| Hi , the following may be way more than it merits on this ,or than you want to know ,for which I apologize but it is sharing a long journey . i have done that too , the smaller AAJ disc that fits in 14” wheels is good, but theoretically and practically about the same or even less brake stop torque = even less whoa power , — to me anyway — than stock (?stock working right) due to small active diameter or moment arm of the clamp force compared to a 12” drum . Physics , — unless way high psi boost . Which then locks rear . And for us , there is a lack of psi in 1960 , not needed . compared to a GM disc car . Let’s call it 67 dart level disc brakes on a much larger car . But yes idiot proof to get to work right .
-- The real Problems with brake fade with our drums has to be purposely induced — by 2-3 stops from 100 mph , or mountain driving — that issue is true — and is due to the energy you have to dissipate when stopping a heavy car. the same total heat goes into a disc or drum , the ability to soak that up depends only on the weight or mass of rotating part but a disc cools way faster . Can do it again sooner . Does it really matter in a 300 ? Maybe in mountains .. Huge 60 Buick aluminum over steel 3x 12” drums with aluminum fins are the best answer , as that race 300 B ( or a stock 60 Buick) shows . . Hot rod guys used those 30 years ago still do Look way cool too . Note that cooling has nothing to do with initial stopping fast , the first few times , - with systems cold . Only shoe area and diameter . gotta love the 3” wide . ours are 2.5 I also like the feel of total contact drum progressive action , discs are totally different , you really have to stomp very hard to get a lot of whoa on conversions . Disc power systems usually have higher boost pressures by design, will cover that issue up in stock use . And that brings on the front / rear balance issue , cannot balance the over all pressures on a mixed system vs whoa. Inherently different due to drum self energizing I got into “ proportional valves “ over that , as from an engineering perspective you cannot reduce pressure “proportionally “ without say stepped hydraulic cylinders etc . The little valve is too small and cheap a thing to have that . real race cars have two masters and a balancing beam between them to adjust or accomplish that , Yes to that, and someone once made a stepped bore master … So what is in proportioning valve ? Questions to guys selling them show completely zero understanding , beyond “ you need it, and ours has a chrome knob” and “famous brand in brakes “ ( but their famous fixed calipers suffer from knock back of pucks in corners , you may crash , pedal travel changes erratically due to puck knock back between uses = wrong design , ( Can’t say that to the experts though ) GM caliper is correct , centers itself So I took a proportional valve apart . What was in it was a needle valve . Now , that slows flow , but end point pressure, and so stop power after a ? short delay has to be identical . So what it is doing is ? delaying back brakes , so fronts do a lot more work — for ? fractional seconds? this is BS to me . And more applicable to front disc rear drum to stop a rear drum self energizing quickly lock up on a sudden hard stop . Nothing “proportional“ about that . If it said “ brake delay valve” might sell a few less .. laugh . But for average driver it is functional , sort of . The last F I did i put the AAJ large disc , to try to improve on all this on a manual master , needs 15” wheels , I used 17 to get good Michelin tires . There are no really good 14” tires , — way more limiting thing than the brakes too And , my dad had a 60 dodge V8 brand new , no power brakes , — but had our same total contact leading shoe setup . Fantastic brake feel , without power —- and the two leading shoes you could readily lock brakes , no power —- but well before that , a beautiful controllable feel .I want that again Perfect front / back balance too , no vacuum bs either . Mopar always changed the pedal ratio and master bore on manual . They knew their brake stuff cold, it was designed as a system by smart guys . Conceptually two leading shoes is the very best , but tricky to work on. Like a hemi .. or dual points .. Except for all the machining to do it , and 5” bolt pattern , Buick drums on mopar 12” total contact backing plates , no boost should be , probably are, the best brakes you could do on a road car , like that current road race B has — and probably all the B nascar winners were manual , ? big imperial drums ( were they power brakes? I bet not ) . Buick did not have two leading shoes, I dont think any GM or Ford ever did. Even mopar gave up in 63 , — only due to service difficulties . A runner up to Buick on our cars is a disc , with rear discs to avoid balance issue. I did that too on an F , custom made Cad rear discs to get good disc e brakes onto a dana 60 , but still the AAJ small fronts . Imperial had that on 60 in 74 era , but an unreliable design of small drum brake inside disc , You really need a power booster on “all discs“ , especially small discs to get enough stop , found that out the hard way So the evolution , = now the big AAJ disc front brakes , a Dana with 12” Ford drums ,( to get a reasonable E brake setup ) “proportioning “ to rear ( can just leave it open, TBD) manual Corvette master( many bore sizes available ) large reservoirs ( discs take more CC to move it)! - our stock pedals thus move down too much-with didc conversion / especially small bore / or no boost —or stock drum boosted master — all subjectively ) The hood is increased whoa of big discs with small bore big reservoir master removes need for boost . tbd Corvette needs are like mine ! It works there , although corvette disc calipers are a horror show . Maybe one day do the Buick thing , no boost, just like a stock F has but no boost , better drums in front .( called going full circle?) runner up is 100 % stock F with manual pedal parts like Dodge . I think the “Big Red 62 “ competition car we saw in Pa . was like that We know Buick swap works, that big heavy race B is right there on road races with all the Euro hot shot 4wd discs , and is driven today ,Great “you tube “ of that car somewhere , gets into brakes Of course today’s huge discs and computer controls , elaborate boost , traction control set up , fix all that . I don’t want that stuff . To get that all you need is a down payment , can even buy a nice leather bra for the front , and service contract for 3500 . Or get a silver camry . laugh jkg Sent from my iPhone On Aug 24, 2023, at 9:24 AM, John Nowosacki <jsnowosacki@xxxxxxxxx> wrote:
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