I have a 1956 Packard 400 (4,300lbs/4 wheel power drum brakes) that we did 4 wheel brakes, shoes, wheel cylinders, springs, master cylinder, hoses & upgraded the master/booster from the Treadlvac to a modern dual resovoir master & dual diaphram booster. The brakes work great for normal braking, can lock up all 4 on dry pavement, the customer lives down a long single lane gravel driveway with a wicked steep continuous grade for .6 mile at the end near his house, even at 10mph & low gear the brakes are gone by the bottom of the hill, nice high pedal but they are so hot they fade to 10% of what they are normal, both feet on the pedal full force & it still keeps rolling, get out & touch the drums through the wire wheels & it will burn your fingerprints off, after 1/2hr they are fine again. I pulled the drums off today, its been about 100 miles of driving since the brake job, figuring I would see very little contact patch between the shoe & drum, the shoes are making contact with at least 90% of the primary & secondary shoes to the drums on all 4 corners, the drums are 12" x 2 1/4" & on their first machining, well within spec. The owner was complaining the car did this before the brake job so its nothing new but not something I feel comfortable giving back to him, I truly feel the car was underbraked from the factory, what the heck can I do to help the fade problem without compromising the integrity of the drums, I would hate to put discs on a 50,000 mile origonal Packard but have not let that out of the equasion, thanks for any ideas you may have.
Four wheel drums and 2 tons of Detroit iron - what can you do? Going over half a mile of continuous braking is gonna take its toll. All I can think of is some kind of scoop system and vents to get more cool air to the shoes and get the heat out; even then I don't know if that'll help after such a long descent.
What shoes are you using? this may be an app for this.. http://www.porterfield-brakes.com/porterfieldckshoes.html They take your original shoes and re-line them with a modern high temp material. It might be a worth a try before s****ping the drums...
Maybe check out adapting aluminium Buick drums to the existing brakes ? Drilling the backing plates has got to help also. You could also check for a better brake shoe compound, semi-metallic or something like that.
I drilled about 100 holes in the backing plates this afternoon, not too exited about drilling the drums due to any liability issues (cracking due to stress risers)if the car was mine I would drill em but not on a customers car, people are too sue happy these days. The shoes are freshly relined with a semi metallic lining but going back for a relining again with some forklift lining, guess its supposed to be even harder than semi metallic. I am going to wrap the drums with a spring like the factory puts on some of them, thanks for the ideas. I am really amazed at the lack of brakes in this car when hot, I have had drum brake cars in the past fade away on me but that was usually slowing down from speeds around 100mph, never had one fade at 10mph.
If the fluid is not bubbled or even possibly boiling then it is the friction material itself. Way too long to go into here but will leave my if you want to talk through it tomorrow. Check your PM's
I'd be looking at the friction material. The "guts" have been removed from today's drum brake lining. The old "Velve-a-Touch" metallic shoes did an incredibly good job stopping drum brake equipped vehicles years ago. Used them on a '69 Ford F-100 trailer towing and on my '69 Road Runner. These shoes from Porterfield look the the new "Hot Set-Up". I talked to the "Brake Man" in CA a few years ago. On the edge of the friction material on drum brake shoes there is a code letter indicating the coefficient of friction. The deeper ya' go in the alphabet, the better the stopping power. I think an "F" or "G" gets into some good stuff. Today, you'll never get good friction material from normal over the counter brake shoes. If anyone out there knows where ya' can buy the old metallic shoes, please let me know.
We were always taught not to ride the (drum) brakes. They were all drum back then. Apply the brakes and then let up a few seconds to let them cool some. Reapply them etc. etc. You have to plan for a long grade. That's one of the reasons for the "long grade ahead" signs on the road. You can't drive drums brakes the same way we have become accustom to with modern discs. If everything is brand new, the shoes may not have fully seated yet and he is not getting 100% of the braking surface concentrating all the heat in a smaller area on the shoe. Brake fade on drum brakes is a natural phenomenon that has to be adjusted for by the driver.
I vote for changing the lining material. My dad had the brakes relined on a 58 Chev years ago with cut rate linings. After one fast stop they would fade. They never did that with the old linings before they were worn out. Also make sure the master cylinder rod has enough free play in it to fully release, so the fluid returns back into the master cylinder. Also check all the rubber hoses, they can collapse internally and not let the fluid return from the wheel cylinders. Brian
During this prolonged braking event, are you sure the booster is not loosing vacuum? Rather than heat buildup, maybe the brake line pressure is dropping over time....
have you thought of using low gear & pumping the breaks during the decent.some compression breaking may help. i've seen alot of insanely steep driveways on Orcas,more than once. BTW..thanks for takeing time for my phone call last weekend Jack.
I think you should tell him the car is junk, cut the quarters and tailights off, s**** the rest and send the quarters and tails to me Best of luck with the brakes.
Different Lining compounds are engineered for different operating temperatures. "stock" part sstore liningns are complete junk and will easily fade (friction coeff goes to 0) at high temperatures. Higher quality linings will continue to maintain friction to much higher temperatures. The porterfields recommened above are fantastic, I have them on all of my cars including my track driven camaro. The problem that you are having on this car is the exact same as a track car has after repetative braking into turns. You overheat the compound. So get higher temperature compound. In my opinion, Stock brake compounds are just scary. I bought a honda accord DD and I faded the brakes to the point of uselessness the first time I drove it on a back road. I immediately switched to Porterfields R4-S compound and now I can drive it like I stole it and it doesn't care.
I just got off the horn with em, and if you are interested in trying a set of the porterfields, PM me.
That's the reason Buick went to their aluminum drum in about '58: Heavy car + overworked brakes = fade. Since the Packard has 12" brakes, you could prabably install Buick drums quite easily.
I have a customer with the same problem. I am working up a bolt on disc brake setup for the front. Interested?
i have a 56 packard 400 and when i got it it was all original and running and i remember the brakes werent working that well in regular driving conditions the first thing i did was change everything i put a front clip and rear end and brake booster out of a monte carlo and a 350 and now it works perfect i have no problem with using it as my daily driver thats my solution hope it helps
That's it. They're getting hot, they are working. What's the idle speed on the motor when it's warmed up?
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