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Proportioning Valve Placement |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19679 |
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But he is correct to a degree, and not only that, when you "called him out" he POLITELY noted that he had not worded his response well, and that he realized he may be sounding like a know-it-all. Smart-*** replies don't do anything but degrade the entire list. If someone is wrong (especially if it's me!) please point it out and explain why you think they are wrong, as that helps everyone. Could end up just being a difference of opinion, but that's ok, at least those reading will know.
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Frank Swygert
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19679 |
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I wrote an extensive article on AMC disc brake balancing systems in AMC Magazine, Issue #19, Summer 2011. Here is a summary of what AMC used for balancing and when: YEAR(S) SERIES DISC BRAKE BALANCING DEVICE 1965-67 10, 80 Non-servo rear brakes 1967 01 Non-servo rear brakes 1968 10, 80 Non-servo rear brakes 1968-70 ALL Proportioning valve only 1971-74 ALL Three-way combination valve (pressure/metering/proportioning) 1975-76 ALL Two-way combination valve (pressure/metering) Early 77 10 Two-way combination valve (pressure/metering) 1977-78 ALL NONE - Pressure differential only 1978 40 (4 cyl) Two-way combination valve (pressure/proportioning) 1979 01, 60 NONE - Pressure differential only 1979 40 (6 cyl) NONE - Pressure differential only 1979 40 (4&8 cyl) Two-way combination valve (pressure/proportioning) 1979 AMX (6&8 cyl) Two-way combination valve (pressure/proportioning) 1980 60 NONE - Pressure differential only 1980-87 ALL Two-way combination valve (pressure/proportioning) Want more information on brake balancing theory? Note that "pressure/..." actually means "pressure differential/...". Not enough room in the original chart to put it all in. If you'd like to see the entire article send me a PM with your e-mail address and I'll send it. It's three pages of text and one of illustrations, a bit much to post here!
Edited by farna - Nov/29/2018 at 7:24am |
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Frank Swygert
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FSJunkie
AMC Addicted Joined: Jan/09/2011 Location: Flagstaff, AZ Status: Offline Points: 4742 |
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Very good, Frank. That makes it easy to keep track of the year to year changes.
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1955 Packard
1966 Marlin 1972 Wagoneer 1973 Ambassador 1977 Hornet 1982 Concord D/L 1984 Eagle Limited |
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RTTComanche17
AMC Apprentice Joined: Apr/19/2009 Location: California Status: Offline Points: 73 |
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Great point! But, don't forget to add that *generally* a larger wheel also increases the rotational inertia and CG height as well. Brakes stop the mass of the car and the rotational inertia of all connected rotating components. Greater wheel inertia puts even more load on the braking system. CG height impacts front/rear weight distribution under braking/acceleration. Too much change (under braking) and you may be able to lock the rear tires when before you could not due to a lighter rear end under hard braking. (ie. proportioning valve is no longer valved correctly for the system) Just some more interesting thoughts! ...or down the rabbit hole we go?... |
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1967 Rambler American #1 - junkyard rescue parts car
1967 Rambler American #2 - project car, but it runs!...for now... |
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Yep... I added some info earlier tovmy brake upgrade about how much bigger wheels and tires and bigger brakes can be negative on weight and off the line performance. The max size on disc is 13" using OEM specs, once you get into 14" and larger... The weight goes up a lot, especially on rotational mass. Though my 18" rims weigh 2 lbs more than the 17" rims I had. The big difference is tire. Though, the tread diameter is the same as stock. What makes it really noticeable is getting up into the 19" and 20" rims with 15" and 16" discs. Thats if you can fit them proeprly in the arch or suspsension. Modernising does not mean better, just looks cooler. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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lol. he might be a good administrator. he's good at cars too. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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tomj
AMC Addicted Joined: Jan/27/2010 Location: earth Status: Offline Points: 7544 |
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INDEED, down we go! lol. it's a *system*, everything interacts! makes one appreciate the solidly decent job AMC (and OEMs in general) did with this stuff. |
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1960 Rambler Super two-door wagon, OHV auto
1961 Roadster American, 195.6 OHV, T5 http://www.ramblerLore.com |
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farna
Supporter of TheAMCForum Moderator Lost Dealership Project Joined: Jul/08/2007 Location: South Carolina Status: Offline Points: 19679 |
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"Though my 18" rims weigh 2 lbs more than the 17" rims I had. The big
difference is tire. Though, the tread diameter is the same as stock.
What makes it really noticeable is getting up into the 19" and 20" rims
with 15" and 16" discs. Thats if you can fit them proeprly in the arch
or suspsension. Modernising does not mean better, just looks cooler." I'm a bit surprised the larger wheels weigh more, but depends on what they are made of and the style. More goes into looks rather than weight savings. The original purpose for "mag" wheels was to save weight, but those originals were made of magnesium (hence "mag" wheels) at first and expensive, now they are all aluminum and usually weigh as much or more than steel wheels. The reason I'm surprised your bigger wheels weigh more is that hte rubber diameter is the same -- more wheel, less tire sidewall height. The rubber tire is usually a bigger weight contributor than the wheel. "Looks cooler" is subjective! I don't mind the 16" wheels at all, 17 & 18 are getting a bit big on the old cars to me, anything over 18" just doesn't look right at all. You're showing your age in saying the big ones look cooler... but then maybe I'm showing mine saying they don't!!
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Frank Swygert
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304-dude
AMC Addicted Joined: Sep/29/2008 Location: Central Illinoi Status: Offline Points: 9082 |
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Main reason my 18" wheels are a wee heavier is that they are wider and taller, with a wee more material in the spokes. From 27 lbs to 29 lbs is not that critical to me, it's when you put the added weight of the wider steel belted tire and big heavy brakes, its a bit of a juggle on balancing performance across the board. I dropped the idea of using big truck axles for my 9" Ford rear, once I found Explorer 4x4 8.8 rear axles were so much lighter. I think they are just as light as a set of AMC axles and hubs, if not lighter. Though the 14" rotors are very heavy compared to 13" and are a wee thicker but not much. I almost want to keep the 13" rotors just because. I too don't like 18" and larger wheels on older cars... and it was a bit of tooth pulling to get myself into giving up my 17" rims for the change to 18". Once I start on body rework for the wheel openings, I hope to make the wheel and tire combo look more reasonable. Mostly my larger wheel / brake change up is for the performance gains with wide sticky tires, and to push the boundary of making my car almost as modern as current Mustangs and Camaros, outside of electronics to control things, like EFI and stability control. I hit my limit as for any other changes, not for the fact of being able to fit, more or less, because i dont see any benifit in going bigger. Once you see the steep curve with larger wheels and brakes start to flaten, then the money is about showing off or making ever so smaller gains. With all the changes to wheels and brakes being out on my own one of a kind, there will be a lot of brake balancing tests for proper function. I learned that long ago with adding bigger drum brakes when I swapped my rear from a Coronet. The extra drum shoe size made the rear a bit touchy compared to stock. Not a great issue, until you got into a panic stop. My trick in fixing was to use the best pads up front and cheapy segmented and riveted shoes in the rear. Simple enough for my driving at the time. |
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71 Javelin SST body
390 69 crank, 70 block & heads NASCAR SB2 rods & pistons 78 Jeep TH400 w/ 2.76 Low 50/50 Ford-AMC Suspension 79 F150 rear & 8.8 axles Ford Racing 3.25 gears & 9" /w Detroit locker |
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