, new ring and pinion, bearings seals and substituting flanged for tapered axles, together I'm up over $1800.00 with labor (I'm not up to heavy duty rear end work and the tools needed) , then the prospect of paying another $400.00+ down the road if I need new drums again, it becomes a "no-brainer" to swap the rear end assembly, put in disks at the same time, and get replacement parts--like new rotors for under $50.00 each! I have no need for disk brakes on the rear really, but since I'm stuck right now at $400.00 plus shipping for something that only partially fixes my problem. Verses a used Ford 8.8 with disk brakes and internal drum style parking brakes, a usable rear ratio, with all new brake parts, cost of welding new spring perches and traction bar mounts for around $600.00 total it makes it hard to spend $400.00 now--. I'd be happy with putting on some slightly used drums if anyone near Delaware had some for sale--inexpensively--as a stop gap measure.

[sweetolbob]

I know. But, driving this car with a 4.09 rear makes it worthless over 45 MPH. If I add the cost of brake drums, new differential carrier for
3.73 and down, new ring and pinion, bearings seals and substituting flanged for tapered axles, together I'm up over $1800.00 with labor (I'm not up to heavy duty rear end work and the tools needed) , then the prospect of paying another $400.00+ down the road if I need new drums again, it becomes a "no-brainer" to swap the rear end assembly, put in disks at the same time, and get replacement parts--like new rotors for under $50.00 each! I have no need for disk brakes on the rear really, but since I'm stuck right now at $400.00 plus shipping for something that only partially fixes my problem. Verses a used Ford 8.8 with disk brakes and internal drum style parking brakes, a usable rear ratio, with all new brake parts, cost of welding new spring perches and traction bar mounts for around $600.00 total it makes it hard to spend $400.00 now--. I'd be happy with putting on some slightly used drums if anyone near Delaware had some for sale--inexpensively--as a stop gap measure.

Well said, couple that with a dual M/C and proportioning valve and you have a winner on your hands. Bob

[karterfred88]

Well said, couple that with a dual M/C and proportioning valve and you have a winner on your hands. Bob

Already did the dual master, and a new booster, just need the proportioning valve. Now if sbca96 can get his Mustang front brake adapters redone, I'll have the equivalent of new Mustang GT brakes, that I can afford to actually use up as needed.

[karterfred88]

Rather than start a new thread, first thanks to those that offered to help but weren't able to. I'm going a different direction by trying some non-Stude drums and adapting as necessary as I don't plan on keeping them on there anyway. As an aside, before putting things together, I noticed the linings, sold to me from a reputable vendor, were incorrectly relined (lining bonded to bottom 2/3 of shoe rather than top 2/3). Before shoving this thing out of the garage again, does anyone have a lead on a vendor selling them done correctly?

[StudeRich]

Some Shoes come with the short Shoe fully Lined, some short in the center, some at the bottom, some at the Top, no one has noticed any difference in braking. The Reliners of today do not know or care which is Engineering "Correct".

[karterfred88]

Some Shoes come with the short Shoe fully Lined, some short in the center, some at the bottom, some at the Top, no one has noticed any difference in braking. The Reliners of today do not know or care which is Engineering "Correct".

I know! But this way the first thing to touch your drum is the metal shoe, since it pivots on the bottom and outward at the top from the wheel cylinder, part of my minimal braking force problem. That spot just under the arrow actually touches as the lining begins to engage the drum.

[StudeRich]

Here is a Set you can buy if you think this is better, the Upper Shoe in the Picture is the Shorter Shoe that goes to the Rear, it's only a 7/8 Inch Shorter.