[Dibbons]

I have a '65 Valiant Signet Convertible with a two-barrel 273 V-8. Currently, the front drums are 10" and the rear drums are 9". I see a previous owner swapped the original 7 1/4" rear end for a 1974 7 1/4' ring gear with 2.76 gears. I wonder if my vehicle's original 7 1/4" rear axle had 9 inch or 10 inch drums in the rear? What do you think/know? Thank you.

 

[ImperialCrown]

Usually the fronts are larger as the fronts do most of the stopping.
Frt/Rr brake imbalance or mismatch can lead to dangerous handling.

 

[DC-93]

I remember the diameter being the same, front to rear, but the widths are different with the front being wider.

Also, the brake cylinders are larger in diameter in the front than the rear.

 

[Dave Z]

Right/left is always the same, front/rear is usually different in olden times; now they often do something like same size front and rear, but higher performing brakes in front. The 1960s-70s were not great times for braking. There often was brake imbalance front/rear and it was not uncommon to have your rear wheels lock up, tossing your car around in a big circle. I suspect the poor brake balancing on RWD cars of that era vs the new FWD cars, which at least at Chrysler did have hydraulic brake force distribution (F/R, and on minivans, believe it or not, with a height adjustment - I'm probably using the wrong words, the correct ones are in the minivan book). Certainly the first car I had with high performing brakes was FWD... back then I didn't know about swapping wheel cylinders to compensate for lack of factory tuning. It is still a recommended process today - keep the existing brakes but change wheel cylinders so the correct brake force will be applied.

 

[ImperialCrown]

 

[DC-93]

I have a '65 Valiant Signet Convertible with a two-barrel 273 V-8. Currently, the front drums are 10" and the rear drums are 9". I see a previous owner swapped the original 7 1/4" rear end for a 1974 7 1/4' ring gear with 2.76 gears. I wonder if my vehicle's original 7 1/4" rear axle had 9 inch or 10 inch drums in the rear? What do you think/know? Thank you.

You would have had 10” in the rear.
The 9” in there now could be because the 1974 donor had front discs.
They had a few disc drum and drum drum packages in 74. You need to do some research or join “forabodiesonly.com”
Lotta smart A body guys on there.

 

[Dibbons]

Courtesy of For Abodies only: Drum Bulletin 1972

 

[AllanC]

. . . . The 1960s-70s were not great times for braking. There often was brake imbalance front/rear and it was not uncommon to have your rear wheels lock up, tossing your car around in a big circle. . . . .

Continuing performance upgrades in automobiles starting in the mid-1960s and into the 1970s era meant that vehicle performance was way ahead of braking ability. The 1965 Corvette was one of the first cars with 4 wheel disc brakes standard. The Mustang had front disc brakes as an option on V8 powered cars. The 1965 Ford Thunderbird adopted front power disc brakes. That was probably needed since the T-Bird was a heavy, personal luxury car and the T-Bird buyer would be more likely to absorb the cost of the better braking system. Cost was a factor that slowed adoption of front disc brakes early on. Manufacturers were sensitive to increasing the cost of vehicles for safety enhancements.

In 1973 Dodge Dart vehicles had manual disc brakes standard if equipped with V8 option. Dart vehicles with a standard slant six had manual drum brakes at all 4-wheel positions. Again the marketing decision was made that someone willing to spend money for an engine upgrade would be less likely to complain about the added braking cost.

Within a few years more and more vehicles even at the low-priced option end had front disc brakes as standard. Probably as more demand from manufacturers for front disc brake assemblies happened, brake suppliers could somewhat mitigate cost increases by economies of scale in production.

 

[Fast Eddie]

Continuing performance upgrades in automobiles starting in the mid-1960s and into the 1970s era meant that vehicle performance was way ahead of braking ability. The 1965 Corvette was one of the first cars with 4 wheel disc brakes standard. The Mustang had front disc brakes as an option on V8 powered cars. The 1965 Ford Thunderbird adopted front power disc brakes. That was probably needed since the T-Bird was a heavy, personal luxury car and the T-Bird buyer would be more likely to absorb the cost of the better braking system. Cost was a factor that slowed adoption of front disc brakes early on. Manufacturers were sensitive to increasing the cost of vehicles for safety enhancements.

In 1973 Dodge Dart vehicles had manual disc brakes standard if equipped with V8 option. Dart vehicles with a standard slant six had manual drum brakes at all 4-wheel positions. Again the marketing decision was made that someone willing to spend money for an engine upgrade would be less likely to complain about the added braking cost.

Within a few years more and more vehicles even at the low-priced option end had front disc brakes as standard. Probably as more demand from manufacturers for front disc brake assemblies happened, brake suppliers could somewhat mitigate cost increases by economies of scale in production.

My mother-in-law's 1976 Aspen had front wheel discs and so did my 1978 Volare Fun Runner with the Super Six.

 

[valiant67]

My mother-in-law's 1976 Aspen had front wheel discs and so did my 1978 Volare Fun Runner with the Super Six.

While Dart and Valiant kept drums up front until almost the end, Aspen and Volare always had front disc brakes.

 

[Dave Z]

I have the front manual disc option on my Valiant. Best brakes I ever had on an old car. However... they too are poorly balanced front/rear. The power front discs on my '76, with the tow/police/taxi package, would grab instantly and lock up. Rick Ehrenberg and Daniel Stern, if memory serves, agree on this - either install a balancer or replace the cylinders. Mopar had all the right cylinders but nobody seemed to be testing the cars to choose the right ones. Chrysler veterans, can you shed insight?

 

[68RT]

Continuing performance upgrades in automobiles starting in the mid-1960s and into the 1970s era meant that vehicle performance was way ahead of braking ability. The 1965 Corvette was one of the first cars with 4 wheel disc brakes standard. The Mustang had front disc brakes as an option on V8 powered cars. The 1965 Ford Thunderbird adopted front power disc brakes. That was probably needed since the T-Bird was a heavy, personal luxury car and the T-Bird buyer would be more likely to absorb the cost of the better braking system. Cost was a factor that slowed adoption of front disc brakes early on. Manufacturers were sensitive to increasing the cost of vehicles for safety enhancements.

In 1973 Dodge Dart vehicles had manual disc brakes standard if equipped with V8 option. Dart vehicles with a standard slant six had manual drum brakes at all 4-wheel positions. Again the marketing decision was made that someone willing to spend money for an engine upgrade would be less likely to complain about the added braking cost.

Within a few years more and more vehicles even at the low-priced option end had front disc brakes as standard. Probably as more demand from manufacturers for front disc brake assemblies happened, brake suppliers could somewhat mitigate cost increases by economies of scale in production.

Perhaps Corvette was first standard but Chrysler offered a much earlier (not so successful) version in the fifties.

1950 Chrysler Crown Imperial: Four Wheel Disc Brakes Standard – But Not Like Modern Discs

(first posted 7/26/2011) One of the more obscure footnotes in automotive history is Chrysler’s premature fling with disc brakes, as fitted standard to the 1950 through 1954 Crown Imperial […]

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